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  • 151.
    Chiu, Justin NingWei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Khodabandeh, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Furberg, Richard
    Advanced Thermosyphon Cooling with Nanoporous Structured Mini Channel Evaporators2010In: PROCEEDINGS OF THE ASME MICRO/NANOSCALE HEAT AND MASS TRANSFER INTERNATIONAL CONFERENCE, VOL 3, NEW YORK: AMER SOC MECHANICAL ENGINEERS , 2010, p. 183-189Conference paper (Refereed)
    Abstract [en]

    Attention has been given to enhance boiling surfaces in order to decrease the temperature difference and to increase heat transfer coefficient. Structured surfaces may provide both surface enlargement and artificial nucleation sites, thus ameliorate the heat transfer coefficient. The goal of the present experimental work is to analyze the influence on heat transfer coefficient (HTC) of enhanced surface structures coated on mini channel heat exchanger working in a closed loop thermosyphon system. Experimental tests were carried out with three types of surface enhanced mini channel evaporators: smooth surface, threaded structure and nanoporous coating. The evaporators are single channel half circularly shaped, adapted for filming purpose, measuring 30mm in length and 3mm in diameter. Surface areas of channels are 1.41cm(2). Experiments were conducted in refrigerant 134a at 4.87bar (reduced pressure pr=0.12) and at heat fluxes ranging from 0.7W/cm(2) to 63.8W/cm(2). A high speed video camera was used for visualization of the two-phase flow in the evaporator channel. It is shown that threaded surface provides the highest heat transfer coefficient (HTC) from no load to heat flux of 7.1W/cm(2), the nanoporous structure shows the highest performance between 7.1W/cm(2) and 49.6W/cm(2), and the smooth surface channel exhibits the best HTC from 49.6W/cm(2) and higher. In this paper, the influences of heat flux and surface structures on HTC are discussed, and the impact of refrigerant flow regimes on heat transfer performance is also highlighted.

  • 152.
    Chiu, Justin NingWei
    et al.
    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.
    ­Multistage Latent Heat Cold Thermal Energy Storage Design Analysis2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 112, no SI, p. 1438-1445Article in journal (Refereed)
    Abstract [en]

    Thermal energy storage in cooling applications contributes to improvements in overall system efficiency as well as to better energy quality management. Latent heat thermal energy storage (LHTES) is used to provide load shifted thermal energy at small temperature swing with high storage density, hence an overall more compact energy system. However, the low thermal conductivity of the majority of the phase change materials (PCMs) necessitates delicate design of the active storage unit to meet power demand (high enough energy extraction/storage per amount of time).

    A performance analysis of two LHTES configurations is carried out in this work. Thermal charge and discharge rate of single PCM is compared with multistage LHTES using a cascade design of multiple PCMs at various phase change temperatures in a submerged finned pipe heat exchanger design. The work is conducted with a validated finite element based numerical simulation for evaluation of both full charge/discharge cycle and continuous half charge/discharge cycles.

    The results show that in full charge/discharge mode, the thermal performance of a multi-PCM LHTES may be improved by 10% to 40% as compared to that of a homogeneous­­ single-PCM storage unit in terms of thermal charge/discharge rate. This is due to the capability of the multistage LHTES to maintain a higher driving temperature difference for the heat transfer process in the charging and discharging processes. In half charge/discharge cycling mode, however, the thermal power rating performance of multi-PCM storage converges towards that of the single-PCM storage in melting process, reducing thus the multi-PCM enhancement. This work provides preliminary insights to multistage latent heat cold thermal energy storage design with finned pipe heat exchanger.

  • 153.
    Chiu, Justin NingWei
    et al.
    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.
    Submerged finned heat exchanger latent heat storage design and its experimental verification2012In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 93, no SI, p. 507-516Article in journal (Refereed)
    Abstract [en]

    Thermal energy storage (TES) has shown potential in improving the overall performance in energy systems, through shifting of thermal load demand, and through matching of uneven energy availability in time and in space. Latent heat TESs demonstrate advantages over sensible heat TESs for their high storage density and small temperature swing; however, lack of accurate knowledge in novel material properties and lack in a holistic design protocol often lead to difficulties in reaching technically viable storage design. With the aim of proposing a sound latent heat based TES design-to-validation protocol, this paper covers material property characterization through Temperature-history (T-history) method, heat exchanger design through heat transfer modeling, and model validation through experimental verification. A model for submerged cylindrically finned heat exchanger latent heat storage unit with phase change material was built. The results show that performance of gelled salt-hydrate based TES can be assessed with a pure conduction based model. This material property characterization-to-model verification approach may serve as a standard in providing accurate storage design for performance evaluation.

  • 154.
    Chiu, Justin NingWei
    et al.
    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.
    Thermal Energy Storage: Climate Change Mitigation Solution?2011In: International Conference for Sustainable Energy Storage, Belfast, UK: University of Ulster , 2011Conference paper (Refereed)
    Abstract [en]

    Environmental well being and technology development are on the verge of collapsing. It has been asserted by IPCC that 30% of fauna and flora will face extinction by mid 21st century in the pursuit of business as usual path with current economic development pace. In order to minimize the anthropogenic related damage to the environment, a maximum level of 450ppm CO2 emission has to be maintained at all cost. Technologies that provide climate change mitigation solution and economic growth are hence the highlight; thermal energy storage (TES) is one among them. Energy storage provides the possibility to shift load from on peak energy demand to off peak thermal and electricity production, this results in lower energy flux in the system and therefore cuts down the marginal thermal and electricity production. This reduction in peak power demand translates to a decrease in marginal power production which, in today’s fossil fuel based economy, often pars with auxiliary and high carbon emitting thermal and electric power plants. This study provides a scenario analysis which quantifies the environmental benefit of TES implementation for the Swedish energy system. In the studied scenario, thermal energy storage will be implemented to the existing energy grid to alleviate peak electric and thermal power demand. The rate of implementation is paired with decrease in technology cost, reproduced from typical Learning Curve Model. The study shows that for the Swedish energy system, the total amount of fossil fuel used in heating of residential and service sectors is 19TWh, while reduction that can be achieved cost effectively with implementation of TES amounts to 2.5TWh. This corresponds to a Green House Gas (GHG) emission reduction of 620kton/year or 13% of total fossil fuel based emissions from heating in residential and service sectors.

     

  • 155.
    Chiu, Justin NingWei
    et al.
    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.
    Thermal energy storage for sustainable future: impact of power enhancement on storage performance2010In: International Conference on Sustainable Refrigeration and Heat Pump Technology, Stockholm, June 13-16, 2010., 2010Conference paper (Refereed)
    Abstract [en]

    Sustainable future may be reached by means of maximizing the use of renewable energies through energy storage solutions. Active thermal storage exploits the potential of storing low cost, off-peak thermal cooling and heating for use at later time. Many studies have been carried out for optimization of energy storage systems through proactive planning of storage capacity design, fine tuning of control systems, and realization of cost effective scenario modeling. In the field of latent heat based thermal energy storage with use of phase change materials (PCM), low material thermal conductivity has shown to be one of the main barriers for providing sufficient cooling and heating power to the system. Thus, despite the apparent benefit of PCM-technology when it comes to large storage energy density, practical implementation of the technology has been hampered in many cases. Although a large number of available power enhancing techniques have been reported, the influence of power enhancement to the energy storage capacity has so far not been thoroughly assessed. In this paper, we perform an evaluation of power enhancing solutions and their impact on thermal energy storage density through theoretical modeling of a set of enhancement techniques. The techniques considered are: extended surfaced heat exchangers with various fin geometries (e.g. radial fins around circular piping) as well as PCM enhanced through blending with high conductive materials. Results analyses show the importance of balancing usable power with storable energy in the design of power enhancement technology, so as to achieve the maximum storage capacity while maintaining required extraction power load.

  • 156.
    Chiu, Justin NingWei
    et al.
    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.
    Setterwall, Fredrik
    A Review of Thermal Energy Storage Systems with Salt Hydrate Phase Change Materials for Comfort Cooling2009In: 11th International Conference on Thermal Energy Storage, June 14-17 , 2009, Stockholm, Sweden., 2009Conference paper (Refereed)
    Abstract [en]

    This paper presents a review of cold thermal energy storage technologies. Latent heat thermal energy storage (LHTES) with phase change materials (PCMs) deserves attention as they provide high energy density and small temperature change interval upon melting/solidifying. Salt hydrates are especially interesting since they demonstrate high latent heat of fusion, high thermal conductivity, low flammability, and facilitate the use in buildings as compared to organic PCMs. A review of system performance obtained from experimental work, theoretical analyses and real case studies has however shown some material shortcomings. To reach cost effectiveness, future work in the field of LHTES with salt hydrates lies in finding suitable methods for limiting incongruent melting and subcooling without compromising the storage density. Also, system integration of LHTES in cold applications can be further developed in terms of innovative design for high power and storage capacity, load optimized sizing, controls, and elimination of PCM encapsulation.

