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  • 51.
    Acuña, José
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Mogensen, Palne
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Distributed Thermal Response Tests on a Multi-pipe Coaxial Borehole Heat Exchanger2011In: HVAC & R RESEARCH, ISSN 1078-9669, E-ISSN 1938-5587, Vol. 17, no 6, p. 1012-1029Article in journal (Refereed)
    Abstract [en]

    In a distributed thermal response test, distributed temperature measurements are taken along a borehole heat exchanger during thermal response tests, allowing the determination of local ground thermal conductivities and borehole thermal resistances. In this article, the first results from six heat injection distributed thermal response tests carried out on a new, thermally insulated leg type, multi-pipe coaxial borehole heat exchanger are presented. The borehole heat exchanger consists of 1 insulated central and 12 peripheral pipes. Temperature measurements are carried out using fiber-optic cables placed inside the borehole heat exchanger pipes. Unique temperature and thermal power profiles along the borehole depth as a function of the flow rate and the total thermal power injected into the borehole are presented. A line source model is used for simulating the borehole heat exchanger thermal response and determining local variations of the ground thermal conductivity and borehole thermal resistance. The flow regime in the peripheral pipes is laminar during all distributed thermal response tests and average thermal resistances remain relatively constant, independently of the volumetric flow rate, being lower than those corresponding to U-pipe borehole heat exchangers. The thermal insulation of the central pipe significantly reduces the thermal shunt to the peripheral pipes even at low volumetric flow rates.

  • 52.
    Acuña, José
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Mogensen, Palne
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Evaluation of a coaxial borehole heat exchanger prototype2010In: Proceedings of the 14th ASME International Heat Transfer Conference, ASME Press, 2010Conference paper (Refereed)
    Abstract [en]

    Different borehole heat exchanger designs have been discussed for many years. However, the U-pipe design has dominated the market, and the introduction of new designs has been practically lacking. The interest for innovation within this field is rapidly increasing and other designs are being introduced on the market. This paper presents a general state of the art summary of the borehole heat exchanger research in the last years. A first study of a prototype coaxial borehole heat exchanger consisting of one central pipe and five external channels is also presented. The particular geometry of the heat exchanger is analyzed thermally in 2-D with a FEM software. An experimental evaluation consisting of two in situ thermal response tests and measurements of the pressure drop at different flow rates is also presented. The latter tests are carried out at two different flow directions with an extra temperature measurement point at the borehole bottom that shows the different heat flow distribution along the heat exchanger for the two flow cases. The borehole thermal resistance of the coaxial design is calculated both based on experimental data and theoretically.

  • 53.
    Acuña, José
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Mogensen, Preben
    Palne Mogensen AB.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Distributed Thermal Response Test on a U-Pipe Borehole Heat Exchanger2009In: Proc. Effstock 2009, 11th International Conference on Thermal Energy Storage, Stockholm, Sweden: Academic Conferences Publishing, 2009Conference paper (Refereed)
    Abstract [en]

    In a Distributed Thermal Response Test (DTRT) the ground thermal conductivity and boreholethermal resistance are determined at many instances along the borehole. Here, such a testis carried out at a 260 m deep water filled energy well, equipped with a U-pipe borehole heatexchanger, containing an aqueous solution of ethanol as working fluid. Distributed temperaturemeasurements are carried out using fiber optic cables placed inside the U-pipe, duringfour test phases: undisturbed ground conditions, fluid pre-circulation, constant heat injection,and borehole recovery. A line source model is used for simulating the borehole thermal response.Fluid temperature profiles during the test are presented. The results show local variationsof the ground thermal conductivity and borehole thermal resistance along the boreholedepth, as well as a deviation of the latter as compared to the one resulting from a standardthermal response test.

  • 54.
    Acuña, José
    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.
    A novel coaxial BHE: Description and first Distributed Thermal Response Test Measurements2010In: Proceedings World Geothermal Congress 2010, 2010, p. paper 2953-Conference paper (Refereed)
    Abstract [en]

    The thermal performance of a Borehole Heat Exchanger plays a significant role when defining the quality of heat exchange with the ground in Ground Source Heat Pumps. Different designs have been discussed and increased interest on innovation within this field has taken place during the last years. This paper presents the first measurement results from a 189 meters deep novel coaxial Borehole Heat Exchanger, consisting of an inner central pipe and an annular channel in direct contact with the surrounding bedrock. The measurements were taken during a distributed thermal response test using fiber optic cables installed in the energy well. Fluid temperature every ten meters along the borehole depth are presented and compared with similar measurements from a common U-pipe heat exchanger. A unique measurement of the borehole wall temperature in the coaxial collector illustrates how effective the heat transfer performance is through the annular channel.

  • 55.
    Acuña, José
    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.
    Comprehensive Summary of Borehole Heat Exchanger Research at KTH2010In: IIR/Eurotherm Sustainable Refrigeration and Heat Pump Technology Conference, Stockholm: KTH Royal Institute of Technology, 2010, p. 69-Conference paper (Refereed)
    Abstract [en]

    A research project that aims at presenting recommendations for improving the COP of ground source heat pump systems by 10-20% through better design of Borehole Heat Exchangers (BHE) is described in this paper. Experiments are carried out with temperature measurements taken in different BHE types during heat pump operation conditions as well as during the thermal response tests. It is also expected to point out methods for having natural fluid circulation in the BHE, i.e. demonstrating that the heat carrier fluid can naturally circulate thanks to temperature induced density differences along the borehole depth, and thereby avoiding the use of electricity consuming pumps. A brief background presenting the most relevant work regarding BHE research around the world is first presented, followed by a comprehensive description of the current research at KTH. Some new measurements and obtained results are presented as an estimation of to what extent the project results have been achieved is discussed. An analysis on how the project results could allow reducing the borehole depth keeping today’s Coefficient of Performance is presented.

  • 56.
    Acuña, José
    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.
    Distributed Temperature Measurements on a Multi-pipe Coaxial Borehole Heat Exchanger2011In: IEA Heat Pump Conference, International Energy Agency , 2011, p. 4.19-Conference paper (Refereed)
    Abstract [en]

    The first experiences with a multi-pipe borehole heat exchanger prototype consisting of an insulated central pipe and twelve parallel peripheral pipes are described. Secondary fluid distributed temperature measurements along the borehole depth, being the only ones of its kind in this type of heat exchanger, are presented and discussed. The measurements are carried out with fiber optic cables during heat injection into the ground, giving a detailed visualization of what happens both along the central and peripheral flow channels. The heat exchange with the ground mainly occurs along the peripheral channels and an indication of almost no thermal short circuiting, even while having large temperature differences between the down and upwards channels, is observed.

