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  • 1.
    Abacar, Armando
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Optimization of Maputo Power Plant2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Electricidade de Moçambique, E.P. (EDM) is the power utility in Mozambique, responsible to generate, transport and distribute electricity all over the country. The company has three gas turbines installed at Maputo Power Plant. All units burn diesel oil and are used only for back up. Currently only the unit #2 is available for operation.

    The main constraint that EDM faces is the high operation costs due to diesel price. Hence the company is considering converting units #2 and #3 to burn natural gas, resource available locally. The country is currently exporting natural gas to the neighbouring Republic of South Africa.

    This MSc thesis project calculates the power output of all gas turbines when burning natural gas and optimizes the power plant capacity by proposing modifications of the current power turbine cycles to allow sustainable operation

    Download full text (pdf)
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  • 2. Abbas, Ghazanfar
    et al.
    Chaudhry, M. Ashraf
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Singh, Manish
    Liu, Qinghua
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Qin, Haiying
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Study of CuNiZnGdCe-Nanocomposite Anode for Low Temperature SOFC2012In: Nanoscience and Nanotechnology Letters, ISSN 1941-4900, Vol. 4, no 4, p. 389-393Article in journal (Refereed)
    Abstract [en]

    Composite electrodes of Cu0.16Ni0.27Zn0.37Ce0.16Gd0.04 (CNZGC) oxides have been successfully synthesized by solid state reaction method as anode material for low temperature solid oxide fuel cell (LTSOFC). These electrodes are characterized by XRD followed by sintering at various time periods and temperatures. Particle size of optimized composition was calculated 40-85 nm and sintered at 800 degrees C for 4 hours. Electrical conductivity of 4.14 S/cm was obtained at a temperature of 550 degrees C by the 4-prob DC method. The activation energy was calculated 4 x 10(-2) eV at 550 degrees C. Hydrogen was used as fuel and air as oxidant at anode and cathode sides respectively. I-V/I-P curves were obtained in the temperature range of 400-550 degrees C. The maximum power density was achieved for 570 mW/cm(2) at 550 degrees C.

  • 3. Abbas, Ghazanfar
    et al.
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. COMSATS Institute of Information Technology, Pakistan .
    Chaudhry, M. A.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Preparation and characterization of nanocomposite calcium doped ceria electrolyte with alkali carbonates (NK-CDC) for SOFC2010In: ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology, FUELCELL 2010, ASME Press, 2010, p. 427-432Conference paper (Refereed)
    Abstract [en]

    The entire world's challenge is to find out the renewable energy sources due to rapid depletion of fossil fuels because of their high consumption. Solid Oxide Fuel Cells (SOFCs) are believed to be the best alternative source which converts chemical energy into electricity without combustion. Nanostructured study is required to develop highly ionic conductive electrolyte for SOFCs. In this work, the calcium doped ceria (Ce0.8Ca0.2O 1.9) coated with 20% molar ratio of two alkali carbonates (CDC-M: MCO3, where M= Na and K) electrolyte was prepared by co-precipitation method in this study. Ni based electrode was used to fabricate the cell by dry pressing technique. The crystal structure and surface morphology was characterized by X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM) and High Resolution Transmission Electron Microscopy (HRTEM). The particle size was calculated in the range of 10-20nm by Scherrer's formula and compared with SEM and TEM results. The ionic conductivity was measured by using AC Electrochemical Impedance Spectroscopy (EIS) method. The activation energy was also evaluated. The performance of the cell was measured 0.567W/cm2 at temperature 550°C with hydrogen as a fuel.

  • 4.
    Abbas, Ghazanfar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Chaudhry, M. Ashraf
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Preparation and Characterization of Nanocomposite Calcium Doped Ceria Electrolyte With Alkali Carbonates (NK-CDC) for SOFC2011In: Journal of Fuel Cell Science and Technology, ISSN 1550-624X, Vol. 8, no 4, p. 041013-Article in journal (Refereed)
    Abstract [en]

    The entire world's challenge is to find out the renewable energy sources due to rapid depletion of fossil fuels because of their high consumption. Solid oxide fuel cells (SOFCs) are believed to be the best alternative source, which converts chemical energy into electricity without combustion. Nanostructure study is required to develop highly ionic conductive electrolytes for SOFCs. In this work, the calcium doped ceria (Ce0.8Ca0.2O1.9) coated with 20% molar ratio of two alkali carbonates (CDC-M: MCO3, where M = Na and K) electrolyte was prepared by coprecipitation method. Ni based electrode was used to fabricate the cell by dry pressing technique. The crystal structure and surface morphology were characterized by an X-ray diffractometer, scanning electron microscopy (SEM), and high resolution transmission electron microscopy (TEM). The particle size was calculated in the range 10-20 nm by Scherer's formula and compared with SEM and TEM results. The ionic conductivity was measured by using ac electrochemical impedance spectroscopy method. The activation energy was also evaluated. The performance of the cell was measured 0.567 W/cm(2) at temperature 550 degrees C with hydrogen as a fuel.

  • 5.
    Abbas, Ghazanfar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. COMSATS Institute of Information Technology, Pakistan.
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. COMSATS Institute of Information Technology, Pakistan.
    Khan, M. Ajmal
    Ahmad, Imran
    Chaudhry, M. Ashraf
    Sherazi, Tauqir A.
    Mohsin, Munazza
    Ahmad, Mukhtar
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Synthesize and characterization of nanocomposite anodes for low temperature solid oxide fuel cell2015In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 40, no 1, p. 891-897Article in journal (Refereed)
    Abstract [en]

    Solid oxide fuel cells have much capability to become an economical alternative energy conversion technology having appropriate materials that can be operated at comparatively low temperature in the range of 400-600 degrees C. The nano-scale engineering has been incorporated to improve the catalytic activity of anode materials for solid oxide fuel cells. Nanostructured Al0.10NixZn0.90-xO oxides were prepared by solid state reaction, which were then mixed with the prepared Gadolinium doped Ceria GDC electrolyte. The crystal structure and surface morphology were characterized by XRD and SEM. The particle size was evaluated by XRD data and found in the range of 20-50 nm, which was then ensured by SEM pictures. The pellets of 13 mm diameter were pressed by dry press technique and electrical conductivities (DC and AC) were determined by four probe techniques and the values have been found to be 10.84 and 4.88 S/cm, respectively at hydrogen atmosphere in the temperature range of 300-600 degrees C. The Electrochemical Impedance Spectroscopy (EIS) analysis exhibits the pure electronic behavior at hydrogen atmosphere. The maximum power density of ANZ-GDC composite anode based solid oxide fuel cell has been achieved 705 mW/cm(2) at 550 degrees C.

  • 6.
    Abdi, Amir
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Numerical Investigation of Latent Thermal Storage in a Compact Heat Exchanger Using Mini-Channels2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 13, p. 5985-, article id 5985Article in journal (Refereed)
    Abstract [en]

    This paper aims to numerically investigate the thermal enhancement of a latent thermal energy storage component with mini-channels as air passages. The investigated channels in two sizes of internal air passages (channel-1 with d(h) = 1.6 mm and channel-2 with d(h) = 2.3 mm) are oriented vertically in a cuboid of 0.15 x 0.15 x 0.1 m(3) with RT22 as the PCM located in the shell. The phase change is simulated with a fixed inlet temperature of air, using ANSYS Fluent 19.5, with a varying number of channels and a ranging air flow rate entering the component. The results show that the phase change power of the LTES improves with by increasing the number of channels at the cost of a decrease in the storage capacity. Given a constant air flow rate, the increase in the heat transfer surface area of the increased number of channels dominates the heat transfer coefficient, thus increasing the mean heat transfer rate (UA). A comparison of the channels shows that the thermal performance depends largely on the area to volume ratio of the channels. The channel type two (channel-2) with a slightly higher area to volume ratio has a slightly higher charging/discharging power, as compared to channel type one (channel-1), at a similar PCM packing factor. Adding fins to channel-2, doubling the surface area, improves the mean UA values by 15-31% for the studied cases. The variation in the total air flow rate from 7 to 24 L/s is found to have a considerable influence, reducing the melting time by 41-53% and increasing the mean UA values within melting by 19-52% for a packing factor range of 77.4-86.8%. With the increase in the air flow rate, channel type two is found to have considerably lower pressure drops than channel type one, which can be attributed to its higher internal hydraulic diameter, making it superior in terms of achieving a relatively similar charging/discharging power in exchange for significantly lower fan power. Such designs can further be optimized in terms of pressure drop in future work, which should also include an experimental evaluation.

  • 7.
    Abdi, Amir
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    State of the art in hydrogen liquefaction2020In: Proceedings of the ISES Solar World Congress 2019 and IEA SHC International Conference on Solar Heating and Cooling for Buildings and Industry 2019, International Solar Energy Society , 2020, p. 1311-1320Conference paper (Refereed)
    Abstract [en]

    Hydrogen is a potential option to replace fossil fuels considering the increasing demand of energy applications. It is naturally abundant and is regarded as a suitable energy carrier. There has been extensive research to improve the efficiency of storing hydrogen with different methods, including gas compression, liquefaction and sorption in metal hydrides or carbon nanotubes. A comparison of the storage methods shows that liquefaction of hydrogen is more beneficial than compression of hydrogen in terms of higher volumetric capacity, and it is more technologically mature than sorption technologies. This makes it more plausible for long distance distribution. On the other hand, the obstacles in full exploitation of the method are low energy efficiency of the liquefaction process and associated high cost. The recent research has been focusing on increasing the energy efficiency of the storage process. This paper provides, with regard to the conventional methods, a state of the art review of the novel and modified liquefaction process and the latest developments in increasing the efficiency of the energy intensive process. Furthermore, the developments in combining the hydrogen liquefaction plants with renewable energy sources are covered and reviewed. Finally, the ongoing development of hydrogen liquefaction is highlighted.