  • 157.
    Chiu, Justin NingWei
    et al.
    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.
    Setterwall, Fredrik
    Next Generation Cost Effective Phase Change Materials: TUD Action COST-STSM-TU0802-052552009Report (Other academic)
  • 158.
    Chiu, Justin NingWei
    et al.
    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.
    Setterwall, Fredrik
    System Integration of Latent Heat Thermal Energy Storage Systems for Comfort Cooling Integrated in district cooling network2009In: 11th International Conference on Thermal Energy Storage, EFFSTOCK 2009, Stockholm, Sweden, June 14-17, 2009., 2009Conference paper (Refereed)
    Abstract [en]

    Latent heat thermal energy storage for comfort cooling with phase change materials (PCMs) has increasingly gained attention. For effective system integration, an optimized strategy for load shifting to cut down peak hour energy use is needed. With the focus on overall system performance, this paper addresses matching of a cold storage capacity and power to a demand while assessing the cost effectiveness of the PCM technology. A simulation model based on one office building cooling load in Stockholm Sweden was used. Storage capacity, power output and PCM cost were shown to be the predominant factors in a system design. It has been found that load leveling can cost effectively reduce the peak load by 5% to 9% in a fixed tariff system. However, with 50% reduction in today’s PCM price combined with removal of district cooling return temperature penalty, the peak power reduction rate may be increased to 30%.

  • 159.
    Chiu, Justin NW
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Alfasfos, Rami
    Swedblomb, Magnus
    Stymneb, Staffan
    Olivier, Jean-François
    Johansson, Bertil
    Cavern Thermal Energy Storagefor District Cooling2018Other (Refereed)
    Abstract [en]

    Sweden currently accounts for 926 GWh of yearly district cooling production from forty one utility plants in 2015 (Statistics Sweden, 2016). The total potential cooling demand is estimated to be actually 2000-5000 GWh/yr (Swedish District Heating Association, 2017), increase in the cooling demand in the long run is thus expected. Nonetheless in the short term, large fluctuation between consecutive years has been observed: 10% increase in 2013 and 11% decrease in 2015 (Statistics Sweden, 2016). A successful transition and backup reserve solution is necessary to cope with such fluctuation, especially for DC network that is expending to reach out to additional customers.

  • 160.
    Chiu, NingWei Justin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Latent Heat Thermal Energy Storage for Indoor Comfort Control2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Equating Earth’s existence to 24 hours, we, the Homo sapiens, came about in the last four seconds. Fossil fuel came to our knowledge with mass extraction dating from the Industrial Revolution two centuries ago, in other words 4 milliseconds out of Earth’s 24-hour equivalent lifetime. With the unruly use of fossil fuel based resources, global temperature increase due to anthropogenic emission is projected by the Intergovernmental Panel on Climate Change (IPCC) to increase between 2 °C and 6 °C by 2100. The expected results are unprecedented climatic phenomena, such as intense tropical cyclones, extreme heat waves, and heavy precipitation among others. Limiting climate change has become one of the most discerning issues in our highly energy dependent society.

    Ever-increasing energy demand goes in hand with improved living standard due to technologic and economic progress. Behavioral change is one of the ultimate solutions to reduce energy demand through adequate life style change; however such approach requires societal paradigm shift. In this thesis, we look into using energy storage technology to peak shave and to load shift energy so as to attain increased renewable energy source utilization, improved system’s energy efficiency, and reduced Greenhouse Gas (GHG) emission without compromising living comfort.

    High energy density thermal energy storage (TES) systems utilize phase change materials as storage mediums where thermal energy is principally stored in the form of latent heat (LH). Advantages of such systems are compact components and small storage temperature swing. However, challenges remain in implementing LHTES to the built environment, namely lack of understanding of system dynamics, uncertainty in component design, and non-documented material property are to be addressed.

    The goal of this thesis is to address the issues on material property characterization, on component heat transfer study and on system integration. A methodology in measuring material’s thermo physical property through T-History setup is defined. Caveats of existing methodology are presented and improvements are proposed. The second part of this thesis consists of establishing valid numerical models of LHTES component for both shape stabilized and free flowing PCMs. Experimental verifications were performed and models were validated. Improvement to the thermal power performance was studied and was reached with multistage multi-PCM storage design. Techno-economic optimization and parametric study were carried out for transient TES integrated system study. Finally, an estimation of the Swedish peak energy demand reduction was performed through study of TES implementation to the existing energy systems. The peak energy shave attained through TES implementation determines the amount of fossil fuel based marginal energy that can be reduced for a greener environment.

  • 161.
    Chiu, NingWei Justin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Recent Development in Phase Change Materials for Thermal Energy Storage2012In: BIT's 1st Annual World Congress of Advanced Materials 2012: Innovation, Cutting-Edge and Smartness / [ed] International Research Center of International Talent, Beijing China, 2012, p. 299-300Conference paper (Refereed)
    Abstract [en]

    Phase change materials (PCMs) have in the past years been in the center of research focus as an energy saving alternative. They have large potential for use in applications where intermittent energy sources are present and where shift of energy supply from user demand in time and in space is required. Examples are solar heating, night time ambient air cooling, and waste heat utilization amongst others. The materials store and release heat through change of phase from solid to liquid in endothermic process and from liquid to solid in exothermic process.

    There are currently two major axes of PCM development driven application-wise. In passive thermal energy storage (TES) systems where the predominant role of PCMs is to serve as insulating material, thermal properties of the PCMs are tailored towards low thermal conductivity so as to limit heat transfer rate. In active TES, however, the research interest has been put in ameliorating the overall thermal power output. Various methods are dispersion of highly conductive particles, impregnation of PCM in graphite matrices, and novel design of heat exchanger apparatus.

    The second research axe lies in improvement of material compatibility with the considered applications. Inorganic PCMs are characterized with subcooling effect, this means start of heat release well below the phase change temperature. While this can be used in the advantage for long term seasonal heat storage, in active cold storage systems where the working temperature range is relatively small, subcooling is to be limited in order to provide efficient thermal charge and discharge cycle. Furthermore, efforts have been put in limiting phase separation; this has a predominant role in assuring the energy storage stability for repeated charge/discharge cycles.

    This presentation will provide insights to the recent material development in the field of thermal energy storage.

  • 162.
    Chiu, NingWei Justin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Castro Flores, José Fiacro
    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, Applied Thermodynamics and Refrigeration.
    Le Corre, Olivier
    École des Mines de Nantes, Energy Systems and Environment.
    Lacarrière, Bruno
    École des Mines de Nantes, Energy Systems and Environment.
    Environomic Assessment of Industrial Surplus Heat Transportation2015In: Smart Energy Infrastructure and Storage Options, 2015Conference paper (Refereed)
    Abstract [en]

    The fourth generation low temperature district heating network (LTDH) has to meet challenges in supplying low temperature heat, achieving low grid losses, integrating renewable heat sources, assimilating smart energy system and ensuring suitable planning structure. The new generation LTDH has promising potential in utilizing low grade waste heat where heat at temperature of as low as 55°C can be injected into the system. Industry generated surplus heat is often released to the ambient environment due to their remote location from end users. A solution is presented here to exploit the potential of recycling low grade industrial surplus heat for use in LTDH network.

    Mobile Thermal Energy Storage (M-TES) is used for shifting thermal energy to meet supply and demands that occur in different locations and that are shifted in time. M-TES technology is explored in this paper for utilization of industrial surplus heat in LTDH. Technical feasibility has been previously established with finned pipe and tube & shell type heat exchangers, however the economic justification is not always demonstrated. In this paper, parametric study on operating conditions, operating strategies and component costs will be performed. Furthermore, environmental impact from CO2 emissions due to different transportation means production will be evaluated against other heat production possibilities, such as conventional natural gas boilers. The results of the study show the optimal transportation distance, transportation means, partial/full storage operating conditions, storage means and power to energy ratio (PER) under which M-TES are technically, economically and environmentally sound for transportation of industrial surplus heat for use in the 4th generation LTDH network.

