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  • 201.
    Anton, R
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Jonsson, HKTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.Palm, BKTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Modeling of Air Conditioning Systems for Cooling of Data Centers2002Conference proceedings (editor) (Other academic)
  • 202. Anton, R.
    et al.
    Jonsson, Hans
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Ramos, J. C.
    Gomez-Acebo, T.
    Rivas, A.
    Refrigerating Cycle Simulator: System Modelling, Educational Implementation and Assessment2009In: International journal of engineering education, ISSN 0949-149X, Vol. 25, no 2, p. 324-332Article in journal (Refereed)
    Abstract [en]

    To leach and explain system modelling in a Thermal-Fluid application is a challenge: learning how one component or even the surrounding conditions can influence the performance of the rest of the components of the system and the system itself is not all easy task. However a suitable educational implementation may help students gain a deeper understanding not only of the system itself bill of the existing interrelation between the Thermal-Fluid fields: Thermodynamics, Heat Transfer and Fluid Mechanics. In this study a refrigerating cycle simulator is used. The simulator is' prepared in such a way that the interrelation between each component, the system and the surroundings call be analysed by the students. This case study is found to be very useful due of its ability to study system performance. A three-step educational implementation, the simulator being the third step, has been used and found to he enriching both for students and instructors.

  • 203.
    Anton, R
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, B
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Spray Cooling, an Overview of Methods and Possibilities2002Conference paper (Refereed)
  • 204.
    Anton, R
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, BjörnKTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Spray Cooling, an Overview of Methods and Possibilities2002Conference proceedings (editor) (Other academic)
  • 205.
    Anton, Raul
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Jonsson, Hans
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Moshfegh, Bahram
    University of Gävle.
    Modelling of EMC Screens for Radio Base Stations: Part 2: Evaluation of Turbulence Models2004In: Proc. 9th  InterSociety Conf. on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm 2004), Las Vegas, NV, USA, IEEE Press, 2004, p. 471-478Conference paper (Refereed)
    Abstract [en]

    The objective of this paper is to investigate the performance of five well-known turbulence models and 2 wall treatments, in order to predict the details of the flow patterns through an EMC (ElectroMagnetic Compatibility) screen. The employed turbulence models are investigated in the present study is four different eddy-viscosity models; the standard k-ε model, the renormalization group (RNG) k-ε model, the realizable k-ε model and the k-ω model, as well as the Reynolds stress model, RSM. The commercial finite volume code Fluent 6.1 was used for simulation.

    A steady-state three-dimensional model, which serves as the most accurate representation of the model, was used in order to predict the details of the air flow paths and pressure field. The flow was assumed to be isothermal, turbulent and incompressible.

    The numerical predictions were validated experimentally by using wind tunnel measurements and smoke visualization. The performances of the turbulence models are discussed and the RSM results are compared with other two-equation turbulence models. The result shows that choosing the right turbulence model and wall treatment does not have a great influence on the prediction of pressure drop and the velocity field. The pressure field is over predicted about 15% and the velocity average deviation at several locations before and after the screen is less than 10%. Simulations using a hydraulic impedance surface, i.e. without a detail modeling of the EMC screen, show that the pressure field is also over predicted and great differences are observed in the velocity field.

  • 206.
    Anton, Raul
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Jonsson, Hans
    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.
    Modeling of Air Conditioning Systems for Cooling of Data Centers2002In: Proc. 8th  InterSociety Conf. on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm 2002), San Diego, CA, USA, IEEE Press, 2002, p. 552-558Conference paper (Refereed)
    Abstract [en]

    Cooling of data centers has emerged as an area of increasing importance in the field of electronics thermal management. As the packaging and power densities are steadily increasing, so will the need for efficient and reliable cooling systems.

    In this paper, a model of an air conditioning unit is described. The model offers considerable flexibility in terms of the ability to choose between different designs of heat exchangers (evaporators and condensers), and working media, and hence the model offers the possibility to optimize the design.

    The model is developed using EES (Engineering Equation Solver), a programming environment that provides the thermo-physical properties for the working media used. The heat transfer and pressure drop in the components are modeled using an integral approach, i.e. the overall behavior of each component is modeled. This approach has been proven to give adequate accuracy.

  • 207.
    Anton Remirez, Raul
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Castiella Sánchez-Ostiz, Miguel
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Jonsson, Hans
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Moshfegh, B.
    Smoke and CFD visualization of the flow after an EMC screen in a sub-rack model2005In: Proceeding of the THERMINIC 05, 2005Conference paper (Refereed)
  • 208.
    Anton Remirez, Raul
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. TECNUN, University of Navarra, Navarra 31080, Spain .
    Jonsson, Hans
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Moshfegh, Bahram
    Compact CFD modelling of EMC screen for radio base stations: a porous media approach and a correlation for the directional loss coefficients2007In: IEEE transactions on components and packaging technologies (Print), ISSN 1521-3331, E-ISSN 1557-9972, Vol. 30, no 4, p. 875-885Article in journal (Refereed)
    Abstract [en]

    A methodology to obtain the directional pressure loss coefficients in a porous media model of an electromagnetically compatible screen of a radio base station model is presented. The directional loss coefficients of this compact model are validated against a detailed computational fluid dynamics model not only by comparing the total pressure drop, but also by evaluating the flow pattern after the screen. The detailed model was validated in an earlier article by the authors. A parametric study is conducted for 174 cases. Seven parameters were investigated: velocity, inlet height, screen porosity, printed circuit board (PCB) thickness, inlet-screen gap, distance between two PCBs and screen thickness. Based on the compact model parametric study, two correlations for the directional loss coefficients are developed as a function of the Reynolds number and the above geometrical parameters. The average disagreement between the compact model that uses the directional loss coefficients from the correlations and the detailed model was of 3% for the prediction of the total pressure drop and less than 6.5% and 9.5% for two coefficients that accurately characterize the flow pattern.

  • 209. Anton Remirez, Raul
    et al.
    Jonsson, Hans
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Moshfegh, Bahram
    Detailed CFD modelling of EMC screen for radio base stations: a benchmark study2007In: IEEE transactions on components and packaging technologies (Print), ISSN 1521-3331, E-ISSN 1557-9972, Vol. 30, no 4, p. 754-763Article in journal (Refereed)
    Abstract [en]

    The objective of this paper is to investigate the performance of five well-known turbulence models, in order to find a model that predicts the details of the flow patterns through an electromagnetic compatibility (EMC) screen. The turbulence models investigated in the present study are five different eddy-viscosity models; the standard k-ε model, the renormalization group (RNG) k-ε model, the realizable k-ε model, the standard k-ω model, as well as the shear stress transport k-ω model. A steady-state 3-D detailed model, which serves as the most accurate representation of the model, was used in order to evaluate the details of the airflow paths and pressure field. The flow was assumed to be isothermal, turbulent and incompressible. A general model that covers a considerable range of velocities and geometries was validated experimentally by wind tunnel measurements. The result shows that for most of the k-ε models used with correct y+ and mesh strategy, the pressure drop and the velocity field deviation is small compared to experimental data. The k-ω models overpredict the overall pressure drop. When using the RNG k-ε model, the total static pressure drop predicted differs around 5%-10% and the average velocity deviation at several locations before and after the screen is around 5%.