  • 57.
    Acuña, José
    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.
    Distributed thermal response tests on pipe-in-pipe borehole heat exchangers2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 109, no SI, p. 312-320Article in journal (Refereed)
    Abstract [en]

    Borehole Thermal Energy Storage systems typically use U-pipe Borehole Heat Exchangers (BHE) having borehole thermal resistances of at least 0.06 K m/W. Obviously, there is room for improvement in the U-pipe design to decrease these values. Additionally, there is a need for methods of getting more detailed knowledge about the performance of BHEs. Performing Distributed Thermal Response Tests (DTRT) on new proposed designs helps to fill this gap, as the ground thermal conductivity and thermal resistances in a BHE can be determined at many instances in the borehole thanks to distributed temperature measurements along the depth. In this paper, results from three heat injection DTRTs carried out on two coaxial pipe-in-pipe BHEs at different flow rates are presented for the first time. The tested pipe-in-pipe geometry consists of a central tube inserted into a larger external flexible pipe, forming an annular space between them. The external pipe is pressed to the borehole wall by applying a slight overpressure at the inside, resulting in good thermal contact and at the same time opening up for a novel method for measuring the borehole wall temperature in situ, by squeezing a fiber optic cable between the external pipe and the borehole wall. A reflection about how to calculate borehole thermal resistance in pipe-in-pipe BHEs is presented. Detailed fluid and borehole wall temperatures along the depth during the whole duration of the DTRTs allowed to calculate local and effective borehole thermal resistances and ground thermal conductivities. Local thermal resistances were found to be almost negligible as compared to U-pipe BHEs, and the effective borehole resistance equal to about 0.03 K m/W. The injected power was found to be almost evenly distributed along the depth.

  • 58.
    Acuña, José
    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.
    Experimental Comparison of Four Borehole Heat Exchangers2008In: Refrigeration Science and Technology Proceedings, Copenhagen: International Institute of Refrigeration, 2008, p. SEC09-W1-09Conference paper (Refereed)
    Abstract [en]

    The most common way to exchange heat with the bedrock in ground source heat pump applications is circulating a secondary fluid through a closed U-pipe loop in a vertical borehole. This fluid transports the heat from the rock to the ground source heat pump evaporator. The quality of the heat exchange with the ground and the necessary pumping power to generate the fluid circulation are dependent on the type of fluid and its flow conditions along the pipe. Four different borehole heat exchangers are tested using ethyl alcohol with 20% volume concentration. The fluid temperatures are logged at the borehole inlet, bottom, and outlet. The collectors are compared based on their borehole thermal resistance and pressure drop at different flow rates. The results indicate that the pipe dimensions play an important roll, spacers might not contribute to better heat transfer, and inner micro fins in the pipes improve the performance of the collectors.

  • 59.
    Acuña, José
    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.
    First Experiences with Coaxial Borehole Heat Exchangers2011In: Proceedings of the IIR Conference on Sources/Sinks alternative to the outside Air for HPs and AC techniques, International Institute of Refrigeration, 2011Conference paper (Refereed)
    Abstract [en]

    Some experiences with coaxial borehole heat exchanger prototypes are discussed here. Four different designs are described as they have been part of a research project at KTH: two pipe-inpipe annular designs, one multi-pipe and one multi-chamber design. A special focus is given to two of the prototypes, a pipe-in-pipe design with the external flow channel consisting of an annular cross section and partly insulated central pipe, and a multi-pipe design with twelve parallel peripheral pipes and an insulated central channel. The secondary fluid temperature profiles at low volumetric flow rates are presented for these two prototypes, measured with fiber optic cables during thermal response tests and allowing a detailed visualization of what happens along the heat exchanger depth. It is the first time this is carried out in these types of borehole heat exchangers. The measurements indicate good thermal performance and point at potential uses for these heat exchangers in different ground coupled applications.

  • 60.
    Acuña, José
    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.
    Hill, Peter
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Characterization of Boreholes: Results from a U-pipe Borehole Heat Exchanger Installation2008In: Proceedings 9th IEA Heat Pump Conference 2008: Conference Proceedings, Zurich, Switzerland: International Energy Agency , 2008, p. 4-19Conference paper (Refereed)
    Abstract [en]

    Heat exchange with the bedrock for ground source heat pumps is commonly done with the help of U-pipe energy collectors in vertical boreholes. At the moment, there exist many uncertainties about how efficient the heat transfer between the rock and the collector is. For a complete performance analysis of these systems, a 260 m deep water filled borehole is characterized, by measuring the borehole deviation, the ground water flow and the undisturbed ground temperature. Significant attention is devoted to detailed temperature measurements along the borehole depth during operation providing a complete description of the temperature variations in time both for the secondary working fluid and for the ground water. The results show a deviated borehole from the vertical direction without any relevant ground water flow. The undisturbed ground temperature gradient varies from negative to positive at approximately half of the borehole depth. The transient response of the borehole during the heat pump start up is illustrated and it is observed that there does not exist any thermal short circuiting between the down and up-going pipes when the system is in operation.

  • 61.
    Acuña, José
    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.
    Khodabandeh, Rahmat
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Weber, Kenneth
    Distributed Temperature Measurements on a U-pipe Thermosyphon Borehole Heat Exchanger With CO22010In: Refrigeration Science and Technology Proceedings, Sydney, Australia: International Institute of Refrigeration, 2010Conference paper (Refereed)
    Abstract [en]

    In thermosyphon Borehole Heat Exchangers, a heat carrier fluid circulates while exchanging heat with the ground without the need of a circulation pump, representing an attractive alternative when compared to other more conventional systems. Normally, the fluid is at liquid-vapor saturation conditions and circulation is maintained by density differences between the two phases as the fluid absorbs energy from the ground. This paper presents some experimental experiences from a 65 meter deep thermosyphon borehole heat exchanger loop using Carbon Dioxide as heat carrier fluid, instrumented with a fiber optic cable for distributed temperature measurements along the borehole depth. The heat exchanger consists of an insulated copper tube through which the liquid CO2 flows downwards, and a copper tube acting as a riser. The results show temperatures every two meters along the riser, illustrating the heat transfer process in the loop during several heat pump cycles.