  • 163.
    Chiu, NingWei Justin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Meany, Bechara Hage
    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, Applied Thermodynamics and Refrigeration.
    Industrial Surplus Heat Utilization through Mobile Thermal Energy Storage with Enhanced Operating Strategy2015In: Greenstock: Industrial Energy Storage Application/ Transportation Energy Storage/ Grid integration, Beijing, 2015Conference paper (Refereed)
    Abstract [en]

    In Europe, 40% of the total energy use originates from the building sector and amounts to 36% of Europe’s Greenhouse Gas (GHG) emission (European Commission, 2013). With the smart use of a Phase Change Material (PCM) integrated Mobile Thermal Energy Storage (M-TES), industrial surplus heat may be transported to a District Heating (DH) network for building space heating and domestic hot water supply. Here, 2D and 3D numerical models were constructed for the design analysis of a latent heat (LH) M-TES. Thermal power performance is shown to be a tradeoff to storage capacity and varies exponentially to the shell and tube’s pitch to diameter ratio (PDR). For a fixed PDR configuration, the performance curve varies nonlinearly. Operating strategy with partial charge is shown to provide high thermal power when the demand arises, reducing thus the additional capital expenditure for extra tailor designed M-TES units. Partial storage is an essential control strategy for reaching economic sound mobile energy storage solution.

  • 164. Christoph, Richter
    et al.
    Ferruzza, Davide
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Dinter, Frank
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Haglind, Fredrik
    Identification of optimum molten salts for use as heat transfer fluids in parabolic trough CSP plants. A techno-economic comparative optimization2017In: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616Article in journal (Refereed)
    Abstract [en]

    Parabolic trough power plants using thermal oil as heat transfer fluid are the most mature concentrating solar power technology and state of the art. To further increase their efficiency and lower costs, molten salts can be used as heat transfer fluid. This results in higher operating temperature differences for improved cycle efficiencies and enables direct thermal energy storage at lower costs due to omission of the oil-to-salt heat exchanger and the need for smaller storage sizes. As a variety of salts are available to choose from, this study uses a multi-objective optimization to identify the most suitable heat transfer fluid for three locations in South Africa, Spain and Chile. The lowest values for the levelized costs of electricity (LCOE) can be found in Chile using Solar Salt as heat transfer fluid (75.0 $/MWhe). Generally, Solar Salt offers the lowest LCOE values followed by thermal oil and Hitec. The results also suggest that the choice of the heat transfer fluid is dependent on the direct normal irradiance (DNI) at each location. Thermal oil is competitive with Solar Salt in small systems at locations with low DNI values, whereas Hitec can be cheaper than thermal oil in large systems at locations with high DNI. Furthermore, it is also investigated at which freeze alert temperature set point the activation of the freeze protection system is optimal. The results indicate that this temperature should be chosen close to the solar field inlet temperature for small systems, while it can be lowered significantly for large systems to reduce electricity consumption from the freeze protection system.

  • 165.
    Chuanfeng, Liu
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Andrew
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Membrane Distillation and Applications for Water Purification in Thermal Cogeneration: A Pre-study2005Report (Refereed)
  • 166.
    Claesson, Per M.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE.
    Dobryden, Illia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    He, Yunjuan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Li, Gen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Surface Nanomechanics of Coatings and Hydrogels2019In: IOP Conference Series: Materials Science and Engineering, Institute of Physics Publishing , 2019, no 1Conference paper (Refereed)
    Abstract [en]

    Due to the increasing use of nanostructured materials and thin coatings as barrier materials, it has become of high importance to measure and understand material properties on the nm to 100 nm length scales. In this article we demonstrate and discuss how atomic force microscopy techniques can be used to this end. It is demonstrated that the classical analysis based on the assumption of a purely elastic material response is a fair approximation for relatively stiff coatings (elastic modulus order of GPa), whereas viscous responses must be considered for soft materials (apparent modulus order of MPa) such as hydrogels.

  • 167.
    Collard, Sophie
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Assessing and Predicting the Impact of Energy Conservation Measures Using Smart Meter Data2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Buildings account for around 40 percent of the primary energy consumption in Europe and in the United States. They also hold tremendous energy savings potential: 15 to 29 percent by 2020 for the European building stock according to a 2009 study from the European Commission. Verifying and predicting the impact of energy conservation measures in buildings is typically done through energy audits. These audits are costly, time-consuming, and may have high error margins if only limited amounts of data can be collected. The ongoing large-scale roll-out of smart meters and wireless sensor networks in buildings gives us access to unprecedented amounts of data to track energy consumption, environmental factors and building operation. This Thesis explores the possibility of using this data to verify and predict the impact of energy conservation measures, replacing energy audits with analytical software. We look at statistical analysis techniques and optimization algorithms suitable for building two regression models: one that maps environmental (e.g.: outdoor temperature) and operational factors (e.g.: opening hours) to energy consumption in a building, the other that maps building characteristics (e.g.: type of heating system) to regression coefficients obtained from the first model (which are used as energy-efficiency indicators) in a building portfolio. Following guidelines provided in the IPMVP, we then introduce methods for verifying and predicting the savings resulting from the implementation of a conservation measure in a building.

  • 168.
    COME, Emilia Ines
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Renewable Energy for Rural Electrification and Development in Mozambique2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Rural areas continue to be home to the majority of the population in Africa. The importance of providing modern energy to rural areas cannot, therefore, be overemphasized.  No wonder that at presently the major energy resource in Mozambique is fuel wood biomass. Total population is estimated to be 25 million and more than 80% of the energy consumed in the country comes from fuel wood biomass.

    The energy from the main grid covers about 45.3% of Mozambican population which 26.8% comes from the National Grid and the remaining 18.5% from renewables and other sources. People outside the grid are mainly those living in rural and suburban areas.

    For most rural households in the region, biomass fuels continue to be the dominant fuel of choice. The present document suggests possible options that could have greater impact on rural clean energy development. Such options could be Solar Photovoltaic and Solar Thermal energy, Wind and Micro- hydropower for pumping water or electricity generator and Biofuels. These energy options are receiving adequate attention from policy makers and are improving rural life.

    These are useful Renewable Energy sources available in the rural areas since they can supply reliable, relatively cost-effective electricity for basic needs in developing countries. They can be used to improve the lives of people in many ways, including supplying clean electricity to light homes, hospitals, schools, small shops, and other infrastructures, pumping water, etc. For example, using the natural resource of wind, sunlight, rivers and Jatropha plants can improve the lives of many people in general and those in rural areas in particular.

    This paper aims to describe and discuss the present status of renewable energy technologies in developing countries (case of Mozambique), to define the plausible ways for expanding rural electrification and improving the life conditions for the rural population.

  • 169.
    Consigny, Pierre
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Time and Space Resolved Measurements from Rocket Engines.2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 170.
    Cordova, Cordova
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Investigation of new heat exchanger design performance for solar thermal chemical heat pump2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The emergence of Thermally Driven Cooling system has received more attention recently due to its ability to utilize low grade heat from engine, incinerator or simple flat plate solar collector which are considered as renewable energy sources. ClimateWell AB located in Stockholm has been developing this cooling system based on its patented chemical heat pump technology. The heat pump with its tube shape is put under the absorber as in simple flat plate solar collector making it possible be directly attached on the roof without any additional solar collector. A high performance heat exchanger is needed by its reactor to absorb the energy efficiently during the desorption process as well as to recover heat during the absorption process. Current heat exchanger design has direct contact with the tube’s surface, yet air gaps between the tube and heat exchanger result in alower amount of heat transferred and non-uniform heat distribution across this surface. Moreover, a special treatment which cannot be done by machinery has to be performed in attaching the tube with this heat exchanger. It becomes a problem during mass production since a lot of man power is needed. A new heat exchanger design was proposed to overcome those limitations. This design has annulus which is filled with thermal fluid inside. This fluid will make perfect contact to the heat pump tube’s surface and eliminate the air gap. Furthermore, the need of man power in its production can be minimized. Even though perfect contact can be achieved, the fluid in this new design will increase thermal resistance in the radial direction. Therefore, an investigation has to be conducted to evaluate the performance of this new heat exchanger design based on heat transfer coefficient under steady state condition. The performance investigation also included the influence of various thermal fluids which will be used for this new heat exchanger. The work performed by doing simulation in COMSOL continued with validation of the result with experiment in laboratory. New heat exchanger design efficiency was only 50% while the current one was 82% during the desorption process. In this process, the fluid’s thermal conductivity was the most influencing fluid property. During absorption process, two heat recovery methods are used. First is by flowing the fluid inside the annulus and second is by using additional heat recovery pipe that is attached outside the heat exchanger surface. The first method gave the highest UA value around 34 W/K while the second one gave almost the same value as the current design which is around 11 W/K. In the first method, the thermal fluid’s viscosity strongly influenced its UA value while the second method is greatly influenced by fluid’s heat conductivity.