  • 210.
    Anton Remirez, Raul
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Jonsson, Hans
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Moshfegh, Bahram
    University of Gävle.
    Detailed CFD Modelling of EMC Screen for Radio Base Stations: A Conjugate Heat Transfer Problem2007In: International Journal of Heat Exchangers, ISSN 1524-5608, Vol. 8, no 1, p. 95-116Article in journal (Refereed)
    Abstract [en]

    The objective of this paper is to perform an experimental as well as CFD investigations of the conjugate heat transfer problem in a sub-rack slot model. A steady-state three-dimensional detailed model, which serves as the most accurate representation of the model, was used in order to evaluate the details of the airflow paths and temperature field.

    A general model that covers a considerable range of velocities, screen porosities and heat fluxes was validated experimentally by wind tunnel measurements. The result shows that the RNG k-ε model used with correct y+ and mesh strategy accurately predicts the temperature field. The average temperature deviation at several locations is less than 4% compared to experimental data. The influence of the velocity, screen porosity, heat flux and presence of the EMC screen on the PCB temperature field is commented.

  • 211.
    Anton Remirez, Raul
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Jonsson, Hans
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Moshfegh, Bahram
    Detailed CFD modelling of EMC screen for radio base stations: a parametric study2009In: IEEE transactions on components and packaging technologies (Print), ISSN 1521-3331, E-ISSN 1557-9972, Vol. 32, no 1, p. 145-155Article in journal (Refereed)
    Abstract [en]

    The objective of this paper is to make a parametric study of the hydraulic resistance and flow pattern of the flow after an electromagnetic compatibility screen and between two printed circuit boards (PCBs) in a model of a 90° subrack cooling architecture. The parametric study is carried out using a detailed 3-D model of a PCB slot. The detailed model was experimentally validated in a previous paper by the authors. Seven parameters were investigated: velocity, inlet height, screen porosity, PCB thickness, distance between two PCBs, inlet-screen gap and screen thickness. A correlation for the static anddynamic pressure drop, the percentage of dimensionless wetted area, Aw*, and the RMS* factor (a function of the flow uniformity along the PCB) after the screen is reported as a function of six geometrical dimensionless parameters and the Reynolds number. The correlations, that are based on 174 three dimensional simulations, yield good results for the total pressure drop, in which the values are predicted within the interval of ±15%. For the, Aw* all the predicted values are within the interval of ±22% of the observed values. Finally, for the RMS* factor, the majority of the values also have a disagreement of less than 20% of the observed values. These last two parameters are believed to provide a correct insight about the flow pattern after the screen.

  • 212.
    Antón Remírez, Raúl
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Experimental and numerical study of the thermal and hydraulic effect of EMC screens in radio base stations: detailed and compact models2006Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Today’s telecommunication cabinets use Electro Magnetic Compliance (EMC) screens in order to reduce electromagnetic noise that can cause some miss functions in electronic equipment.

    Many radio base stations (RBSs) use a 90-degree building architecture: the flow inlet is perpendicular to the EMC screen, which creates a complex flow, with a 90-degree air turn, expansions, compressions, perforated plates and PCBs. It is of great interest to study how the EMC screen interacts with the rest of components and analyze the total pressure drop and how much the flow pattern changes due to the placement of the screen.

    Velocity, pressure and temperature measurements as well as flow pattern visualizations have been carried out to gain good insight into the flow and heat transfer characteristics in a subrack model of an RBS. Furthermore, these measurements have been very useful for validating detailed CFD models and evaluating several turbulence models.

    Nowadays, industrial competition has caused a substantial decrease in the time-to-market of products. This fact makes the use of compact models in the first stages of the design process of vital importance. Accurate and fast compact models can to a great extent decrease the time for design, and thus for production.

    Hence, to determine the correlations between the pressure drop and flow pattern on the PCBs as a function of the geometry and the Reynolds number, based on a detailed CFD parametric study, was one objective. Furthermore, the development of a compact model using a porous media approach (using two directional-loss coefficients) has been accomplished. Two correlations of these directional loss coefficients were found as a function of the geometry and Reynolds number.

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  • 213.
    António Soares, Castro
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    The Energy Balance of Jatropha Plantation in Sun Biofuel Farm in Central Mozambique2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Jatropha constitutes one of promising species suitable for providing oil for biodiesel production. So, looking for good practice and sustainable use of energy during Jatropha cultivation and lack of information about Jatropha in Mozambique, this study pretends to estimate the energy balance in Jatropha plantation in Sun biofuel farm, by calculating the energy indicators based on a life cycle approach in Sun Biofuel farm located in Manica province, Central Mozambique. Energy balance is a tool which can help to calculate all energy indicators in order to evaluate and analyse the energy efficiency, sustainability and environmental benefits. This study estimated the indicator of energy balance namely: energy input is the sum of all energy used during the process of Jatropha cultivation and oil production, energy output is the amount of energy produced, Net energy value can be calculated subtracting the energy output from the energy input, Energy productivity is the division of Jatropha produced by the respective input energy, specific energy is the division of energy input by Jatropha seed output and energy ratio is the energy output divided by energy input. Also data was collected on the farm of Sun Biofuel to estimate the sustainability of agricultural production of the company. The Jatropha production in Sun Biofuel farm (SBF) absorbed around 28 579 MJ/ha of energy during the production and 121 820 MJ/ha of energy gain as result of the all production. The total energy input was direct energy with 77% and Indirect energy with 23% used in Jatropha farm, and also the total energy input was divided into renewable with 26% and non-renewable with 74% of its contribution. The results revealed that the contribution of seed husks was (8%), woody products (38%), raw seed oil (30%), Shell (9%) and press cake (15%) of total energy output in Jatropha oil production farm. Net energy value (NEV), energy productivity, energy use efficiency and Specific energy was 93 241 MJ ha-1, 0.067 Kg MJ-1, 4.3 and 15.04 MJ Kg-1, respectively. According to these results the energy balance is positive and the energy use in Jatropha production is efficient.

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  • 214.
    Anund Vogel, Jonas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Incentivising Innovation in the Swedish Construction Industry2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Almost 40 percent of global final energy use and CO2 emissions are connected to buildings and building-related activities; it is therefore important to incentivise the design and construction of resource-efficient buildings. Unfortunately, energy demand and associated emissions in the sector continue to grow. Such incentives will help achieve energy and environmental targets, reduce costs, and make smart and sustainable buildings and cities possible at a larger scale. Because novel technologies carry risks alongside their advantages, developers, contractors and consultants must have incentives to reduce and share those risks in a rational way if we are to meet the crucial long-term societal goals of reduced use of resources and emissions.

     

    I hypothesise that there are legal and institutional frameworks (rules, building codes, regulations, standard contracts, etc.) that result in weak or negative incentives for construction industry actors to invest in, propose, and install resource-efficient technologies. If the hypothesis holds true, then the goal is to identify ways to better incentivise construction industry actors to fully engage in the design and construction of smart and sustainable buildings.