  • 62.
    Adesanya, Adewale A.
    et al.
    Energy and Environmental Analysis Group, New York State Energy Research and Development Authority (NYSERDA), Albany, NY, 12203, USA; Havenergy Consulting Inc, Albany, NY, 12203, USA.
    Sommerfeldt, Nelson
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Pearce, Joshua M.
    Department of Electrical and Computer Engineering, Ivey School of Business, University of Western Ontario, London, ON, N6A 5B9, Canada.
    Achieving 100% Renewable and Self-Sufficient Electricity in Impoverished, Rural, Northern Climates: Case Studies from Upper Michigan, USA2022In: Electricity, E-ISSN 2673-4826, Vol. 3, no 3, p. 264-296Article, review/survey (Refereed)
    Abstract [en]

    The development of 100% renewable electricity (RE) systems play a pivotal role in ensuring climate stability. Many municipalities blessed with wealth, an educated and progressive citizenry, and large RE resources, have already reached 100% RE generation. Impoverished municipalities in unwelcoming environments both politically and climatically (e.g., northern latitudes with long, dark winter conditions) appear to be incapable of transitioning to renewables. This study challenges that widespread assumption by conducting a detailed technical and economic analysis for three representative municipalities in the Western Upper Peninsula of Michigan. Each municipality is simulated with their own hourly electricity demand and climate profiles using an electrical supply system based on local wind, solar, hydropower, and battery storage. Sensitivities are run on all economic and technical variables. Results show that transition to 100% RE is technically feasible and economically viable. In all baseline scenarios, the 100% RE systems produced a levelized cost of electricity up to 43% less than the centralized utility rates, which are predominantly fueled by gas and coal. Current policies, however, prevent such self-sufficient systems from being deployed, which are not only detrimental to the global environment, but also aggravate the economic depression of such regions. Potential energy savings advance the prohibitive energy justice principle.

  • 63.
    Admasu, Alemshet Ayele
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Solar PV based rural electrification in Rema rural village2011Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Energy is a basic need for the overall growth and improvements of people’s living standard.But around 2 to 3 billion people in the world have no access to electric lighting. Like otherdeveloping countries the rural electrification in Ethiopia is very low and government takessome actions to promote the investment in these areas but due to economic constraints andlow level of technological advancement the growth is very low.This study focuses on solar PV based rural electrification, its impact on environment andsocio-economic development in Rema village. Three cases studies: typical households,small scale business center and public services are considered for systematic study.Interviews from villagers, existing energy system, literature data and HOMER software areused to calculate energy demand and cost of electrification. A comparison between theresults is carried out.According to the village survey the existing PV home system has a positive impact on a socioeconomic development of the village of Rema. Solar PV electricity can be used in generatingincomes. It is also used for climate mitigation by curbing CO2 emission and can be used forclimate adaptation by reducing the deforestation and facilitate carbon sequestration. PVbased electrification of health center and schools have played a vital role in improving thequality of services. The presence of refrigerator helped to have vaccines and medicines4preserved for different types of killer diseases. The teaching-learning process of schoolsimproved due the presence of electricity. The solar powered water supply in near areasreduced the time required for fetching water and made girls to focus on their education.Most villagers has positive attitude towards the technology but unsatisfied with the currentsystem size. The high level of technical skills required for maintenance and the small numberof solar technicians’ available in the village is also a problem reported in the village. HOMERsoftware is used to model the existing energy system and the required energy demandbefore PV based rural electrification and after PV based rural electrification. A new model isdeveloped depending on the villagers demand. . Modeling result shows that 3 kWP and 12kWP were found to be enough to fulfill the demand in clinics and schools with an initialinvestment of 18576 and 80704US$, respectively and a PV size of 165 Wp, 250 Wp and 350Wp is required for households with agriculture only, mixed and small scale business income,respectively. This led a requirement of initial capital of US$ 654, 1848 and 2339,respectively. However, these initial investments are unaffordable for most of the villagers.PV systems required for households with agriculture only, has lower investment per Wattthan others, while investment per Watt for small scale business has lower than householdswith mixed type. Therefore, the battery size plays an important role in the investment,operation and maintenance costs.The two main problems associated with solar PV in rural electrification are financial capabilityand technical problems. These problems can be curbed by loan arrangement and trainingthe villagers. But to make sustainable it must be used for income generating activities.

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    MSc Thesis
  • 64.
    Adolphe, Cyril
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Commissioning the Heating and Cooling Systems on an FPSO (Floating Production Storage and Offloading facility)2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

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    fulltext
  • 65.
    af Burén, Claës
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Piska eller morot?: En studie av möjligheter och hinder samt förslag på åtgärder till förändringar inom den svenska industrin i syfte att öka energieffektiviseringsarbetet.2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Our nation is dependent on secure energy supply at competitive prices. Even though energy efficiency tools are available Sweden hasn’t achieved its full potential. The Swedish industry and its energy efficiency is affected by a number of instruments concerning climate and energy, such as energy- and carbon taxes, the European emission trading system (EU ETS) and the Swedish program for energy efficiency (PFE). 

    Optional or obligatory, today there is a difference of opinion concerning the design of energy efficiency instruments. This paper focus on the research of energy efficiency instruments in the industry and to identify potential opportunities, obstacles and give recommendations of actions to improve the energy efficiency. This paper is a part of a project,”Ett energieffektivt samhälle”,   initiated by the Royal Swedish Academy of Engineering Sciences (IVA).  The research is based on interviews with industry related representatives of companies, associations, government agencies and other independent operators.

    PFE, EKC, the environmental code, ErP, energy- and carbon taxes, ETS and the Swedish system of electricity certificates, influences the energy efficiency work. None of these instruments have an overall impact on the industry. PFE and ErP are popular instruments but EKC has to improve to be an incentive for the industry.  The environmental code is criticized for its interpretation and enforcement. Competitiveness is adversely affected by taxes and ETS in contrary to PFE and EKC. Continuously energy work is only required by PFE and the environmental code.

    Both authorities and companies have to provide clear guidelines, follow-ups and the gains to be obtained of the energy efficiency work. Authorities have to support critical investments and to avoid interfering with the competition on the market. Long-term planning, cost-effectiveness, technology neutrality and being a legitimate stakeholder is of vital importance. Companies have to provide the financial structure suited for energy efficiency work. They also have to apply a continuous and long-term efficiency work, for example by highlighting new ratios and to encourage employees to participate in the development process. Collaboration in the form of co-production between different universities, institutes, lobby-associations and companies have to be encouraged to improve knowledge exchange and reduced costs.

    The question is if energy efficiency instruments should be based on “the stick or carrot approach”? Research about energy efficiency shows, that a combination of voluntary, mandatory and economical instruments is absolutely necessary for a favourable development.  Parts with different interests and qualifications demands a number of arrangements that both is a “stick and a carrot approach” to a necessary energy efficiency work.  Many of the participants in the study underline the importance to address the heterogeneity of the parts otherwise it will disfavour the energy efficiency work when the industry moves abroad. Actually the following conclusion could be made, that the initial question about the “stick or carrot approach” must be put in a different way. About an effective energy efficiency work it’s absolutely necessary to create a combination of both “the stick and the carrot” approach and the wider look on the concept energy efficiency. It’s most important to have a very well done combination and harmonization of the instruments to support the energy efficiency work, the industry and the society at large.