  • 8.
    Abdi, Amir
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Ignatowicz, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Gunasekara, Saman Nimali
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Experimental investigation of thermo-physical properties of n-octadecane and n-eicosane2020In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 161, article id 120285Article in journal (Refereed)
    Abstract [en]

    Reliable knowledge of phase change materials (PCM) thermo-physical properties is essential to model and design latent thermal energy storage (LTES) systems. This study aims to conduct a methodological measurement of thermo-physical properties, including latent enthalpy, isobaric specific heat, thermal conductivity and dynamic viscosity, of two n-alkanes, n-octadecane and n-eicosane. The enthalpy and isobaric specific heat of the materials are measured via differential scanning calorimetry (DSC) technique, using a pDSC evo7 from Setaram Instrumentation with a sample mass of 628.4 mg. The influence of the scanning rates, varying from 0.5 K/min to 0.025 K/min, in dynamic continuous mode within temperature range of 10-65 degrees C is investigated. The thermal conductivity and the dynamic viscosity are measured via Hot Disk TPS-2500S instrument and Brookfield rotational viscometer, respectively, up to 70 degrees C. The thermal analysis results via the pDSC show that the isothermal condition can be approached at a very low scanning rate, however at the cost of a higher noise level. A trade-off is observed for n-octadecane, achieving the lowest deviation of 0.7% in latent heat measurement at 0.05 K/min, as compared to the American Petroleum Table values. For n-eicosane, the lowest deviation of 1.2% is seen at the lowest scanning rate of 0.025 K/min. The thermal conductivity measured values show good agreements with a number of documented literature studies in the solid phase, within deviations of 2%. Larger deviations of 5-16% are found for the measurement in the liquid phase. The viscosity values also show a good agreement with the literature values with maximum deviations of 2.9% and 6.3%, with respect to the values of American Petroleum Tables, for n-octadecane and n-eicosane, respectively. The good agreements achieved in measurements establish the reliable thermo-physical properties contributing to the future simulations and designs. 

  • 9.
    Abdi, Amir
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Numerical investigation of melting in a cavity with vertically oriented fins2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 235, p. 1027-1040Article in journal (Refereed)
    Abstract [en]

    This paper investigates the effect of vertical fins, as an enhancement technique, on the heat transfer rate and energy density of a latent heat thermal energy storage system. This contributes with knowledge on the interaction of heat transfer surface with the storage material for optimizing storage capacity (energy) and power (heat transfer rate). For the assessment, numerical modeling is employed to study the melting process in a two-dimensional rectangular cavity. The cavity is considered heated isothermally from the bottom with surface temperatures of 55 degrees C, 60 degrees C or 70 degrees C, while the other surfaces are insulated from the surrounding. Aluminum and lauric acid are considered as fin/enclosure material and phase change material, respectively. Vertical fins attached to the bottom surface are employed to enhance the charging rate, and a parametric study is carried out by varying the fin length and number of fins. Thus, a broad range of data is provided to analyze the influence of fin configurations on contributing natural convection patterns, as well as the effects on melting time, enhanced heat transfer rate and accumulated energy. The results show that in addition to increasing the heat transfer surface area, the installation of vertically oriented fins does not suppress the natural convection mechanism. This is as opposed to horizontal fins which in previous studies have shown tendencies to reduce the impact of natural convection. This paper also highlights how using longer fins offers a higher rate of heat transfer and a better overall heat transfer coefficient rather than increasing the number of fins. Also, fins do not only enhance the heat transfer performance in the corresponding melting time, but also maintain similar total amount of stored energy as compared to the no-fin case. This paper discusses how this is the result of the enhanced heat transfer allowing a larger portion of sensible heat to be recovered. For example, in the case with long fins, the relative mean power enhancement is about 200% with merely 6% capacity reduction, even though the amount of PCM in the cavity has been reduced by 12% as compared to the no-fin case. Although the basis for these results stems from the principles of thermodynamics, this paper is bringing it forward with design consideration. This is because despite its importance for making appropriate comparisons among heat transfer enhancement techniques in latent heat thermal energy storage, it has not been previously discussed in the literature. In the end, the aim is to accomplish robust storage systems in terms of power and energy density.

  • 10.
    Abdi, Amir
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Shahrooz, Mina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Experimental investigation of solidification and melting in a vertically finned cavity2021In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 198, article id 117459Article in journal (Refereed)
    Abstract [en]

    Extending the heat transfer area is a simple technique to improve the thermal performance of phase change materials with low thermal conductivity. However, as the governing mechanisms differ in solidification and melting, fins can affect the processes in different ways. This demands assessment of fin enhancement in a combined analysis on both solidification and melting, often neglected in literature. This paper presents visual-izations of solidification and melting of n-eicosane in a rectangular cavity and experimentally investigates the enhancing effect of vertical fins with varying number and length. Experiments were conducted at water inlet temperature ranges of 15-25 degrees C and 50-60 degrees C for the solidification and melting processes, respectively. The results show that the vertical fins can be more influential in solidification rather than in melting with similar losses in the storage capacity. In the solidification process, as natural convection is absent, the mean power is enhanced by a maximum of 395% with a 10% loss in the storage capacity, as compared to the benchmark. In the melting case, the mean power is increased by a maximum of 90% with a 9% loss in the storage capacity. Although increasing the surface area with vertical fins contributes to development of convective structures, it makes a modest enhancement. In overall, increasing the fin volume fraction, in exchange for the loss in the storage capacity, enhances the solidification significantly while it has relatively low enhancement effect in melting. At the end, the performed experiments could be helpful for validation of future simulation tools with complex features, particularly solidification models lacking in literature.

  • 11.
    Abeywardana, Asela M.A.J.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Solar-Biomass hybrid system for process heat supply in medium scale hotels in Sri Lanka2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study aimed at evaluating and demonstrating the feasibility of using Concentrated Solar Thermal technology combined with biomass energy technology as a hybrid renewable energy system to supply the process heat requirements in small scale industries in Sri Lanka. Particularly, the focus was to apply the concept to the expanding hotel industry, for covering the thermal energy demand of a medium scale hotel.

    Solar modules utilize the rooftop area of the building to a valuable application. Linear Fresnel type of solar concentrator is selected considering the requirement of the application and the simplicity of fabrication and installation compared to other technologies. Subsequently, a wood-fired boiler is deployed as the steam generator as well as the balancing power source to recover the effects due to the seasonal variations in solar energy. Bioenergy, so far being the largest primary energy supply in the country, has a good potential for further growth in industrial applications like small hotels. 

    When a hotel with about 200-guests capacity and annual average occupancy of 65% is considered, the total annual CO2 saving is accounted as 207 tons compared with an entirely fossil fuel (diesel) fired boiler system. The annual operational cost saving is around $ 40,000 and the simple payback period is within 3-4 years. The proposed hybrid system can generate additional 26 employment opportunities in the proximity of the site location area.  

    This solar-biomass hybrid concept mitigates the weaknesses associated with these renewable technologies when employed separately. The system has been designed in such a way that the total heat demand of hot water and process steam supply is managed by renewable energy alone. It is thus a self-sustainable, non-conventional, renewable energy system. This concept can be stretched to other critical medium temperature applications like for example absorption refrigeration. The system is applicable to many other industries in the country where space requirement is available, solar irradiance is rich and a solid biomass supply is assured.

    Download full text (pdf)
    fulltext
  • 12.
    Abeywecra, Ruchira
    et al.
    OUSL, Dept Mech Engn, Nugegoda, Sri Lanka..
    Scnanavakc, Nihal S.
    OUSL, Dept Mech Engn, Nugegoda, Sri Lanka..
    Jayasuriya, Jeevan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten H.
    EIT InnoEnergy, Eindhoven, Netherlands..
    A Remote Mode High Quality International Master Degree Program in Environomical Pathways for Sustainable Energy Systems (SELECT) -Pilot Program Experiences During First Year of Studies2018In: PROCEEDINGS OF 2018 IEEE GLOBAL ENGINEERING EDUCATION CONFERENCE (EDUCON) - EMERGING TRENDS AND CHALLENGES OF ENGINEERING EDUCATION, IEEE , 2018, p. 276-284Conference paper (Refereed)
    Abstract [en]

    Remote mode study programs at master degree level are becoming more popular than undergraduate level programs. Students after graduation with Bachelors degree very often are employed and the most appropriate mode for them to pursue higher studies is the remote mode. Postgraduate programs with one or two year duration mostly focus on specific areas of research based industrial application. Traditional remote education is thought to be more centered on web based on-line programs with a little opportunity for teacher student interaction and interaction with peers. In such programs motivation for studies has been a problem and as a result many students drop off and also those remain in the program for prolonged periods do not show good performance. One of the reasons for failures of students in remote studies is the isolation leading to discouragement for the completion studies. A remote mode Master Degree Program in Environomical Pathways for Sustainable Energy Systems (MSc-SELECT), consisting of a number of innovative features aimed at improved student engagement, motivation, exposure to experiences in multi-national setting and team work, was developed and implemented by the Master School of the EIT-InnoEnergy, as a pilot project. The program was offered, collaboratively and simultaneously to students in three locations, Royal Institute of Technology in Sweden, Universitat Politecnica de Catalunya in Spain and the Open University of Sri Lanka. The students in Sweden and Spain each followed 50% of the courses on-campus and 50% in remote mode depending upon the university they registered with. The students in Sri Lanka followed the entire 1st year fully remotely. All the students (from KTH, OUSL and UPC) will spend the 2nd year on-campus at another university in the consortium. This paper discusses, from the perspective of the fully remote site, the remote program with its innovative aspects, student performance and experience together with future tasks for making the program viable and beneficial to all partner countries.