     

    To tackle this, four studies were carried out using a mixed-method approach. Paper 1 identifies 38 barriers to energy efficiency in Swedish multifamily buildings. The next study (Paper 2) develops a categorisation framework in order to understand where to engage to overcome or bypass barriers to energy efficiency. Paper 3 and 4 are devoted to analysing two sets of barriers and propose possible solutions to overcome or avoid them: (1) how the current legal framework guiding start and operation of housing co-operatives (mainly the Co-operative Act) influences incentives for engaging in resource-efficient construction, and (2) how the legal instrument for collaboration between developers and consultants incentivises resource-efficient construction. In this case, the contract under investigation is the General Conditions of Contract for Consulting Agreements for Architectural and Engineering Assignments (ABK 09)”. Changes to these two sets of legal and institutional frameworks could have a significant impact on how buildings are designed, produced and used. The changes proposed could incentivise construction industry actors to fully pursue the creation of smart, sustainable buildings that deliver services to users and reduce negative environmental impacts stemming from both the building construction and operation phases.

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  • 215.
    Anund Vogel, Jonas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lind, Hans
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management, Real Estate Economics and Finance.
    Att styra allmänningar – en studie av svenska bostadsrättsföreningar2017In: Ekonomisk Debatt, ISSN 0345-2646, no 2, p. 55-66Article in journal (Other academic)
    Abstract [sv]

    Det är viktigt i ett samhälle att ha institutioner som bidrar till ett effektivt utnyttjande av resurser. Syftet med denna artikel är att granska den svenska bostadsrättsformen utifrån de kriterier som Elinor Ostrom formulerat rörande vad som bidrar till en effektiv förvaltning av en ”allmänning”. Avslutningsvis presenteras också reformförslag som vi bedömer skulle minska problemen i dagens strukturer, problem som främst sammanhänger med att den som startar föreningen och bygger dess hus inte har något långsiktigt ansvar.

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  • 216.
    Anund Vogel, Jonas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lind, Hans
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Holm, Cyril
    A Note on Developing A New Type of Construction Contracts to Promote New Technologies and Sustainability2024In: Civil Engineering Research Journal, E-ISSN 2575-8950, Vol. 14, no 5Article in journal (Refereed)
    Abstract [en]

    In its different forms, the built environment is the single largest energy consumer in the EU, and one of the largest carbon dioxide emitters. Green buildings and smart technologies are two of the most important elements to reach this goal. In a situation where the use of new technologies and new knowledge becomes more important as well as the news flow increase the role of the technical consultant becomes more important. Also, the client/developer role become increasingly important when buildings turn from storage facilities to service generating entities. A closer alliance between client and consultant is necessary to align business models with new technologies. Contracts are the most important instrument to shape incentive structures for optimal economic outcomes, as well as for shaping incentives for optimal operation of smart and sustainable buildings. In this paper we propose a contract design that incentivise consultants to fully use their knowledge to make sure that planned systems are installed and operated in an optimal manner. There are in general two approaches to this type of contract design. The first is to write a detailed contract setting out how to deal with possible outcomes going forward. The second, and the approach used in this paper, is to write a less detailed contract that sets out a framework of incentives for continuing cooperation and to keep a good reputation.

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  • 217.
    Anund Vogel, Jonas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lind, Hans
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Holm, Cyril
    Univ Oxford, Fac Law, St Cross Bldg,St Cross Rd, Oxford OX1 3UL, England..
    Incentivising innovation in the construction sector: the role of consulting contracts2019In: Australasian Journal of Construction Economics and Building, ISSN 1835-6354, E-ISSN 1837-9133, Vol. 19, no 2, p. 181-196Article in journal (Refereed)
    Abstract [en]

    The issue of whether contracts promote innovation and sustainability is an important but overlooked aspect for achieving energy and environmental targets, as well as for creating smart and sustainable cities. In this article, based on the principle/agent problem and Holmstrom and Milgrom's work on optimal contracts it is argued that the current general conditions of architectural and engineering consulting agreements in Sweden (ABK 09)-a standard type of contract often used in developer/consultant relations-may not incentivize choices that support the long-term goals of society. Furthermore, although this exploratory study specifically analyses a Swedish standard contract, the question of how contractual incentive structures can optimize real-world performance is a general one, and thus the article's findings have general applicability. This exploratory study also points to further research into how contractual structures impact climate-neutral buildings. In this way, Swedish consultants who use ABK 09 are incentivized to include low-risk, well-proven, and widely used technologies in order to minimize risks for themselves. This study contributes to resolving this dilemma by suggesting how ABK 09 could be restructured to change the balance between incentives and risk and incentivize innovation and sustainability. As mentioned above, the current study operates at a theoretical level. It discusses six possible changes that would better align the contract with the societal goals of innovation and sustainability.

  • 218.
    Anund Vogel, Jonas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lind, Hans
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management, Building and Real Estate Economics.
    Lundqvist, Per
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Who is Governing the Commons: Studying Swedish Housing Cooperatives2016In: Housing, Theory and Society, ISSN 1403-6096, E-ISSN 1651-2278, Vol. 33, no 4, p. 424-444Article in journal (Refereed)
    Abstract [en]

    This study examines current governance structures related to multifamily buildings designed by single actors (developers) and operated in cooperative forms. The study analyses the long-term sustainability of the resource regime of study (multifamily buildings) and inked governance structures by applying Ostrom’s eight design principles for long-term survival of self-organized resource regimes (Common-pool resources or CPR’s). The study also searches for signs of movement towards social innovation and collective action in current governance structures. We argue that the structures governing planning, production and operation of housing cooperatives in Sweden do not fulfil the eight design principles for the long-term survival of the resource regime of study, nor do they encourage movement towards social innovation or collective action. In order to ensure the long-term survival of the resource regime of study and to increase innovation in governance structures, five adjustments are proposed; changes in the structures governing risk/profit distribution, communication, collaboration and information between actors in the Swedish cooperative housing sector.

  • 219.
    Anund Vogel, Jonas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lundqvist, Per
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Arias, Jaime
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Blomkvist, Pär
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Sustainability and Industrial Dynamics.
    Problem areas related to energy efficiency implementation in Swedish multifaily buildings2015In: Energy Efficiency, ISSN 1570-646X, E-ISSN 1570-6478Article in journal (Refereed)
    Abstract [en]

    This paper investigates problem areas related to energy efficiency implementation in Swedish multifamily buildings. The paper first presents a generic list of (theoretical) problem areas identified through a literature survey. Using a qualitative approach, the paper also investigates if the problem areas identified in the literature also have an impact on the Swedish building sector. Results from the interview study reveal a strong coherence between problem areas in the literature and those expressed by the interviewees. However, this paper identifies seven novel challenges that cannot be derived from the list of barriers in the literature. Moreover, results reveal that as many as 12 problem areas have their origin in national factors such as agreement structures, incentive schemes, and cost calculation methods.