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    af Burén Claës EGI-2013-100MSC
  • 66.
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Semiconductor-ionic Materials for Low Temperature Solid Oxide Fuel Cells2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

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

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

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

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

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

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

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    Doctoral Thesis of Muhammad Afzal
  • 67.
    Afzal, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Hubei University, Faculty of Physics and Electronic Science, Wuhan, Hubei, 430062, China.
    Anwar, M.
    Asghar, M. I.
    Lund, P. D.
    Jhamat, N.
    Raza, R.
    Zhu, B.
    Charge transfer, transportation, and simulation2020In: Solid Oxide Fuel Cells: From Electrolyte-Based to Electrolyte-Free Devices, Wiley , 2020, p. 319-246Chapter in book (Refereed)
    Abstract [en]

    This chapter discusses charge transfer and transportation in energy materials and devices, especially focusing on single layer or electrolyte-free fuel cells (EFFCs). Here, charge means electrons and both positive and negative ions, e.g. H+ and O2-. We will study the factors that affect the charges resulting in conduction either externally for electrons or internally for both electrons and ions in EFFCs. Theoretical simulations are carried out by considering specific characteristics EFFC processes. Moreover, the enhancement in ionic conductivity is discussed leading to superionic conduction.

  • 68.
    Afzal, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Madaan, Sushant
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Dong, Wenjing
    Raza, Rizwan
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei University, China.
    Analysis of a perovskite-ceria functional layer-based solid oxide fuel cell2017In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 42, no 27, p. 17536-17543Article in journal (Refereed)
    Abstract [en]

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

  • 69.
    Afzal, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Raza, R.
    Du, S.
    Lima, R.B.d
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei Univ, Fac Phys & Elect Technol, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Peoples R China.
    Synthesis of Ba0.3Ca0.7Co0.8Fe0.2O3-δ composite material as novel catalytic cathode for ceria-carbonate electrolyte fuel cells2015In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 178, p. 385-391Article in journal (Refereed)
    Abstract [en]

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

  • 70.
    Afzal, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Saine, Kari
    Wärtsilä Finland OyResearch and Development, WSSCVaasaFinland.
    Paro, Claus
    Wärtsilä Finland OyResearch and Development, WSSCVaasaFinland.
    Dascotte, Eddy
    Dynamic Design Solutions (DDS) NVLeuvenBelgium.
    Experimental evaluation of the inertia properties of large diesel engines2021In: Conference Proceedings of the Society for Experimental Mechanics Series, Springer , 2021, p. 205-213Conference paper (Refereed)
    Abstract [en]

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

  • 71.
    Afzal, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Saleemi, Mohsin
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Wang, Baoyuan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Zhang, Wei
    He, Yunjuan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Jayasuriya, Jeevan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Zhu, Binzhu
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fabrication of novel electrolyte-layer free fuel cell with semi-ionic conductor (Ba0.5Sr0.5Co0.8Fe0.2O3-delta- Sm0.2Ce0.8O1.9) and Schottky barrier2016In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 328, p. 136-142Article in journal (Refereed)
    Abstract [en]

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

  • 72.
    Afzal, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei University, China.
    Lanthanum-doped Calcium Manganite (La0.1Ca0.9MnO3) Cathode for Advanced Solid Oxide Fuel Cell (SOFC)2016In: Materials Today-Proceedings, Elsevier BV , 2016, Vol. 3, no 8, p. 2698-2706Conference paper (Refereed)
    Abstract [en]

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

  • 73.
    Aga, Aboma Emiru
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fuel Supply Investigation for an Externally Fired Microturbine based Micro CHP System: Case study on a selected site in Bishoftu, Ethiopia2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

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

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    Fuel Supply Investigation for an Externally Fired Microturbine based Micro CHP System
  • 74.
    Agostini Fantini, Francesco
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Izaguirre Carbonell, Javier
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    GIS-Based approach to estimate the energy requirements of the post-harvest activities in Souss-Massa basin in Morocco2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Over the last decades the Moroccan agriculture has passed through a complete transformation: due to the low workforce cost and its favourable climate, the sector has attracted the attentions of national and foreign investment and thus has expanded rapidly. Among the different productions, tomatoes proved to be one of the most profitable, generating 4.867 billion dirhams in 2016 from exports. In order to remain competitive and attractive, the sector needs to be constantly monitored and controlled: abuses of the environment and of available resources may affect or even compromise the future of the Moroccan agriculture. Energy in particular has a remarkable role and has to be analysed in order to quantify its impact over costs and environment. The aim of this study is to build a GIS-based model of tomato’s postharvest system and study the agriculture and energy nexus interactions in the Souss-Massa region. Post harvesting activities such as: Transportation, conditioning, packaging, storing and transformation of tomato, occurs within Souss-Massa’s geographical boundaries and have been the focus of in this study. Results of current system highlight the dominance of packaging activity as the main energy consumer with 77%, followed by storing, transportation and transformation with 14 %, 6% and 3% respectively. In terms of cost the transportation becomes the most relevant activity due to the cost of fuels and transport conditions. Energy costs and wastes in transportation represent 15% of the local revenues (9% Transportation, 5% Packaging and 1% Storing). Four different scenarios about the future situation have been implemented to measure the possible impact of changes in the different activities: Business as Usual (BAU), Transport Efficiency (TE), Waste Reduction (WR) and Renewable Penetration (RP). -3- In BAU current trends have been followed to forecast the total production, the export and the power generation. In TE trucks with bigger capacity have been implemented and in WR refrigeration is considered in every transport stage. Finally, in RP higher renewable penetration has been considered

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  • 75.
    Agrawal, Tarun Kumar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Sustainable production development.
    Angelis, Jannis
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Thakur, Jagruti
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems.
    Wiktorsson, Magnus
    KTH, School of Industrial Engineering and Management (ITM), Sustainable production development, Avancerad underhållsteknik och produktionslogistik.
    Kalaiarasan, Ravi
    KTH, School of Industrial Engineering and Management (ITM), Sustainable production development, Avancerad underhållsteknik och produktionslogistik.
    Enabling circularity of electric vehicle batteries-the need for appropriate traceability2021In: 2021 IEEE International Conference on Technology Management, Operations and Decisions, ICTMOD 2021, Institute of Electrical and Electronics Engineers (IEEE) , 2021Conference paper (Refereed)
    Abstract [en]

    With the increased electrification of transportation, there is a growth in the number of electric vehicles (EV) in use, and hence also discarded EV batteries. It is critical to trace the batteries so that the policy of electrification does not lead to a negative impact on sustainability. To achieve the goals of circular economy, it is necessary to consider the sustainable extended life cycle strategies of reduce, reuse and recycle. Information gathering and sharing through the supply chain is the key driver for enabling the tracking and tracing of materials and services needed. Traceability indicators across the value chain may enable the creation of a comprehensive database that aids the circular economy goals. In this study, we discuss three different circular economy business models and identify the key traceability indicators for enabling circularity in the lithium-ion battery application in the automotive sector. Insights are used to develop a framework for viable EV battery circularity, capturing three key circular economy elements and four traceability characteristics for different circularity types.