  • 13. Abeyweera, Ruchira
    et al.
    Senanayake, Nihal S.
    Senaratne, Chamindie
    Jayasuriya, Jeevan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. EIT InnoEnergy, Sweden.
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. EIT InnoEnergy, Sweden.
    Capacity Building Through a Web Based Master Degree Programme in Sustainable Energy Engineering2017In: PROCEEDINGS OF 2017 IEEE GLOBAL ENGINEERING EDUCATION CONFERENCE (EDUCON2017), IEEE, 2017, p. 800-805Conference paper (Refereed)
    Abstract [en]

    Open Distance Learning is gaining popularity as a successful alternative for on-campus higher education especially with the emergence of web based platforms which enable the online delivery of courses worldwide. This emerging educational pedagogy can successfully be employed as means of capacity building of the people living in the less fortunate parts of the world where higher education especially at master level are scarce. This paper presents a two-year collaborative master study programme in sustainable energy engineering offered in synchronous with an on-campus study programme conducted by the KTH Royal Institute of Technology of Sweden, to students of Sri Lanka, which was facilitated by the Open University of Sri Lanka. The paper describes the need of such a programme, the format of course delivery and assessment thereof, plus the benefits gained. This programme has produced 72 post graduates in Sri Lanka alone and more than 200 distant postgraduates worldwide in the field of sustainable energy engineering during last 10 years period. In terms of capacity building in the energy sector in Sri Lanka this is considered a great achievement. The experience gained by the local staff in the role of local facilitators who engaged in some of the academic related activities such as evaluation of students' presentation and co-supervision of thesis projects have been greatly appreciated as being additional benefits to the staff in terms of their own academic development and capacity building. Finally, conclusions are made on how remote programmes of study could successfully be delivered to places where such know-how is scarce by adapting appropriate technologies in training personnel at postgraduate level to meet the needs of the industry.

  • 14.
    Abou Jaoudeh, Elie
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Developement of Optimization Method/A Tool for RE applications in Intermittent Grids with focus on Lebanon2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Renewable energy applications require sound design and optimization of life cycle costs because they need upfront investments and as long as possible operating lifetimes are expected. Using modern tools for optimizing designs of grid-tied and autonomous plants allows investors to deploy these technologies while keeping risks within acceptable limits.

    Nevertheless in Lebanon, the grid is intermittent and the most adapted solutions are dual-mode plants that can operate autonomously and with grid-tie. There are no existent simulation models particularly adapted to optimize these applications for such a situation. The objective of this research is to suggest and test a model adapted from commercially available software that can simulate the particular conditions of Lebanon. The studied solution has a PV generator associated with a PV charge controller, lead acid battery, a dual mode inverter, and transfer switchgear and protections. The research successfully met the objective of finding a setup in HOMER 2.68beta for simulating and optimizing a PV-Battery AC plant for an intermittent grid with scheduled blackouts.

    The setup and adaptation in HOMER is made to replicate an existing reference PV-Battery plant at a public school. The measured data from this public school is used to validate the results obtained from the adapted HOMER simulation. The grid is supplied for an average of 12 hours per day at the reference site with a tariff of USD 0.1/kWh.

    After the validation process, a sensitivity analysis is performed to simulate this plant under

    1. Different grid supply hours, 12 and 18 hours of supply daily
    2. Different grid electricity prices, USD 0.1 and 0.1375 /kWh
    3. Simulation of PV plants to meet other load profiles typical of community and municipality building centers

    All the simulations cross matched 20 different PV generator sizes to 7 different battery sizes for 5 different total setups.

    The levelized cost of electricity, COE, is the main parameter used to find the optimum setups, whereas options that shortened the battery life to less than 12 years or couldn’t meet at least 90% of the required yearly load were filtered out. The COE is calculated manually since several corrections related to grid and net-metering limitations are not obtained directly from HOMER.

    The simulated results can serve as a good indicator on how the systems would perform for typical public institutions in Lebanon, given the current conditions, and knowing that the range of this study is limited to small scale institutions with consumption levels less than 30 kWh/day. Storage capacity should also be limited to 100 kWh/day of useful storage, since batteries are not the best option to use for storage capacities higher than the mentioned limit.

    The setup has a great potential for advancement and acts as a first step for Lebanon to have a specialized tool for simulating the performance of PV-battery AC plants optimized for the conditions existing in the country. Future steps could be made to improve and diversify the software to include:

    • irradiation data that come from actual data logging data from other PV sites which are installed around the whole country, almost a 100
    • financial analysis for offsetting private generation with fossil fueled gensets, which is the main backup for electricity blackouts
    • wind turbine simulations, several installations are provisioned to be completed by the end of 2012, and it would be possible to carry out a similar validation process for small wind turbines
    • pollution and other environmental costs
    • value of lost load, “VOLL”, to compare different options in parallel with COE.

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    Abou Jaoudeh Elie EGI-2012-81MSC-EKV-910
  • 15.
    Abrahamsson, Cajsa
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Miljöpåverkan, hälsopåverkan och LCC för direktdrivna kontra växellådsdrivna vindkraftverk med avseende på deras innehåll av jordartsmetaller2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Vindkraftverk med olika magnetiseringsmetoder (elektromagneter eller permanentmagneter) och maskindriftstyper (direktdrift eller växellådsdrift) undersöks i denna rapport, gällande användningen av jordartsmetaller i dessa. I första delen av rapporten studeras miljö- och hälsopåverkan från jordartsmetallindustrin i den kinesiska provinsen Baotou. Detta då Baotou står för en stor del av försörjningen av jordartsmetaller till vindkraftverksindustrin. I den andra delen av rapporten undersöks skillnaderna i livscykelkostnader mellan vindkraftverk med olika generator- och maskindriftsystem. Rapporten innehåller informationssökningar om olika aspekter som berör dessa teman såsom exempelvis olika typer av vindkraftverksgeneratorer på marknaden, miljöpåverkan från olika ämnen i jordartsmineraler, återvinning av jordartsmetaller och processen från jordartsmineral till permanent-magnet. Informationen är främst inhämtad från vindkraftverkstillverkare, tekniska rapporter och artiklar.

    I miljö- och hälsoanalysen blev slutsatsen att den negativa påverkan från jordartsmetallindustrin i Kina var för omfattande för att användningen av jordartsmetaller skulle rättfärdigas ur ett etiskt och miljömässigt perspektiv. Gruvdriften och bearbetningen av jordartsmetaller har lett till stora utsläpp av skadliga ämnen, såsom exempelvis tungmetaller och radioaktivt avfall, i provinsen Baotou. Dessa har gett allvarliga negativa konsekvenser för djur, människor och växtlighet.

    Livscykelkostnaderna för vindkraftverk med olika generatorsystem beräknades med hjälp av LCC-metoden. Slutsatsen blev att det i dagsläget inte skiljde så mycket kostnadsmässigt i valet av maskindrifttyp eller magnetiseringsmetod. Enligt beräkningar ledde användningen av permanent-magneter inte till några ekonomiska fördelar. Istället var det kostnadsförhandlingar och osäkerhet i indata som gav de största kostnadsskillnaderna. Drift och underhållskostnaderna stod för de definitivt största utgifterna och investeringskostnaderna till generatorsystemen för de näststörsta utgifterna.

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  • 16.
    Adolphe, Cyril
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Commissioning the Heating and Cooling Systems on an FPSO (Floating Production Storage and Offloading facility)2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The project under discussion is the FPSO Ichthys. The FPSO is a ship comprising the offshore production facility for an oil&gas field, financed by INPEX/Total. An oil platform extracts the product received via the flexible risers and separates it into gas and condensate. The condensate is transferred to the FPSO, which processes it, and separates it between natural gas and oil. The oil is stored in the FPSO and then exported via a tanker. The gas is transferred via a pipeline.

    An FPSO is a complex installation in many respects. It is a condensate treatment factory, installed on a 450-metre-long ship. It should have the capacity to store one week’s condensate production. The FPSO is self-sufficient in terms of energy production (electricity, heating and cooling). Owing to the proximity of the hazardous production area to the living quarters, strict safety regulations are applied. For instance, all equipment has to be designed with redundancy (2x50% or 3x33% for critical equipment); the heating and cooling systems are managed with the help of emergency logic diagrams. These enable vital functions to be maintained even in cases of extreme failure.

    Despite its complexity, the FPSO has to be constructed within a short period of time. However, safety issues are important, and maintenance of defective equipment is expensive since the ship will be located 300km away from the coast. This is the reason why the constructor contracted Actemium, a part of VINCI Energies. Actemium commissions the FPSO. The commissioning mission has to prove that the systems function in accordance with the designs. Commissioning occurs right after the pre-commissioning (de-energized verifications). Commissioning is divided into three main activities: functional tests (which prove that individual pieces of equipment work in accordance with the designs); operational tests (which prove that all subsystems work in accordance with the designs of different modes); and piping and vessels pressurization (which prove that there is no leak).

    This master thesis describes the requirements of such projects and focuses on the operational tests. A description of the installation is detailed. Secondly, the subcontractor for the commissioning of the project, Actemium, and the method used for the commissioning are presented thereafter. Finally, the operational test procedures of the cooling and heating systems are examined in detail.

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  • 17.
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Semiconductor-ionic Materials for Low Temperature Solid Oxide Fuel Cells2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Solid oxide fuel cell (SOFC) is considered as an attractive candidate for energy conversion within the fuel cell (FC) family due to several advantages including environment friendly, use of non-noble materials and fuel flexibility. However, due to high working temperatures, conventional SOFC faces many challenges relating to high operational and capital costs besides the limited selection of the FC materials and their compatibility issues. Recent SOFC research is focused on how to reduce its operational temperature to 700 ºC or lower. Investigation of new electrolytes and electrode materials, which can perform well at low temperatures, is a comprehensive route to lowering the working temperature of SOFC. Meanwhile, semiconductor-ionic materials based on semiconductors (perovskite/composite) and ionic materials (e.g. ceria based ion conductors) have been identified as potential candidates to operate in low temperature range with adequate SOFC power outputs.

