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  • 1.
    Björner Brauer, Hanna
    et al.
    University West, Department of Social and Behavioural Studies, Division of Psychology, Pedagogy and Sociology.
    Håkansson, Maria
    Division of Built Environment RISE Research Institutes of Sweden, Göteborg (SWE).
    Willis, Morgan
    Division of Built Environment RISE Research Institutes of Sweden, Göteborg (SWE).
    The Ghost in the Heat Pump: Examining social flexibility potential in thermal comfort practices through an experiment of remote-controlled heating in detached houses2023In: Conference Proceedings  BEHAVE 2023 the 7th European Conference on Behaviour Change for Energy Efficiency / [ed] Marta Lopes, Kaisa Matschoss, Thijs Bouman, European Energy Network; Netherlands Enterprise Agency , 2023, p. 240-251Conference paper (Refereed)
    Abstract [en]

    Utilizing energy flexibility in households through smart steering of appliances has received attention as one way to reduce power peaks and adapt demand to a renewable energy system. Heating is a big part of the electricity consumption in households, and heat pump technology is growing in popularity for heating detached houses. While there is ongoing research calculating the technical potential for energy flexibility from heat pumps, few studies combine remote control of heat pumps with qualitative research on how households experience this control. The purpose of this study is to find out how long-term steering of heat pumps is experienced by households, how it affects their heating practices, and how they make sense of remote steering as a service. The data originates from an interdisciplinary project combining a field trial where heat pumps of selected Swedish households were remotely controlled for two winter periods, with qualitative interviews with the households. We conducted interviews with 12 participants, before and after the trial.The results show that households were overall positive towards offering flexibility through remote-controlled heat pumps, and that the steering of the heating blended well with normal temperature variation associated with having a villa in Sweden. However, the respondents were mystified by the procedure, which created a ghost in the heat pump. Furthermore, remote steering as a service comes with challenges related to reliability, security, and agency over the heat pump. Important social conditions for adopting flexibility through remote steering of heat pumps are discussed.

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    fulltext
  • 2.
    Chourushi, T.
    et al.
    School of Mechanical and Aerospace Engineering and ACTRC, Gyeongsang National University, Jinju, Gyeongnam (KOR).
    Rahimi, Amin
    University West, Department of Engineering Science, Division of Welding Technology.
    Singh, S.
    School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link (SGP).
    Ejtehadi, O.
    Supercomputing Modeling and Simulation Center, Korea Institute of Science and Technology Information (KISTI), Daejeon (KOR).
    Mankodi, T. K.
    Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Assam (IND).
    Myong, R. S.
    School of Mechanical and Aerospace Engineering and ACTRC, Gyeongsang National University, Jinju, Gyeongnam (KOR).
    Thermal and flow characteristics of nonequilibrium monatomic, diatomic, and polyatomic gases in cylindrical Couette flow based on second-order non-Navierâ-Fourier constitutive model2022In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 187Article in journal (Refereed)
    Abstract [en]

    The thermal and flow characteristics of nonequilibrium monatomic, diatomic, and polyatomic gases in cylindrical Couette flow are investigated using first- and second-order Boltzmann-Curtiss-based constitutive models. The mixed modal discontinuous Galerkin scheme is used for solving the conservation laws in conjunction with the Maxwell velocity-slip and Smoluchowski temperature-jump boundary conditions. Also derived are new analytic solutions for compressible cylindrical Couette gas flow including the temperature profile, and they are used to verify the numerical scheme. Further, the second-order non-Navier-Fourier constitutive relations are derived for the cylindrical coordinates. Various abnormal behaviour is found in the second-order constitutive model, such as non-zero normal stress and excess normal stress, non-zero tangential heat flux, and flattened pressure and density profiles. The physical mechanisms behind this abnormal behaviour are found to be similar to the Knudsen layer in planar Couette gas flow, and the curvature of the cylindrical geometry does not affect the fundamental second-order physics. Moreover, two new abnormal mechanisms are found in diatomic and polyatomic gases: (i) the subtle interplay of excess normal stress (and bulk viscosity) with the nonlinear coupled constitutive relation, and (ii) the combined role of the bulk viscosity ratio and the specific heat ratio.