  • 76.
    Ahangar Zonouzi, S.
    et al.
    University of Tabriz, P.O. Box 51666-16471, Tabriz, Iran.
    Khodabandeh, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Safarzadeh, H.
    University of Tabriz, P.O. Box 51666-16471, Tabriz, Iran.
    Aminfar, H.
    University of Tabriz, P.O. Box 51666-16471, Tabriz, Iran.
    Mohammadpourfard, M.
    University of Tabriz, P.O. Box 51666-16471, Tabriz, Iran.
    Ghanbarpour, Morteza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Experimental study of the subcooled flow boiling heat transfer of magnetic nanofluid in a vertical tube under magnetic field2020In: Journal of thermal analysis and calorimetry (Print), ISSN 1388-6150, E-ISSN 1588-2926, Vol. 140, no 6, p. 2805-2816Article in journal (Refereed)
    Abstract [en]

    In this study, the subcooled boiling heat transfer of a Fe3O4/water magnetic nanofluid flowing through a vertical tube has been investigated experimentally in the presence and absence of a magnetic field. The magnetic field has been generated by quadrupole magnets. The subcooled boiling heat transfer coefficient and the boiling curves of the ferrofluid flow under the action of the magnetic field have been compared with those in the absence of magnetic field. The results showed that magnetic actuation contributes to have higher heat fluxes at the same wall superheat in comparison with heat fluxes achieved in the no magnetic field case. Therefore, the local subcooled boiling heat transfer coefficients are increased by the magnetic field. The maximum measured enhancement in local subcooled boiling heat transfer coefficient along the length of the tube by applying magnetic field is 46.58% at applied heat flux of 77,000 W m−2 and mass flux of 270 kg m−2 s−1. Furthermore, the enhancement of local heat transfer coefficient by applying magnetic field decreases as the applied heat flux in the subcooled boiling region is increased.

  • 77. Ahangar Zonouzi, S.
    et al.
    Khodabandeh, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Safarzadeh, H.
    Aminfar, H.
    Trushkina, Y.
    Mohammadpourfard, M.
    Ghanbarpour, Morteza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Salazar Alvarez, G.
    Experimental investigation of the flow and heat transfer of magnetic nanofluid in a vertical tube in the presence of magnetic quadrupole field2018In: Experimental Thermal and Fluid Science, ISSN 0894-1777, E-ISSN 1879-2286, Vol. 91, p. 155-165Article in journal (Refereed)
    Abstract [en]

    In this paper, the effects of applying magnetic field on hydrodynamics and heat transfer of Fe3O4/water magnetic nanofluid flowing inside a vertical tube have been studied experimentally. The applied magnetic field was resulted from quadrupole magnets located at different axial positions along the tube length. The variations of the local heat transfer coefficient and also the pressure drop of the ferrofluid flow along the length of the tube by applying the magnetic quadrupole field have been investigated for different Reynolds numbers. The obtained experimental results show maximum enhancements of 23.4%, 37.9% and 48.9% in the local heat transfer coefficient for the magnetic nanofluid with 2 vol% Fe3O4 in the presence of the quadrupole magnets located at three different axial installation positions for the Reynolds number of 580 and the relative increase in total pressure drop by applying the magnetic field is about 1% for Re = 580. The increase of the heat transfer coefficient is due to the radial magnetic force toward the heated wall generated by magnetic quadrupole field acting over the ferrofluid flowing inside the tube so that the velocity of the ferrofluid in the vicinity of the heated wall is increased. It is also observed that the enhancement of heat transfer coefficient by applying magnetic quadrupole is decreased with increasing the Reynolds number.

  • 78.
    Ahl, Amanda
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Eklund, Johanna
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    A Study of the Potential and Energy Balance of the Emergency Energy Module in Mozambique2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study investigates the potential for implementation of a solar PV-biodiesel hybrid system with battery storage in two rural villages in the Cabo Delgado province in Mozambique. These villages, Nicuita and Quirimize, have at present very limited access to electricity which greatly inhibits an increase in living standards and development of the respective communities.

     

    Based on the results of conducted surveys mapping potential electricity demand, the load profiles of the villages alongside an investigation of the availability of different resources are the input of the model of this study with which appropriate dimensions of the hybrid system are suggested for each village.

     

    The targeted biofuel of the solar PV-biodiesel hybrid parallel configuration suggested in this study is jatropha based biodiesel for both Nicuita and Quirimize. The biodiesel fueled diesel generator and battery storage meets the nighttime load of the villages, while the solar PV system meets the load during daylight hours and also charges the battery bank to supply the nighttime load not covered by the diesel generator. The electricity production of the hybrid system is distributed through a mini-grid.

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  • 79.
    Ahl, Amanda
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Eklund, Johanna
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Success Factor of Woody Biomass Supply Chains in Japan2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There is an abundance of forest in Japan, yet a lack of utilization of woody biomass in energy systems. Small-scale woody biomass can enable a supply chain based on domestic forest integrated with local industry and demands, in turn facilitating local vitalization. Successful creation of collective energy systems is strongly connected to supply chain design based on local conditions and stakeholder integration. A supply chain perspective is key in enabling woody biomass energy systems. In these supply chains lies a complex stakeholder network across different industries, in turn incurring a need to understand both formal factors, such as technology, and informal factors, such as social relations and culture across these industries.The purpose of this study is to investigate the main challenges, success factors and convergence or divergence of perceptions of key stakeholders across the supply chain of small-scale woody biomass energy systems in Japan. In this study, the concept of small-scale woody biomass involves a supply chain based on domestic forest and integrated with local supply and demand. If the challenges and success factors, as well as balance of perceptions, can be highlighted and managed, small-scale woody biomass can be enabled by incorporating a system’s approach in supply chain analysis. This study employs a methodology incorporating literature studies and semi-structured interviews with experts to create an initial “pentagon model” presenting hypothesized success factors, including both formal and informal elements divided into five categories: technology, structure, social relations & network, culture and interaction. This is a base for the case studies, involving in-depth, semi-structured interviews with four key stakeholders in the woody biomass energy system supply chain, exploring their perceived challenges and success factors. The case studies are carried in Kyushu, the southernmost of the Japanese main islands, known for an abundance of forest alongside activity in the field of woody biomass.The main success factors emphasized by one or more of the interviewed case study stakeholders are respect of values & traditions, transportation infrastructure, business model integration, relationship & trust, local vitalization and biomass quality control. Interesting findings related to the relative success factor perceptions include the high emphasis in the upstream supply chain on respect & traditions of the forest industry, and lack of emphasis downstream. Moreover, biomass quality control is more discussed by the downstream supply chain as a main success factor. The success factors and balance of perceptions found in this study indicate the importance of both informal and formal elements in supply chain success, as well as managing a potential imbalance of perceptions. This study is meant to serve as a base for further studies on factors of the woody biomass energy system supply chain, and promote a system’s approach incorporating both formal and informal aspects in this research.