    This investigation focuses on the development of semiconductor-ionic materials for low temperature solid oxide fuel cell (SOFC) and electrolyte-layer free fuel cell (EFFC). The content of this work is divided into four parts:

    First part of the thesis consists of the work on conventional SOFC to build knowledge and bridge from conventional SOFC to the new EFFC. Novel composite electrode (semiconductor) materials are synthesized and studied using established electrochemical and analytical methods such as x-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The phase structure, morphology and microstructure of the composite electrodes are studied using XRD and SEM, and the weight loss is determined using TGA. An electrical conductivity of up to 143 S/cm of as-prepared material is measured using DC 4 probe method at 550 ºC. An electrolyte, samarium doped ceria (SDC) is synthesized to fabricate a conventional three component SOFC device. The maximum power density of 325 mW/cm2 achieved from the conventional device at 550 ºC.

    In the second part of the thesis, semiconductor-ionic materials based on perovskite and composite materials are prepared for low temperature SOFC and EFFC devices. Semiconductor-ionic materials are prepared via nanocomposite approach based on two-phase semiconductor electrode and ionic electrolyte. This semiconductor-ionic functional component was shown to integrate all fuel cell components anode, electrolyte and cathode functions into a single component, i.e. “three in one”, resulting in enhanced catalytic activity and improved SOFC performance.

    The third part of the thesis addresses the development and optimization of the EFFC technologies by studying the Schottky junction mechanism in such semiconductor-ionic type devices. Perovskite and functional nanocomposites (semiconductor-ionic materials) are developed for EFFC devices. Materials characterizations are performed using a number of standard experimental and analytical techniques. Maximum power densities from 600 mW/cm2 up to 800 mW/cm2 have been achieved at 600 ºC.

    Fourth part of the thesis describes the theoretical simulation of EFFCs. In this work, an updated numerical model is applied in order to study the EFFC device, which introduces some modifications to the existing relations for traditional fuel cell models. The simulated V-I and P-I curves have been compared with experimental curves, and both types of curves show a good consistency.

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    Doctoral Thesis of Muhammad Afzal
  • 18.
    Afzal, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Madaan, Sushant
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Dong, Wenjing
    Raza, Rizwan
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei University, China.
    Analysis of a perovskite-ceria functional layer-based solid oxide fuel cell2017In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 42, no 27, p. 17536-17543Article in journal (Refereed)
    Abstract [en]

    A fuel cell based on a functional layer of perovskite Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) composited samarium doped ceria (SDC) has been developed. The device achieves a peak power density of 640.4 mW cm(-2) with an open circuit voltage (OCV) of 1.04 Vat 560 degrees C using hydrogen and air as the fuel and oxidant, respectively. A numerical model is applied to fit the experimental cell voltage. The kinetics of anodic and cathodic reactions are modeled based on the measurements obtained by electrochemical impedance spectroscopy (EIS). Modeling results are in well agreement with the experimental data. Mechanical stability of the cell is also examined by using analysis with field emission scanning electron microscope (FESEM) associated with energy dispersive spectroscopy (EDS) after testing the cell performance.

  • 19.
    Afzal, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Raza, R.
    Du, S.
    Lima, R.B.d
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei Univ, Fac Phys & Elect Technol, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Peoples R China.
    Synthesis of Ba0.3Ca0.7Co0.8Fe0.2O3-δ composite material as novel catalytic cathode for ceria-carbonate electrolyte fuel cells2015In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 178, p. 385-391Article in journal (Refereed)
    Abstract [en]

    This work reports a new composite BaxCa1-xCoyFe1-yO3-delta (BCCF) cathode material for advanced and low temperature solid oxide fuel cells (SOFCs). The BCCF-based composite material was synthesized by sol gel method and investigated as a catalytic cathode for low temperature (LT) SOFCs. XRD analysis of the as-prepared material revealed the dominating BCCF perovskite structure as the main phase accompanied with cobalt and calcium oxides as the secondary phases resulting into an overall composite structure. Structure and morphology of the sample was observed by Field Emission Scanning Electron Microscope (FE-SEM). In particular, the Ba0.3Ca0.7Co0.8Fe0.2O3-delta (BCCF37) showed a maximum conductivity of 143 S cm(-1) in air at 550 degrees C measured by DC 4 probe method. The BCCF at the optimized composition exhibited much higher electrical conductivities than the commercial Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) perovskite cathode material. A maximum power density of 325 mW cm(-2) at 550 degrees C is achieved for the ceria-carbonate electrolyte fuel cell with BCCF37 as the cathode material.

  • 20.
    Afzal, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Saine, Kari
    Wärtsilä Finland OyResearch and Development, WSSCVaasaFinland.
    Paro, Claus
    Wärtsilä Finland OyResearch and Development, WSSCVaasaFinland.
    Dascotte, Eddy
    Dynamic Design Solutions (DDS) NVLeuvenBelgium.
    Experimental evaluation of the inertia properties of large diesel engines2021In: Conference Proceedings of the Society for Experimental Mechanics Series, Springer , 2021, p. 205-213Conference paper (Refereed)
    Abstract [en]

    Inertia properties of several medium speed large diesel engines are evaluated using the Inertia Restrain Method (IRM). This method requires measuring frequency response functions (FRFs) at several well-chosen locations and under dynamic loading in different directions that stimulate rigid body movements. The mass line values of the measured FRFs are then evaluated and, together with the sensor locations, are used by IRM to determine center of gravity, mass and mass moments of inertia. The aim of the study is to investigate the accuracy and robustness of the IRM for extracting the inertia properties of complex structures. Therefore, several line- and V-engines were measured. The experimental results are compared with finite element models and result obtained from weighing tests. Different types of excitation source such as hammer and shaker are used to excite the structure. The result obtained from two excitation sources are compared and discussed. The effect of measurement point locations and driving point accelerometers on the FRFs and inertia properties are investigated. The extracted inertia properties in all cases are considered sufficiently accurate. This indicates that the IRM is a robust tool for identifying the inertia properties of large and complex structures and can be employed at an industrial level. 

  • 21.
    Afzal, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Saleemi, Mohsin
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Wang, Baoyuan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Zhang, Wei
    He, Yunjuan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Jayasuriya, Jeevan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Zhu, Binzhu
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fabrication of novel electrolyte-layer free fuel cell with semi-ionic conductor (Ba0.5Sr0.5Co0.8Fe0.2O3-delta- Sm0.2Ce0.8O1.9) and Schottky barrier2016In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 328, p. 136-142Article in journal (Refereed)
    Abstract [en]

    Perovskite Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) is synthesized via a chemical co-precipitation technique for a low temperature solid oxide fuel cell (LTSOFC) (300-600 degrees C) and electrolyte-layer free fuel cell (EFFC) in a comprehensive study. The EFFC with a homogeneous mixture of samarium doped ceria (SDC): BSCF (60%:40% by weight) which is rather similar to the cathode (SDC: BSCF in 50%:50% by weight) used for a three layer SOFC demonstrates peak power densities up to 655 mW/cm(2), while a three layer (anode/ electrolyte/cathode) SOFC has reached only 425 mW/cm(2) at 550 degrees C. Chemical phase, crystal structure and morphology of the as-prepared sample are characterized by X-ray diffraction and field emission scanning electron microscopy coupled with energy dispersive spectroscopy. The electrochemical performances of 3-layer SOFC and EFFC are studied by electrochemical impedance spectroscopy (EIS). As-prepared BSCF has exhibited a maximum conductivity above 300 S/cm at 550 degrees C. High performance of the EFFC device corresponds to a balanced combination between ionic and electronic (holes) conduction characteristic. The Schottky barrier prevents the EFFC from the electronic short circuiting problem which also enhances power output. The results provide a new way to produce highly effective cathode materials for LTSOFC and semiconductor designs for EFFC functions using a semiconducting-ionic material.

  • 22.
    Afzal, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei University, China.
    Lanthanum-doped Calcium Manganite (La0.1Ca0.9MnO3) Cathode for Advanced Solid Oxide Fuel Cell (SOFC)2016In: Materials Today-Proceedings, Elsevier BV , 2016, Vol. 3, no 8, p. 2698-2706Conference paper (Refereed)
    Abstract [en]

    We present here a new perovskite oxide with low lanthanum content doped in calcium manganite, La0.1Ca0.9MnO3 (LCM) as a functional material for low temperature solid oxide fuel cell (LTSOFC) and electrolyte-layer free fuel cell (EFFC). The LCM introduces an intrinsic mixed-ion and electron conduction. Electrochemical impedance spectroscopy (EIS) analysis shows high oxygen reduction reaction (ORR) activity with an extremely low activation energy which enables an excellent cathode activity. Fuel cells using LCM as cathode with oxide ion conducting electrolyte samarium doped ceria (SDC) and NCAL as an anode, demonstrate a maximum power density of 650 mW cm(-2) at 550 degrees C, which is higher than most of the cathode materials reported for SOFC at this temperature. For EFFC, maximum power density of 750 mW cm(-2) is achieved using LCM as a semiconductor material with SDC ion conducting material. The present work highlights the development of new active air electrode especially for developing low temperature solid oxide fuel cells.

  • 23.
    Aga, Aboma Emiru
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fuel Supply Investigation for an Externally Fired Microturbine based Micro CHP System: Case study on a selected site in Bishoftu, Ethiopia2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sudden change on earth’s climate, which is a result of an increase in CO2 in the atmosphere, is mainlycaused by burning of fossil fuels for various energy services. However, for the energy services to befavourable to the environment, there should be a balance with the environmental protection, and we cancall that “Sustainable Innovative Development”.

    “EXPLORE Polygeneration” initiative will serve as an important tool to promote the application ofrenewable technologies extending to the future sustainable energy engineering field. This paper is intendedin investigating a suitable fuel supply for the microturbine based micro CHP system available at theDivision of Heat and Power Technology, KTH, Sweden; for a site called “Alema Farm PLC”, Bishoftu,Ethiopia.

    Though there is a large biomass energy resource and a huge potential to produce hydroelectric power inEthiopia, the modern energy sector is very small and the energy system is mainly characterized by biomassfuel supplies and household energy consumption. The nation’s limited biomass energy resource is believedto have been depleting at an increasingly faster rate.

