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  • 101.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental evaluation of a novel solar receiver for a micro gas-turbine based solar dish system in the KTH high-flux solar simulator2018In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 159, p. 184-195Article in journal (Refereed)
    Abstract [en]

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

  • 102.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental Flux Measurement of a High-Flux Solar Simulator using a Lambertian Target and a Thermopile Flux Sensor2016In: AIP Conference Proceedings 1734, American Institute of Physics (AIP), 2016, Vol. 1734, article id 130001Conference paper (Refereed)
    Abstract [en]

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

  • 103.
    Ajmal Khan, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Bohn Lima, Raquel
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Chaudhry, M. Asharf
    Ahmed, E.
    Abbas, Ghazanfar
    Comparative study of the nano-composite electrolytes based on samaria-doped ceria for low temperature solid oxide fuel cells (LT-SOFCs)2013In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 38, no 36, p. 16524-16531Article in journal (Refereed)
    Abstract [en]

    Ceria-based electrolyte materials have great potential in low and intermediate temperature solid oxide fuel cell applications. In the present study, three types of ceria-based nanocomposite electrolytes (LNK-SDC, LN-SDC and NK-SDC) were synthesized. One-step co-precipitation method was adopted and different techniques were applied to characterize the obtained ceria-based nano-composite electrolyte materials. TGA, XRD and SEM were used to analyze the thermal effect, crystal structure and morphology of the materials. Cubic fluorite structures have been observed in all composite electrolytes. Furthermore, the crystallite sizes of the LN-SDC, NK-SDC, LNK-SDC were calculated by Scherrer formula and found to be in the range 20 nm, 21 nm and 19 nm, respectively. These values emphasize a good agreement with the SEM results. The ionic conductivities were measured using EIS (Electrochemical Impedance Spectroscopy) with two-probe method and the activation energies were also calculated using Arrhenius plot. The maximum power density was achieved 484 mW/cm(2) of LNK-SDC electrolyte at 570 degrees C using the LiCuZnNi oxide electrodes.

  • 104.
    Akay, Haluk
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems. KTH, School of Industrial Engineering and Management (ITM), Centres, KTH Climate Action Centre, CAC. MIT, Dept Mech Engn, Cambridge, MA 02139 USA..
    Lee, Sang Hyun
    Hyundai Motor Grp, Res & Dev Div, Gyeonggi, South Korea.;Sungkyunkwan Univ, Sch Mech Engn, Gyeonggi, South Korea..
    Kim, Sang -Gook
    MIT, Dept Mech Engn, Cambridge, MA 02139 USA..
    Push-pull digital thread for digital transformation of manufacturing systems2023In: CIRP annals, ISSN 0007-8506, E-ISSN 1726-0604, Vol. 72, no 1, p. 401-404Article in journal (Refereed)
    Abstract [en]

    Current digitalized manufacturing systems do not yet achieve the goal of smart manufacturing: precise con-trol and agility under unexpected disruptions. Push-Pull Digital Thread is a solution concept to enable contex-tual data and knowledge exchange across operational and functional units in a manufacturing enterprise. The extraction of decision reasoning and functional information can be facilitated by Large Language Models proc-essing information obtained from a decision maker at the point of decision. This concept shows a potential to address critical limitations in previous endeavours for smart manufacturing systems by building a semanti-cally searchable and sharable knowledge base in manufacturing systems and beyond.

  • 105.
    Akbar, M.
    et al.
    Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    Tu, Z.
    Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    Jin, B.
    Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    Mushtaq, N.
    Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    He, Z.
    Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    Dong, W.
    Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    Wang, B.
    Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    Wang, X.
    Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Key Laboratory of Ferro & Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, 430062, PR China.
    Demonstrating the dual functionalities of CeO2–CuO composites in solid oxide fuel cells2021In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 46, no 15, p. 9938-9947Article in journal (Refereed)
    Abstract [en]

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

  • 106.
    Akbar, Nabeela
    et al.
    China Univ Geosci, Fac Mat Sci & Chem, Engn Res Ctr Nanogeo Mat, Minist Educ, 388 Lumo Rd, Wuhan 430074, Peoples R China..
    Paydar, Sara
    China Univ Geosci, Fac Mat Sci & Chem, Engn Res Ctr Nanogeo Mat, Minist Educ, 388 Lumo Rd, Wuhan 430074, Peoples R China..
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Southeast Univ, Sch Energy & Environm, Energy Storage Joint Res Ctr, Jiangsu Prov Key Lab Solar Energy Sci & Technol, 2 Si Pai Lou, Nanjing 210096, Peoples R China.
    Akbar, Muhammad
    Hubei Univ, Fac Phys & Elect Sci, Hubei Key Lab Ferro & Piezoelect Mat & Devices, Wuhan 430062, Hubei, Peoples R China..
    Shah, Muhammad Ali Kamran Yousaf
    Southeast Univ, Sch Energy & Environm, Energy Storage Joint Res Ctr, Jiangsu Prov Key Lab Solar Energy Sci & Technol, 2 Si Pai Lou, Nanjing 210096, Peoples R China..
    Ge, Wen
    China Univ Geosci, Fac Mat Sci & Chem, Engn Res Ctr Nanogeo Mat, Minist Educ, 388 Lumo Rd, Wuhan 430074, Peoples R China..
    Zhu, Bin
    China Univ Geosci, Fac Mat Sci & Chem, Engn Res Ctr Nanogeo Mat, Minist Educ, 388 Lumo Rd, Wuhan 430074, Peoples R China.;Southeast Univ, Sch Energy & Environm, Energy Storage Joint Res Ctr, Jiangsu Prov Key Lab Solar Energy Sci & Technol, 2 Si Pai Lou, Nanjing 210096, Peoples R China..
    Tunning tin-based perovskite as an electrolyte for semiconductor protonic fuel cells2022In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 47, no 8, p. 5531-5540Article in journal (Refereed)
    Abstract [en]

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

  • 107.
    Akdemir, Gabriel
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Tellgren, Sebastian
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Styr- och reglerstrategier i termisktenergilager med fasändring2020Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today the energy usage and storage is a crucial subject around the world as the need for energy is largerthan ever. In thermodynamics, three current methods exist for thermal storage: sensible heat storage,latent heat storage, and heat storage by chemical reaction. The sensible heat storage is currently themost commonly used one and involves storing heat by shifting the temperature for the storage mediumwithout causing a phase change. The latent heat storage is very much similar but with the dierencethat the medium goes through a phase change. Finally the thermochemical heat storage which diersfrom the two earlier methods by utilizing the advantage of reversible chemical processes.The purpose of this thesis is rst to establish a literature study on current studies and applications oncontrol strategy's for primarily latent heat storage, but for sensible as well. The literature study willbe composed of scientic articles and books, and a few interviews. The second part of this thesis is togenerate concept solutions for latent heat storage control strategies and a nalized design is visualizedby CAD.Based on the literature study, it can be concluded that the control technique between sensible heatstorage and latent heat storage varies because of the principles of storage. Sensible heat storage usesthe transfer uid as the material of storage which facilitate the control strategy as it is therefore only amatter of ow rate. Latent heat storage's have the transfer uid and the material of storage separatedand it requires a heat transfer process between them. Therefore, controlling the latent heat storage becomesnot only a matter of ow rate but also of contact area and conduction. On top of this, the storagematerial changes phase, which causes a reduction in power over time due to thermal resistance, andthe storage capacity will decrease because storage material for latent heat storage usually deteriorateover time. Since the storage principles dier between latent and sensible heat storage's, the establishedcontrol strategy for sensible heat storage's cannot be easily applied to latent heat storage's. Controlstrategies for latent heat storage's need to be developed, but as each challenge for latent heat storage isa dicult control-technical challenge, advanced control technology and strategy are therefore required.The result of the literature study consists of summary of all the source material to conclude the resultin matrix form and a discussion that suggested control strategy for latent heat storage is a lowdeveloped subject. The state of charge for latent heat storage is a matter that has been researchedbut has no result yet with an obvious strategy to measure the state of charge. Sensible heat storagehave control strategy solutions that could work for latent heat storage such as a general control of thelatent heat storage by a human operator or a production plan.The result on the concept creation solved a group of control strategy problems that was formulated forlatent heat storage. These are to hold constant mass ow and power, holding constant power but tobe able to adjust the mass ow, atten the power curve for the latent heat storage such that it fulllsthe requirements on power, and to calibrate the state of charge when the storage capacity has reduceddue to deterioration of the storage material. The concepts was evaluated for their pros and cons anda nal design was constructed from the best concepts. The design solves all the problems formulated,however to be something to regard as a product suggestion for a latent heat storage the design needsto solve more or all control strategy problems.