  • 220.
    Anund Vogel, Jonas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Van Bueren, Ellen
    Delft University of Technology.
    Verhoef, Leendert
    Amsterdam Institute for Advanced Metropolitan Solutions.
    Goldberg, Brian
    Office of Sustainability MIT.
    Lundqvist, Per
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Sarin, Emma
    HSB Living Lab.
    Co-Creation in Living Labs to Accelerate Innovation2020In: Civil Engineering Research Journal, ISSN 2575-8950, Vol. 10, no 1, article id 555776Article in journal (Other academic)
    Abstract [en]

    Innovation in the construction sector occurs as stepwise reconfigurations of subsystems, but sometimes the effect of many systems coincides and there is so called radical change. Stepwise reconfigurations of individual systems such as windows, insulation, and heat recovery systems have made it possible to heat buildings with preheated inlet air instead of water radiators. Thus, making building more sustainable, cheaper and resource-efficient; the potential for radical change has been achieved. The question is then why not every new building uses preheated inlet air? The reason is not the lack of innovation or new technologies. It is rather connected to malfunctioning structures related to incentives, collaboration, testing, and validation, resulting in norms and standards that aim to reproduce existing technologies, preferring incremental innovations over radical ones.This article argues that testbeds and Living Labs are a way to work on complex, multi-stakeholder and urgent problems in a co-creative way. In these labs there are possibilities to test technologies, in systems, in real buildings and cities. There are possibilities to follow-up, measure and adjust; to live, study, work and develop. The Living Labs have the potential of making new technologies standard to use in the course of years instead of decades and thus minimize unnecessary use of resources linked to the construction and use of buildings. In addition, it will help to make technologies more user-friendly, considering user needs, wishes and experiences, thus contributing to the effectiveness of the technologies developed and tested.

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    Co-Creation in Living Labs to Accelerate Innovation
  • 221.
    Anwar, Aran
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Menezes, Bryan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Sheibeh, Rasam
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Studie av vind- och vattenkraft i Sverige2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report has been conducted within the realms of a bachelor thesis by three engineering students at KTH Royal Institute of Technology studying Mechanical Engineering. The field of this report is Sustainable Energy Engineering. A background study within this field has been conducted with the subset being, how suitable wind power and hydro power and at what price it is produced in Sweden.

    A multitude of variables has been taken into consideration such as economic, environmental and social. The reason why these sources of electricity were chosen is due to the large scale that they contribute towards the overall Swedish electricity production. Also, the share of wind power has risen dramatically in the last few years. The efficacy of the two power sources has been studied.

    A literature study was conducted in the initial phase of the project. The study was divided in three parts; wind power, hydro power, and an analysis of previous studies researching the production cost from these sources. Studies are provided from the 1970s to the present. Hydro power has been the largest contributor to Swedish power system during this period. Predictions for future scenarios have conducted.

    A thorough analysis of how the wind power and hydro power works has been conducted. A study has also been done on the productions cost from these sources. Three cost models have served as a basis an analysis such that parameters that affect the price could be understood. The analysis is available in the results and discussion section of this report.

    Results showed that the efficiency is higher for hydro power compared to wind power. Both wind power and hydro power are preferable from an environmental perspective, depending on the specific situation such as geographic location. It was noted that from a social perspective that wind power is not suitable to be located near Sweden’s major cities. Also, the productions costs for both sources are relativity close to each other. Thereby the prices of wind power are between 328 and 644 [SEK/MWh] and hydropower, 390 and 470 [SEK/MWh].

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  • 222. Anwar, Z.
    et al.
    Palm, Björn E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Khodabandeh, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Dryout characteristics of natural and synthetic refrigerants in single vertical mini-channels2015In: Experimental Thermal and Fluid Science, ISSN 0894-1777, E-ISSN 1879-2286, Vol. 68, p. 257-267Article in journal (Refereed)
    Abstract [en]

    Experimental results on dryout of seven refrigerants (R134a, R1234yf, R152a, R22, R245fa, R290 and R600a) in small, single vertical tubes under upward flow conditions are reported in this study. The experiments were conducted under a wide range of operating conditions in stainless steel tubes (0.64-1.70. mm and 213-245. mm heated length). The effects of operating parameters like mass flux, vapor quality, saturation pressure and channel size are discussed in detail. In general, dryout heat flux increased with increasing mass flux, and with increasing tube diameter. No effect of varying saturation temperature was observed. The experimental findings were compared with well-known macro and micro-scale correlations from the literature and it was found that Wu's correlation (in modified form) quite satisfactorily predicted the whole database. A new correlation for prediction of heat flux at dryout conditions is also proposed.

  • 223. Anwar, Z.
    et al.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Khodabandeh, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Flow boiling heat transfer and dryout characteristics of R152a in a vertical mini-channel2014In: Experimental Thermal and Fluid Science, ISSN 0894-1777, E-ISSN 1879-2286, Vol. 53, p. 207-217Article in journal (Refereed)
    Abstract [en]

    This article reports on flow boiling heat transfer and dryout characteristics of R152a in a vertical mini-channel. The experiments were carried out with a resistively heated stainless steel tube (1.60mm in diameter and 245mm heated length) at 27 and 32°C saturation temperature. Five mass fluxes in the range 100-500kg/m2s with heat fluxes from 5 to 245kW/m2 were tested. Under similar operating conditions experiments were repeated with R134a in the same setup to compare thermal performance of R152a. The results showed that the heat transfer was strongly influenced by the applied heat flux with insignificant convective contributions. The dryout heat flux increased with increasing mass flux but no effect of varying operating pressure was noticed. The experimental results for heat transfer and dryout heat flux were compared with well-known macro and micro-scale correlations from the literature.

  • 224.
    Anwar, Zahid
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Experimental Investigation of heat recovery from R744 based refrigeration system2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
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    Thesis Report
  • 225.
    Anwar, Zahid
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Flow boiling heat transfer, pressure drop and dryout characteristics of low GWP refrigerants in a vertical mini-channel2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Two-phase heat transfer in mini/micro-channels is capable of meeting the high cooling demands of modern high heat flux applications. The phase change process ensures better temperature uniformity and control for local hot spots. Furthermore, these compact channels could be helpful in reducing the required charge and material inventories.Environmental concerns—mainly ozone depletion and global warming—have instigated a search for new alternatives in refrigeration industry. While new compounds are being developed to address stringent legislative demands, natural alternatives are also coming into prominence. A limited number of investigators have reported on thermal performance of such alternatives. The current study is therefore focused on saturated flow boiling heat transfer, pressure drop and dryout characteristics for three low global warming potential (GWP) refrigerants (R152a, R600a and R1234yf) in a vertical mini-channel.In this study experiments were carried out by uniformly heating a test section (stainless steel tube with 1.60 mm inside diameter and 245 mm heated length) at 27 and 32 oC saturation temperature with 50-500 kg/m2s mass velocities. The effects of various parameters of interest (like heat flux, mass flux, system pressure, vapor quality, operating media) on flow boiling heat transfer, frictional pressure drop and dryout characteristics were recorded. R134a, which has been widely used in several applications, is utilized as a reference case for comparison of thermal performance in this study.Experimental results for saturated boiling heat transfer showed strong influence of heat flux and system pressure with insignificant contributions from mass flux and vapor quality. Two phase frictional pressure drop increased with mass flux, vapor quality and with reduced operating pressure. The dryout heat flux remained unaffected with variation in saturation temperature, critical vapor quality in most cases was about 85%. The experimental results (boiling heat transfer, two-phase pressure drop and dryout heat flux) were compared with well-known macro and micro-scale correlations from the literature.