    Of the many and surplus amount of renewable energy resources available in and around Alema FarmPLC, poultry litter and pig’s manure are selected to be the two main energy sources for the CHP systemavailable in the lab, after passing through different conversion techniques. However, after consideringsome basic properties like: Energy content and Bulk Density of the fuel, Moisture content , Ashcharacteristic, Tar content, Fuel logistics, Local storage, Fuel feeder system, and Magnitude of GHGReduction; poultry litter is found to be the most convenient to produce a syngas with a Downdraftatmospheric gasifier available in the HPT lab.

    Finally, For the problems caused by the nature of the poultry litter by itself and the methods used in theconversion process, the 40 TRIZ principles of TRIZ inventive principles is used and some major pointsare recommended.

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    Fuel Supply Investigation for an Externally Fired Microturbine based Micro CHP System
  • 24.
    Ahmad, Nawaz
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. KTH Royal Institute of Technology.
    Numerical Modeling and Analysis of Small Gas Turbine Engine: Part I: Analytical Model and Compressor CFD2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The thesis work aims at devising analytical thermodynamic model and numerical modeling of the compressor of a small gas turbine to be operated on producer gas with lower heating contents. The turbine will serve as a component of “EXPLORE-Biomass Based Polygeneration” project to meet the internal electrical power requirements of 2-5 KW. The gas turbine engine is of radial type (one stage radial compressor, one stage radial turbine). Small gas turbines give less electrical efficiencies especially when operated with lower heating contents fuels like producer gas. This necessitates for optimum designing of components of the entire machine.

    Detailed analytical thermodynamic modeling of the engine has been analyzed for both internally and externally fired gas turbine cycles. Efforts are put on optimum utilization of energy available in the cycle and to enhance the efficiency thereby including various components.

    Numerical modeling of compressor using CFX has been performed for both steady and unsteady states. First different mesh sizes have been investigated followed by study of RMS residual targets on the results. Compressor performance has been studied for various speed lines. Thereafter, detailed steady state and unsteady simulations are performed for various cases including compressor single blade passage, 360 degree complete compressor, compressor connected with straight inlet pipe and for the compressor connected with 90 degree bended pipe.

    The operating point of the entire engine is analyzed. The numerical results are compared with each other and then to the ones from the 1D modeling. A good agreement has been found between the numerical results. Compared to 1D modeling, CFD presents higher performance at higher mass flow rates. However, for lower mass flow rates both 1D model and CFD present a similar performance.  

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    Ahmad Nawaz EGI-2009-001MSc EKV1128 Master Thesis
  • 25.
    Ahmed, Alia Amber
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Techno-economic analysis of PV and energy storage systems for Swedish households2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As more countries progress towards renewable energy, intermittency in the power system is causing an unreliable power supply. Flexibility solutions from prosumers, which both consume and produce electricity, is one solution to provide stability to the power system. Households with both PV and energy storage are studied for this purpose in this thesis where the following flexibility services for both a household and the electricity grid of Sweden are studied: Increasing PV self-consumption, peak shaving, energy arbitrage at the day-ahead electricity market and providing the frequency regulation reserves FCR-N, FCR-D, aFRR and mFRR. Each house is assumed to have a 10 kW PV capacity and a battery capacity of 7.68 kWh. The services are studied in the software HOMER Grid and are modelled in different scales to see how the load in different aggregated levels affect the services. The case studies are a single family house, an overloaded transformer, an energy community and on a national scale. For the aggregated case studies, the potential capacity for PV will be based on the existing Swedish policies and the number of energy storages will be inspired by one the leading countries in Europe in energy storage installations, Germany.

    The results showed that for a single household the self-consumption and self-sufficiency increased the most with an addition of a battery. The battery was most efficient in peak shaving and reducing the overall electricity cost when the electricity fee targeted both the electricity consumption during peak hours and the monthly peaks. With this price scheme, the payback time of the battery and PV system is around 14 years. However, when the electricity fee is only targeting the electricity consumption during peak hours, the results showed that the monthly electricity demand peaks actually increase with an addition of a battery.

    For the aggregated case studies, it showed that decentralized batteries are not as effective in decreasing the electricity demand peaks if the peak lasts more than a few hours. On a national scale the results show that 20% of the aggregated batteries capacity is sufficient to provide around 70-100% of each of the frequency reserves individually. The highest savings are gained for the households when both the primary frequency reserves, FCR-N and FCR-D, are provided by the aggregated batteries together with increasing the PV self-consumption, peak shaving and energy arbitrage. The battery payback time is then reduced to 11 years. Based on a sensitivity analysis, the costs that affects the battery payback the most are the investment cost and the power fee.

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  • 26.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Solar Receiver Design and Verification for Small Scale Polygeneration Unit2011Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Against a backdrop of our world’s changing climate solar thermal power generation shows great potential to move global energy production away from fossil fuels to non-polluting sources. The Department of Energy Technology at the Royal Institute of Technology Stockholm is contributing to the development and research of solar thermal power by building a solar driven small scale polygeneration unit based on an externally fired micro gas turbine.

    This project focused on the design, analysis and verification of a high temperature solar receiver for integration into this planned solar polygeneration unit. Mean irradiance levels at the focal spot of the solar receiver of 5.5 MW/m² and peak levels of 14 MW/m² were identified as major design challenges. A preliminary heat transfer analysis found volumetric receivers to be the only applicable receiver type capable of withstanding these expected high irradiance levels.

    With volumetric receivers selected as the receiver type, a basic volumetric receiver model was evaluated using a multi-objective optimization tool based on advanced evolutionist algorithms and a numerical heat transfer model. The results were a set of Pareto-optimal solutions showing a tradeoff between a pressure drop in the receiver and material temperature especially at the window of the receiver.

    A parameter study was conducted based on the previous analysis to improve specific aspects of the initial design using a value of benefit analysis to evaluate the different designs. Of all the investigated receiver parameters, the absorber properties and shape had the biggest positive influence on material temperature and thermal stresses without significantly increasing the pressure drop. External cooling of the receiver window with ambient air was found to beneficial influence the window temperature without greatly decreasing the thermal efficiency. For non-uniform high irradiance levels ceramic absorber materials were found to be most suitable. Furthermore, mechanically decoupling the window and the absorber from their surrounding parts was found to be very important; enabling them to expand more or less independently with changing temperature minimizing thermal stresses.

    It can be concluded, when properly designed, volumetric solar receivers for small scale solar polygeneration units are feasible as designs with material temperature, thermal stresses and pressure drop below acceptable limit were found within this work.

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    Aichmayer L. 2011 - Solar Receiver Design and Verification for Small Scale Polygeneration Unit.pdf
  • 27.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Solar receiver development for gas-turbine based solar dish systems2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Small-scale concentrating solar power plants such as micro gas-turbine based solar dish systems have the potential to harness solar energy in an effective way and supply electricity to customers in remote areas. In such systems, the solar receiver transfers the power of concentrated solar radiation to the working fluid of the power conversion cycle. It is one of the key components as it needs to operate at high temperatures to ensure a high power cycle efficiency and under high flux densities to ensure a high receiver efficiency. In order to address these challenges and to ensure efficient and reliable operation innovative designs are needed.

    This research work focuses on the complete development of a novel solar receiver applying a new systematic design and analysis methodology. Therefore, a comprehensive receiver design and experimental evaluation process were developed and implemented. The design process includes the identification of technical specifications and requirements, the development of receiver design tools of different investigation levels coupled with multi-objective optimization tools, the evaluation of scaling effects between tests in the KTH high-flux solar simulator and the full-scale solar dish system. As a result of the design process a representative final receiver was established with material temperatures and stresses below critical limits while respecting the design specification.

    The experimental evaluation includes the enhancement of the KTH high-flux solar simulator to provide stable and reliable operating conditions, the precise characterization of the radiative boundary conditions, the design of a receiver test bed recreating the operating behavior of a gas-turbine, and the final receiver testing for multiple operating points. It was shown that the prototype reaches an efficiency of 69.3% for an air outlet temperature of 800°C and a mass flow of 29.5 g/s. For a larger mass flow of 38.4 g/s a receiver efficiency of 84.8% was achieved with an air outlet temperature of 749°C.

    The measurement results obtained were then used for a multi-point validation of the receiver design tools, resulting in a high level of confidence in the accuracy of the tools. The validated models were then harnessed to calculate the performance of a full-scale solar receiver integrated into the OMSoP solar dish system. It was shown that a solar receiver can be designed, which delivers air at 800°C with a receiver efficiency of 82.2%.

    Finally, the economic potential of micro gas-turbine based solar systems was investigated and it was shown that they are ideally suited for small-scale stand-alone and off-grid applications.

    The results of the receiver development highlight the feasibility of using volumetric solar receivers to provide heat input to micro gas-turbine based solar dish systems and no major hurdles were found.

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    Aichmayer 2018 - Solar receiver development for gas-turbine based solar dish systems
  • 28.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Performance Improvements of the KTH High-Flux Solar Simulator2017In: AIP Conference Proceedings 1850, American Institute of Physics (AIP), 2017, Vol. 1850, article id 150001Conference paper (Refereed)
    Abstract [en]

    This paper presents the performance improvements implemented in the KTH high-flux solar simulator to deliver a total power on target closer to the working conditions of real CSP systems. Therefore, additional rectifiers were installed in the power conversion unit of the high-power lamps as well as the back reflector was coated providing more favorable spectral reflectance properties. The results of a single lamp/lens-combination show that the power on target in an aperture of 280mm in diameter was increased from 831W to 1446W while the peak flux was increased from 675kW/m² to 905kW/m².