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  • 80.
    Ahl, Amanda
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Eklund, Johanna
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Lundqvist, Per
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Yarime, M.
    Balancing formal and informal success factors perceived by supply chain stakeholders: A study of woody biomass energy systems in Japan2018In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 175, p. 50-59Article in journal (Refereed)
    Abstract [en]

    Small-scale woody biomass energy systems have an inherent ability to aid in emissions reduction while stimulating local economies and, as collective energy systems, are strongly connected to supply chain design based on local conditions and stakeholder integration. Despite an abundance of forest area alongside the promotion of biomass in energy policies, however, woody biomass utilization still remains low in Japan. The woody biomass supply chain, considered as a socio-technical system, involves a complex, cross-sectoral stakeholder network in which inter-organizational dynamics necessitates well-organized management based on an understanding of formal factors such as technology, as well as informal factors such as social relations and culture. In this paper, success factor perceptions from across the woody biomass supply chain are investigated based on semi-structured interviews with four stakeholders in the Kyushu region of Japan. Identified success factors here are: 1) respect of values & traditions, 2) transportation infrastructure, 3) business model integration, 4) relationship & trust, 5) local vitalization and 6) biomass quality control. A convergence as well as divergence of perceptions are observed, involving both formal and informal dimensions. Aiming to balance perceptions and to enable long-term success of woody biomass in Japan, a series of policy implications are drawn, including cross-ministerial integration, knowledge building on wood logistics, forest certification, local coordinators, biomass quality control standards and a feed-in-tariff for heat. This paper suggests a new arena of policy-making based on the importance of considering both informal and formal dimensions in energy policy.

  • 81.
    Ahlström, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Björklund, Jacob
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Reglering av energikostnader med hjälp av energilagring i Danmark2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Compressed Air Energy Storage (CAES) implies compressing air, store it and expand it later on. CAES is together with Pumped Hydro Energy Storage (PHES) the only commercial viable bulk energy storage systems today. With respect to the geological conditions of low land in Denmark, two different types of CAES-technologies were further investigated for energy arbitrage.

    Denmark participates in the Nordic electricity market and the electricity trading occurs through Nord Pool Spot (Elspot) where the electricity price is determined specifically for every hour, the day before. The daily variation of prices in 2013 could from an empirical analysis locate hours with peak and off-peak prices.  The main goal of this report was therefore to investigate possible revenues with chosen energy storage system to buy electricity on off-peak price hours and store it, then sell it during peak price hours.

    Currently, there are two CAES facilities, one located in Huntorf, Germany, and one in Alabama, USA. A couple of different cases were investigated. Four cases, H1, H2, H3 and H4 are included in “Current Scenario” with similar features as the conventional CAES-facility, Huntorf. Conventional CAES-facilities use natural gas in the combustion chamber to heat up the air before the expansion phase to prevent the turbines from freezing. Two additional cases were investigated, A1 and A2 are included in the “Future Scenario” that is based on information about a planned future advanced adiabatic CAES facility called ADELE, by the energy company RWE in Germany.

    The calculations about the first case, H1 were based on the original performance characteristics with a total compressor capacity of 60 MW and a total output of 290 MW with charge-and discharge times of 4 and 2 hours respectively. The H2-case was assumed to be similar to the first H1-case with the only difference of a reduced consumption of natural gas by 25 %. The H3-case is based on the assumption of a compressor capacity of 480 MW and an output of 580 MW which gives the same charge- and discharge time of 1 hour. The H4-case is similar to H3 with the only difference of a reduced consumption of natural gas by 25 %. The A1-case concerns an AA-CAES facility of charge-and discharge time of 8 hours and 4 hours respectively with a compressor capacity of 200 MW and a total output of 260 MW. The second case assumes to have a total compressor capacity of 1600 MW and a total output of 1040 MW which gives the same discharge and charge time of 1 hour.

    The economic calculation model consists of two investment calculations, net present value- and payback-method. Calculations made, indicates that an investment in these observed CAES-cases under given assumptions is not economically profitable within the estimated economic and technical lifetime. The net present value ratio has a range of -1 for case H1 to -0,88 for case A1. The payback-time varies between having no payback at all (case H1) to 113 years for case A1.

    The calculations should be seen as rough estimations and just be considered as a hint for the future potential of CAES as a tool for energy arbitrage. The sensitivity analysis proves for the derived cases from the CAES-facility in Huntorf that a decreased price for natural gas did a huge impact on the operational revenues. Generally for all the different cases were that a reduction of the total plant investment, operation and maintenance costs and an increasing number of days with greater price variations would make the different CAES-cases more profitable.

    Advanced adiabatic CAES-facilities can potentially, with the necessary technical improvements, be a part of the future sustainable development.

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  • 82. Ahmad, Muhammad Ashfaq
    et al.
    Akram, Nadeem
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Structural and electrical characterisation of nanostructure electrodes for SOFCs2014In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 39, no 30, p. 17487-17491Article in journal (Refereed)
    Abstract [en]

    This paper reports the effects of sintering temperature on structure, particle size and conductivity of electrodes (Sn0.2Zn0.8Fe0.2O & Sn0.8Zn0.2Fe0.2O). The electrode material was prepared by the chemical method combining a solid state reaction. Structural analyses were performed using X-ray diffraction and scanning electron microscopy. The particle size of the material obtained using Scherrer's formula was 50-60 nm and the nanostructure's surface was studied using electrochemical characterisations tools. Electrical conductivity was determined using the 4-probe DC method, which was compared with the 4-probe AC method. These results suggest a promising substitute for the conventional electrodes of solid oxide fuel cells (SOFCs). It is known that a sintering temperature above 1000 degrees C causes an increase in density and a reduction of porosity. Therefore, we optimised the sintering temperature at 1000 degrees C and obtained electrical conductivity of about 5 S Thus, this electrode could play a vital role in the development of high performance SOFCs at intermediate temperatures.