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    Thesis
  • 226.
    Anwar, Zahid
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration. Department of Mechanical, Mechatronics and Manufacturing Engineering (KSK-Campus), University of Engineering and Technology, Lahore, Pakistan .
    Palm, Björn E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Khodabandeh, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Flow boiling heat transfer, pressure drop and dryout characteristics of R1234yf: Experimental results and predictions2015In: Experimental Thermal and Fluid Science, ISSN 0894-1777, E-ISSN 1879-2286, Vol. 66, p. 137-149Article in journal (Refereed)
    Abstract [en]

    Flow boiling heat transfer, pressure drop and dryout characteristics of R1234yf in a vertical stainless steel test section (1.60mm inside diameter and 245mm heated length) under upward flow conditions are reported in this article. The experiments were carried out at 27 and 32°C saturation temperatures with five mass fluxes in the range of 100-500kg/m2s while the applied heat flux was in the range of 5-130kW/m2. The experiments were carried out with gradual increase of the applied heat flux til completion of dryout. Under similar conditions, tests were repeated with R134a in the same test setup to compare thermal performance of these two refrigerants. The results showed that boiling heat transfer was strongly controlled by the applied heat flux and operating pressure with insignificant dependence on mass flux and vapor quality. The frictional pressure drop increased with mass flux and vapor quality and decreased with increasing saturation temperature as expected. Signs of dryout first appeared at vapor qualities of 85%, with the values generally increasing with increasing mass flux. The effect of varying system pressure was insignificant. The experimental results (boiling heat transfer, pressure drop and dryout heat flux) were compared with the predictions from well-known correlations (for macro and micro-scale channels) from the literature.

  • 227.
    Anwar, Zahid
    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, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Dryout characteristics of natural and synthetic refrigerants in vertical mini-channelsManuscript (preprint) (Other academic)
  • 228.
    Anwar, Zahid
    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, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Dryout characteristics of R1234yf in a vertical mini-channel2013In: Eurotherm seminar on convective heat transfer, 2013Conference paper (Refereed)
    Abstract [en]

    This article reports dryout characteristics of R1234yf in a single, uniformly heated vertical stainless steel channel (d=1.6mm, Lh=245mm). Tests were conducted at 27 and 32 oC saturation temperature with 100-500 kg/m2s. Results of various operating parameters (mass flux, vapor quality, saturation temperature) were discussed in detail. Comparison with R134a revealed lower (about 18%) critical heat flux values with R1234yf.  Experimental findings were compared with various macro & micro scale correlations from the literature. Katto- Ohno and Wu’s correlations [7,8] accurately predicted the data from macro and micro scale models respectively.

  • 229. Anwar, Zahid
    et al.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Khodabandeh, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Flow Boiling Heat Transfer and Dryout Characteristics of R600a in a Vertical Minichannel2015In: Heat Transfer Engineering, ISSN 0145-7632, E-ISSN 1521-0537, Vol. 36, no 14-15, p. 1230-1240Article in journal (Refereed)
    Abstract [en]

    Refrigerant-related environmental concerns forced legislative bodies to phase out some types of refrigerants, namely, chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) and in the near future European legislation will be affecting hydrofluorocarbons (HFCs) as well. Natural refrigerants such as hydrocarbons can thus be expected to be more common as refrigerants in the future. Experimental findings on flow boiling heat transfer and dryout characteristics of isobutane (R600a) in a uniformly heated, vertical, stainless-steel test section (1.60mm inside diameter and 245mm heated length) are reported in this article. The experiments were conducted at two saturation pressures corresponding to the temperatures of 27 and 32 degrees C, with five mass fluxes in the range 50-350kg/m(2)-s and at outlet vapor qualities up to dryout conditions. Analysis showed that heat transfer was primarily controlled by the applied heat flux with insignificant effect of mass flux and vapor quality. The dryout heat flux increased with increasing mass flux; however, no significant effect of varying saturation temperature was observed. The experimental results (for heat transfer and dryout) were compared with different macro and microscale correlations from the literature.

  • 230.
    Anwar, Zahid
    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, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Flow boiling heat transfer of R600a in a uniformly heated smooth vertical minichannel2013In: Proceedings of the 13th UK Heat Transfer Conference Sept. 2-3, 2013, UKHTC2013, 2013Conference paper (Refereed)
    Abstract [en]

    Refrigerant related environmental concerns forced legislative bodies to phase out some types of refrigerants namely CFC’s and HCFC’s and in the near future European legislation will be affecting HFCs as well. Natural refrigerants such as hydrocarbons can thus be expected to be more common as refrigerants in the future. Experimental studies with these fluids are important in understanding their performance and potential. Experimental findings on flow boiling of Isobutane in a uniformly heated, vertical, stainless steel test section (1.6 mm inside diameter and 245mm heated length) are reported in this article. Experiments were conducted at two saturation pressures corresponding to the temperature of 27 and 32 oC, with five mass fluxes in the range 50-350 kg/m2s and at outlet vapour qualities up till dryout conditions. Analysis showed that heat transfer was primarily controlled by the applied heat flux with insignificant effect of mass flux and vapor quality. The experimental results were compared with different macro and micro-scale correlations from the literature, and Owhaib, Liu & Winterton and Mikielewicz correlations quite accurately predicted the heat transfer data.

  • 231.
    Anwar, Zahid
    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, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Flow boiling of R1234yf in a uniform smooth vertical minichannel2013In: Science et Technique du Froid. Comptes Rendus/Refrigeration Science and Technology. Proceedings, 2013, Vol. 3, Institut International du Froid , 2013, p. 1-11Conference paper (Refereed)
    Abstract [en]

    This study describes experimental findings on flow boiling heat transfer with R1234yf in a smooth, vertical stainless steel tube of 1.6 mm inner diameter and 245 mm heated length. Tests were conducted at two saturation pressures corresponding to saturation temperatures of 27 and 32 °C. Other operating parameters were: mass flux 100-500 kg/m²s with heat flux 3-65 kW/m² while quality change was up to 60%. The heat transfer coefficient appeared to be a strong function of the applied heat flux and insignificant effect of mass flux and quality was observed. Increase in saturation temperature/pressure increased the heat transfer performance. Experiments were repeated with R134a in the same test section to compare the two fluids, almost similar results were duplicated with R134a. Experimental results were compared with different correlations, Tran et al. (1996), Gungor and Winterton (1986) and Martín-Callizo et al. (2007) correlations accurately predicted the data.