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  • 108.
    Akhlagi, Ali
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    A Modelica-based framework for modeling and optimization of microgrids2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Microgrids have lately drawn much attention due to their considerable financial benefits and the increasing concerns about environmental issues. A solution that can address different engineering problems - from design to operation - is desired for practical reasons and to ensure consistency of the analyses. In this thesis, the capabilities of a Modelicabased framework is investigated for various microgrid optimization problems. Various sizing and scheduling problems are successfully formulated and optimized using nonlinear and physical component models, covering both electrical and thermal domains. Another focus of the thesis is to test the optimization platform when varying the problem formulation; performance and robustness tests have been performed with different boundary conditions and system setups. The results show that the technology can effectively handle complex scheduling strategies such as Model Predictive Control and Demand Charge Management. In sizing problems, although the platform can efficiently size the components while simultaneously solving for the economical load dispatch for short horizons (weekly or monthly), the implemented approach would require adaptations to become efficient on longer horizons (yearly).

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  • 109.
    Akter, Nasrin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Energy Need Assessment and Preferential Choice Survey o fMatipukur Village in Bangladesh: Energy Need Assessment and Preferential Choice Survey of Rural People in Bangladesh2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this study is to perform a baseline energy survey to understand the existing energy demand and usepattern and to verify the feasibility of a small scale poly-generation project supported by renewable sources ofenergy (biogas based) in a rural area of Bangladesh. A poly-generation solution shall provide multiple outputservices of clean gas, electricity and arsenic free water supply. The project requires using animal dung oragricultural waste to produce biogas and electric energy. The study has analyzed the demand of domesticenergy and water of the village named ‘Matipukur’ in the Jessore district in Bangladesh. The study alsoconsidered available biomass feedstock and energy potential surrounding the village area, as well as the socioeconomicstatus of villagers. The case study included a door to door survey to collect relevant information.Three different economic groups in terms of income scale were investigated throughout the study to obtainbetter insight of the energy-water access situation, requirements and related problems in the village.

    Almost 98% household of this village relies on biomass for energy due to limited access of modern fuel. Thevillage has various biomass potential in the form of animal dung, fuel wood and agricultural waste which can beused for cooking or serve as the basis for other energy carriers. Kerosene is used for lighting. Among thedifferent fuels, dung meets about 44% of the total demand. The contribution of other fuels for domestic use is24% firewood, 22% agricultural waste, and 2% kerosene. The analytical observation found that the annualaverage energy demand of the village is 8.45 GJ per capita. The share of average demand for cooking and3lighting energy is 8.24 GJ per person/year and 0.21 GJ per person/year respectively. The energy consumptionvaries within different income groups. This study has examined the income per capita, family size, education,agricultural land holding per capita, priorities of their annual expenditure etc. which have direct influence onthe fuel consumption pattern of the household. It could be observed that expenses on energy changes as theincome level increases. About awareness of biogas opportunities and willingness to provide feedstock for apoly generation project, the majority of households answered positively, that is, indicating that they wouldcontribute. Educated respondents showed more positive attitude. Regarding changing of traditional cooking,about 95% of the respondents want to change to a more efficient and reliable cooking system to avoid healthand environmental problems associated with indoor biomass cooking.

    The study has revealed that only cow dung is not enough to produce clean energy according to demand so theco-digestion method is considered to producing biogas from various energy potentials (animal manure &agricultural waste). The poly-generation system could work with the scenario providing electricity and watersupply for the entire household and cooking gas is limited only for 2/3rd household. Rest 1/3rd household fromlow income group then could be supplied with improve cook stove to meet their daily cooking demand and tominimize indoor pollutions. It is observed that, majority of household has expressed their willingness toprovide raw materials for poly-generation plant though they are using.

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  • 110.
    Al Naami, Adam
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Techno-economic Feasibility Study of a Biogas Plant for Treating Food Waste Collected from Households in Kartamantul Region, Yogyakarta2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis presents the potential of biogas production using food waste collected from the region of Kartamantul in Yogyakarta, Indonesia. Biogas can be used for cooking and generating electricity. The study compares two different end uses or markets for utilizing the biogas in the region. The daily food waste collected in the region of Kartamantul is 120 tonnes. This corresponds to a daily biogas production of 13 087 m3. Electricity generated from biogas can replace fossil-based coal electricity while cooking biogas can substitute the common fossil fuel liquefied Petroleum Gas (LPG). The price for selling one kWh of electricity to the state owned enterprise PLN is 16.5 USD cents. The price for selling one m3 of biogas for cooking is 38.5 USD cents, which is equivalent to the available price of LPG. The study finds that the avoided emission due to the substitution of fossil-based coal electricity and cooking LPG-gas is around 64 GgCO2-eq per year.

    Considering the economical results for a life span of 20 years in the first utilization option Biogas for Electricity gives a net present value (NPV) of 2 MUSD while for the utilization option Biogas for Cooking gives a net present value (NPV) of 5.82 MUSD. The breakeven for Biogas for Electricity is 13.8 USD cents per kWhe while for Biogas for Cooking is 25.5 USD cents per m3-biogas. The study concludes that it is feasible to invest in AD plant in the region of Kartamantul where both markets are profitable and environmentally friendly. 

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  • 111.
    Al Naami, Mahdi
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Thermal Conversion of MSW a Comparison of the System Performance: Direct Combustion Versus Conversion Through Syngas in CHP Plant2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis is a study comparing two different thermal conversion paths for Municipal Solid Waste (MSW). The comparison will be focused on technical, economic and emission aspects. One path is the direct incineration of the MSW. Meanwhile the other consists of submitting the MSW to the process of gasification obtaining syngas which will be used for the production of energy. The thermal conversion is produced in a Combined Heat and Power system (CHP-system) looking at the economic, emission and technical aspects.

    CHP-incineration plant produces heat and power from mass burning MSW directly without pre-treatment and CHP-gasification plant produces heat and power from converting MSW to syngas in a gasifier and then use the syngas to produce heat and electricity. To get the result of the objective, the following questions have been answered:

    • What is the overall economic performance of the two thermal conversion paths?
    • What are the differences in emission depending on the path selected?
    • What is the overall efficiency?

    The results shows that the most profitable thermal conversion path is directly incinerated MSW in the CHP-incineration since it is a more mature technology and therefore the costs of applying it are much less than applying the other alternative, however there are other economic cases that is the opposite. In case of pollution, thermal conversion of MSW into syngas for production of heat and power is much more environmental friendly and in case of the overall efficiency is the thermal conversion of MSW into syngas higher.

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  • 112.
    Al Sayegh, Safi
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Bengtsson, Tobias
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Solenergisystem i Hammarby Sjöstad2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Problems with the current energy system, which partially relies on non-renewable fuels, are increasingly recognized. Emissions of greenhouse gases from fossil fuels may speed up global warming, which in turn leads to a number of negative consequences. Nuclear energy is risky and relies on consumption of a scarce resource. This leads to a demand of renewable energy that is also economically feasible. One possible renewable source of energy is solar energy. This thesis investigates the possibilities of new solar energy systems in Hammarby sjöstad, a relatively new urban district in Stockholm, Sweden with a focus on sustainable development. Different technical solutions are presented along with their economic value for apartment houses in Hammarby sjöstad. The systems considered are based on either electricity generation by solar cells or heat generation by solar water heaters. Different uses of the obtained energy are discussed – grid-connected systems, local direct current systems and heating of tap water. The results show that two technologies are profitable – ordinary silicon cells and thin film cells in a local direct current system. Grid-connected systems are not profitable because of the cost of power converters, and also because of prohibition of net metering in Sweden. Solar water heaters are not profitable because there is currently no subsidy available.