  • 3.
    Ehnberg, Jimmy S. G.
    et al.
    Chalmers University of Technology, Department of Electric Power Engineering.
    Bollen, Math H.J
    Chalmers University of Technology, Department of Electric Power Engineering.
    Simulation of global solar radiation based on cloud observations2005In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 78, no 2, p. 157-162Article in journal (Refereed)
  • 4.
    Ehnberg, Jimmy S.G.
    University West, Department of Technology, Mathematics and Computer Science, Division for Electrical Engineering and Land Surveying.
    Autonomous power systems based on renewables: On generation reliability and system control2007Doctoral thesis, comprehensive summary (Other academic)
  • 5.
    Ehnberg, Jimmy S.G.
    et al.
    Chalmers University of Technology,Department of Electric Power Engineering.
    Bollen, Math H.J.
    STRI Ab,Ludvika.
    Generation Reliability for Small Isolated Power Systems entirely based on Renewable Sources2004In: Power Engineering Society General Meeting, 2004. IEEE, 2004, p. 2322-2327 Vol 2Conference paper (Refereed)
  • 6.
    Gupta, Mohit Kumar
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Nylén, Per
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Design of Low Thermal Conductivity Thermal Barrier Coatings by Finite Element Modelling2011In: Surface Modification Technologies XXIV: SMT24, Dresden, September 7-9, 2010 / [ed] T. S. Sudarshan, Eckhard Beyer, and Lutz-Michael Berger, 2011, p. 353-365Conference paper (Refereed)
    Abstract [en]

    Fundamental understanding of relationships between coating microstructure and thermal conductivity is important to be able to understand the influence of coating defects, such as delaminations and pores, on heat insulation in thermal barrier coatings (TBC). Object Oriented Finite element analysis (OOF) has recently been shown as an effective tool for evaluating thermo-mechanical material behaviour as this method is capable of incorporating the inherent material microstructure as an input to the model. The objective of this work was to evaluate a procedure where this technique is combined with Tbctool, a plasma-sprayed TBC like morphology generator, thus enabling development of low thermal conductivity coatings by simulation. Input parameters for Tbctool were computed from SEM images of sprayed microstructures using the image analysis software, Aphelion. Microstructures for as-sprayed as well as heat treated samples were evaluated. The thermal conductivities of the artificially generated microstructures were determined using OOF. Verification of the modelling procedure was performed by comparing predicted values by OOF with corresponding measured values using the laser flash technique. The results, although tentative in nature, indicate that the proposed simulation approach can be a powerful tool in the development of new low conductivity coatings.

  • 7.
    Gupta, Mohit Kumar
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Nylén, Per
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Structure-property Relationships in Thermal Barrier Coatings by Finite Element Modelling2012In: Surface Modification Technologies XXV : proceedings of the Twenty Fifth International Conference on Surface Modification Technologies: SMT25, Trollhättan, June 20-22, 2011 / [ed] T. S. Sudarshan, and P. Nylén, [Chennai]: Valardocs , 2012, p. 175-184Conference paper (Refereed)
    Abstract [en]

    The thermal and mechanical properties of Thermal Barrier Coating systems (TBCs) are strongly influenced by coating defects, such as delaminations and pores, thus making it essential to have a fundamental understanding of microstructure-property relationships in TBCs, to produce a desired coating. Object-Oriented Finite element analysis (OOF) has been shown previously as an effective tool for evaluating thermal and mechanical material behaviour, as this method is capable of incorporating the inherent material microstructure as an input to the model. In this work, OOF was used to predict the thermal conductivity and effective Young’s modulus of TBC topcoats. A Design of Experiments (DoE) was conducted by varying selected spray parameters for spraying Yttria Partially Stabilized Zirconia (YPSZ) topcoat. Characterisation of the coatings included microstructure, porosity and crack content and thermal conductivity measurements. The relationships between microstructural features, thermal conductivity and Young’s modulus are discussed.