  • 232.
    Anwar, Zahid
    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, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Flow boilingheat transfer and dryout characteristics of R600a in a vertical mini-channelManuscript (preprint) (Other academic)
  • 233.
    Anwar, Zahid
    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.
    Rahmatollah, Khodabandeh
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Dryout characteristics of R1234yf in a uniformly heated vertical mini-channel2013In: UK Heat Transfer Conference, 2013Conference paper (Refereed)
    Abstract [en]

    Two phase heat transfer in small channels has many practical applications like, miniature heatexchangers, high powered electronics, miniature refrigeration system. Flow boiling in these compactchannels offers many potential advantages like, cope with high heat flux, less fluid inventory,compactness in size. It is well known that two phase heat transfer is drastically reduced when theheater surface becomes partially dry, for any reason. Moving beyond the point where this happensresults in a sharp increase in the temperature of the heated surface and eventually leads towardsburnout. So the upper operational limit (from safety and efficiency point of view) is extremelyimportant to be able to predict.Experimental findings on dryout of Isobutane in a uniformly heated, vertical, stainless steel testsection (1.6 mm inside diameter and 245mm heated length) are reported in this article. Experimentswere conducted at two saturation pressures corresponding to temperatures of 27 and 32 oC, with fivemass fluxes in the range 50-350 kg/m2s and with vapor fractions at the outlet up till dryout conditions.Analysis showed that the dryout heat flux increased with increasing mass flux, while no effect ofvarying the operating pressure was observed. Experimental results were compared with differentcorrelations from the literature, Wu [5], Mikielewicz [6], Callizo [3] and Katto-Ohno [4] correlationsquite satisfactorily predicted the data.

  • 234. Aoun, M. -C
    et al.
    Pešut, D.
    Matosović, M.
    Bošnjak, R.
    Deane, P.
    Glynn, J.
    Gallachóir, B. Ó
    Nagy, S.
    Badouard, T.
    Desbrosses, N.
    Taliotis, Constantinos
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis.
    de Boncourt, M.
    Keramidas, K.
    Gas Security of Supply in the European Union2017In: Europe's Energy Transition: Insights for Policy Making, Elsevier, 2017, p. 67-78Chapter in book (Refereed)
    Abstract [en]

    The EU remains widely dependent on external gas supplies, with imports representing 70% of its consumption in 2013. Member States have different import profiles with divergent levels of dependency on Russian imports. Several European Member States rely heavily on Russian supplies, which shows that the EU gas supply security needs to be examined both from an internal and international perspective. Since the 2009 crisis between Russia and Ukraine, the EU has adopted several legislative tools to strengthen EU gas security of supply. The third legislative package, the security of supply Regulation (EU) 994/2010 and the Energy Infrastructure package identifying Projects of Common Interest have significantly improved the ability of the EU to face import disruptions. However, several countries remain particularly vulnerable to the occurrence of disruption. When considering national production, storage, and the diversity of suppliers, Bulgaria, Czech Republic, Estonia, Finland, Latvia, and Lithuania seem to be at risk. Romania, Poland, and Hungary also import the bulk of their gas from Russia, but have either domestic production or significant storage capacity.

  • 235.
    Aragaw, Zereay
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Mainstreaming sustainable energy access in the development planning proccess of Ethiopia2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    For least developing countries with large rural population living in severe poverty such as Ethiopia, access to modern and sustainable energy services is a real challenge. Dealing with the lack of modern energy services at local level and the needs for economic development at national level is a major challenge in the policy and decision making process. This particular study takes the case of Ethiopia to investigate the existing challenges and future prospects of mainstreaming sustainable energy access into the country’s development planning process, and the consequences for international development financiers, national policy makers, private actors and local energy planners and experts. The roles and approaches of various developmental agencies are reviewed based on the effectiveness and sustainability of cooperation models with governmental institutions. To this end, this study establishes an understanding of institutional, financial and policy elements related to both state and non-state actors. Accordingly, readiness of the rural energy sector to adopt sector–perspective and national development approaches to mainstream sustainable energy access is investigated. The thesis emphasizes the need for all stakeholders to cooperate and take advantage of local potentials and external opportunities in light of the new momentum for sustainable energy access in the global agenda.

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    Mainstreaming sustainable energy access in the development planning proccess of Ethiopia
  • 236.
    Aranzabal, Nordin
    et al.
    UV, Dept Elect Engn, Burjassot 46100, Spain..
    Martos, Julio
    UV, Dept Elect Engn, Burjassot 46100, Spain..
    Stokuca, Milan
    Bengt Dahlgren Geoenergi, Hammarby Alle 47, S-12030 Stockholm, Sweden..
    Mazzotti Pallard, Willem
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Bengt Dahlgren Geoenergi, Hammarby Alle 47, S-12030 Stockholm, Sweden..
    Acuna, Jose
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Soret, Jesus
    UV, Dept Elect Engn, Burjassot 46100, Spain..
    Blum, Philipp
    KIT, Inst Appl Geosci AGW, D-76131 Karlsruhe, Germany..
    Novel instruments and methods to estimate depth-specific thermal properties in borehole heat exchangers2020In: Geothermics, ISSN 0375-6505, E-ISSN 1879-3576, Vol. 86, article id 101813Article in journal (Refereed)
    Abstract [en]

    Standard thermal response tests (TRT) are typically carried out to evaluate subsurface thermal parameters for the design and performance evaluation of borehole heat exchangers (BHE). Typical interpretation methods apply analytical or numerical solutions, which assume that the ground is homogeneous, isotropic and infinite. However in reality, the underground is commonly stratified and heterogeneous, and therefore thermal properties might significantly vary with depth. Thus, novel instruments and methods are necessary to characterize thermophysical properties along the BHE. In this study, two novel in-borehole temperature measurement instruments, Geoball and Geowire, are assessed during the performance of a distributed TRT (DTRT). The latter is evaluated in comparison to the widely used fiber optical thermometers. Our results suggest that both novel instruments have several advantages. For instance, both devices are able to instantaneously measure temperature with a higher spatial resolution. In addition, our study evaluates two methods to estimate depth-specific thermal conductivities: (1) a computer program based on infinite line source (ILS) approach and (2) a recently suggested inverse numerical procedure. For the latter less data is required, while demonstrating an accurate resolution to even detect thin conductive geological layers. Moreover, the average value of the depth-specific local effective estimates for both methods is significantly close to the effective subsurface conductivity of 3.20 W/m-K calculated based on standard TRT: 1.27 % below for the computer program and 0.28 % below for the numerical procedure.