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    Solenergisystem i Hammarby Sjöstad
  • 113.
    Al Shadidi, Kamilla
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Oil Cooling of Electric Motor using CFD2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis investigated the heat transfer of internally oil cooled rotors in permanent magnet electric machines which are, among other things, used in hybrid vehicles or zero emission vehicles. The magnets become sensitive and can be demagnetized at high working temperatures, hence the need of cooling. The scope of this work included CFD simulations in STAR-CCM+. Three different 3D multiphase models simulating the oil propagation in the rotor were performed. A Lagrangian multiphase model combined with a fluid film model was the most suitable model for simulating the spray of the oil and the film thickness along the inner rotor wall. It was noticed that periodic boundaries caused problems for the fluid film model, therefore a complete geometry was preferred over a truncated model. The 3D solutions provided thicker film thicknesses than the analytical solutions from the fluid film thickness theory. The maximum analytical thickness was of the same order of magnitude as the surface average film thickness provided by the multiphase models. This thickness was assumed to be constant when used as the base for the fluid region in the 2D one-phase models.The study showed that aluminum was the most suitable rotor material due to its high conductive capacity, which provided a more even distribution of the temperature in the solid and hence resulted in lower overall temperatures. The cooling power increased linearly with the volumetric flow rate, however the heat transfer coefficient decreased for the higher flow rates. A volumetric flow rate of 10dl/min was recommended. A 2D model was compared to a preliminary experiment and showed that these were not correlated. The conclusion was that more experiments and simulations are needed in order to confirm the validity of the 2D model.

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    Oil Cooling of Electric Motor using CFD
  • 114.
    Al Shadidi, Kamilla
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Ghattas, Andreas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Solenergi i Norrra Djurgårdsstaden2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report will examine various solar energy technologies in order to decide if they could be applied in the Royal Seaport. The Royal Seaport is a Swedish urban district under development in Stockholm, with the goal of becoming a sustainable district. Two main techniques, solar collectors and solar cells, including sub-categories, are addressed in this report. Another sub-category, a hybrid system, will also be mentioned. The main difference between solar collectors and solar cells is the type of energy produced by the system. Solar collectors generate heat, while solar cells generate electricity.Analysis of the different systems shows that solar collectors can supply the entire domestic hot water need, during the summer, in the Royal Seaport. While the electricity from the solar cells is negligible in comparison to the buildings electricity need, even during summertime. Nevertheless, the solar cells could provide electricity to the electric vehicles that will be used in the area. A solution that is suitable for the royal Seaport would be to cover 25% of the roof area by flat plate collectors and solar cells integrated into the rest of the roof surface, i.e. 75%. With this solution, the Royal Seaport of Stockholm will achieve its objectives in the best possible way.

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    Solenergi i Norra Djurgårdsstaden
  • 115.
    Al Taweel, Maher
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    CFD simulering av kallras: Undersökning av temperatur- och luftbeteende intill höga glasfasader och i vistelsezon med golvvärme som en värmekälla2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Glass has sophisticated front properties and are used as facades in high buildings. During cold periods, these glass facades could cause thermal discomfort, due to cold downdraught. Cold downdraught can be countered by placing heaters under glass surfaces. Nowadays technology offers highly insulating windows, which is why there is an interest to investigate the indoor climate with only underfloor heating. The research in this area is limited, and few empirical methods are available. Theoretical analysis has begun but it still brand new.

    The aim of this investigation was to present the thermal indoor climate influenced by various parameters, such as outdoor temperature, U-value and the glass height. The results were also meant to be used as reference tools in future projects. A reference building was modeled in simulation software called CFD Star-CCM+.

    The assignment was initiated by Incoord, a leading consulting company in energy, indoor climate and installation planning.

    The results showed that the air velocity increases with decreasing outdoor temperature and decreases with increasing thermal insulation (lower U-value). At the edges of the glass the air velocity becomes twice as large compared to the velocity of the air in the middle of the atrium. The air velocity (maximum and average) at 0.1 m above the floor is always higher than at 2.0 m. The lowest air velocities start from about 0.25 m/s at 0 ℃ and reaches to 0.60 m/s at -20 ℃. That means these air velocities are too high for what is accepted as a good indoor climate, where the maximum allowable air velocity is 0.15 m/s.

    The outdoor temperatures and the glass facade’s U-value also have an effect on the surface temperature of the glass facade. This decreases the surface temperature with decreased outdoor temperature, and the surface temperature increases at lower U-value.

    The height of the glass facades proved to affect both the air velocity in the occupied zone and in the glass surface temperature. The air velocity increases with the glass’ height. The increase is higher at 0.1 m than at 2.0 m above the floor.

    The result shows also that the average air velocity is lower than 0,15 m/s at window height lower than 5 m. But, at the same height the maximum air velocity is higher than 0.3 m/s. The surface temperature of the glass facades increases with the glass’ height. This is because the indoor heat transfer coefficient increases with height. The outdoor heat transfer coefficient is a function of the wind speed and was assumed to be constant.

    The underfloor heating, which is represented in the simulations with a floor surface temperature of 27 ℃, is not enough to maintain a good indoor climate in any of simulations.

    The results of this thesis showed a strong relation between indoor climate, outdoor temperature, U-value and the glass height. This study also showed that the floor heating is not enough to counteract the cold draft during extreme cold periods, in high glass buildings. The presented results can be used as a reference tool for the assessment of air velocities and surface temperatures, in similar high buildings.

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    Al Taweel Maher EGI-2013-150MSC
  • 116. Alameldin, A.
    et al.
    El-Gabry, L. A.
    Fridh, Jens
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Saha, Ranjan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    CFD analysis of suction and pressure side film cooling influence on vane aero performance in a transonic annular cascade2014In: Proceedings of the ASME Turbo Expo, 2014Conference paper (Refereed)
    Abstract [en]

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

  • 117.
    Alanne, Kari
    et al.
    Department of Energy Technology, Aalto University.
    Kari, Saari
    Department of Energy Technology, Aalto University.
    Mannu, Kuosa
    Department of Energy Technology, Aalto University.
    Md., Rahman
    Department of Energy Technology, Aalto University.
    Martin, Andrew
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Microgeneration and Desalination Using Rotary Steam Engine (RTE) Technology2011Conference paper (Refereed)
    Abstract [en]

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

  • 118.
    Alanne, Kari
    et al.
    Department of Energy Technology, Aalto University.
    Saari, Kari
    Department of Energy Technology, Aalto University.
    Jokisalo, Juha
    Department of Energy Technology, Aalto University.
    Martin, Andrew R.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermo-economic analysis of a micro-cogeneration system based on a rotary steam engine (RSE)2012In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 44, p. 11-20Article in journal (Refereed)
    Abstract [en]

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

  • 119.
    Albiz, Niccolas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Identifying Relevant Versus Received Sustainability Education at Industrial Engineering and Management Programs2017In: Handbook of Theory and Practice of Sustainable Development in Higher Education Vol 3 / [ed] Walter Leal Filho, Mark Mifsud, Chris Shiel, Rudi Pretorius, Springer , 2017, p. 115-131Chapter in book (Refereed)
    Abstract [en]

    Implementing and evaluating sustainable development in higher education poses particular difficulties, as the field remains contested. This paper presents an innovative approach to understanding the current sustainability education at university programs and envisioning its desired future state. This approach is based on the convergence seen in current scientific literature within the field. This study utilized this method on Sweden's five largest industrial engineering and management programs (covering 74% of the particular population), involving 111 interviews and resulting in identification of the relevant sustainability content and mapping of the received content at these programs. This paper documents the process-oriented, as supposed to results-oriented, approach used, as well as certain key results and insights. The revealed adoption challenges were structured according to their interconnectedness, allowing points of high leverage to be found for future interventions. This paper is appealing to all who wish to conduct pre-studies to engaging in developing program curricula at larger scale through collaboration between various universities. The paper will outline the process, the key success factors (as identified by the author) and the insights that have a bearing on a broader audience than industrial engineering faculty.