  • 29.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Scaling effects of a novel solar receiver for a micro gas-turbine based solar dish system2018In: International Journal of Solar Energy, ISSN 0142-5919, E-ISSN 1477-2752, Vol. 162, p. 248-264Article in journal (Refereed)
    Abstract [en]

    Laboratory-scale component testing in dedicated high-flux solar simulators is a crucial step in the developmentand scale-up of concentrating solar power plants. Due to different radiative boundary conditions available inhigh-flux solar simulators and full-scale power plants the temperature and stress profiles inside the investigatedreceivers differ between these two testing platforms. The main objective of this work is to present a systematicscaling methodology for solar receivers to guarantee that experiments performed in the controlled environmentof high-flux solar simulators yield representative results when compared to full-scale tests. In this work theeffects of scaling a solar air receiver from the integration into the OMSoP full-scale micro gas-turbine based solardish system to the KTH high-flux solar simulator are investigated. Therefore, Monte Carlo ray-tracing routines ofthe solar dish concentrator and the solar simulator are developed and validated against experimental characterizationresults. The thermo-mechanical analysis of the solar receiver is based around a coupled CFD/FEManalysislinked with stochastic heat source calculations in combination with ray-tracing routines. A geneticmulti-objective optimization is performed to identify suitable receiver configurations for testing in the solarsimulator which yield representative results compared to full-scale tests. The scaling quality is evaluated using aset of performance and scaling indicators. Based on the results a suitable receiver configuration is selected forfurther investigation and experimental evaluation in the KTH high-flux solar simulator.

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  • 30.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermo-mechanical solar receiver design and validation for a micro gas-turbine based solar dish system2020In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 196, article id 116929Article in journal (Refereed)
    Abstract [en]

    This work presents the comprehensive development of a solar receiver for the integration into a micro gas-turbine solar dish system. Special focus is placed on the thermo-mechanical design to ensure the structural integrity of all receiver components for a wide range of operating conditions. For the development, a 3-dimensional coupled multi-physics model is established and is validated using experimental data. Contrary to previous studies, the temperature of the irradiated front surface of the absorber is included in the comprehensive validation process which results in a high level of confidence in the receiver design.

    Finally, a full-scale solar receiver for the integration into the OMSoP solar dish system is designed and its performance determined for a wide operating range to define its safe operating envelope using the validated model. It is shown that the receiver is capable of operating at 803_C with an efficiency of 82.1% and a pressure drop of 0.3% at the nominal operating point, while at the same time functioning effectively   for a wide range of off-design conditions without compromising its structural integrity. At the nominal operating point, the maximum comparison stress of the porous absorber is 5.6 MPa compared to a permissible limit of 7.4 MPa.

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  • 31.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Preliminary design and analysis of a novel solar receiver for a micro gas-turbine based solar dish system2015In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 114, no 4, p. 378-396Article in journal (Refereed)
    Abstract [en]

    The solar receiver is one of the key components of hybrid solar micro gas-turbine systems, which would seem to present a number of advantages when compared with Stirling engine based systems and photovoltaic panels. In this study a solar receiver meeting the specific requirements for integration into a small-scale (10 kWel) dish-mounted hybrid solar micro gas-turbine system has been designed with a special focus on the trade-offs between efficiency, pressure drop, material utilization and economic design. A situation analysis, performed using a multi-objective optimizer, has shown that a pressurized configuration, where the solar receiver is placed before the turbine, is superior to an atmospheric configuration with the solar receiver placed after the turbine. Based on these initial design results, coupled CFD/FEM simulations have been performed, allowing detailed analysis of the designs under the expected operating conditions. The results show that the use of volumetric solar receivers to provide heat input to micro gas-turbine based solar dish systems appears to be a promising solution; with material temperatures and material stresses well below permissible limits.

  • 32.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Small Scale Hybrid Solar Power Plants for Polygeneration in Rural Areas2014In: Energy Procedia 57, Elsevier, 2014, Vol. 57, p. 1536-1545Conference paper (Refereed)
    Abstract [en]

    Small scale micro gas-turbine based hybrid solar power plants are a promising technology for supplying multiple energy services in a controllable and sustainable manner using polygeneration technologies. Compared to a conventional diesel generator based system where electricity is used as the main energy carrier, these systems show great potential to reduce costs and carbon dioxide emissions. Depending on the design, carbon dioxide emissions are reduced by around 9% and equivalent annual costs are reduced by 21% - 26%, as compared to a base polygeneration configuration where cooling services are provided centrally by an absorption chiller without integrating a solar micro gas-turbine. Compared to the system where electricity is used as the main energy carrier a reduction of equivalent annual costs of up to 20% and a reduction of carbon dioxide emissions of up to 33.5% was achieved.

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  • 33.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    IMDEA Energy Institute, Spain.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermoeconomic Analysis of a Solar Dish Micro Gas-Turbine Combined-Cycle Power Plant2015In: Energy Procedia 69, Elsevier, 2015, Vol. 69, p. 1089-1099Conference paper (Refereed)
    Abstract [en]

    A novel solar power plant concept is presented, based on the use of a coupled network of hybrid solar-dish micro gas-turbines, driving a centralized heat recovery steam generator and steam-cycle, thereby seeking to combine the high efficiency of the solar dish collector with a combined-cycle power block. A 150 MWe solar power plant was designed based on this concept and compared with both a conventional combined-cycle power plant and a hybrid solar-tower combined-cycle. The solar dish combined-cycle power plant could reach higher levels of solar integration than other concepts but was shown to be more expensive with current technology; solar electricity costs are double those of the hybrid solar-tower combined cycle.

  • 34.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Micro Gas-Turbine Design for Small-Scale Hybrid Solar Power Plants2013In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 135, no 11, p. 113001-Article in journal (Refereed)
    Abstract [en]

    Hybrid solar micro gas-turbines are a promising technology for supplying controllable low-carbon electricity in off-grid regions. A thermoeconomic model of three different hybrid micro gas-turbine power plant layouts has been developed, allowing their environmental and economic performance to be analyzed. In terms of receiver design, it was shown that the pressure drop is a key criterion. However, for recuperated layouts, the combined pressure drop of the recuperator and receiver is more important. In terms of both electricity costs and carbon emissions, the internally-fired recuperated micro gas-turbine was shown to be the most promising solution of the three configurations evaluated. Compared to competing diesel generators, the electricity costs from hybrid solar units are between 10% and 43% lower, while specific CO2 emissions are reduced by 20–35%.

  • 35.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Micro Gas-Turbine Design for Small-Scale Hybrid Solar Power Plants2013In: Proceedings of the ASME Turbo Expo 2013. San Antonio, USA. June 3-7, ASME , 2013Conference paper (Refereed)
    Abstract [en]

    Hybrid solar micro gas-turbines are a promising technology for supplying controllable low-carbon electricity in off-grid regions. A thermoeconomic model of three different hybrid micro gas-turbine power plant layouts has been developed, allowing their environmental and economic performance to be analyzed. In terms of receiver design, it was shown that the pressure drop is a key criterion. However, for recuperated layouts the combined pressure drop of the recuperator and receiver is more important. The internally-fired recuperated micro gas-turbine was shown to be the most promising solution of the three configurations evaluated, in terms of both electricity costs and carbon emissions. Compared to competing diesel generators, the electricity costs from hybrid solar units are between 10% and 43% lower, while specific CO2 emissions are reduced by 20 – 35%.

  • 36.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Design and Analysis of a Solar Receiver for Micro Gas Turbine based Solar Dish Systems2012In: Proceedings of the International SolarPACES Conference 2012. Marrakesh, Morocco. September 11-14, 2012, 2012Conference paper (Refereed)
    Abstract [en]

    The solar receiver is one of the key components of hybrid solar micro gas turbine systems which would seem to present a number of advantages when compared with Stirling engine systems. A solar receiver meeting the specific requirements for integration into the power conversion system of the solar laboratory of the Royal Institute of Technology - which will emulate a solar dish system and is currently under construction - was designed. The simulations that have been performed utilize a heat transfer and pressure drop model coupled with a multi-objective optimizer as well as a coupled-CFD/FEM tool, allowing determination of the ideal receiver design for the expected conditions. The analysis has shown that the use of volumetric solar receivers to provide heat input to micro gas turbine based solar dish systems appears to be a promising solution; with pressurized receiver configurations as the preferred choice due to significant lower pressure drops as compared to atmospheric configurations.

  • 37.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental evaluation of a novel solar receiver for a micro gas-turbine based solar dish system in the KTH high-flux solar simulator2018In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 159, p. 184-195Article in journal (Refereed)
    Abstract [en]

    This work presents the experimental evaluation of a novel pressurized high-temperature solar air receiver for the integration into a micro gas-turbine solar dish system reaching an air outlet temperature of 800°C. The experiments are conducted in the controlled environment of the KTH high-flux solar simulator with well-defined radiative boundary conditions. Special focus is placed on providing detailed information to enable the validation of numerical models. The solar receiver performance is evaluated for a range of operating points and monitored using multiple point measurements. The porous absorber front surface temperature is measured continuously as it is one of the most critical components for the receiver performance and model validation. Additionally, pyrometer line measurements of the absorber and glass window are taken for each operating point. The experiments highlight the feasibility of volumetric solar receivers for micro gas-turbine based solar dish systems and no major hurdles were found. A receiver efficiency of 84.8% was reached for an air outlet temperature of 749°C. When using a lower mass flow, an air outlet temperature of 800°C is achieved with a receiver efficiency of 69.3%. At the same time, all material temperatures remain below permissible limits and no deterioration of the porous absorber is found.

  • 38.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental Flux Measurement of a High-Flux Solar Simulator using a Lambertian Target and a Thermopile Flux Sensor2016In: AIP Conference Proceedings 1734, American Institute of Physics (AIP), 2016, Vol. 1734, article id 130001Conference paper (Refereed)
    Abstract [en]

    A measurement system for the experimental determination of the flux distribution at the focal plane of the KTH high-flux solar simulator was designed and implemented. It is based on a water-cooled Lambertian target and a thermopile flux sensor placed close to the focal point of the solar simulator. Correction factors to account for systematic effects were determined and an uncertainty analysis was performed. The measurement system was successfully used to evaluate the flux distribution of a single lamp/lens-arrangement with a peak flux of 675kW/m².