  • 237.
    Araoz, Joseph Adhemar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Universidad Mayor de San Simon (UMSS), Bolivia.
    Salomon, Marianne
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Alejo, Lucio
    Universidad Mayor de San Simon (UMSS), Bolivia.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Non-ideal Stirling engine thermodynamic model suitable for the integration into overall energy systems2014In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, ISSN 1359-4311, Vol. 73, no 1, p. 203-219Article in journal (Refereed)
    Abstract [en]

    The reliability of modelling and simulation of energy systems strongly depends on the prediction accuracy of each system component. This is the case of Stirling engine-based systems, where an accurate modelling of the engine performance is very important to understand the overall system behaviour. In this sense, many Stirling engine analyses with different approaches have been already developed. However, there is a lack of Stirling engine models suitable for the integration into overall system simulations. In this context, this paper aims to develop a rigorous Stirling engine model that could be easily integrated into combined heat and power schemes for the overall techno-economic analysis of these systems. The model developed considers a Stirling engine with adiabatic working spaces, isothermal heat exchangers, dead volumes, and imperfect regeneration. Additionally, it considers mechanical pumping losses due to friction, limited heat transfer and thermal losses on the heat exchangers. The predicted efficiency and power output were compared with the numerical model and the experimental work reported by the NASA Lewis Research Centre for the GPU-3 Stirling engine. This showed average absolute errors around ±4% for the brake power, and ±5% for the brake efficiency at different frequencies. However, the model also showed large errors (±15%) for these calculations at higher frequencies and low pressures. Additional results include the calculation of the cyclic expansion and compression work; the pressure drop and heat flow through the heat exchangers; the conductive, shuttle effect and regenerator thermal losses; the temperature and mass flow distribution along the system; and the power output and efficiency of the engine.

  • 238.
    Araoz Ramos, Joseph A.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Facultad de Ciencias y Tecnología (FCyT), Universidad Mayor de San Simon (UMSS), Cochabamba, Bolivia.
    Salomon, Marianne
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Alejo, Lucio
    Fransson, Torsten H.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Numerical simulation for the design analysis of kinematic Stirling engines2015In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 159, p. 633-650Article in journal (Refereed)
    Abstract [en]

    The Stirling engine is a closed-cycle regenerative system that presents good theoretical properties. These include a high thermodynamic efficiency, low emissions levels thanks to a controlled external heat source, and multi-fuel capability among others. However, the performance of actual prototypes largely differs from the mentioned theoretical potential. Actual engine prototypes present low electrical power outputs and high energy losses. These are mainly attributed to the complex interaction between the different components of the engine, and the challenging heat transfer and fluid dynamics requirements. Furthermore, the integration of the engine into decentralized energy systems such as the Combined Heat and Power systems (CHP) entails additional complications. These has increased the need for engineering tools that could assess design improvements, considering a broader range of parameters that would influence the engine performance when integrated within overall systems. Following this trend, the current work aimed to implement an analysis that could integrate the thermodynamics, and the thermal and mechanical interactions that influence the performance of kinematic Stirling engines. In particular for their use in Combined Heat and Power systems. The mentioned analysis was applied for the study of an engine prototype that presented very low experimental performance. The numerical methodology was selected for the identification of possible causes that limited the performance. This analysis is based on a second order Stirling engine model that was previously developed and validated. The simulation allowed to evaluate the effect that different design and operational parameters have on the engine performance, and consequently different performance curves were obtained. These curves allowed to identify ranges for the charged pressure, temperature ratio, heat exchangers dimensions, crank phase angle and crank mechanical effectiveness, where the engine performance was improved. In addition, the curves also permitted to recognise ranges were the design parameters could drastically reduce the brake power and efficiency. The results also showed that the design of the engine is affected by the conditions imposed by the CHP interactions, and that the engine could reach a brake power closer to 832 W with a corresponding brake efficiency of 26% when the adequate design parameters were considered. On the other hand, the performance could also be very low; as the reported in experimental tests, with brake power measurements ranging 52-120W.

  • 239.
    Araoz Ramos, Joseph Adhemar
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermodynamic analysis of Stirling engine systems: Applications for combined heat and power2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Increasing energy demands and environmental problems require innovative systems for electrical and thermal energy production. In this scenario, the development of small scale energy systems has become an interesting alternative to the conventional large scale centralized plants. Among these alternatives, small scale combined heat and power (CHP) plants based on Stirling Engines (SE) have attracted the interest among research and industry due to the potential advantages that offers. These include low maintenance, low noise during operation, a theoretically high electrical efficiency, and principally the fuel flexibility that the system offers. However, actual engine performances present very low electrical efficiencies and consequently few successful prototypes reached commercial maturity at elevated costs.Considering this situation, this thesis presents a numerical thermodynamic study for micro scale CHP-SE systems. The study is divided in two parts: The first part covers the engine analysis; and the second part studies the thermodynamic performance of the overall CHP-SE system. For the engine analysis a detailed thermodynamic model suitable for the simulation of different engine configurations was developed. The model capability to predict the engine performance was validated with experimental data obtained from two different engines: The GPU-3 Stirling engine studied by Lewis Research Centre; and the Genoa engine studied on the experimental rig built at the Energy Department at the Royal Institute of Technology (KTH). The second part of the research complemented the study with the analysis of the overall CHP-SE system. This included numerical simulations of the different CHP components and the sensitivity analysis for selected design parameters.The complete study permitted to assess the different operational and design configurations for the engine and the CHP components. These improvements could be implemented for test field evaluations and thus foster the development of more efficient SE-CHP systems. In addition, the detailed thermodynamic-design methodology for the SE-CHP systems was established and the numerical tool for the design assessment was developed.

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    Thesis
  • 240.
    Araoz Ramos, Joseph Adhemar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Universidad Mayor de San Simon (UMSS), Bolivia.
    Cardozo, Evelyn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Universidad Mayor de San Simon (UMSS), Bolivia.
    Salomon, Marianne
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Alejo, Lucio
    Universidad Mayor de San Simon (UMSS), Bolivia.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Development and validation of a thermodynamic model for the performance analysis of a gamma Stirling engine prototype2015In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 83, p. 16-30, article id 6439Article in journal (Refereed)
    Abstract [en]

    This work presents the development and validation of a numerical model that represents the performance of a gamma Stirling engine prototype. The model follows a modular approach considering ideal adiabatic working spaces; limited internal and external heat transfer through the heat exchangers; and mechanical and thermal losses during the cycle. In addition, it includes the calculation of the mechanical efficiency taking into account the crank mechanism effectiveness and the forced work during the cycle. Consequently, the model aims to predict the work that can be effectively taken from the shaft. The model was compared with experimental data obtained in an experimental rig built for the engine prototype. The results showed an acceptable degree of accuracy when comparing with the experimental data, with errors ranging from +/- 1% to +/- 8% for the temperature in the heater side, less than +/- 1% error for the cooler temperatures, and +/- 1 to +/- 8% for the brake power calculations. Therefore, the model was probed adequate for study of the prototype performance. In addition, the results of the simulation reflected the limited performance obtained during the prototype experiments, and a first analysis of the results attributed this to the forced work during the cycle. The implemented model is the basis for a subsequent parametric analysis that will complement the results presented.

  • 241.
    Araoz Ramos, Joseph Adhemar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Salomon, Marianne
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Alejo, Lucio
    Universidad Mayor de San Simon.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Integration of Stirling engines into residential boilers for combined heat and power services: Thermodynamic modelling and analysisManuscript (preprint) (Other academic)
    Abstract [en]

    The use of simulation techniques for the study of Combined Heat and Power systems based on Stirling Engines (CHP-SE) has been focused on dynamic simulations that guide the sizing of the system components. These are valuable tools for the performance evaluation of determined designs. However, there is a need to complement these studies with additional analysis that could permit to assess the design improvement and the integration of the system components. For this reason, the present work developed a model that coupled the design equations of each component with the equations that describe the thermal interactions presented in the overall system.