  • 120.
    Albiz, Niccolas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Nilsson, Jonatan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Feasibility Study of Heating and Cooling Solutions for Wuxi Eco-City2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Wuxi city has a strong economy and is well located for an eco city project, only 128 km from Shanghai. Wuxi Eco-City is a Sino-Swedish initiative to build an environmentally friendly district. The 2.4 km2 area will include residential buildings, commercial buildings, offices and potentially a stadium. A preliminary urban plan has been made, providing housing for 20 000 people. China has a large energy demand and heating in the northern regions is responsible for around 30% of the annual energy usage. A heating solution that is efficient, scalable, sustainable and economical needs to be developed for the eco city to not increase the burden on the system. This report investigates what heating and cooling solutions would be optimal for the eco city, basing its evaluation on the performance, implementability, scalability and risk of the different solutions. A model was constructed for visualization purposes and to create a scenario of what the overall energy usage could be given certain parameters. The GSHP technology is deemed the most appropriate solution for Wuxi Eco-City and the estimated annual energy usage for the scenario was 1822 MWh.

     

    Further economic analyses of the cases when the annual heating/cooling load is low should be made to determine if there are cases in which an ASHP or a VRV system should be preferred. An alternative suggestion is to implement a minor centralized heating and cooling system using WSHPs. Studies should be performed concerning effect on Lake Taihu, economic viability, and expected performance before an implementation.

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  • 121.
    Albutov, Alexey
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Reducing Energy Consumption through Optimization of the Operating Conditions of the Gas Trunk Pipeline2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

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  • 122.
    Aldajani, Waleed
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Towards Nearly Zero-Energy Buildings Renovation2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The objective of this thesis is to investigate the potential for a nearly Zero-Energy Building (nZEB) renovation, its benefits for real estate owners in Sweden, and their ability to comply with the current Swedish definition of nZEB. The study is carried out in co-operation with the Swedish real estate company Vasakronan, one of the country’s largest real estate owners. Several energy-efficiency and renewable energy measures are implemented in a case study at the building complex Telefonplan. The improvement measures chosen are based on their proven cost-optimality and potential to bring the buildings to nZEB energy consumption levels, and are calculated using an array of tools; PVSOL, EED and Excel. The results are analyzed using Boverket’s regulation for nZEB, which was set for new builds. The economic performance of the renovation is analyzed considering capital and operational expenses, energy savings, and the increase in property value. The results show that Telefonplan failed to reach the Swedish nZEB targets with pre-selected energy efficiency measures. However, the financial results in terms of annual savings as well as raised property value can stand as a strong motivation for real estate owners to consider such investments.

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  • 123.
    ALDAJANI, WALEED
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Towards Nearly Zero-Energy Buildings Renovation: Case Study: Telefonplan2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The objective of this thesis is to investigate the potential for a nearly Zero-Energy Building (nZEB) renovation, its benefits for real estate owners in Sweden, and their ability to comply with the current Swedish definition of nZEB. The study is carried out in co-operation with the Swedish real estate company Vasakronan, one of the country’s largest real estate owners. Several energy-efficiency and renewable energy measures are implemented in a case study at the building complex Telefonplan. The improvement measures chosen are based on their proven cost-optimality and potential to bring the buildings to nZEB energy consumption levels, and are calculated using an array of tools; PVSOL, EED and Excel. The results are analyzed using Boverket’s regulation for nZEB, which was set for new builds. The economic performance of the renovation is analyzed considering capital and operational expenses, energy savings, and the increase in property value. The results show that Telefonplan failed to reach the Swedish nZEB targets with pre-selected energy efficiency measures. However, the financial results in terms of annual savings as well as raised property value can stand as a strong motivation for real estate owners to consider such investments.

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  • 124.
    Alf Svensson, Joel
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Knowledge base and perception on sustainability in the long-haul transport sector in Brazil2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    demand for truck transportation is increasing and in the shadow the CO2 (carbon dioxide) emissions. In many parts of the world the majority of the transportation of goods is done by long-haulage trucks. More than 60% of all goods transported in Brazil are made by trucks (André Luiz Cunhaa, 2011). Therefore, it is critical to find solutions and actions on how to reduce the CO2 footprint.This thesis presents an evaluation of the knowledge and perceptions of sustainability among truck drivers and long-haulage freight transport companies in Brazil. For this, surveys to drivers and with a combination of surveys and interviews to logistics companies were done. The surveys and interviews covered energy and environmental related questions such as eco-driving, alternative fuels, fuel reductions actions, emissions, engine efficiency and the EU emissions standards.It has been found that only slightly more than half of the truck drivers have education in eco-driving despite that eco-driving is considered as the strongest action for reducing fuel consumption. In addition, many drivers do not know the benefits with eco-driving. However, this lack of knowledge among the drivers is in contrast known by the logistic companies. All logistics companies stated that eco-driving can decrease the fuel consumption by 10%, based on experience. The results are also an indication that there is a connection between companies with profit and eco-driving education. For companies with profit, 70% of the truck drivers have been educated in eco-driving, whereas companies with economic loss only 50% of the truck drivers are educated eco-driving . Another finding is that around half of the driver does not know the difference between the European emissions standards, again in contrast to the logistic companies management were all contacted knew the difference, i.e. emissions. This potentially indicates a lack of knowledge exchange between the management in logistic companies and the truck drivers.In addition to eco-driving, the drivers and logistics companies consider driving outside peak hours and the use of connectivity as strong actions for reducing their fuel consumption. Increasing the load capacity and custom made truck was not a frequent answer when asking how the drivers think they can reduce their fuel consumption. A result is also that one third of the logistic companies have been considering switching from petroleum diesel to alternative fuels.Both the truck drivers and the logistic companies know that the currently used trucks are not a sustainable transportation mode. They see the lack of economic incentives as the highest barrier for a more environment friendly transportation system and not the technology needed.In order to reduce the greenhouse gas emissions from the long-haulage sector, more drivers must be educated in eco-driving and the knowledge has to be increased regarding among other the benefits with eco-driving and the difference between the Euro standards. Decreasing the amount of empty trips is also an approach that should receive more attention.

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  • 125.
    Alfasfos, Rami
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Cavern Thermal Energy Storage for District Cooling. Feasibility Study on Mixing Mechanism in Cold Thermal Energy Storage2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
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  • 126. Ali, A.
    et al.
    Rafique, A.
    Kaleemullah, M.
    Abbas, G.
    Ajmal Khan, M.
    Ahmad, M. A.
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Chinese Academy of Sciences, China.
    Effect of Alkali Carbonates (Single, Binary, and Ternary) on Doped Ceria: A Composite Electrolyte for Low-Temperature Solid Oxide Fuel Cells2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 1, p. 806-818Article in journal (Refereed)
    Abstract [en]

    Samarium-doped ceria (SDC) carbonate has become an attractive electrolyte for fuel cells because of its remarkable ion conductivity and high performance. Different doped ceria-carbonate (single-carbonate SDC, binary-carbonate SDC, and ternary-carbonate SDC) electrolytes were synthesized by the coprecipitation/oxalate method, to optimize the electrochemical performance. The structure; morphology; and thermal, optical, and surface properties have been studied using a variety of techniques. The X-ray diffraction results confirmed the successful incorporation of samarium into ceria as a crystalline structure and inclusion of carbonate, which is amorphous in nature. To analyze the conduction mechanism, direct current conductivity was measured in a H2/O2 atmosphere. Doped ceria-binary carbonate ((Li/Na)CO3-SDC) showed the best conductivity of 0.31 S cm-1 and power density of 617 mW cm-2, at 600 °C. The enhancement in the ionic conductivity and performance of the composites is due to the contribution of hybrid ions (O2-, H+). The crystallite size of the composites was in the range 21-41 nm. For the calculation of band gaps, optical absorption spectra of the synthesized powders were analyzed, and they showed a red shift with the band gap energy in the range 2.6-3.01 eV, when compared to that of pure ceria (3.20 eV).