  • 83.
    Ahmad, Nawaz
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. KTH Royal Institute of Technology.
    Numerical Modeling and Analysis of Small Gas Turbine Engine: Part I: Analytical Model and Compressor CFD2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

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    Ahmad Nawaz EGI-2009-001MSc EKV1128 Master Thesis
  • 84. Ahmed, A.
    et al.
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. COMSATS Institute of Information Technology, Pakistan.
    Khalid, M. S.
    Saleem, M.
    Alvi, F.
    Javed, M. S.
    Sherazi, T. A.
    Akhtar, M. N.
    Akram, N.
    Ahmad, M. A.
    Rafique, A.
    Iqbal, J.
    Ali, A.
    Ullah, M. K.
    Imran, S. K.
    Shakir, I.
    Khan, M. A.
    Zhu, B.
    Highly efficient composite electrolyte for natural gas fed fuel cell2016In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, no 16, p. 6972-6979Article in journal (Refereed)
    Abstract [en]

    Solid oxide fuel cells (SOFCs) have the ability to operate with different variants of hydro carbon fuel such as biogas, natural gas, methane, ethane, syngas, methanol, ethanol, hydrogen and any other hydrogen rich gas. Utilization of these fuels in SOFC, especially the natural gas, would significantly reduce operating cost and would enhance the viability for commercialization of FC technology. In this paper, the performance of two indigenously manufactured nanocomposite electrolytes; barium and samarium doped ceria (BSDC-carbonate); and lanthanum and samarium doped ceria (co-precipitation method LSDC-carbonate) using natural gas as fuel is discussed. The nanocomposite electrolytes were synthesized using co-precipitation and wet chemical methods (here after referred to as nano electrolytes). The structure and morphology of the nano electrolytes were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The fuel cell performance (OCV) was tested at temperature (300-600 °C). The ionic conductivity of the nano electrolytes were measured by two probe DC method. The detailed composition analysis of nano electrolytes was performed with the help of Raman Spectroscopy. Electrochemical study has shown an ionic conductivity of 0.16 Scm-1 at 600 °C for BSDC-carbonate in hydrogen atmosphere, which is higher than conventional electrolytes SDC and GDC under same conditions. In this article reasonably good ionic conductivity of BSDC-carbonate, at 600 °C, has also been achieved in air atmosphere which is comparatively greater than the conventional SDC and GDC electrolytes.

  • 85.
    Ahmed, Alia Amber
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Techno-economic analysis of PV and energy storage systems for Swedish households2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

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

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

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  • 86.
    Ahmed, Hassan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Energy need assessment and preferential choice survey of rural people in Bangladesh2013Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study is a part of a poly generation project which will use animal waste or agricultural waste to produce biogas and will provide cooking gas, electricity and arsenic free clean water for drinking in rural areas of Bangladesh.  The study mainly analyzes the cooking and lighting energy demand of households across different income groups in a village named “Pani Para” in the Faridpur district in Bangladesh and also looks at the potential of biogas in the village. It has been done by adopting case study method and conducting a survey in the village using a questionnaire.

    Fuel mix across different income groups for meeting their cooking and lighting energy needs have also been studied along with socio-economic situation of the villagers and their preferences to change their current cooking fuel utilization patterns. Various scenarios like variation in fuel consumption patterns, priority of income expenditure and access to fuel with income level have been examined. The study also focuses to analyze the awareness of the villagers about biogas technology and their willingness to contribute for the poly generation project along with the willingness of households to pay for embracing change in current cooking and lighting fuels. Biomass potential i.e. cow dung and agricultural waste is also calculated in the surveyed village along with the production of biogas from the available biomass resources. The scenarios to provide the cooking gas, electricity and clean water through biogas poly generation project from the available resources are also investigated.

    Analysis reveals that the total energy consumption (cooking and lighting) increases with the increase in the income level among the households. Average household cooking and lighting energy demand by low, medium and high income groups is 8492 kWh/yr, 9789 kWh/yr and 14806 kWh/yr respectively. Cooking energy demand and agricultural waste consumption also show an increasing trend with the increase in land holding size. Among the income expenditure priorities food is one of the most important priorities and energy being less important due to availability of biomass at little or no cost. Awareness of biogas technology among the households and willingness to contribute for the poly generation plant shows an increasing trend with the increase in education level. The study shows that there is a positive response of the villagers for being willing to embrace the change in the current cooking patterns as well as welcoming new technologies that could support such a change.

    It was found that the cow dung resource in the village is not enough to produce sufficient biogas for the poly generation project. With the incorporation of the agricultural waste with the cow dung, biogas production comes quite close to requirement of the poly generation plant but however could not suffice it completely due to the lack of raw material in the studied village. In that case the scenario of providing electricity and clean water to all the villagers and providing all the three facilities to the 2/3rd of households is investigated. 1/3rd of the low income households then could meet their cooking demands by provision of improved cooking stoves as cooking gas could not be provided to them due to limited feedstock. The study shows that despite of the fact that cooking and lighting energy needs increase with income but there is not much variation in the fuel mix and almost everyone in the village rely on biomass to meet their energy demand. It is because there is very limited access to the modern fuel for cooking and no electricity access in the village, so the households have to rely on the traditional fuels. 

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    Ahmed Hassan EGI- 2013-030MSC
  • 87.
    Ahrens Kayayan, Vartan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Are Carnot Batteries an AlternativeWhen Repurposing Coal Power Plants in Europe?2023In: Proceedings of the International Renewable Energy Storage Conference, IRES 2022 / [ed] Schossig, P Droege, P Riemer, A Speer, M, Atlantis Press SARL , 2023, Vol. 16, p. 3-13Conference paper (Refereed)
    Abstract [en]

    As Europe transitions away from coal-fired power plants, there is indecision regarding the fate of the retiring sites. This paper tests the feasibility of an alternative to consider: Carnot Batteries. Refurbishing existing power plants has several advantages. Components can be put to a new purpose. The locations are connected to the electricity and district-heating grids. Both reduce the costs of a Carnot Battery. The literature regarding retrofit operating power plants with thermal energy storage focuses on improving an existing power plant. This paper determines the technoeconomic feasibility of replacing the boiler as the source of heat with a direct heater and thermal energy storage. Carnot Batteries can contribute to mitigating the variability of renewable energy and increase its proportion of the energy production mix. The first step is a deterministic analysis of dispatch and then genetic optimization for the sizing. The optimization relies on open-source software for replicability and further development. The results point to feasible arrangements for the European electricity market if the assumptions regarding the possibility to reutilize the power block is true. For the electricity markets analyzed in detail here, it is possible to find a solution with a market competitive Internal Rate of Return, positive Net Present Value, and comparable Levelized Costs of Storage, particularly for the Romanian electricity market. Analysis of technical parameters highlights the importance of round-trip efficiency and shows a possible reduction in carbon emissions. This broad analysis argues for further investigating Carnot Batteries as an alternativewhen determining howa retired coal-fired power plant can be repurposed.