  • 171.
    Cortese, Ignacio
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Comparison of Utility-scale Solar Power Generation Technologies in Yunnan Province, China2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 172.
    Costanzo, Anthony
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental Investigation of Shock Wave-Boundary Layer Interaction on a Generic Oscillating Bump2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The presented research investigates the effects of shock wave boundary layer interaction on the unsteady pressure response of the surface of an oscillating structure. A simplified structure, a 2D prismatic bump, located in a straight channel is used to better understand the bending flutter phenomenon. Time-resolved measurements of the unsteady surface pressures and the instantaneous model geometry measurements are performed in order to study the effect of the shock wave on the aerodynamic load acting over the flexible generic bump. The bump is oscillated in a controlled manner with amplitude of ±0.5mm for four reduced frequencies ranging from k=0.123 to k=0.492. The experiments are performed for a transonic flow operating point characterized by an inlet Mach number of 0.69 and a total inlet pressure of 160 kPa, with an outlet Mach number and outlet static pressure of 0.79 and 106 kPa, respectively. The unsteady pressure measurements were performed using recessed mounted pressure transducers with Kulite fast response sensors. The presented results demonstrate that the shock wave induces a strong amplification of the unsteady pressure at the foot of the shock. This amplification was shown to decrease with the increase in reduced frequency, specifically between k=0.123 and k=0.246.

  • 173.
    Dahlqvist, Johan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Cavity Purge Flows in High Pressure Turbines2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Turbomachinery forms the principal prime mover in the energy and aviation industries. Due to its size, improvements to this fleet of machines have the potential of significant impact on global emissions. Due to high gas temperatures in stationary gas turbines and jet engines, areas of flow mixing and cooling are identified to benefit from continued research. Here, sensitive areas are cooled through cold air injection, but with the cost of power to compress the coolant to appropriate pressure. Further, the injection itself reduces output due to mixing losses.A turbine testing facility is center to the study, allowing measurement of cooling impact on a rotating low degree of reaction high pressure axial turbine. General performance, flow details, and cooling performance is quantified by output torque, pneumatic probes, and gas concentration measurement respectively. The methodology of simultaneously investigating the beneficial cooling and the detrimental mixing is aimed at the cavity purge flow, used to purge the wheelspace upstream of the rotor from hot main flow gas.Results show the tradeoff between turbine efficiency and cooling performance, with an efficiency penalty of 1.2 %-points for each percentage point of massflow ratio of purge. The simultaneous cooling effectiveness increase is about 40 %-points, and local impact on flow parameters downstream of the rotor is of the order of 2° altered turning and a Mach number delta of 0.01. It has also been showed that flow bypassing the rotor blading may be beneficial for cooling downstream.The results may be used to design turbines with less cooling. Detrimental effects of the remaining cooling may be minimized with the flow field knowledge. Stage performance is then optimized aerodynamically, mixing losses are reduced, and the cycle output is maximized due to the reduced compression work. The combination may be used to provide a significant benefit to the turbomachinery industry and reduced associated emissions.

  • 174.
    Dahlqvist, Johan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Impulse Turbine Efficiency Calculation Methods with Organic Rankine Cycle2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A turbine was investigated by various methods of calculating its efficiency. The project was based on an existing impulse turbine, a one-stage turbine set in an organic Rankine cycle with the working fluid being R245fa.

    Various methods of loss calculation were explored in the search for a method sufficiently accurate to make valid assumptions regarding the turbine performance, while simple enough to be time efficient for use in industrial research and development.  The calculations were primarily made in an isentropic manner, only taking into account losses due to the residual velocity present in the exit flow. Later, an incidence loss was incorporated in the isentropic calculations, resulting in additional losses at off-design conditions. Leaving the isentropic calculations, the work by Tournier, “Axial flow, multi-stage turbine and compressor models” was used. The work presents a method of calculating turbine losses separated into four components: profile, trailing edge, tip clearance and secondary losses. The losses applicable to the case were implemented into the model.

    Since the flow conditions of the present turbine are extreme, the results were not expected to coincide with the results of Tournier. In order to remedy this problem, the results were compared to results obtained through computational fluid dynamics (CFD) of the turbine. The equations purposed by Tournier were correlated in order to better match the present case.

    Despite that the equations by Tournier were correlated in order to adjust to the current conditions, the results of the losses calculated through the equations did not obtain results comparable to the ones of the available CFD simulations. More research within the subject is necessary, preferably using other software tools.

  • 175.
    Dahlqvist, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fridh, Jens
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    EXPERIMENTAL INVESTIGATION OF TURBINE STAGE FLOW FIELD AND PERFORMANCE AT VARYING CAVITY PURGE RATES AND OPERATING SPEEDS2016In: PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2016, VOL 2B, AMER SOC MECHANICAL ENGINEERS , 2016Conference paper (Refereed)
    Abstract [en]

    The aspect of hub cavity purge has been investigated in a high-pressure axial low-reaction turbine stage. The cavity purge is an important part of the secondary air system, used to isolate the hot main annulus flow from cavities below the hub level. A full-scale cold-flow experimental rig featuring a rotating stage was used in the investigation, quantifying main annulus flow field impact with respect to purge flow rate as it was injected upstream of the rotor. Five operating speeds were investigated of which three with respect to purge flow, namely a high loading case, the peak efficiency, and a high speed case. At each of these operating speeds, the amount of purge flow was varied across a very wide range of ejection rates. Observing the effect of the purge rate on measurement plane averaged parameters, a minor outlet swirl decrease is seen with increasing purge flow for each of the operating speeds while the Mach number is constant. The prominent effect due to purge is seen in the efficiency, showing a similar linear sensitivity to purge for the investigated speeds. An attempt is made to predict the efficiency loss with control volume analysis and entropy production. While spatial average values of swirl and Mach number are essentially unaffected by purge injection, important spanwise variations are observed and highlighted. The secondary flow structure is strengthened in the hub region, leading to a generally increased over-turning and lowered flow velocity. Meanwhile, the added volume flow through the rotor leads to higher outlet flow velocities visible in the tip region, and an associated decreased turning. A radial efficiency distribution is utilized, showing increased impact with increasing rotor speed.

  • 176.
    Dahlqvist, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fridh, Jens
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental Investigation of Turbine Stage Flow Field and Performance at Varying Cavity Purge Rates and Operating Speeds2018In: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 140, no 3, article id 031001Article in journal (Refereed)
    Abstract [en]

    The aspect of hub cavity purge has been investigated in a high-pressure axial lowreaction turbine stage. The cavity purge is an important part of the secondary air system, used to isolate the cavities below the hub level from the hot main annulus flow. A fullscale cold-flow experimental rig featuring a rotating stage was used in the investigation, quantifying main annulus flow field impact with respect to purge flow rate as it was injected upstream of the rotor. Five operating speeds were investigated of which three with respect to purge flow, namely, a high loading design case, and two high-speed points encompassing the peak efficiency. At each of these operating speeds, the amount of purge flow was varied from 0% to 2%. Observing the effect of the purge rate on measurement plane averaged parameters, a minor flow angle decrease and Mach number increase is seen for the low speed case, while maintaining near constant values for the higher operating speeds. The prominent effect due to purge is seen in the efficiency, showing a linear sensitivity to purge of 1.3%-points for every 1% of added purge flow for the investigated speeds. While spatial average values of flow angle and Mach number are essentially unaffected by purge injection, important spanwise variations are observed and highlighted. The secondary flow structure is strengthened in the hub region, leading to a generally increased over-turning and lowered flow velocity. Meanwhile, the added volume flow through the rotor leads to higher outlet flow velocities visible at higher span, with associated decreased turning. A radial efficiency distribution is utilized, showing negative impact through span heights from 15% to 70%. Pitchwise variation of investigated flow parameters is significantly influenced by purge flow, making this a parameter to include for instance when evaluating benefits of stator clocking positions.