  • 127. Ali, A.
    et al.
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Kaleem Ullah, M.
    Rafique, A.
    Wang, B.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Hubei University, China.
    Alkaline earth metal and samarium co-doped ceria as efficient electrolytes2018In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, no 4, article id 043902Article in journal (Refereed)
    Abstract [en]

    Co-doped ceramic electrolytes M0.1Sm0.1Ce0.8O2-δ (M = Ba, Ca, Mg, and Sr) were synthesized via co-precipitation. The focus of this study was to highlight the effects of alkaline earth metals in doped ceria on the microstructure, densification, conductivity, and performance. The ionic conductivity comparisons of prepared electrolytes in the air atmosphere were studied. It has been observed that Ca0.1Sm0.1Ce0.8O2-δ shows the highest conductivity of 0.124 Scm-1 at 650 °C and a lower activation energy of 0.48 eV. The cell shows a maximum power density of 630 mW cm-2 at 650 °C using hydrogen fuel. The enhancement in conductivity and performance was due to increasing the oxygen vacancies in the ceria lattice with the increasing dopant concentration. The bandgap was calculated from UV-Vis data, which shows a red shift when compared with pure ceria. The average crystallite size is in the range of 37-49 nm. DFT was used to analyze the co-doping structure, and the calculated lattice parameter was compared with the experimental lattice parameter.

  • 128.
    Ali, Amjad
    et al.
    COMSATS Univ, Dept Phys, CERL, Lahore Campus, Lahore 54000, Pakistan.;Univ Okara, Dept Phys, Okara 56300, Pakistan.;KTH, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    Bashir, Farrukh Shehzad
    COMSATS Univ, Dept Phys, CERL, Lahore Campus, Lahore 54000, Pakistan..
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. COMSATS Univ, Dept Phys, CERL, Lahore Campus, Lahore 54000, Pakistan.;Royal Inst Technol KTH, Dept Energy Technol, S-10044 Stockholm, Sweden..
    Rafique, Asia
    COMSATS Univ, Dept Phys, CERL, Lahore Campus, Lahore 54000, Pakistan..
    Ullah, Muhammad Kaleem
    COMSATS Univ, Dept Phys, CERL, Lahore Campus, Lahore 54000, Pakistan..
    Alvi, Farah
    COMSATS Univ, Dept Phys, CERL, Lahore Campus, Lahore 54000, Pakistan..
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Ghauri, Moinuddin
    COMSATS Univ Islamabad, Dept Chem Engn, Lahore Campus, Lahore 54000, Pakistan..
    Belova, Lyubov
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Structures.
    Electrochemical study of composite materials for coal-based direct carbon fuel cell2018In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 43, no 28, p. 12900-12908Article in journal (Refereed)
    Abstract [en]

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

  • 129.
    Ali, Amjad
    et al.
    COMSATS Univ Islamabad, Dept Phys, Clean Energy Res Lab CERL, Lahore 54000, Pakistan.;Univ Okara, Dept Phys, Okara 56300, Pakistan..
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. COMSATS Univ Islamabad, Dept Phys, Clean Energy Res Lab CERL, Lahore 54000, Pakistan..
    Khalil, M. Arif
    Bahauddin Zakariya Univ, Mat Simulat Res Lab MSRL, Dept Phys, Multan 60800, Pakistan..
    Hussain, M. Iqbal
    Univ Educ, Dept Phys, Lahore 54000, Pakistan..
    Electrochemical Analysis of a Titanate-Based Anode for Direct Carbon Fuel Cells2020In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 3, no 9, p. 9182-9189Article in journal (Refereed)
    Abstract [en]

    The grand challenge in the commercialization of direct carbon fuel cell (DCFC) technology is the development of a cost-effective and thermally stable material, which facilitates fast ionic and electronic conduction and exhibits good resistance for carbon deposition at electrodes. Titanate-based materials have high ionic and electronic conductivity at higher temperature. Perovskite anodes based on titanate and transition metals show a good catalytic activity for hydrocarbon fuels. Therefore, perovskite materials, based on lanthanum strontium and copper titanate La0.4Sr0.6CuxTi1-3O3-delta (x = 0.02, 0.04, 0.06, and 0.08), were synthesized using the sol-gel method and examined as anodes for DCFCs. The powders were analyzed using various characterization techniques. X-ray diffraction shows that the material has a cubic perovskite structure. The conductivity of the synthesized powder LS8CT was found to be 4.21 Scm(-1) at 600 degrees C. The button cell developed using LS8CT exhibits a performance of 61mWcm 72. at 600 degrees C. The computational study using the Wien2k code has been performed, which shows that the Fermi level is at nonzero density of states (DOS) and reveals that the compound is metallic in nature. Therefore, no forbidden region occurs between the maxima of the valence band and minima of the conduction band. Results of DOS confirm the metallic nature of the compound. On the basis of theoretical and experimental studies, it can be depicted that substitution of Cu in La0.3Sr0.7TiO3 increases the conductivity. Therefore, a La0.4Sr0.6CuxTi1-xO3-delta perovskite material can be used as an anode for DCFCs.

  • 130.
    Ali, Rashid
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Phase Change Phenomena During Fluid Flow in Microchannels2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Phase change phenomena of a fluid flowing in a micro channel may be exploited to make the heat exchangers more compact and energy efficient. Compact heat exchangers offer several advantages such as light weight, low cost, energy efficiency, capability of removing high heat fluxes and charge reduction are a few to mention. Phase change phenomena in macro or conventional channels have been investigated since long but in case of micro channels, fewer studies of phase change have been conducted and underlying phenomena during two-phase flow in micro channels are not yet fully understood. It is clear from the literature that the two-phase flow models developed for conventional channels do not perform well when extrapolated to micro scale.

    In the current thesis, the experimental flow boiling results for micro channels are reported. Experiments were conducted in circular, stainless steel and quartz tubes in both horizontal and vertical orientations. The internal diameters of steel tubes tested were 1.70 mm, 1.224 mm and the diameter of quartz tube tested was 0.781 mm. The quartz tube was coated with a thin, electrically conductive, transparent layer of Indium-Tin-Oxide (ITO) making simultaneous heating and visualization possible. Test tubes were heated electrically using DC power supply. Two refrigerants R134a and R245fa were used as working fluids during the tests. Experiments were conducted at a wide variety of operating conditions.

    Flow visualization results obtained with quartz tube clearly showed the presence of confinement effects and consequently an early transition to annular flow for micro channels. Several flow pattern images were captured during flow boiling of R134a in quartz tube. Flow patterns recorded during the experiments were presented in the form of Reynolds number versus vapour quality and superficial liquid velocity versus superficial gas velocity plots. Experimental flow pattern maps so obtained were also compared with the other flow pattern maps available in the literature showing a poor agreement. Flow boiling heat transfer results for quartz and steel tubes indicate that the heat transfer coefficient increases with heat flux and system pressure but is independent on mass flux and vapour quality. Experimental flow boiling heat transfer coefficient results were compared with those obtained using different correlations from the literature. Heat transfer experiments with steel tubes were continued up to dryout condition and it was observed that dryout conditions always started close to the exit of the tube. The dryout heat flux increased with mass flux and decreased with exit vapour quality. The dryout data were compared with some well known CHF correlations available in the literature. Two-phase frictional pressure drop for the quartz tube was also obtained under different operating conditions. As expected, two-phase frictional pressure drop increased with mass flux and exit vapour quality.

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  • 131.
    Ali, Rashid
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Dryout Characteristics During Flow Boiling of R134a in Vertical Circular Minichannels2011In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 54, no 11-12, p. 2434-2445Article in journal (Refereed)
    Abstract [en]

    In this paper, the experimental results of dryout during flow boiling in minichannels are reported and analysed. Experiments were carried out in vertical circular minichannels with internal diameters of 1.22 mm and 1.70 mm and a fixed heated length of 220 mm. R134a was used as working fluid. Mass flux was varied from 50 kg/m(2) s to 600 kg/m(2) s and experiments were performed at two different system pressures corresponding to saturation temperatures of 27 degrees C and 32 degrees C. Experimental results show that the dryout heat flux increases with mass flux and decreases with tube diameter while system pressure has no clear effect for the range of experimental conditions covered. Finally, the prediction capabilities of the well known critical heat flux (CHF) correlations are also tested.