  • 8.
    Gupta, Mohit Kumar
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Weber, André
    Karlsruhe Institute of Technology, Germany.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Gindrat, Malko
    Oerlikon Metco, Switzerland.
    Electrochemical Performance of Plasma Sprayed Metal Supported Planar Solid Oxide Fuel Cells2016In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 163, no 9, p. F1059-F1065Article in journal (Refereed)
    Abstract [en]

    High production cost is one of the major barriers to widespread commercialization of solid oxide fuel cells (SOFCs). Thermal spraytechniques are a low cost alternative for the production of SOFCs. The objective of this work was to evaluate the electrochemicalperformance of cells produced by plasma spraying. The anode was deposited on a porous metallic support by atmospheric plasmaspraying (APS) whereas the electrolyte was deposited by plasma spray-thin film (PS-TF) technique, which can produce thin anddense coatings at high deposition rates. The cathode was deposited by screen-printing and in-operando sintering. The electrochemicaltests were performed at 650–800◦C. Current-voltage characteristics and impedance spectra were measured and analyzed. The impactof electrolyte composition and layer thickness on the gas tightness of the electrolyte and the area specific resistance of the cell isdiscussed. The results show that the applied thermal spraying techniques are a potential alternative for producing SOFCs.

  • 9.
    Gupta, Mohit Kumar
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Weber, André
    Karlsruhe Institute of Technology, Germany.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Helden, Nadine
    Oerlikon Metco, Germany.
    Development of plasma sprayed Ni/YSZ anodes for metal supported solidoxide fuel cells2017In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 318, p. 178-189Article in journal (Refereed)
    Abstract [en]

    Solid oxide fuel cells (SOFCs) offer a promising technique for producing electricity by clean energy conversionthrough an electrochemical reaction of fuel and air. Plasma spraying could be a potential manufacturing routefor commercial SOFCs, as it provides a distinct advantage especially in case of metal supported cells (MSCs) byallowing rapid processing at relatively low processing temperatures preventing thus the degradation of themetallicsubstrate. The objective of this work was to develop nickel/yttria stabilised zirconia (Ni/YSZ) anodes withhigh porosity and homogeneous phase distribution by atmospheric plasma spraying forMSCs. Various feedstockmaterial approaches were explored in this study, both with single injection aswell as separate injection of differentfeedstock materials , and with and without the use of pore formers to create additional porosity. The advantagesand issues with each material route were investigated and discussed. It was shown that agglomerated Ni/YSZ/polyester feedstock material resulted in the best distribution of Ni and YSZ in the anodemicrostructurewithhomogeneous porosity. Subsequently, the Ni/YSZ/polyester material route with different amounts and size distributionsof polyester was chosen to develop anode symmetrical cells using a commercial zirconia sheet as supportfor electrochemical testing. The Ni/YSZ/polyester anode powder with 10 wt.% standard size polyesterexhibited the best electrochemical performance. The results show that plasma spraying of the agglomeratedNi/YSZ/polyester could be a promising route to achieve high performance and rapid production anodes withoutusing the carcinogenic nickel oxide.

  • 10.
    Isaksson, Charlotta
    et al.
    University West, Department of Social and Behavioural Studies, Division of Social Work and Social Pedagogy. RISE Research Institutes of Sweden, Division Built Environment, Energy and Circular Economy, Box 857, Borås, SE-501 15, Sweden.
    Hiller, Carolina
    RISE Research Institutes of Sweden, Division Built Environment, Energy and Circular Economy, Box 857, Borås, SE-501 15, Sweden.
    Lane, Anna-Lena
    RISE Research Institutes of Sweden, Division Built Environment, Energy and Circular Economy, Box 857, SE-501 15, Borås, Sweden.
    Active, passive, non-existing or conditional?: Social relations shaping energy use at workplaces2019In: Energy Research & Social Science, ISSN 2214-6296, E-ISSN 2214-6326, Vol. 51, p. 148-155Article in journal (Refereed)
    Abstract [en]

    Energy efficiency concerns the entire workplace and a cooperative approach is important for achieving ambitious energy reduction targets. Despite this, many organisations still mainly regard energy efficiency as a technical issue involving just a few specialists. A focus on the social relations and processes that shape work on energy issues is lacking. The aim of this paper is to illuminate and explore social relations between the staff driving energy issues and their co-workers. The analysis presented is based upon two features shaping their mutual engagement for reducing energy use: the communication strategy on energy issues undertaken by the workplace and the support for energy efficiency and conservation among the staff. The study provides insights gained from an interview study done in a Swedish organisation as well as from social science research in the field. The result is a conceptual framework that describes four relationships between the drivers of change and their co-workers. These relationships are characterized as active, passive, non-existing and conditional engagement in energy efficiency and conservation. The framework can be used as a tool for identifying social constraints and possibilities for reducing the use of energy at workplaces as well as in other contexts. © 2019 Elsevier Ltd