  • 177.
    Dahlqvist, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fridh, Jens
    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.
    TEST TURBINE INSTRUMENTATION FOR CAVITY PURGE INVESTIGATIONS2014In: The XXII Symposium on Measuring Techniques in Turbomachinery, Lyon, 4-5 September 2014, 2014Conference paper (Other academic)
    Abstract [en]

    The upstream wheelspace of the KTH Test Turbine has been instrumented with the aim of investigating cavity flow phenomena, as well as cavity-main annulus interaction. Measurements include static pressure, unsteady pressure and temperature.The stage used is of high pressure steam turbine design. The trials include investigating the design point and also a high pressure, high speed operating point, assimilating gas turbine operation. At each point, varying amounts of purge flow are superposed and the influences on the measurements studied.Initial results show considerable dependence of both operating

  • 178.
    Dargahi, Borzou
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Numerical Investigation of Various Modelling Strategies for Throttling a Transonic Compressor Rig Diffuser2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The concern of this study is modeling of the flow field in the diffuser of a 1.5 stage compressor test rig in which the mass flow is constrained at the exit of the diffuser. Constraining method is is applied through, throttling by means of a slab at the exit of the diffuser, where the flow enters the exit volute. Mass flow constraining enables achieving different mass flow rates through the machine. For this reason, modeling of the flow field in the diffuser during the throttling stages and how the compressor will be affected by that, is the question this study is answering. In attempt to answer the research questions, Ansys CFX platform has been used for numerical investigation. Various geometries of the diffuser are studied to examine the sensitivity of outflow to modelling strategies of the upstream diffuser and how the flow parameters at the outlet of the upstream compressor stage would change accordingly. In this study various geometry designs are considered including simplification of geometry according to flow behaviour in the diffuser, horizontal nozzle diffuser and annular diffuser design including slab with three sizes of outlet area.. From the model setup it is realized that extending the height of the outlet of diffuser has a significant effect on the model stability although changing the outlet area does not impact the results in terms of mass flow rate and inlet pressure profile. In addition transient studies were carried out to assess how the outlet flow is changing with the variations in the flow field at the inlet. The results indicate that the fluctuations die out before reaching the slab and do not affect the outlet flow.

  • 179.
    Darwish, Mazen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Modular Hybridization of Solar Thermal Power Plants For Developing Nations2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The current energy scenario in the developing nations with abundant sun resource (e.g. southern Mediterranean countries of Europe, Middle-East & North Africa) relies mainly on fossil fuels to supply the increasing energy demand. Although this long adopted pattern ensures electricity availability on demand at all times through the least cost proven technology, it is highly unsustainable due to its drastic impacts on depletion of resources, environmental emissions and electricity prices. Solar thermal Hybrid power plants among all other renewable energy technologies have the potential of replacing the central utility model of conventional power plants, the understood integration of solar thermal technologies into existing conventional power plants shows the opportunity of combining low cost reliable power and Carbon emission reduction.

    A literature review on the current concentrating solar power (CSP) technologies and their suitability for integration into conventional power cycles was concluded, the best option was found be in the so called Integrated solar combined cycle systems (ISCCS); the plant is built and operated like a normal combined cycle, with a solar circuit consisting of central tower receiver and heliostat field adding heat to the bottoming Rankine cycle.

    A complete model of the cycle was developed in TRNSYS simulation software and Matlab environment, yearly satellite solar insolation data was used to study the effect of integrating solar power to the cycle throw-out the year. A multi objective thermo economic optimization analysis was conducted in order to identify a set of optimum design options. The optimization has shown that the efficiency of the combined cycle can be increased resulting in a Levelized electricity cost in the range of 10 -14 USDcts /Kwhe. The limit of annual solar share realized was found to be around 7 %

    The results of the study indicate that ISCCS offers advantages of higher efficiency, low cost reliable power and on the same time sends a green message by reducing the environmental impacts in our existing power plant systems.

  • 180. Dascomb, John
    et al.
    Krothapalli, Anjaneyulu
    Fakhrai, Reza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermal conversion efficiency of producing hydrogen enriched syngas from biomass steam gasification2013In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 38, no 27, p. 11790-11798Article in journal (Refereed)
    Abstract [en]

    This paper presents the results from an experimental study on the energy conversion efficiency of producing hydrogen enriched syngas through uncatalyzed steam biomass gasification. Wood pellets were gasified using a 100 kWth fluidized bed gasifier at temperatures up to 850 degrees C. The syngas hydrogen concentration and cold gas efficiency were found to increase with both bed temperature and steam to biomass weight ratio, reaching a maximum of 51% and 124% respectively. The overall energy conversion to syngas (based on heating value) also increased with bed temperature but was inversely proportional to the steam to biomass ratio. The maximum energy conversion to syngas was found to be 68%. The conversion of energy to hydrogen (by heating value) increased with gasifier temperature and gas residence time, but was found to be independent of the S/B ratio. The maximum conversion of all energy sources to hydrogen was found to be 25%.

  • 181.
    Dayananda, Chathuri
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Ecole Mines Nantes, France.
    Jayasuriya, Jeevan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. EIT InnoEnergy Scandinavia AB, Sweden.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. EIT InnoEnergy Scandinavia AB, Sweden.
    Constructive learning methodology for distant based online education in renewable energy technologies2017In: PROCEEDINGS OF 2017 IEEE GLOBAL ENGINEERING EDUCATION CONFERENCE (EDUCON2017), IEEE , 2017, p. 1033-1041Conference paper (Refereed)
    Abstract [en]

    With the rising concerns about global warming, climate change and the rapid development in the renewable energy industry, many higher educational institutes such as engineering and technological schools around the world have started to offer various educational programs related to sustainable energy pedagogical topics. The knowledge of renewable energy will be a crucial part of scientific literacy for the future; hence it is an absolute necessity to develop easily accessible and flexible-learning approaches in order to succeed in this. Due to various factors, today, the digital online education concept is becoming very popular, both as blended on-campus and as stand-alone studies. Moreover, the traditional teacher driven education system is being also challenged and new student oriented teaching approaches are currently being identified and practiced by various educational experts. This paper discusses a case study developed by applying the learner-centered teaching concept and implemented as part of an online learning course offered for one month (14 hours of learning time was recommended per week) focusing on renewable energy technology innovations for five student groups in three countries. The methodology section of this paper discuss the application of aligned teaching methodology for designing and constructing the course, content deployment of an existing learning management tool and the implementation and course evaluation. Finally, the assessments were graded and results were analyzed to identify success of the new educational concept applied A survey questionnaire was also prepared to receive the thoughts about online learning courses and their experience with the online course performed From an overall point of view, the evaluation and the results exemplify the success and the acceptance of the offered online course by the participants providing good average grading and positive opinions of the method of implementation. Participants also expressed their greater enthusiasm and interest of participating in such online courses for renewable energy engineering, as many of the topics offered through the course are lacking in their existing or past study curriculums.

  • 182.
    de Montaignac, Renaud
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Investigation of a district heating network expansion possibility with a 60% share of renewable energy input: A case study – Sevran district heating network in France2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Climate change is making energy an important matter for scientists, politics and industries. Public concerns and energy supply limitations are changing the rules of energy markets. Fossils fuels are becoming expensive and energy policy makers encourage the development of renewable energies. Every energy sector is impacted by those changes.

    With a significant potential in reducing greenhouse-gas emissions and fossil fuels dependency, the heating market is moving towards greener solutions. It is within this context that Dalkia is developing district heating solutions. This French company is one of the two large actors in the heating market in France and try to keep being part of the energy sector.

    This thesis work was realized within Dalkia and focuses on a study case: Sevran district heating network. This network provides about 50 GWh of heat with a 60% share of renewable energy (biomass). Developing this network is one way of increasing the renewable share in France. This master thesis tackles two extension possibilities. The study case starts with drawing the state of the existing district heating network. This allows to know a consumption limit in order to keep the 60% share of renewable energy. The district heating network is then modelled with a software called Termis to know hydraulic limits. Extension projects are simulated with this same model to evaluate their technical feasibility. An economical study is finally performed. The study concludes that both extensions are technically feasible, but only one is economically relevant for Dalkia.

    This master thesis was also the opportunity to observe the French heating market from an industrial point of view. Sevran study case is a typical example of how district heating companies are changing considering economy, energy policies and public acceptance.