  • 132.
    Ali, Rashid
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Claudi, Martin-Callizo
    Maqbool, Mohammad H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Flow Patterns and Flow Pattern Maps for Microchannels2010In: 2010 3rd International Conference on Thermal Issues in Emerging Technologies, Theory and Applications - Proceedings, ThETA3 2010, 2010, p. 33-42Conference paper (Refereed)
    Abstract [en]

    Dense packaging of electronic components generates very high heat fluxes and therefore results in challenges for proper thermal management of such components. Microchannel based evaporators with phase changing liquids are regarded as a promising solution for such high heat flux cooling applications. Due to confinement of flow and differences in the relative importance of governing phenomena, the two-phase flow and heat transfer characteristics of microchannels have been shown to be different from those of conventional sized channels. The fact that microchannel is an attractive cooling option but at the same time there is a clear lack of understanding of related hydrodynamic and thermal transport phenomena which provides an impetus for microchannel research. This paper presents the flow patterns and flow pattern maps obtained for an experimental study of R134a during flow boiling in a horizontal microchannel. The microchannel was a fused silica tube, the outer surface of which was coated with thin, transparent and electrically conductive layer of Indium-Tin-Oxide (ITO). The microchannel was 781 m in internal diameter and 191 mm in heated length. Operating parameters during the experiments were: mass flux 100-400 kg/m2 s, heat flux 5-45 kW/m2, saturation temperature 25 and 30 °C. A High speed camera was used with a close up lens to capture the flow patterns evolved along the channel. Flow pattern maps are presented in terms of superficial gas and liquid velocity and in terms of Reynolds number and vapor quality plots. The results are compared with some flow pattern maps for conventional and micro scale channels available in literature.

  • 133.
    Ali, Rashid
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Maqbool, Mohammad H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    A Visualization Study During Flow Boiling of R134a In A Horizontal Microchannel2010In: ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels Collocated with 3rd Joint US-European Fluids Engineering Summer Meeting, ICNMM2010, 2010, p. 85-94Conference paper (Refereed)
    Abstract [en]

    In this paper, the experimental flow boiling visualization results of a microchannel are presented and discussed. A series of visualization experiments have been conducted in a horizontal, circular, uniformly heated microchannel, to record the two-phase flow patterns evolved during the boiling process and to study the ebullition process. A high speed camera (REDLAKE HG50LE) with a maximum of 100000 fps together with tungsten lights was used to capture the images along the test section. Microchannel was made of circular fused silica tube having an internal diameter of 0.781 mm and a uniformly heated length of 191 mm. Outside of the test tube was coated with a thin, electrically conductive layer of Indium Tin Oxide (ITO) for direct heating of the test section. Refrigerant R134a was used as working fluid and experiments were performed at two different system pressures corresponding to saturation temperatures of 25 degrees C and 30 degrees C. Mass flux was varied from 100 kg/m(2)s to 400 kg/m(2)s and heat flux ranged from 5 kW/m(2) to 45 kW/m(2). Visualization results show that the bubble growth is restricted by the tube diameter which results in very short existence of isolated bubbly flow regime except essentially restricted to a very short length of test tube. Flow patterns observed along the length were: Isolated bubble, elongated bubble, slug flow, semi annular and annular flow. Rigorous boiling and increased coalescence rates were observed with increase in heat flux. Bubble frequency was observed to increase with both heat and mass flux. A comparison with our previous flow boiling visualization studies, carried out for a test tube of 1.33 mm internal diameter, shows that the number of active nucleation sites is less while the bubble frequency is higher for the current study. Mean bubble length and bubble velocity during elongated bubble flow pattern have also been calculated from the images obtained during the tests.

  • 134.
    Ali, Rashid
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Maqbool, Mohammad H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Experimental Investigation of Two-phase Pressure Drop in a Microchannel2011In: Heat Transfer Engineering, ISSN 0145-7632, E-ISSN 1521-0537, Vol. 32, no 13/14, p. 1126-1138Article in journal (Refereed)
    Abstract [en]

    Experimental results of two-phase pressure drop in a horizontal circular microchannel are reported in this paper. A test tube was made of fused silica having an internal diameter of 781 mu m with a total length of 261 mm and a heated length of 191 mm. The outer surface of the test tube was coated with an electrically conductive thin layer of ITO (indium tin oxide) for direct heating of the test section. Refrigerants R134a and R245fa were used as the working fluids, and mass flux during the experiments was varied between 100 and 650 kg/m(2)-s. Experiments were performed at two different system pressures corresponding to saturation temperatures of 25 degrees C and 30 degrees C for R134a and at three different system pressures corresponding to saturation temperatures of 30 degrees C, 35 degrees C, and 40 degrees C for R245fa. Two-phase frictional pressure drop characteristics with variation of mass flux, vapor fraction, saturation temperature, and heat flux were explored in detail. Finally, the prediction capability of some well-known correlations available in the literature, some developed for macrochannels and others especially developed for microchannels, was assessed.

  • 135.
    Ali, Rashid
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Maqbool, Mohammad H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Flow Boiling Heat Transfer Characteristics of a Minichannel up to Dryout Condition2011In: Journal of heat transfer, ISSN 0022-1481, E-ISSN 1528-8943, Vol. 133, no 8, p. 081501-Article in journal (Refereed)
    Abstract [en]

    In this paper, the experimental flow boiling heat transfer results of a minichannel are presented. A series of experiments was conducted to measure the heat transfer coefficients in a minichannel made of stainless steel (AISI 316) having an internal diameter of 1.70 mm and a uniformly heated length of 220 mm. R134a was used as a working fluid, and experiments were performed at two different system pressures corresponding to saturation temperatures of 27 degrees C and 32 degrees C. Mass flux was varied from 50 kg/m(2) s to 600 kg/m(2) s, and heat flux ranged from 2 kW/m(2) to 156 kW/m(2). The test section was heated directly using a dc power supply. The direct heating of the channel ensured uniform heating, which was continued until dryout was reached. The experimental results show that the heat transfer coefficient increases with imposed wall heat flux, while mass flux and vapor quality have no considerable effect. Increasing the system pressure slightly enhances the heat transfer coefficient. The heat transfer coefficient is reduced as dryout is reached. It is observed that the dryout phenomenon is accompanied with fluctuations and a larger standard deviation in outer wall temperatures.

  • 136.
    Ali, Rashid
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Maqbool, Mohammad H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Flow Boiling Heat Transfer Characteristics of a Minichannel up to Dryout Condition2010In: MNHMT2009, VOL 2, New York: AMER SOC MECHANICAL ENGINEERS , 2010, p. 25-34Conference paper (Refereed)
    Abstract [en]

    In this paper the experimental flow boiling heat transfer results of a minichannel are presented. A series of experiments was conducted to measure the heat transfer coefficients in a minichannel made of stainless steel (AISI 316) having an internal diameter of 1.7mm and a uniformly heated length of 220mm. R134a was used as working fluid and experiments were performed at two different system pressures corresponding to saturation temperatures of 27 degrees C and 32 degrees C. Mass flux was varied from 50 kg/m(2) s to 600 kg/m(2) s and heat flux ranged from 2kW/m(2) to 156 kW/m(2). The test section was heated directly using a DC power supply. The direct heating of the channel ensured uniform heating and heating was continued until dry out was reached. The experimental results show that the heat transfer coefficient increases with imposed wall heat flux while mass flux and vapour quality have no considerable effect. Increasing the system pressure slightly enhances the heat transfer coefficient. The heat transfer coefficient is reduced as dryout is reached. It is observed that dryout phenomenon is accompanied with fluctuations and a larger standard deviation in outer wall temperatures.