  • 11.
    Mandati, Sreenkanth
    et al.
    Centre for Solar Energy Materials, International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur, Hyderabad, Telangana 500005, India ; Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502285, India.
    Dey, Suhash R.
    Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502285, India.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Sarada, Bulusu V.
    Centre for Solar Energy Materials, International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur, Hyderabad, Telangana 500005, India.
    Two-dimensional CuIn1−xGaxSe 2 nano-flakes by pulse electrodeposition for photovoltaic applications2019In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 181, p. 396-404Article in journal (Refereed)
    Abstract [en]

    Fabrication of Cu(In,Ga)Se 2 (CIGS) absorber layers containing two-dimensional nano-flake structures using a single stage pulse electrodeposition technique is reported for the first time, wherein CuCl 2 , InCl 3 , GaCl 3 and H 2 SeO 3 are used as precursors in a pH 3 buffer. The method employs tri-sodium citrate as complexing agent. The phenomenon of intrinsic electrochemical dissolution associated with pulse electrodeposition technique is efficiently utilized to obtain CIGS nano-flakes. The presence of tri-sodium citrate and the relaxation time during pulse electrodeposition play crucial role in achieving control over composition and morphology of CIGS films thereby aiding in the formation of nano-flakes. Evolution of nano-flake structures is systematically investigated with the increase in deposition time during pulse electrodeposition. Elemental analysis reveals the stoichiometric composition of nano-flake films while the formation of chalcopyrite phase-pure CIGS is confirmed by XRD and Raman analyses. The bandgap of CIGS nano-flakes is inferred to be about 1.21 eV from Tauc's plot. Mott-Schottky studies unveil the p-type conductivity of the CIGS with a flat-band potential and carrier density values of −0.15 V and 5.2 × 10 16 cm −3 , respectively. Photoelectrochemical characterization of CIGS films affirms their photoactivity and the photoresponse is almost 20 times compared to the traditional planar CIGS films. Nanostructured CIGS films fabricated by low-cost pulse electrodeposition method reduce materials consumption while promising excellent photoresponse and are suitable for photovoltaic and photoelectrochemical applications. © 2019 International Solar Energy Society

  • 12.
    Mehrabi, M.
    et al.
    Clean Energy Research Group, Department of Mechanical and Aeronautical Engineering, University of Pretoria,Hatfield (ZAF).
    Noori Rahim Abadi, Seyyed Mohammad Ali
    University West, Department of Engineering Science, Division of Welding Technology.
    Modeling of condensation heat transfer coefficients and flow regimes in flattened channels2021In: International Communications in Heat and Mass Transfer, ISSN 0735-1933, E-ISSN 1879-0178, Vol. 126, article id 105391Article in journal (Refereed)
    Abstract [en]

    In this paper, an adaptive neuro-fuzzy inference system (ANFIS) with fuzzy C-means clustering (FCM) structure identification is proposed to model condensation heat transfer and flow regimes in flattened smooth tubes with different aspect ratios. The FCM-ANFIS model was trained by using experimental data points for six effective chosen parameters of saturation temperature, heat flux, mass flux, aspect ratio and hydraulic diameter of the flattened tube, and vapor quality. Three flow regimes of annular flow, stratified, and intermittent flow were linked to the effective parameters based on the experimental data. Two models were proposed to predict the condensation heat transfer coefficient and the flow regime of R134a and R410a in flattened smooth tubes. Three statistical criteria were used to ascertain the accurateness of the models compared to the experimental results. It is found that while among benchmarked cases, the proposed model for the condensation heat transfer coefficient performs well, the best result with the lowest error (MAE = 0.029, RMSE = 0.036 and MRE = 2.83%) is when T-sat = 45 degrees C, q ‘’ = 10 kW/m(2), G = 100 kg/m(2). s, beta = 6 and D-h = 2.3 mm. On the other hand, in the worst-performing case when the errors are MAE = 0.239, RMSE = 0.239 and MRE = 13.36%, the predicted results are still in the uncertainty range of the experimental result when T-sat = 45 degrees C, q ‘’ = 5 kW/m(2), G = 200 kg/m(2). s, beta = 6 and D-h = 2.3 mm.