  • 183.
    Denbow, Christopher
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Pedagogical development and technical research in the area of geothermal power production2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This work describes the types of power plants used for geothermal power generation in the world; the dry steam power plant, the flash steam power plant and the binary cycle power plant. The objective of the MSc work was the development of learning content on the subject of geothermal power generation for the CompEdu platform in the energy department at KTH. The power plants are described from a system perspective followed by an explanation of the operation of major components. Examples and calculations are given with the aim of illustrating which parameters are most important to the operation of each plant from a performance perspective. An important point is that the report does not go into detail for auxiliary components such as piping and valves. These components are essential from the point of view of fluid handling, however are less important in terms of understanding the mode of operation of the power plant. The power plants must consider the fact that geothermal fluid is corrosive and contains non-condensable gases. The choice of the type of geothermal power plant depends on the temperature and state of the geothermal fluid being utilised (liquid or vapour dominated). The research shows that each power plant has its own significant optimisation criteria, to summarise these: the dry steam power plant uses the selected wellhead pressure for extraction of geothermal fluid to optimise power output, the flash steam power plant uses the operating conditions in the steam separator to optimise power output and the binary cycle uses the required heat exchanger area per unit of power generated to select the optimal working fluid for power generation. Finally, innovative alternatives for power generation from geothermal resources that are on the horizon are introduced.

  • 184. Deng, Hui
    et al.
    Feng, Chu
    Zhang, Wei
    Mi, Youquan
    Wang, Xunying
    Dong, Wenjing
    Wang, Baoyuan
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei University, China.
    The electrolyte-layer free fuel cell using a semiconductor-ionic Sr2Fe1.5Mo0.5O6-delta - Ce0.8Sm0.2O2-delta composite functional membrane2017In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 42, no 39, p. 25001-25007Article in journal (Refereed)
    Abstract [en]

    Commercial double Perovskite Sr2Fe1.5Mo0.5O6-delta (SFM), a high performance and redox stable electrode material for solid oxide fuel cell (SOFC), has been used for the electrolyte (layer)-free fuel cell (EFFC) and also as the cathode for the electrolyte based SOFC in a comprehensive study. The EFFC with a homogeneous mixture of Ce0.8Sm0.2O2-delta (SDC) and SFM achieved a higher power density (841 mW cm(-2)) at 550 degrees C, while the SDC electrolyte based SOFC, using the SDC-SFM composite as cathode, just reached 326 mW cm(-2) at the same temperature. The crystal structure and the morphology of the SFM-SDC composite were characterized by X-ray diffraction analysis (XRD), and scanning electron microscope (SEM), respectively. The electrochemical impedance spectroscopy (EIS) results showed that the charge transfer resistance of EFFCs were much lower than that of the electrolyte-based SOFC. To illustrate the operating principle of EFFC, we also conducted the rectification characteristics test, which confirms the existence of a Schottky junction structure to avoid the internal electron short circuiting. This work demonstrated advantages of the semiconductor-ionic SDC-SFM material for advanced EFFCs.

  • 185. Deng, Hui
    et al.
    Zhang, Wei
    Wang, Xunyin
    Mi, Youquan
    Dong, Wenjin
    Tan, Wenyi
    Zhu, Binzhu
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    An ionic conductor Ce0.8Sm0.2O2_(delta) (SDC) and semiconductor Sm0.5Sr0.5CoO3 (SSC) composite for high performance electrolyte-free fuel cell2017In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 42, no 34, p. 22228-22234Article in journal (Refereed)
    Abstract [en]

    An advanced electrolyte-free fuel cell (EFFC) was developed. In the EFFC, a composite layer made from a mixture of ionic conductor (Ce0.8Sm0.2O2_(delta), SDC) and semiconductor (Sm0.5Sr0.5CoO3, SSC) was adopted to replace the electrolyte layer. The crystal structure, morphology and electrical properties of the composite were characterized by X-ray diffraction analysis (XRD), scanning electron microscope (SEM), and electrochemical impedance spectrum (EIS). Various ratios of SDC to SSC in the composite were modulated to achieve balanced ionic and electronic conductivities and good fuel cell performances. Fuel cell with an optimum ratio of 3SDC:2SSC (wt.%) reached the maximum power density of 741 mW cm(-2) at 550 degrees C. The results have illuminated that the SDC-SCC layer, similar to a conventional cathode, can replace the electrolyte to make the EFFC functions when the ionic and electronic conductivities were balanced.

  • 186.
    Desai, Ranjit
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermo-Economic Analysis of a Solar Thermal Power Plant with a Central Tower Receiver for Direct Steam Generation2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 187.
    Dhununjoy, Rakesh Kumar
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Meeting the Challenges for Increasing the Share of Variable Renewable Energy in the Generation Mix of Mauritius2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As a Small Island Developing State (SIDS), Mauritius is exceptionally vulnerable. It faces similar threats to its survival as other SIDS, which include, inter alia, a strong reliance on a depleting natural resource base, loss of biodiversity and degradation of essential components of the ecosystem, and a heavy dependency on fossil fuels and other imported commodities that support society. Climate change, long distances that separating Mauritius from Africa and Asia, coupled with rising fuel costs exacerbates the situation considerably. Unless substantial and effective interventions are put in place soonest, the current and future generations may not be able to meet their needs.

    Being aware of the susceptibility of the island towards energy security, the Government of Mauritius is focused on diversifying the country’s energy supply, improving energy efficiency, addressing environmental and climate changes and modernizing our energy infrastructure in order to meet the challenges ahead. Besides security of supply and affordability the Government is attempting a rapid shift to a low carbon, efficient and environmentally benign energy system. This policy is integrated in a Long-Term Energy Strategy (LTES) that aims at reducing the dependency on fossil fuels and promoting energy generation from local renewable sources. However, increasing the current share of renewable energy from 20% to 35% by 2025 as  provided in the LTES, implies major investment in both RE technologies and at the same time in research studies in view to mitigate the upcoming challenges with increasing renewable generations in particular caused by VRE sources such as wind and solar.

    The aim of this thesis is therefore to identify the major problems and complexities arising with increasing share of VRE more specifically related to grid stability, security operation and power quality. The various problems related to unconscious continuous addition of VRE were identified and solutions were proposed on how to mitigate them in order to be able to reach the RE targets set out in the LTES.

  • 188. Di, J.
    et al.
    Chen, M. M.
    Wang, C. Y.
    Zheng, J. M.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Low temperature solid oxide fuel cells with SDC-carbonate electrolytes2010In: Chinese Ceramics Communications, Trans Tech Publications Inc., 2010, no 1, p. 687-690Conference paper (Refereed)
    Abstract [en]

    Composites consisting of Ce0.8Sm0.2O1.9 (SDC)-carbonate were developed as electrolytes for low temperature solid oxide fuel cells (LTSOFC). The SDC power was prepared by sol-gel method. The carbonates were binary eutectics of (Li/Na)2CO3, (Li/K)2CO3 and (K/Na)2CO3. Conductivity measurements showed that the conductivities were depended on the type of carbonates. Discontinuities were found in the Arrhenius plots for both SDC-(Li/Na)2CO3 and SDC-(Li/K)2CO3. For SDC-(Na/K)2CO3 composite electrolyte, the conductivity increased as temperature rose following one slope. Single cells based on various composites were fabricated by a uniaxial die-press method and tested at 450-600 °C. The results showed all cells exhibited improved performances upon that of pure SDC-based cell. The best power density of 532 mW cm -2 at 600 °C was achieved for LTSOFC using composite of SDC and (Li/Na)2CO3. Conductivity mechanism was also discussed.

  • 189. Dong, Wenjing
    et al.
    Yaqub, Azra
    Janjua, Naveed K.
    Raza, Rizwan
    Afzal, Muhammad
    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. Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, China.
    All in One Multifunctional Perovskite Material for Next Generation SOFC2016In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 193, p. 225-230Article in journal (Refereed)
    Abstract [en]

    Multifunctional roles of La0.2Sr0.25Ca0.45TiO3 (LSCT) perovskite material as anode, cathode, and electrolyte for low temperature solid oxide fuel cell (LT-SOFC) are discovered for the first time, and have been investigated via electrochemical impedance spectroscopy (EIS) and fuel cell (FC) measurements. LSCT resistance decreases prominently in FC environment as shown in this study. An improved performance was observed by compositing LSCT with samaria doped ceria (SDC) at 550 degrees C when the FC power density increased from tens of mW cm(-2) for the pure LSCT system up to hundreds of mW cm(-2). The improved conductivity of LSCT-SDC composite is highlighted. The multifunctionality of LSCT as cathode, anode and electrolyte could be attributed to different conducting behavior at high and low oxygen partial pressures and ionic conduction at intermediate oxygen partial pressures. These new discoveries not only indicate great potential for exploring multifunctional perovskites for the next generation SOFC, but also deepen SOFC science and develop new technologies.