  • 137.
    Ali, Rashid
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Maqbool, Mohammad H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Flow Boiling Heat Transfer Of Refrigerants R134a And R245fa In A Horizontal Micro-Channel2012In: Experimental heat transfer, ISSN 0891-6152, E-ISSN 1521-0480, Vol. 25, no 3, p. 181-196Article in journal (Refereed)
    Abstract [en]

    Micro-channel-based evaporators are a promising option for high heat flux cooling applications. Micro-channels offer several advantages, including a smaller coolant inventory, superior heat transfer performance, compactness, lightness of weigh. Despite being attractive, the governing phenomena in micro-channels, especially during phase change, are less understood. This article reports the experimental flow boiling heat transfer results of refrigerants R134a and R245fa in a horizontal micro-channel. A series of experiments was conducted to measure the heat transfer coefficients in a circular micro-channel made of fused silica having an internal diameter of 781 mu m and a uniformly heated length of 191 mm. The outer surface of the test tube was coated with a thin, electrically conductive layer of indium-tin-oxide. The surface coating with the electrically conductive layer of indium-tin-oxide made it possible to visualize the flow boiling process simultaneously with uniform heating of the test section. R134a and R245fa were used as working fluids and experiments were performed at a system pressure of 7.7 bar for R134a and at 1.8 bar for R245fa, corresponding to saturation temperature of 30 degrees C. Mass flux was varied from 175 kg/m(2)s to 500 kg/m(2)s, and heat flux ranged from 5 kW/m(2) to 60 kW/m(2). A high-speed camera was used to capture the images in the case of flow boiling of R134a. The experimental results indicated that the heat transfer coefficient increased with heat flux while the mass flux proved to have a negligible effect on heat transfer coefficient.

  • 138.
    Ali, Rashid
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Maqbool, Mohammad H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Flow Boiling Heat Transfer of Refrigerants R134a and R245fa in a Horizontal Microchannel2010In: Proceedings of 2nd European Conference on Microfluidics, 2010Conference paper (Refereed)
  • 139.
    Ali, Rashid
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Maqbool, Mohammad H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Experimental investigation of two phase pressure drop in a microchannel2009In: Proceedings of 2nd Micro & Nano flows Conference, Academic Conferences Publishing, 2009Conference paper (Refereed)
  • 140.
    Ali, Rashid
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Martin-Callizo, C.
    Maqbool, Muhammad Hamayun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Study of flow boiling characteristics of a microchannel using high speed visualization2013In: Journal of heat transfer, ISSN 0022-1481, E-ISSN 1528-8943, Vol. 135, no 8, p. 081501-Article in journal (Refereed)
    Abstract [en]

    This paper presents the visualization results obtained for an experimental study of R134a during flow boiling in a horizontal microchannel. The microchannel used was a fused silica tube having an internal diameter of 781 lm, a heated length of 191mm, and was coated with a thin, transparent, and electrically conductive layer of indium-tin-oxide (ITO) on the outer surface. The operating parameters during the experiments were: mass flux 100-400 kg/m2 s, heat flux 5-45 kW/m2, saturation temperatures 25 and 30 °C, corresponding to saturation pressures of 6.65 bar and 7.70 bar and reduced pressures of 0.163 and 0.189, respectively. A high speed camera with a close up lens was used to capture the flow patterns that evolved along the channel. Flow pattern maps are presented in terms of the superficial gas and liquid velocity and in terms of the Reynolds number and vapor quality plots. The results are compared with some flow pattern maps for conventional and micro scale channels available in the literature. Rigorous boiling and increased coalescence rates were observed with an increase in the heat flux.

  • 141.
    Alisic, Rijad
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    Molinari, Marco
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Pare, P. E.
    Sandberg, Henrik
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    Maximizing Privacy in MIMO Cyber-Physical Systems Using the Chapman-Robbins Bound2020In: Proceedings of the IEEE Conference on Decision and Control, Institute of Electrical and Electronics Engineers Inc. , 2020, p. 6272-6277Conference paper (Refereed)
    Abstract [en]

    Privacy breaches of cyber-physical systems could expose vulnerabilities to an adversary. Here, privacy leaks of step inputs to linear time-invariant systems are mitigated through additive Gaussian noise. Fundamental lower bounds on the privacy are derived, which are based on the variance of any estimator that seeks to recreate the input. Fully private inputs are investigated and related to transmission zeros. Thereafter, a method to increase the privacy of optimal step inputs is presented and a privacy-utility trade-off bound is derived. Finally, these results are verified on data from the KTH Live-In Lab Testbed, showing good correspondence with theoretical results. 

  • 142.
    Alisic, Rijad
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control). KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Molinari, Marco
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration. KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    Pare, Philip E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration. KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    Sandberg, Henrik
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration. KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    Ensuring privacy of occupancy changes in smart buildings2020In: CCTA 2020 - 4th IEEE Conference on Control Technology and Applications, Institute of Electrical and Electronics Engineers Inc. , 2020, p. 871-876Conference paper (Refereed)
    Abstract [en]

    Smart building management systems rely on sensors to optimize the operation of buildings. If an unauthorized user gains access to these sensors, a privacy leak may occur. This paper considers such a potential leak of privacy in a smart residential building, and how it may be mitigated by corrupting the measurements with additive Gaussian noise. This corruption is done in order to hide when the occupancy changes in an apartment. A lower bound on the variance of any estimator that estimates the change time is derived. The bound is then used to analyze how different model parameters affect the variance. It is shown that the signal to noise ratio and the system dynamics are the main factors that affect the bound. These results are then verified on a simulator of the KTH Live-In Lab Testbed, showing good correspondence with theoretical results.

  • 143.
    Alkan, Deniz
    KTH, Superseded Departments (pre-2005), Energy Technology. KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Investigating CVT as a Transmission System Option for Wind Turbines2013Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

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

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  • 144.
    Allington, Lucy
    et al.
    Loughborough Univ, STEER Ctr, Dept Geog & Environm, Loughborough, Leics, England..
    Cannone, Carla
    Loughborough Univ, STEER Ctr, Dept Geog & Environm, Loughborough, Leics, England..
    Pappis, Ioannis
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Usher, William
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems.
    Taliotis, Constantinos
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Cyprus Inst, Nicosia, Cyprus..
    Sundin, Caroline
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Sridharan, Vignesh
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Ramos, Eunice
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Rogner, Hans-Holger
    To, Long Seng
    Loughborough Univ, STEER Ctr, Dept Geog & Environm, Loughborough, Leics, England..
    Selected 'Starter kit' energy system modelling data for selected countries in Africa, East Asia, and South America (#CCG, 2021)2022In: Data in Brief, E-ISSN 2352-3409, Vol. 42, p. 108021-, article id 108021Article in journal (Refereed)
    Abstract [en]

    Energy system modeling can be used to develop internally consistent quantified scenarios. These provide key insights needed to mobilise finance, understand market development, infrastructure deployment and the associated role of institutions, and generally support improved policymaking. However, access to data is often a barrier to starting energy system modeling, especially in developing countries, thereby causing delays to decision making. Therefore, this article provides data that can be used to create a simple zero-order energy system model for a range of developing countries in Africa, East Asia, and South America, which can act as a starting point for further model development and scenario analysis. The data are collected entirely from publicly available and accessible sources, including the websites and databases of international organisations, journal articles, and existing modeling studies. This means that the datasets can be easily updated based on the latest available information or more detailed and accurate local data. As an example, these data were also used to calibrate a simple energy system model for Kenya using the Open Source Energy Modeling System (OSeMOSYS) and three stylized scenarios (Fossil Future, Least Cost and Net Zero by 2050) for 2020-2050. The assumptions used and the results of these scenarios are presented in the appendix as an illustrative example of what can be done with these data. This simple model can be adapted and further developed by in-country analysts and academics, providing a platform for future work.