  • 88.
    Ahrens Kayayan, Vartan Jakob
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Are Carnot Batteries an Alternative to Converting Coal Power Plants?: An open-sourced technoeconomic optimization approach for testing a new niche for Carnot Batteries.2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As Europe transitions away from coal-fired power plants, there is an opportunity to reshape the electrical infrastructure. Many of the current plans are to make a switch to natural gas, another fossil fuel. Refurbishing existing power plants has several advantages. Components can be put to a new purpose. Employees of the plant can remain in their capacity. The locations are connected to the electricity and the district-heating grid. Whilst natural gas can have relatively low emissions and address peak loads, it is a fossil fuel with high marginal costs and its sourcing can be problematized. There is an alternative to consider: Thermal Energy Storage system.

    The literature regarding the retrofit of operating power plants with thermal energy storage is improving the key performance indicators of an existing power plant. This paper determines the technoeconomic feasibility of replacing the boiler as the source of heat. A thermal energy storage system is more profitable in energy markets where the price varies in a forecastable way. To determine the technoeconomic feasibility a bi-level optimization is carried out. The first step is a deterministic analysis of dispatch and then genetic optimization for the sizing. The optimization relies on open-source software for replicability and further development. The economic aspects are Net Present Value, capital expenses, Power Purchase Agreement price, and Levelized Costs of Storage. Technical aspects are round trip efficiency, Capacity Factor, Utilization Factor, and carbon dioxide emissions from the grid or fuels.

    For the electricity markets analyzed in detail here, it is possible to find a solution with a high but competitive Levelized Costs of Storage of 300 €/MWh. It is possible for a district heating grid connected to Combined Heat and Power plants to achieve competitive Levelized Costs of Heating of circa 50€/MWh. Technical parameters have highlighted the importance of round-trip efficiency.

    The results show that even with optimistic assumptions regarding capital costs, operational costs, and electricity market variations, price arbitrage is not an economically feasible business model for repurposing coal-fired power plants. It is possible to find insights regarding the relative sizing of Carnot Battery components and the properties of the electricity market. Round trip efficiency and utilization factors are important technical indicators of the economic success of a given configuration. Conversely providing heat to a district heating grid can be a viable market for Carnot batteries.

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  • 89.
    Ahrnstein, Lina
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Dahlberg, Johanna
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    En jämförelse av RDF och avfall som förbränningsbränsle2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the EU the amount of waste increased by 14 percent during the years 2000 to 2010. EU’s target to reduce waste generation runs parallel with the aim of increasing the efficiency and profitability aligned with energy recovery. In Sweden the energy recovery through incineration is increasing steadily, and 46 percent of the municipal solid waste (MSW) is treated by combustion. This report aims to examine the profitability of processing MSW into Refuse Derived Fuel (RDF) from an economic-, energy- and environmental perspective. In order to obtain a comparison with incineration of MSW the starting point of the feasibility study is one ton of combustible MSW incinerated directly in a stocker grate type incinerator, compared to the same ton of MSW processed to RDF and incinerated in a fluidized bed.The proportion of MSW processed to RDF varies between 23-85 percent, which leads to an average of 540 kg, 54 percent, processed RDF from a ton of MSW. One ton of RDF has a calorific value between 18.5-23 MJ/kg. The calorific value of combustible MSW is calculated to 10.38 MJ/kg. The two different boilers for combustion of the fuels have the same power of 28 MW. The comparison shows the total energy recovery, of heat and electricity, for the combustible MSW in the stocker grate to 2.51 MWh, and for the 540 kg RDF incinerated in a fluidized bed to be 2,56 MWh. As long as the proportion of RDF processed from a ton of MSW is greater than 51 percent, the energy recovery is higher for the RDF.A cost-benefit analysis, calculated from the combustion of 70 000 tons of MSW, and 54 percent of the amount processed to RDF, shows a higher net present value for RDF, 1042 million. However, the net present value of the combusted MSW was also positive, 1024 million, which indicates that both investments are profitable. The payback method showed the same result, with a payback time of 3.17 years for RDF-combustion and 4.24 years for combustion of MSW.Emissions of carbon dioxide and nitrogen oxide are both higher when incineration of 540 kg RDF takes place in a fluidized bed, than of a ton of MSW in a stocker grate incinerator. Emission of carbon dioxide is 17,7 percent higher and for nitrogen oxide 23 percent higher.

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    En jämförelse av RDF och avfall som förbränningsbränsle
  • 90.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Solar Receiver Design and Verification for Small Scale Polygeneration Unit2011Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

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

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

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

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

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

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    Aichmayer L. 2011 - Solar Receiver Design and Verification for Small Scale Polygeneration Unit.pdf
  • 91.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Solar receiver development for gas-turbine based solar dish systems2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

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

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

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

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

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

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

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    Aichmayer 2018 - Solar receiver development for gas-turbine based solar dish systems
  • 92.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Performance Improvements of the KTH High-Flux Solar Simulator2017In: AIP Conference Proceedings 1850, American Institute of Physics (AIP), 2017, Vol. 1850, article id 150001Conference paper (Refereed)
    Abstract [en]

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

  • 93.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Scaling effects of a novel solar receiver for a micro gas-turbine based solar dish system2018In: International Journal of Solar Energy, ISSN 0142-5919, E-ISSN 1477-2752, Vol. 162, p. 248-264Article in journal (Refereed)
    Abstract [en]

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

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  • 94.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermo-mechanical solar receiver design and validation for a micro gas-turbine based solar dish system2020In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 196, article id 116929Article in journal (Refereed)
    Abstract [en]

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

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

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  • 95.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Preliminary design and analysis of a novel solar receiver for a micro gas-turbine based solar dish system2015In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 114, no 4, p. 378-396Article in journal (Refereed)
    Abstract [en]

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

  • 96.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Small Scale Hybrid Solar Power Plants for Polygeneration in Rural Areas2014In: Energy Procedia 57, Elsevier, 2014, Vol. 57, p. 1536-1545Conference paper (Refereed)
    Abstract [en]

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

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  • 97.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    IMDEA Energy Institute, Spain.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermoeconomic Analysis of a Solar Dish Micro Gas-Turbine Combined-Cycle Power Plant2015In: Energy Procedia 69, Elsevier, 2015, Vol. 69, p. 1089-1099Conference paper (Refereed)
    Abstract [en]

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

  • 98.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Micro Gas-Turbine Design for Small-Scale Hybrid Solar Power Plants2013In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 135, no 11, p. 113001-Article in journal (Refereed)
    Abstract [en]

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

  • 99.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Micro Gas-Turbine Design for Small-Scale Hybrid Solar Power Plants2013In: Proceedings of the ASME Turbo Expo 2013. San Antonio, USA. June 3-7, ASME , 2013Conference paper (Refereed)
    Abstract [en]

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

  • 100.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Design and Analysis of a Solar Receiver for Micro Gas Turbine based Solar Dish Systems2012In: Proceedings of the International SolarPACES Conference 2012. Marrakesh, Morocco. September 11-14, 2012, 2012Conference paper (Refereed)
    Abstract [en]

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

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