  • 190. Dong, Wenjing
    et al.
    Zhang, Tianning
    Chen, Xin
    Wang, Baoyuan
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei University, China.
    Charge transport study of perovskite solar cells through constructing electron transport channels2017In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 214, no 10, article id 1700089Article in journal (Refereed)
    Abstract [en]

    Perovskite solar cells (PSC) have attracted much attention in the recent years. It is important to understand their working principle in order to uncover the reasons behind their high efficiency. In this study, the carrier transport mechanism of PSC by controlling the structure of a scaffold is investigated. CeO2 is used as an electron blocking material in PSCs to study the electron transport behavior for the first time. The influence of light absorption can be excluded because CeO2 has a similar bandgap to TiO2. A variety of scaffolds are constructed using nano-TiO2 and CeO2. The results show that electrons can transport from light absober (perovskite) to FTO electrode (external circuit) through two kinds of channels. The energy band level, as well as the electronic conductivity of the scaffolds, is are key issues that affect electron transport. Although perovskites are able to transport both electrons and holes, it is still necessary to have effective electron transport channels (ETCs) between perovskite and external circuit for the sake of high efficiency. Electrochemical impedance spectroscopy analysis suggests that the lack of such channels will result in high recombination. The number of ETCs and effecient electron-hole separation are also proven to be important for cell performance.

  • 191.
    Dulac, Adrien
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A CFD Analysis towards Flow Characteristics of three Pre-swirler Designs2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Although pre-swirlers play a determinant role in the transport of air from stationary parts to rotating holes, knowledge about their actual performance is limited. Therefore, this paper aims to relate how the pre-swirler pressure drop affects the performance of different pre-swirlers in terms of discharge coefficient, adiabatic pre-swirl effectiveness, and swirl ratio. The results are extracted from numerical simulations carried out on three different designs, two guide vanes, and a nozzle. When available, the results are compared to experimental data.

    The guide vanes have shown similar responses to the pressure drop variations. Their discharge coefficients remain relatively insensitive with an average value of 97%. The swirl ratio range from 0.704 to 1.013 and 0.703 to 1.023 respectively for a pressure drop varying from 3 to 7 bars. The adiabatic pre-swirl effectiveness is of 96% and 94%, respectively, under steady state operation.The nozzle design has shown inferior performance as compared to the guide vane designs. Its discharge coefficient remains around 91% and the swirl ratio varies between 0.678 and 1.121 for a pressure drop ranging from 3 to 10 bars. Under steady state operation, the adiabatic pre-swirl effectiveness is 1.22.

    The influence of through-flows on the aforementioned parameters was also analyzed. It was observed that the through-flow deteriorates the performance of the pre-swirlers, whether in terms of dimensionless pre-swirl effectiveness, or swirl ratio. The discharge coefficient was however not affected.

  • 192.
    Duyar, Serkan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Modeling diesel combustion in heavy duty engine using detailed chemistry approach and CFD2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Emission and fuel consumption are among the key parameters when designing a combustion system. Combustion CFD can assist in this task only if good enough accuracy is achieved regarding combustion and emission predictions.

    The aim of this master thesis is to evaluate the use of detailed reaction mechanisms (as a substitute for standard combustion model) in terms of computational time and result accuracy. Several mechanisms for n-heptane are tested. Lund University optical engine experimental case is used for this evaluation.Results showed that detailed chemistry can predict ignition accurately but differences are observed in the peak cylinder pressure. The computational time also increased significantly as size and complexity of the mechanism increased.

    Recommendations are given to improve predictions using detailed chemistry approach which is found to be an interesting approach especially for lift-off length predictions.

  • 193.
    Ebuy Teka, Axumawi
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Utilization of Alternative Fuels in Cement Pyroprocessing: the Messebo Factory case study in Ethiopia2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Energy costs and environmental standards encouraged cement manufacturers worldwide to evaluate to what extent conventional fuels (Furnace oil, Coal and Petcock) can be replaced by alternative fuels in cement production, i.e. biomass or processed waste materials like sewage sludge, MSW (municipal solid waste), Refuse Derived Fuels (RDF), Tire Derived Fuel (TDF), Plastic Derived Fuel (PDF), Biomass Derived Fuels (BDF), meat and bone meal (MBM), etc. 

    High temperature of >1500 C, long residence times of up to 10 seconds and high turbulence in the cement kiln ensure complete destruction of organic constituents in the waste materials. The main benefits of using solid alternative fuels in cement kilns include enhanced energy recovery and conservation of non-renewable fossil fuels which in other words translates into an immediate reduction of greenhouse gas emissions related not only to conventional fuel mining and utilization but also helping the cement industry to clear its image of being among the most polluting and CO2 emitting industries. Most notably, a reduction in cement production costs is also expected. 

    Varying amounts of different alternative fuels have been studied in this thesis and referred to an actual cement plant in Ethiopia, located in the northern province of Mekelle. The availability of alternative fuels in the region has been estimated. Calculations have been performed for the comparison with the reference case for each alternative fuel option. Possible technical challenges in the combustion process and the supply feed chain as well as in the resource base have been identified. The environmental benefits for the reference plant and the impact on cement costs have been evaluated and discussed. The results show a clear advantage for alternative fuel utilization, both in terms of environmental parameters and also in production costs for the cement plant. 

  • 194.
    Edström, Elin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Öberg, Christoffer
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Review of Bioenergy with Carbon Capture and Storage (BECCS) and Possibilities of Introducing a Small-Scale Unit2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the ever-increasing level of carbon dioxide in the atmosphere, there is an enormous need to find new ways to minimize CO2 emissions. One way to tackle this problem is with Bioenergy with Carbon Capture and Storage (BECCS). BECCS is a new technology, which captures CO2 from biomass and stores it geologically. As biomass is considered to be CO2-neutral, this technology creates negative emissions and could thus in the long run decrease the level of CO2 in the atmosphere.

    There is currently a large unawareness of BECCS as a mitigation technology, preventing the break through as it does not receive enough attention and most importantly enough funding or promotion by incentives. By introducing small-scale showcase units to policy makers and the industry, BECCS as a technology with its many benefits can be successfully demonstrated.

    During this project, an extensive literature review has been done in order to evaluate the current status of the technology and to investigate the maturity and possibilities in the field to introduce small-scale units. Injection sites worldwide have been contacted, to research the possibilities of external small-scale projects to inject CO2. These sites are strictly regulated and it is therefore difficult to inject as an external partner. Industry and field experts were also contacted regarding the different technologies and their scalability.

    The various capture technologies have potential to work in small scale. As most technologies, the capture technologies used in BECCS processes are first developed in micro-scale in laboratories. This means that the technologies are known to work in small scale, the problem being that they are not commercially available and therefore questions regarding reliability and economy remain to be solved.

  • 195.
    Eide, Isabelle
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Flywheel Energy Storage for Telecom Applications2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Energy storage at radio base stations is crucial in case of power failure. Short power disturbances are today generally secured by lead-acid batteries. In locations with unreliable grid supply, diesel generators are used for power backup. Flywheel energy storage is an efficient, environmentally friendly and sustainable solution to handle short power disturbances at base stations.

    This Master of Science thesis, in collaboration with Ericsson, investigates the technology of flywheels, if and how the advantages of storing kinetic energy can be used in telecom applications. Power requirements ranging from 1 to 50 kW and a backup-time from five minutes up to two hours are included in this study. Products available on the market today offer high power output with a very short discharge time. A major question in this thesis is if it is possible to supply the load with a lower power for a longer time. Flywheel rotors of composite and magnetic levitation makes is possible to reduce standby and friction losses that traditionally have been a difficulty for the technology.

    The main conclusion is that flywheels are an alternative solution for energy storage for telecom applications but there are however no products available on the market today. Conclusions of calculations and discussions with researchers are that flywheels have the potential to be feasible at locations requiring several discharge and recharge cycles per day, high power outputs and short backup times. Theoretical calculations show that higher energy contents than what the products offered today have is possible to achieve. Further development of the technology will most probably make flywheels available for a wider range of applications and capital costs will be lowered as the market grows.