  • 39.
    Akbar, M.
    et al.
    Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    Tu, Z.
    Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    Jin, B.
    Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    Mushtaq, N.
    Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    He, Z.
    Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    Dong, W.
    Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    Wang, B.
    Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    Wang, X.
    Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    Demonstrating the dual functionalities of CeO2–CuO composites in solid oxide fuel cells2021In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 46, no 15, p. 9938-9947Article in journal (Refereed)
    Abstract [en]

    Nowadays, lowering the operating temperature of solid oxide fuel cells (SOFCs) is a major challenge towards their widespread application. This has triggered extensive material studies involving the research for new electrolytes and electrodes. Among these works, it has been shown that CeO2 is not only a promising basis of solid oxide electrolytes, but also capable of serving as a catalytic assistant in anode. In the present work, to develop new electrolytes and electrodes for SOFCs based on these features of CeO2, a new type of functional composite is developed by introducing semiconductor CuO into CeO2. The prepared composites with mole ratios of 7:3 (7CeO2–3CuO) and 3:7 (3CeO2–7CuO) are assessed as electrolyte and anode in fuel cells, respectively. The cell based on 7CeO2–3CuO electrolyte reaches a power outputs of 845 mW cm−2 at 550 °C, superior to that of pure CeO2 electrolyte fuel cell, while an Ce0.8Sm0.2O2-δ electrolyte SOFC with 3CeO2–7CuO anode achieves high power density along with open circuit voltage of 1.05 V at 550 °C. In terms of polarization curve and AC impedance analysis, our investigation manifests the developed 7CeO2–3CuO composite has good electrolyte capability with a hybrid H+/O2− conductivity of 0.1–0.137 S cm−1 at 500–550 °C, while the 3CeO2–7CuO composite plays a competent anode role with considerable catalytic activity, indicative of the dual-functionalities of CeO2–CuO in fuel cell. Furthermore, a bulk heterojunction effect based on CeO2/CuO pn junction is proposed to interpret the suppressed electrons in 7CeO2–3CuO electrolyte. Our study thus reveals the great potential of CeO2–CuO to develop functional materials for SOFCs to enable low-temperature operation. 

  • 40.
    Akbar, Nabeela
    et al.
    China Univ Geosci, Fac Mat Sci & Chem, Engn Res Ctr Nanogeo Mat, Minist Educ, 388 Lumo Rd, Wuhan 430074, Peoples R China..
    Paydar, Sara
    China Univ Geosci, Fac Mat Sci & Chem, Engn Res Ctr Nanogeo Mat, Minist Educ, 388 Lumo Rd, Wuhan 430074, Peoples R China..
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Southeast Univ, Sch Energy & Environm, Energy Storage Joint Res Ctr, Jiangsu Prov Key Lab Solar Energy Sci & Technol, 2 Si Pai Lou, Nanjing 210096, Peoples R China.
    Akbar, Muhammad
    Hubei Univ, Fac Phys & Elect Sci, Hubei Key Lab Ferro & Piezoelect Mat & Devices, Wuhan 430062, Hubei, Peoples R China..
    Shah, Muhammad Ali Kamran Yousaf
    Southeast Univ, Sch Energy & Environm, Energy Storage Joint Res Ctr, Jiangsu Prov Key Lab Solar Energy Sci & Technol, 2 Si Pai Lou, Nanjing 210096, Peoples R China..
    Ge, Wen
    China Univ Geosci, Fac Mat Sci & Chem, Engn Res Ctr Nanogeo Mat, Minist Educ, 388 Lumo Rd, Wuhan 430074, Peoples R China..
    Zhu, Bin
    China Univ Geosci, Fac Mat Sci & Chem, Engn Res Ctr Nanogeo Mat, Minist Educ, 388 Lumo Rd, Wuhan 430074, Peoples R China.;Southeast Univ, Sch Energy & Environm, Energy Storage Joint Res Ctr, Jiangsu Prov Key Lab Solar Energy Sci & Technol, 2 Si Pai Lou, Nanjing 210096, Peoples R China..
    Tunning tin-based perovskite as an electrolyte for semiconductor protonic fuel cells2022In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 47, no 8, p. 5531-5540Article in journal (Refereed)
    Abstract [en]

    The use of ceramic semiconductors to serve as an efficient proton conductor is an evolving approach in the novel emerging field of semiconductor protonic fuel cells (SPFCs). One of the most critical challenges in SPFCs is to design a sufficient proton-conductivity of 0.1 S cm(-1) below <600 degrees C. Here we report to tune the perovskite BaSnO3 (BSO), a semi-conductor single-phase material, to be applied as a proton-conducting electrolyte for SPFC. It was found that the oxygen vacancies play a vital role to promote proton transport while the electronic short-circuiting issue of BSO semiconductor has been justified by the Schottky junction mechanism at the anode/electrolyte interface. We have demonstrated a SPFC device to deliver a maximum power density of 843 mW cm(-2) with an ionic conductivity of 0.23 S cm(-1) for BSO at 550 degrees C. The oxygen vacancy formation by increasing the annealing temperature helps to understand the proton transport mechanism in BSO and such novel low-temperature SPFC (LT-SPFC).

  • 41. Alameldin, A.
    et al.
    El-Gabry, L. A.
    Fridh, Jens
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Saha, Ranjan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    CFD analysis of suction and pressure side film cooling influence on vane aero performance in a transonic annular cascade2014In: Proceedings of the ASME Turbo Expo, 2014Conference paper (Refereed)
    Abstract [en]

    Operating at temperatures well above their melting point, gas turbines' components are subject to terribly high thermal stresses. In order to keep them intact and performing, different cooling techniques are implemented. One of these methods is film cooling. Film cooling implementation in vane cascades has a potential loss expense. Proper assessment of its impact on the vane performance has to be conducted. The CFD approach of modeling each hole and cooling tube autonomously is very computationally expensive. In the current work an assessment of a new, more computationally efficient CFD approach for modelling film cooling was conducted on a vane cascade operating in the transonic regime (M =0.89). The film cooling holes were represented by orifice boundary condition at the vane surface, omitting the need to model internal coolant plenum and cooling tubes mesh, resulting in 180% reduction in grid size and attributed computational cost interpreted in 300% saving in computation time. Uncooled, and film cooled with different configurations and at different blowing ratios (BR) simulations were performed and compared to experimental measurements. A good agreement was obtained for the exit flow angles, vorticity and aerodynamic loss for all the cases (uncooled and cooled). Pitch-averaged exit flow angle outside endwalls regions remains unchanged for all cooling configurations and blowing ratios. The aerodynamic loss was found to be more sensitive to increasing the blowing ratio on the suction side than on the pressure side. The proposed approach of coolant injection modeling is shown to yield reliable results, within the uncertainty of the measurements in most cases. Along with lower computational cost compared to conventional film cooling modeling approach, the new approach is recommended for further analysis for aero and thermal vane cascade flows.

  • 42.
    Alanne, Kari
    et al.
    Department of Energy Technology, Aalto University.
    Kari, Saari
    Department of Energy Technology, Aalto University.
    Mannu, Kuosa
    Department of Energy Technology, Aalto University.
    Md., Rahman
    Department of Energy Technology, Aalto University.
    Martin, Andrew
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Microgeneration and Desalination Using Rotary Steam Engine (RTE) Technology2011Conference paper (Refereed)
    Abstract [en]

    This paper discusses the conditions to develop a micro-cogeneration plant based on biomass-fuelled rotary steam engine (RSE). The use of RSE in micro-cogeneration is justifiable due to relatively high electrical efficiency, capability of applying versatile thermal sources and low operational temperatures and pressures. At steam temperatures 200…300ºC, the electrical efficiency of 20 % may be obtained with the electrical power varying between 1…20 kWe. The other advantages of an RSE are that it is lubricant free and the noise level is low. In residential applications, an RSE may be considered an alternative for Stirling Engines and internal combustion engines, when integrated into a hydronic heating system and electrical grid. Another promising adaptation is desalination. A solar-powered RSE micro-cogeneration system would provide an inexpensive option to supply fresh water and electricity for the rural areas in developing countries that have access to sea water. A 10 kWe RSE plant combined with a once-through multi-stage flash (MSF) distillation plant is estimated to have potential of producing pure water from 180 to 800 kg/h.

  • 43.
    Alanne, Kari
    et al.
    Department of Energy Technology, Aalto University.
    Saari, Kari
    Department of Energy Technology, Aalto University.
    Jokisalo, Juha
    Department of Energy Technology, Aalto University.
    Martin, Andrew R.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermo-economic analysis of a micro-cogeneration system based on a rotary steam engine (RSE)2012In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 44, p. 11-20Article in journal (Refereed)
    Abstract [en]

    A rotary steam engine (RSE) is a simple, small, quiet and lubricant-free option for micro-cogeneration. It is capable of exploiting versatile thermal sources and steam temperatures of 150 to 180 ºC, which allow operational pressures less than 10 bar for electrical power ranges of 1 to 20 kWe. An RSE can be easily integrated in commercially available biomass-fired household boilers. In this paper, we characterize the boiler-integrated RSE micro-cogeneration system and specify a two-control-volume thermodynamic model to conduct performance analyses in residential applications. Our computational analysis suggests that an RSE integrated with a 17 kWth pellet-fuelled boiler can obtain an electrical output of 1.925 kWe, in the design temperature of 150 ºC, the electrical efficiency being 9% (LHV) and the thermal efficiency 77% (LHV). In a single-family house inFinland, the above system would operate up to 1274 h/a, meeting 31% of the house’s electrical demand. The amount of electricity delivered into the grid is 989 kWh/a. An economic analysis suggests that incremental costs not exceeding € 1,500 are justifiable at payback periods less than five years, when compared to standard boilers.