  • 13.
    Ndiwe, Benoit
    et al.
    University West, Department of Engineering Science, Division of Welding Technology. Department of Mechanical Engineering, Higher Technical Teacher Training College Douala (ENSET), University of Douala, Douala (CMR); Laboratory of Forest Resources and Wood Valorization (Larefob), ENSET of Douala, Douala (CMR).
    Pizzi, Antonio
    LERMAB-ENSTIB, University of Lorraine, Epinal (FRA).
    Chapuis, Hubert
    Laboratoire D’Etudes et de Recherche sur le Matériau Bois LERMAB, Faculté des Sciences et Technologies, Université de Lorraine, Nancy (FRA).
    Konai, Noel
    Laboratory of Materials Mechanics, Structures and Integrated Manufacturing, National Advanced School of Engineering, Yaoundé 1 University, Yaoundé (CMR).
    Karga, Lionel
    Department of Mechanical Petroleum and Gas Engineering, Faculty of Mines and Petroleum Industries, University of Maroua, Kaélé (CMR).
    Girods, Pierre
    LERMAB-ENSTIB, University of Lorraine, Epinal (FRA).
    Danwe, Raidandi
    Laboratory of Materials Mechanics, Structures and Integrated Manufacturing, National Advanced School of Engineering, Yaoundé 1 University, Yaoundé (CMR).
    Desorption Behavior and Thermogravimetric Analysis of Bio-Hardeners2022In: Journal of Renewable Materials, ISSN 2164-6325, E-ISSN 2164-6341Article in journal (Refereed)
    Abstract [en]

    In this work, the thermal degradation and drying of bio-hardeners are investigated. Four bio-hardeners based on exudates of Senegalia senegal, Vachellia nilotica, Vachellia seyal, and Acacia Siebteriana were analyzed by FTIR and thermogravimetric analysis, and a desorption study was also conducted. The analysis by infrared spectroscopy indicates the existence of oligomers of different types all giving 5-hydroxy-2-hydroxymethylfuran and 2, 5-dihydroxymethylfuran which are then the real hardening molecules. The pyrolysis of these extracts reveals three main regions of mass loss, a first region is located between 25 degrees C and 110 degrees C reflecting the loss of water from the adhesive and the formation of some traces of volatile organic compounds such as CO2 and CO, a second zone characterized by the release of CO, CO2 and CH4 gases with peaks between 110 degrees and 798.8 degrees C. At the end of the analysis, about 22% of the initial mass remains undecomposed, this mass corresponds to the rigid segments of the bio-hardener which are not completely decomposed.

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    TachScience
  • 14.
    Rohdin, Patrik
    et al.
    Linköpings universitet.
    Johansson, M
    Saab Automobile AB.
    Löfberg, J
    Automatic Control, Linköping University, Sweden.
    Ottosson, Mattias
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Energy efficient process ventilation in paint shops in the car industry: Experiences and an evaluation of a full scale implementation at Saab Automobile in Sweden.2012In: Ventilation 2012, 2012, p. 1-6Conference paper (Refereed)
    Abstract [en]

    Support processes in industrial energy systems, such as heating, ventilation and cooling systems, are important processes in industrial premises as they are related to energy cost, product quality as well as the indoor environment.

    In the vehicle production process the paint shop is the most energy intensive part, and about 75% of the energy is used in the ovens and spray booths. The spray booth line, which includes paint application and the oven, uses large quantities of air in order to keep the air quality in an optimal range to achieve the desired paint quality. The approach used in paint shops has up to now been to keep as much of steady state conditions as possible to avoid paint defects due to disturbances in the balance. This means that these high air flows are used also at low and non production hours. There is thus a large potential to increase energy efficiency by controlling the air flow and heating without losing the critical balances. This paper will present an initial post-implementation evaluation of the energy efficiency potential and experiences after running this type of system. CFD has been used to investigate the control strategy.