    This integration allowed to obtain a deeper insight into the thermodynamic characteristics of the overall system, and thus was used for the study of a micro CHP-SE experimental rig.  The results for this case study allowed to quantify the main energy outputs, the energy losses, and the influence of different parameters on the system. The overall efficiency under the original conditions presented values ranging from 60%-64% with very low exergy efficiencies ranging from 5%-7%. The simulation analysis permitted to identify design and operational parameters that would increase the overall efficiency to values closer to 80% and the exergy to values closer to 14%. These increments would correspond to the reduction of the energy losses, improvements on the conditions for the biomass combustion, and the use of engines with higher electrical outputs. 

  • 242.
    Araoz Ramos, Joseph Adhemar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Salomon, Marianne
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Alejo, Lucio
    Universidad Mayor de San Simon.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Numerical simulation for the performance analysis of a gamma Stirling engine prototypeManuscript (preprint) (Other academic)
    Abstract [en]

    Computer assisted modelling and simulation of energy systems asses the performance and suggest improvements to achieve energy efficient solutions. This is the case of the Stirling engine technology, where computer simulations combined with experimental work have helped to the development of different prototypes. Following this trend, the current work aims to study possible improvements towards the design of a gamma Stirling engine prototype through numerical simulations. The prototype was first experimentally studied and presented low performances. For this reason and considering a lack of reports for this prototype, the numerical simulation was the approach to identify the possible problems that limited the performance. In this regard, this paper presents the development and validation of a numerical model that represent the performance of the Stirling prototype. The model follows a modular approach considering ideal adiabatic working spaces; limited internal and external heat transfer through the heat exchangers; and mechanical and thermal losses during the cycle. In addition, it includes the calculation of the mechanical efficiency taking into account the crank mechanism effectiveness and the forced work during the cycle. Consequently, the model aims to predict the work that can be effectively taken from the shaft. The model was compared with experimental data obtained in an experimental rig built for the engine prototype. The results showed an acceptable degree of accuracy when comparing with the experimental data, with errors ranging from 1%-8% for the temperature in the heater side, less than 1% error for the cooler temperatures, and 1-8% for the brake power calculations. Therefore, the model was probed adequate for study the prototype performance. In addition, the results of the simulation reflected the limited performance obtained during the prototype experiments, and a first analysis of the results attributed this to the forced work during the cycle. The implemented model is the basis for a subsequent parametric analysis that will complement the results presented.

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  • 243.
    Arco Sola, Javier
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Nelson, Oscar
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Applications of biomass Stirling engines for electrification -A case study of rural areas in Bolivia.2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report provides a study and a simulation of a feasible system configuration for the implementation of a Stirling engine for electrification of rural areas in Bolivia. The aim of the review is to determine if a hybrid system combining a biomass-fired Stirling engine and photovoltaic technology may respond to a basic electricity need.

    An introductory literature study about the Stirling engine technology and the energy resources and characteristics of Bolivia leads to a further proposal of the selected system for rural electrification.

    The chosen Stirling engine for this study is a 3 kW electric output engine combined with a PV array of 0.9 kW and a battery bank with a capacity of 1200 Ah. The power demand that must be satisfied is based on a rural village in the department of Beni with an amount of 24 households.

    The simulation is performed in the software Homer Energy where an energy balance between the generated power and the demand can be analysed in order to optimise the power generation strategy. Two scenarios are simulated with monthly demands of 45 and 60 kWh per household.

    Results from the study indicate that the decision on the size of the Stirling engine must be attached to the demand that is going to satisfy in order to avoid insufficient or excessive power production. In addition, although the PV technology allows an increase on the power demand that the system can handle and makes it more flexible, its contribution is not of the same order of the Stirling engine. The described system configuration is able to attend a demand up to 55 kWh/day and a peak power of 3.8 kW.

    In conclusion, Stirling engines have the potential to become a good solution for rural electrification, especially when making use of CHP strategies to increase the overall efficiency of the energy generation and fulfil both the electric and thermal demands of rural populations. 

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    fulltext
  • 244.
    Arderne, Christopher
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    A climate, land-use, energy and water nexus assessment of Bolivia2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Land, energy and water are the foundational resources of a country, and have a number of complex interactions with a changing climate. Their exploitation can have significant impacts on climate change, which in turn can affect the future availability of these resources. Thus it is important to properly manage these resources, to ensure that they can continue to provide long into the future. This thesis aims to assess the climate, land-use, energy and water systems (CLEWs) nexus in Bolivia, to determine critical points of interactions, and to produce recommendations for policy actions. This includes both mitigation and adaptation actions. The results show that Bolivia’s projected demand increases are certainly manageable, and with the investments as outlined, they can easily be satisfied, while reducing emissions and increasing climate resilience. An important result is that municipal and thermal water demand don’t appear to be limiting constraints, and so water management efforts should focus on agricultural and hydropower use. Recommended future work is to increase the scope and detail of the water and land model, so that all of the planned hydropower projects are included, and so that agriculture and irrigation demands and impacts can be more accurately predicted.

    Download full text (pdf)
    fulltext
  • 245.
    Arias Hurtado, Jaime
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Whole Supermarket System Modelling2015In: Sustainable Retail Refrigeration, Wiley Blackwell , 2015, p. 263-290Chapter in book (Other academic)
    Abstract [en]

    The supermarket sector has more or less used the trial and error approach to implement and evaluate new ideas and concepts for decreasing energy usage and minimizing refrigerant charge. To estimate the energy requirement in a supermarket, it is necessary to evaluate the interrelatedness between the different subsystems and their energy demands. The main subsystems included in computer simulation models for energy use in supermarkets are the building envelope, outdoor climate, HVAC system, refrigeration system and retail display cabinets. The chapter also analyzes four different whole-building simulation models for supermarkets: EnergyPlus developed by the US Department of Energy; CyberMart developed by the Royal Institute of Technology in Sweden; RETScreen developed by Natural Resources Canada; and SuperSim developed by Brunel University in the UK. The implementation of new energy-saving technologies in supermarkets requires an extensive analysis of energy performance of refrigeration systems, HVAC systems, lighting, appliances, and of total energy consumption. 

  • 246.
    Arias, J
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lundqvist, PKTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    A computer model that compares different refrigeration systems in supermarkets2003Conference proceedings (editor) (Refereed)
  • 247.
    Arias, J
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lundqvist, P
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Advanced Supermarket refrigeration2003Report (Refereed)
  • 248.
    Arias, J
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lundqvist, P
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Comparison of Recent refrigeration systems in supermarkets2001Conference paper (Refereed)
  • 249.
    Arias, J
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lundqvist, P
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Den energieffektiva butiken i teori och praktik – slutrapport2001Report (Refereed)
  • 250.
    Arias, J
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lundqvist, P
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Heat recovery in recent refrigeration systems in supermarkets2002Conference paper (Refereed)
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