  • 44.
    Albutov, Alexey
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Reducing Energy Consumption through Optimization of the Operating Conditions of the Gas Trunk Pipeline2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Gas supplying process for consumers needs sufficient share of energy for upstream, midstream and downstream purposes. In spite of a huge amount of great investments into the industry it is still available to improve the efficiency of energy usage inside the industry. The biggest share of energy consumption is within transportation sector. Optimization of operating conditions of gas pipeline is a one of the cheapest ways for reducing energy consumption. Optimization doesn’t need any investments into the industry. It works only within operating parameters. Adjustable operating parameters of a gas pipeline are operative pressure, rotation speed of compressors, amount of operating units, gas temperature after a compressor station and others. The energy consumption depends on the combination of the parameters which determine an appropriate operation mode to provide the particular gas flow through a pipeline, the maximum capacity, the minimum energy consumption and others. From energy saving point of view it is possible to reduce energy demand in the gas industry due to optimization of the operation mode. A few approaches to achieving energy reduction through optimization are investigated in this work and presented in this article, such as saving energy through changing of loading between compressor stations, varying the depth of gas cooling and changing the loading of gas pumping units. The results of analyzing inside the study model reflect the possibility for improving efficiency of gas trunk pipelines.

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  • 45.
    Alfasfos, Rami
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Cavern Thermal Energy Storage for District Cooling. Feasibility Study on Mixing Mechanism in Cold Thermal Energy Storage2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
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  • 46.
    Ali, Amjad
    et al.
    COMSATS Univ, Dept Phys, CERL, Lahore Campus, Lahore 54000, Pakistan.;Univ Okara, Dept Phys, Okara 56300, Pakistan.;KTH, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    Bashir, Farrukh Shehzad
    COMSATS Univ, Dept Phys, CERL, Lahore Campus, Lahore 54000, Pakistan..
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. COMSATS Univ, Dept Phys, CERL, Lahore Campus, Lahore 54000, Pakistan.;Royal Inst Technol KTH, Dept Energy Technol, S-10044 Stockholm, Sweden..
    Rafique, Asia
    COMSATS Univ, Dept Phys, CERL, Lahore Campus, Lahore 54000, Pakistan..
    Ullah, Muhammad Kaleem
    COMSATS Univ, Dept Phys, CERL, Lahore Campus, Lahore 54000, Pakistan..
    Alvi, Farah
    COMSATS Univ, Dept Phys, CERL, Lahore Campus, Lahore 54000, Pakistan..
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Ghauri, Moinuddin
    COMSATS Univ Islamabad, Dept Chem Engn, Lahore Campus, Lahore 54000, Pakistan..
    Belova, Lyubov
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Structures.
    Electrochemical study of composite materials for coal-based direct carbon fuel cell2018In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 43, no 28, p. 12900-12908Article in journal (Refereed)
    Abstract [en]

    The efficient conversion of solid carbon fuels into energy by reducing the emission of harmful gases is important for clean environment. In this regards, direct carbon fuel cell (DCFC) is a system that converts solid carbon directly into electrical energy with high thermodynamic efficiency (100%), system efficiency of 80% and half emission of gases compared to conventional coal power plants. This can generate electricity from any carbonaceous fuel such as charcoal, carbon black, carbon fiber, graphite, lignite, bituminous coal and waste materials. In this paper, ternary carbonate-samarium doped ceria (LNK-SDC) electrolyte has been synthesized via co-precipitation technique, while LiNi-CuZnFeO (LNCZFO) electrode has been prepared using solid state reaction method. Due to significant ionic conductivity of electrolyte LNK-SDC, it is used in DCFC. Three types of solid carbon (lignite, bituminous, sub-bituminous) are used as fuel to generate power. The X-ray diffraction confirmed the cubic crystalline structure of samarium doped ceria, whereas XRD pattern of LNCZFO showed its composite structure. The proximate and ultimate coal analysis showed that fuel (carbon) with higher carbon content and lower ash content was promising fuel for DCFC. The measured ionic conductivity of LNK-SDC is 0.0998 Scm(-1) and electronic conductivity of LNCZFO is 10.1 Scm(-1) at 700 degrees C, respectively. A maximum power density of 58 mWcm(-2) is obtained using sub bituminous fuel.

  • 47.
    Alkan, Deniz
    KTH, Superseded Departments (pre-2005), Energy Technology. KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Investigating CVT as a Transmission System Option for Wind Turbines2013Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    In this study, an innovative solution is examined for transmission problems and frequency control for wind Turbines. Power electronics and the gear boxes are the parts which are responsible of a significant amount of failures and they are increasing the operation and maintenance cost of wind turbines. Continuously transmission (CVT) systems are investigated as an alternative for conventional gear box technologies for wind turbines in terms of frequency control and power production efficiency. Even though, it has being used in the car industry and is proven to be efficient, there are very limited amount of studies on the CVT implementation on wind turbines. Therefore, this study has also an assertion on being a useful mechanical analyse on that topic. After observing several different types of possibly suitable CVT systems for wind turbines; a blade element momentum code is written in order to calculate the torque, rotational speed and power production values of a wind turbine by using aerodynamic blade properties. Following to this, a dynamic model is created by using the values founded by the help of the blade element momentum theory code, for the wind turbine drive train both including and excluding the CVT system. Comparison of these two dynamic models is done, and possible advantages and disadvantages of using CVT systems for wind turbines are highlighted. The wind speed values, which are simulated according to measured wind speed data, are used in order to create the dynamic models, and Matlab is chosen as the software environment for modelling and calculation processes. Promising results are taken out of the simulations for both in terms of energy efficiency and frequency control. The wind turbine model, which is using the CVT system, is observed to have slightly higher energy production and more importantly, no need for power electronics for frequency control. As an outcome of this study, it is possible to say that the CVT system is a candidate of being a research topic for future developments of the wind turbine technology.

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    fulltext
  • 48.
    Allégret-Bourdon, Davy
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Study of shock movement and unsteady pressure on 2D generic model2006In: Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity of Turbomachines / [ed] Hall, KC; Kielb, RE; Thomas, JP, 2006, p. 409-421Conference paper (Refereed)
    Abstract [en]

    A flexible generic model has been developed at the Chair of Heat and Power Technology in order to perform fatter experiments in a more fundamental fashion. It is made of engineered flexible material and oscillate in a controlled way at non-uniform amplitude and variable frequencies. Time-resolved measurements of the unsteady surface pressures, the instantaneous model geometry as well as unsteady Schlieren visualizations are performed in order to study the shock wave motion and the aerodynamic load acting over this flexible generic bump. The model oscillates at reduced frequencies from 0.015 to 0.294 at transonic flow condition. The mode shapes of such a flexible bump strongly depends on the excitation frequency of the generic model. Schlieren pictures are obtained for an operating point characterized by an inlet Mach number of 0.63. Moreover, the presented results demonstrate that the phase of shock wave movement towards bump local motion shows a decreasing trend for the third bending mode shapes at reduced frequency higher than k=0.074. At the pressure taps located after the shock wave formation, the phase of pressure fluctuations towards bump local motion presents the same decreasing trend.

  • 49.
    Alm, Jonathan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Biogasproduktion på Utö2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study was to investigate the conditions and opportunities to produce biogas at Utö, an island in the Stockholm archipelago. The intention was that the sludge from the local sewage treatment plant could be used as a resource. The Master Thesis was conducted as part of the EU-funded project Green Islands, where the Archipelago Foundation in Stockholm County is Lead Partner.

    In addition to the sludge, other possible substrates were investigated. Food waste from Utö Inn and slaughterhouse waste from a small slaughterhouse were determined best suited. An estimate of the amounts of substrate gave that a suitable size of a biogas reactor would be about 50 m3. Local uses of produced gas and the digestate were investigated. Several small scale biogas digesters were investigated. The closest examined digesters are the research reactor Renowaste at Henriksdalsberget, MR120 which is developed by Energiutvecklarna and an ordinary, small scale digester constructed by concrete segments. The microbiology of the biogas process has also been studied and potential difficulties were analyzed. Practical, economic and environmental aspects were examined.

    If CHP were to be applied, electricity and heat could be utilized at the waste water treatment plant. No suitable usage of the nutrient-rich digestate was found. The nearby organic farm could not use the digestate since human sludge cannot be spread on organic farming land.

    The report states that the construction of a biogas plant in Gruvbyn on Utö cannot be economically justified. Several practical problems were also noted, where mainly the small scale and the uneven flows of substrates are expected to contribute. The low carbon/nitrogen ratio of the substrates, about 8, could also pose difficulties in obtaining a stable process.Environmental and climatic benefits deemed relatively small, mainly due to that upgrading of biogas to vehicle fuel, thus replacing fossil fuels, cannot be seen as a realistic possibility.

    A number of possible improvements that are considered more realistically feasible are suggested, like local treatment of sludge in a bed of reed, making the heating system of the waste water plant more efficient and local composting of the inn’s food waste.

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    Biogasproduktion på Utö
  • 50.
    Amindezfooli, Soroor
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Analysing the Effect of Angle of Attack on Turbulence Intensity, Wake and Power Production for Hexicon Floating Platform2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    When the wind passes through the wind turbine, it losses a part of its energy and as a result a low momentum region creates behind the wind turbine that refers to the wake.  This effect is more significant in a wind farm, where a group of wind turbines are located close to each other in a specific region. Since the wind speed slows down after passing the first row of the turbine, the other rows at the downstream experience lower wind velocity and consequently they can capture less energy in the wind. Wake effect influences the annual power production of a wind farm, not only because of the reduction in the wind velocity but also because of creating  turbulence in the flow and generating more vibration loads on the rotors which can reduce the lifetime of the turbines and increase fatigue on the blades.  Also when the Angle Of Attack (AOA) changes the shape of the wake varies which influence the annual power production and turbulence intensity of a wind farm. 

    The main purpose of this work is to investigate the effect of changing the AOA on the annual power production and the turbulence intensity of Hexicon platform. For this aim, different AOA between zero and 15 degrees are considered in the simulations.

    ANSYS CFX is applied to model the wind turbine configuration and simulate the fluid flow in different wind direction using unstructured meshing method. In addition wind characteristics profiles such as mean wind velocity, turbulence intensity and length scale at different height are imposed at the inlet of the domain to present the Atmospheric Boundary Layer (ABL). RNG k-ε model is implemented for turbulence modeling. In addition roughness modification is utilized in simulation to get more accurate results in terms of turbulence intensity. 

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