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    Ventilation_2012
  • 15.
    Seal, M. K.
    et al.
    Clean Energy Research Group, Department of Mechanical and Aeronautical Engineering, University of Pretoria,Hatfield (ZAF).
    Noori Rahim Abadi, Seyyed Mohammad Ali
    University West, Department of Engineering Science, Division of Welding Technology.
    Mehrabi, M.
    Clean Energy Research Group, Department of Mechanical and Aeronautical Engineering, University of Pretoria, Hatfield (ZAF).
    Meyer, J. P.
    Clean Energy Research Group, Department of Mechanical and Aeronautical Engineering, University of Pretoria, Hatfield (ZAF).
    Machine learning classification of in-tube condensation flow patterns using visualization2021In: International Journal of Multiphase Flow, ISSN 0301-9322, E-ISSN 1879-3533, Vol. 143, article id 103755Article in journal (Refereed)
    Abstract [en]

    Identifying two-phase flow patterns is fundamental to successfully design and subsequently optimize highprecision heat transfer equipment, given that the heat transfer efficiency and pressure gradients occurring in such thermo-hydraulic systems are dependent on the flow structure of the working fluid. This paper shows that with visualization data and artificial neural networks, the flow pattern images of condensation of R-134a refrigerant in inclined smooth tubes can be classified with more than 98% accuracy. The study considers 10 classes of flow pattern images acquired from previous experimental works for a wide range of flow conditions and the full range of tube inclination angles. Although not the focus of this paper, the use of a Principal Component Analysis allowed feature dimensionality reduction, dataset visualization, and decreased associated computational cost when used together with multilayer perceptron neural networks. In addition, the superior two-dimensional spatial learning capability of convolutional neural networks allowed improved image classification and generalization performance. In both cases, the classification was performed sufficiently fast to enable real-time implementation in two-phase flow systems.

  • 16.
    Torkfar, A.
    et al.
    Amirkabir Univ Technol, Dept Mech Engn, Tehran 1591634311, Iran (IRN).
    Noori Rahim Abadi, Seyyed Mohammad Ali
    University West, Department of Engineering Science, Division of Welding Technology.
    Ahmadpour, A.
    Amirkabir Univ Technol, Dept Mech Engn, Tehran 1591634311, Iran (IRN).
    Natural Convection Heat Transfer of Non-Newtonian Power-Law Fluids Within an Array of Elliptic Cylinders2020In: Journal of Fluids Engineering, ISSN 0098-2202, E-ISSN 1528-901X, Vol. 142, no 1, article id 011105Article in journal (Refereed)
    Abstract [en]

    In this study, natural convection of non-Newtonian power-law fluids around an array of elliptic cylinders has been investigated numerically. The governing equations have been solved using an in-house computational fluid dynamics code based on the well-known finite volume method. It is assumed that the flow and temperature fields are laminar, steady, and two-dimensional. Furthermore, due to the low-temperature difference between the tube walls and the surrounding fluid, the changes in the physical properties of the fluids are neglected. The numerical results are validated against the available experimental and numerical results. The results show that by increasing the non-Newtonian fluid power-law index, the ratio of average Nusselt number of the ith cylinder to the average Nusselt number of a single cylinder under identical thermal conditions decreases. Moreover, it is found that the increase in the ratio of the distance between elliptic centers and the elliptic vertical diameter increases the ratio of the average Nusselt number of ith cylinder to the average Nusselt number for a single cylinder. Finally, a mathematical expression is given for the array averaged Nusselt number.

  • 17.
    Uczak de Goes, Wellington
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Somhorst, Joop
    Volvo Car Corporation, Göteborg, Sweden.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Gupta, Mohit Kumar
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Illkova, Kseniya
    Institute of Plasma Physics, Prague, Czech Republic.
    Suspension Plasma-Sprayed Thermal Barrier Coatings for Light-Duty Diesel Engines2019In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 28, no 7, p. 1674-1687Article in journal (Refereed)
    Abstract [en]

    Demands for improved fuel efficiency and reduced CO2 emissions of diesel engines have been the driving force for car industry in the past decades. One way to achieve this would be by using thermal spraying to apply a thermal insulation layer on parts of the engine’s combustion chamber. A candidate thermal spray process to give coatings with appropriate properties is suspension plasma spray (SPS). SPS, which uses a liquid feedstock for the deposition of finely structured columnar ceramic coatings, was investigated in this work for application in light-duty diesel engines. In this work, different spray processes and materials were explored to achieve coatings with optimized microstructure on the head of aluminum pistons used in diesel engine cars. The functional properties of the coatings were evaluated in single-cylinder engine experiments. The influence of thermo-physical properties of the coatings on their functional properties has been discussed. The influence of different spray processes on coating formation on the complex piston head profiles has been also discussed. The results show that SPS can be a promising technique for producing coatings on parts of the combustion chamber, which can possibly lead to higher engine efficiency in light-duty diesel engines.

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    fulltext
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