  • 145.
    Allmér, Gustaf
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Chen, Beichen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Renovering av flerbostadshus - en studie om energieffektivisering och lönsamhet2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In today’s society a large focus is put on energy systems and how our energy systems are built up. In order to make sure that we in the future still can enjoy the living standards that we are used to today, Sweden and EU have made a number of decisions on making our energy system more energy efficient and consequently reduce the usage of energy resources. By 2020 the European Union should have reduced its energy consumption by 20 % compared to 1990’s level, and by 2050, 50%. The building sector comprises a large part of Sweden’s national energy usage, and therefore strict requirements are put on improvements on the energy usage in buildings, in the near future. The goal of this study is to develop strategies on different energy efficiency measures that building owners can implement when refurbishing multifamily apartment buildings, where the technical energy saving measures and the economic incentives come hand-in-hand.The object of study is a multifamily apartment building in Södermalm, owned by a property owner. The heating of the building comes from district heating. The property is built in 1962 and will in the near future be deeply renovated. Many current heating and ventilation solutions in the building are outdated and there is great potential for improvements.A study visit to the property was carried out in order to investigate the condition of the building and thereby discover where the largest improvement potentials are and to see what energy saving measures, e.g. a supply and exhaust ventilation system with heat recovery, or low energy windows, are possible to implement in the building. The study visit showed that many of the new technologies that can be adopted in general in connection with renovation actually have the possibly to be implemented in the studied property. A wide range of areas where energy effectivising measures could be taken are studied, including old windows that leak large amounts of heat, and the fact that there is no heat recovery in the building.In order to know which measures that are suitable to implement in the studied building, an investigation on different technologies and measures for making buildings more energy efficient was carried out. Both established and traditional measures and new technologies are studied.A model for energy savings have been developed, where a simulation program and energy calculation formulas have been used. The profitability of different energy efficiency measures are analyzed using the Life Cycle Cost, LCC method, using results obtained from the technical analysis. The conclusion made from the results and analysis is that improvements in the energy performance in windows is profitable, and should if possible be made by changing the inner glass to an isolating glass, and in the cases where current windows must be replaced, by changing them to triple-glass windows with a low U-value. If the building owner presupposes a large increase in energy prices in the future, then additional isolation for the façade of the building should also be installed. According to this research a supply and exhaust ventilation system with heat recovery should be installed since this measure led to the largest economic profit.

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    Renovering av flerbostadshus
  • 146.
    Allégret-Bourdon, Davy
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Study of shock movement and unsteady pressure on 2D generic model2006In: Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity of Turbomachines / [ed] Hall, KC; Kielb, RE; Thomas, JP, 2006, p. 409-421Conference paper (Refereed)
    Abstract [en]

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

  • 147.
    Alm, Jonathan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Biogasproduktion på Utö2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

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

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    Biogasproduktion på Utö
  • 148.
    Alm, Malin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Simulering av spillvattenflödet i Solnaverkets värmepumpar2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Norrenergi has four heat pumps in their heating plant in Solna. These heat pumps use waste water from the Bromma sewage treatment plant as a heat source to produce district heating to distribute in Solna and Sundbyberg. This waste water is led into a duct where it is pumped through the evaporators of the heat pumps. The waste water is first pumped up into the first heating pump. The water that is not used in the first heat pump is passed by to be pumped up into the second heat pump, if it is in operation. In the winter months, the waste water flow into the duct is limited and the temperature can be lower. The consequence of this is that the waste water to heat pump 2 may have lower temperature, because it has already partially passed through the evaporator in heat pump 1.

    The aim of this study is to simulate this plant and investigate the possibility to optimize the distribution of the waste water to increase the total heating capacity of heat pump 1 and 2, and investigate if it is possible to operate the heat pumps with better economy.

    By developing heat pump specific equations based on measured data in the plant and build a model in Excel, these questions have been answered mathematically. The results of this study shows that it is not profitable to redistribute the waste water flow by reducing the flow into the evaporator of heat pump 1, to achieve a higher temperature of the water into heat pump 2. This is due to a lower flow through the evaporator in heat pump 1 affecting the overall heat transfer coefficient negatively, which in turn leads to a poorer heat transfer from the waste water to the refrigerant. It also results in a lower evaporation pressure within the evaporator of heat pump 1, which means the risk of freezing increases.

    To secure the operation of both heat pump 1 and 2, the heating capacity of heat pump 1 should be reduced to reach an incoming waste water temperature into heat pump 2 that is high enough to keep the second heat pump in operation.

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  • 149.
    Almebäck, Julia Linnea Hildur
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Magnius, Rebecka
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Heat Export from Supermarkets: Refrigeration Systems Field Measurements and a Techno-economic Analysis2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Supermarkets have a high energy demand where almost half of the energy is used within the refrigeration system. The refrigeration system utilises a cycle where heat is taken and rejected. The rejected heat could be recovered and utilised for other purposes, such as covering internal heating demand or be exported to other facilities. Implementation of heat recovery could create business opportunities between the supermarket and other actors involved. The aim of this thesis was to investigate the potential for heat export from the refrigeration system insupermarkets to neighbours. Case studies were conducted on three different supermarkets in Sweden. This project evaluated field measurements for the current heat recovery within the systems, investigated heat recovery during optimal operation conditions as well as a techno-economic analysis of the heatrecovery system. All three supermarkets within the study recovered heat in the current configuration. In both CG Ytterby and CG Eskilstuna, the recovered heat covered the majority of the internal heating demand. Nevertheless, there was a great potential to recover more heat, since most of the heat was rejected through the gas cooler. The system was also limited by the discharge pressure and the return temperature in the heat recovery unit. The techno-economic analyses indicated that all supermarkets had the potential to cover both internal heating demand with the recovered heat, as well as produce excess to export. It was observed to be more profitable to disconnect from the DHN and become self-sufficient. Heat export from supermarkets would create new innovative business models which can be profitable for both the supermarket and the heat consumer. To produce excess heat, the system had to operate at optimal conditions, increasing electricity usage and hence associated operational costs. This demonstrated the importance of revenues to make it an economically feasible solution.

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  • 150.
    Almulla, Youssef
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems.
    Energy-Water and Agriculture Nexus to Support the Sustainable Management of Shared Water Resources2023Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Throughout history, major rivers and shared water bodies have allowed civilizations to flourish, and the effective management of shared water bodies has always been a priority for societies and nations. Today, about 40% of the world’s population lives in proximity to the 286 transboundary river and lake basins that supply 60% of the world’s freshwater flows and make up about half of the Earth’s land area. Moreover, around 2 billion people in the world depend on groundwater sources, which include over 460 transboundary aquifer systems.

    The mismanagement of water resources can result in catastrophic disasters that are often exacerbated by a domino effect so that the impacts of poor water management often extend beyond the water system. The interdependency of the water system with other systems such as energy and food, or with land-use, highlights the importance of ”systems thinking and planning” in resource management. Such a concept is not easily encapsulated into policy-making processes in many parts of the world because consideration of the resource systems in isolation as individual entities and ‘silo” thinking still dominate. Climate change adds another layer of complexity and exacerbates the issue of water management. Another important factor is geographical location because precipitation varies among and within continents. This results in some regions suffering from water shortages and some regions facing the risks of water redundancy and floods. 

    The concept of the Water-Energy-Food (WEF) nexus was introduced in 2011 as a response to help address some of the issues mentioned above. Over the last decade, research on the WEF nexus has gained momentum in both the policy and academic areas and several methods have been introduced to operationalize the nexus in different contexts. One of the flagship methodologies is the Transboundary Basins Nexus Approach (TBNA) introduced by the United Nations Economic Commission of Europe (UNECE) in 2015 and designed to assess the nexus in shared (transboundary) water basins.

    The aim of this thesis is to support shared water management by using the WEF-nexus approach to quantify the benefits of coordinated management, motivate cooperation, and identify trade-offs in the optimal use of resources. To achieve this aim, four research questions are explored over the course of four academic publications.  

    The first question explores the role of the energy sector in motivating shared water cooperation. The second question studies the risks and opportunities emerging from the interplay between climate and renewable energy in shared basins. The third question focuses on groundwater management and explores what benefits the consideration of the energy-water-agriculture nexus could bring to shared groundwater management in water-scarce areas. The fourth question examines how consideration of the energy-water-agriculture nexus could accelerate the low-carbon transition in the agricultural sector. 

    These research questions are examined in two different, yet complementing, geographic locations. One is the Balkans in Southeastern Europe, which faces water redundancy and flood issues and the other is the Middle East and North Africa (MENA) region which suffers from water scarcity. In the first region, the Drina and the Drin River Basins represent the characteristics of Southeastern Europe while the North Western Sahara Aquifer System (NWSAS) and the Souss-Massa basin represent the characteristics of the MENA region. Three of the case applications are transboundary (Drina, Drin and NWSAS) while the last application (Souss-Massa Basin) is a subnational basin.  

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