  • 196.
    Einberg, Gery
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Air diffusion and solid contaminant behaviour in room ventilation: a CFD based integrated approach2005Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    One of the most fundamental human needs is fresh air. It has been estimated that people spend comparatively much time in indoor premises. That creates an elevated need for high-quality ventilation systems in buildings. The ventilation airflow rate is recognised as the main parameter for measuring the indoor air quality. It has been shown that the ventilation airflow rates have effects on respiratory diseases, on “sick building syndrome” symptoms, on productivity and perceived air quality. Ventilation is necessary to remove indoor-generated pollutants by diluting these to an acceptable level. The choice of ventilation airflow rate is often based on norms or standards in which the airflow rate is determined based on epidemiological research and field or laboratory measurements. However, the determination of ventilation flow rate is far more complex. Indoor air quality in the occupied zone can be dependent of many factors such as outdoor air quality, airflow rate, indoor generation of pollutants, moisture content, thermal environment and how the air is supplied into the human occupied zone. One needs to acknowledge the importance of air distribution which clearly affects the comfort of occupants. To design a ventilation system which considers all aspects of room ventilation can only be achieved by computer modelling. The objective of this thesis is to investigate air diffusion, indoor air quality and comfort issues by CFD (computational fluid dynamics) modelling. The crucial part of the CFD modelling is to adopt BCs (boundary conditions) for a successful and accurate modelling procedure. Assessing the CFD simulations by validated BCs enabled constructing the ventilation system virtually and various system layouts were tested to meet given design criteria. In parallel, full-scale measurements were conducted to validate the diffuser models and the implemented simplified particle-settling model. Both the simulations and the measurements reveal the full complexity of air diffusion coupled with solid contaminants. The air supply method is an important factor for distribution of heat, air velocity and solid contaminants. The influence of air supply diffuser location, contaminant source location and air supply method was tested both numerically and by measurements to investigate the influence of different parameters on the efficiency of room ventilation. As example of this, the well-known displacement ventilation is not fully able to evacuate large 10 μm airborne particles from a room. Ventilation should control the conditions in the human breathing zone and therefore the ventilation efficiency is an important parameter. A properly designed ventilation system could use less fresh air to maintain an acceptable level of contaminant concentration in the human breathing zone. That is why complete mixing of air is not recommended as the ventilation efficiency is low and the necessary airflow rate is relatively high compared to other ventilation strategies. Especially buoyancy-driven airflows from heat sources are an important part of ventilation and should not be hampered by supply airflow from the diffusers. All the results revealed that CFD presently is the only reliable method for optimising a ventilation system considering the air diffusion and contaminant level in all locations of any kind of room. The last part of the thesis addresses the possibility to integrate the CFD modelling into a building design process where architectural space geometry, thermal simulations and diffuser BCs could be embedded into a normal building design project.

  • 197.
    Ejigu, Netsanet Adgeh
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Bahir Dar Energy Center .
    Energy Modelling in Residential Houses: A Case Study of Single Family Houses in Bahir Dar City, Ethiopia2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Several studies have been conducted and revealed that household is the major energy consumer sector in developing countries like Ethiopia. This study focuses on evaluation of the existing residential energy consumption and projection of the energy demand.  

    The energy consumption has been studied by conducting survey on 350 households using stratified random sampling technique. Then the analyzed data have been used to model the energy demand and to project the future energy consumption till 2030 using LEAP (Long Range Energy Alternative Planning) simulation software.   The model is done based upon baseline scenario and energy efficiency improvement scenario (mitigation scenario).

    The total energy consumption in Bahir dar in 2014 is nearly 330 Giga watt hour per year, and of this value about 83.8% is used for cooking and TV, lighting, refrigerator, and water heater consume 7%, 4.5%, 3.5%, 1%  of the total energy and remaining 0.2% is consumed for other auxiliary appliances. The projection of the energy consumption in 2030 will be more 450 Giga-watt-hour with business as usual scenario compared to just less than 350 Giga-watt-hour with mitigation scenario.

    As the result of the poor consumption efficiency, households that use traditional biomass tend to have more primary energy intensity than household that use electricity. The consumption of electricity is projecting rapidly while charcoal and firewood will still be the significant energy sources. The potential for energy saving is from improving the efficiency of stoves. Comparing with developed countries, for example Sweden, where the energy in dwellings is mostly used for space and water heating and the energy saving mostly target on improving wall insulations, the energy saving on Bahir dar is based mostly on cooking.

    The findings obtained in this shows options to improve household energy efficiency intervention planning and to enhance the effectiveness of policy interventions. Further studies could be done on modeling of other sectors.

  • 198. Eldensten, L.
    et al.
    Kucinski, A.
    El-Dorghamy, Ahmed
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Kallner, P.
    Simonsson, N.
    Introduction of co-combustion of coal and biomass in a 315 MWth CFB boiler2005In: VGB PowerTech, ISSN 1435-3199, Vol. 85, no 8, p. 60-62+6Article in journal (Other academic)
    Abstract [en]

    Elektrocieplownie Warszawskie S.A, has tested various mixtures of coal with biomass. This has been done both as full-scale trials and in separate lab-scale investigations. The main goal of the measurement program, during full-scale trials, was to evaluate influence of co-combustion on emissions, overall efficiency and full load of boiler.

  • 199. El-Gabry, Lamyaa
    et al.
    Saha, Ranjan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fridh, Jens
    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.
    Measurements of Hub Flow Interaction on Film Cooled Nozzle Guide Vane in Transonic Annular Cascade2012In: Proceedings of the ASME Turbo Expo, ASME Press, 2012Conference paper (Refereed)
    Abstract [en]

    An experimental study has been performed in a transonic annular sector cascade of nozzle guide vanes to investigate the aerodynamic performance and the interaction between hub film cooling and mainstream flow. The focus of the study is on the endwalls, specifically the interaction between the hub film cooling and the mainstream. Carbon dioxide (CO2) has been supplied to the coolant holes to serve as tracer gas. Measurements of CO2 concentration downstream of the vane trailing edge can be used to visualize the mixing of the coolant flow with the mainstream.

    Flow field measurements are performed in the downstream plane with a 5-hole probe to characterize the aerodynamics in the vane. Results are presented for the fully cooled and partially cooled vane (only hub cooling) configurations. Data presented at the downstream plane include concentration contour, axial vorticity, velocity vectors, and yaw and pitch angles. From these investigations, secondary flow structures such as the horseshoe vortex, passage vortex, can be identified and show the cooling flow significantly impacts the secondary flow and downstream flow field. The results suggest that there is a region on the pressure side of the vane trailing edge where the coolant concentrations are very low suggesting that the cooling air introduced at the platform upstream of the leading edge does not reach the pressure side endwall, potentially creating a local hotspot.

  • 200. El-Gabry, Lamyaa
    et al.
    Saha, Ranjan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fridh, Jens
    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.
    Measurements of Hub Flow Interaction on Film Cooled Nozzle Guide Vane in Transonic Annular Cascade2015In: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 137, no 8, article id 081004Article in journal (Refereed)
    Abstract [en]

    An experimental study has been performed in a transonic annular sector cascade of nozzle guide vanes (NGVs) to investigate the aerodynamic performance and the interaction between hub film cooling and mainstream flow. The focus of the study is on the endwalls, specifically the interaction between the hub film cooling and the mainstream. Carbon dioxide (CO2) has been supplied to the coolant holes to serve as tracer gas. Measurements of CO2 concentration downstream of the vane trailing edge (TE) can be used to visualize the mixing of the coolant flow with the mainstream. Flow field measurements are performed in the downstream plane with a five-hole probe to characterize the aerodynamics in the vane. Results are presented for the fully cooled and partially cooled vane (only hub cooling) configurations. Data presented at the downstream plane include concentration contour, axial vorticity, velocity vectors, and yaw and pitch angles. From these investigations, secondary flow structures such as the horseshoe vortex, passage vortex, can be identified and show the cooling flow significantly impacts the secondary flow and downstream flow field. The results suggest that there is a region on the pressure side (PS) of the vane TE where the coolant concentrations are very low suggesting that the cooling air introduced at the platform upstream of the leading edge (LE) does not reach the PS endwall, potentially creating a local hotspot.

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