Academic literature on the topic 'Domestic refrigerator - Natural convection'
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Journal articles on the topic "Domestic refrigerator - Natural convection"
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Logeshwaran, S., and P. Chandrasekaran. "CFD analysis of natural convection heat transfer in a static domestic refrigerator." IOP Conference Series: Materials Science and Engineering 1130, no. 1 (April 1, 2021): 012014. http://dx.doi.org/10.1088/1757-899x/1130/1/012014.
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Laguerre, O., and D. Flick. "Heat transfer by natural convection in domestic refrigerators." Journal of Food Engineering 62, no. 1 (March 2004): 79–88. http://dx.doi.org/10.1016/s0260-8774(03)00173-0.
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da Silva, José Antônio, Matheus dos Santos Guzella, Cristiana Brasil Maia, Sérgio de Morais Hanriot, and Luben Cabezas-Gómez. "Evaluation of Correlations for Natural Convection on the Behavior of a Wire-on-Tube Condenser." Advanced Materials Research 1016 (August 2014): 774–77. http://dx.doi.org/10.4028/www.scientific.net/amr.1016.774.
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This paper outlines the evaluation of the influence of different empirical correlations to compute air-side heat transfer coefficient on the behavior of a wire-on-tube condenser by performing numerical simulations. A fully predictive simulation model based on first-principles equations and empirical correlations for heat transfer and friction factor is considered. Two-phase flow is modeled using homogeneous model and a void fraction correlation available in the literature is considered. Results show that for the correlations tested, different estimations of heat rate rejected to the environment can be obtained and hence, different thermal hydraulic behavior of the condenser can be obtained. This influence is critical, especially when the global numerical simulation of a domestic refrigerator is considered.
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Laguerre, O., S. Ben Amara, and D. Flick. "Experimental study of heat transfer by natural convection in a closed cavity: application in a domestic refrigerator." Journal of Food Engineering 70, no. 4 (October 2005): 523–37. http://dx.doi.org/10.1016/j.jfoodeng.2004.10.007.
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Laguerre, O., S. Ben Amara, M. C. Charrier-Mojtabi, B. Lartigue, and D. Flick. "Experimental study of air flow by natural convection in a closed cavity: Application in a domestic refrigerator." Journal of Food Engineering 85, no. 4 (April 2008): 547–60. http://dx.doi.org/10.1016/j.jfoodeng.2007.08.023.
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Adelaja, A. O., and B. I. Babatope. "Analysis and Testing of a Natural Convection Solar Dryer for the Tropics." Journal of Energy 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/479894.
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Solar dryers are imperative for the tropical and sub-Saharan African countries, which are faced with the duo challenges of inadequate electrical energy supply, which has severely limited the application of conventional refrigeration as a means of preservation of agricultural produce, and the need to make produce competitive in the international market. In this study, a cost-effective natural convection solar dryer was developed; the thermal and drying analyses were done and tested to obtain some performance evaluation parameters for the system in order to examine its efficiency and effectiveness by drying some plantain fillets. The collector and system efficiencies are found to be 46.4% and 78.73%, respectively, while a percentage moisture removal of 77.5% was achieved at the 20th hour in order to give final moisture contents of 15.75% in the product, which still maintained its integrity. With a cost of about $195.00, it has been affordable for the small- and medium-scale enterprises as well as for private use in domestic applications.
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Han, Jun-Qing, and Qiu-Sheng Liu. "Suppression of Natural Convection in a Thermoacoustic Pulse Tube Refrigerator." Chinese Physics Letters 30, no. 5 (May 2013): 054301. http://dx.doi.org/10.1088/0256-307x/30/5/054301.
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JIRACHEEWANUN, S., S. W. ARMFIELD, and M. BEHNIA. "COMBINED NATURAL CONVECTION COOLING OF A DRINK CAN." ANZIAM Journal 52, no. 1 (July 2010): 59–68. http://dx.doi.org/10.1017/s1446181111000538.
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AbstractWe investigate natural convection cooling of the fluid in a drink can placed in a refrigerator by simulating the full combined boundary layer system on the can wall. The cylindrical can is filled with water at initial nondimensional temperature 0, and located within a larger cylindrical container filled with air at initial temperature −1. The outer container walls are maintained at constant temperature −1. Initially both fluids are at rest. Two configurations are examined: the first has the inner can placed vertically in the middle of the outer container with no contact with the outer container walls, and the second has the inner can placed vertically at the bottom of the outer container. The results are compared to those obtained by assuming that the inner can walls are maintained at a constant temperature, showing similar basic flow features and scaling relations, but with very different proportionality constants.
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HARA, Toshitsugu, Masanori YAMAKAWA, Takayuki FUSHIKI, and Shigeki TOHNOSU. "NUMERICAL AND EXPERIMENTAL STUDIES ON FREE CONVECTION HEAT TRANSFER AROUND A DOMESTIC REFRIGERATOR-FREEZER." Journal of the Visualization Society of Japan 11, Supplement1 (1991): 35–38. http://dx.doi.org/10.3154/jvs.11.supplement1_35.
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R. Mohanty, A., and S. Fatima. "Noise Control of a Domestic Refrigerator Using a Natural Material Based Composite." Sound&Vibration 54, no. 4 (2020): 247–56. http://dx.doi.org/10.32604/sv.2020.011011.
Full textDissertations / Theses on the topic "Domestic refrigerator - Natural convection"
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Kinoshita, Denise [UNESP]. "Simulação numérica da convecção natural no interior de um refrigerador doméstico." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/88860.
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kinoshita_d_me_ilha.pdf: 2189895 bytes, checksum: 18c800e5f3dc7c91ac3187a97f2410b9 (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Neste trabalho realizou-se um estudo numérico do escoamento em gabinetes de refrigeradores domésticos operando em regime de convecção natural, usando-se o Método de Volumes Finitos. No procedmento numérico, o problema do acoplamento pressão-velocidade foi resolvido pelo algoritmo SIMPLE - Semi Implicit Method for Pressure Linked Equations para malha desencontrada. O esquema Power-Law foi utilizado como função de interpolação para os termos convectivo-difusivos e o TDMA-Tri Diagonal Matrix Algorithm foi usado para resolver os sistemas de equações algébricas. O gabinete do refrigerador foi modelado como uma cavidade tridimensional vazia sem prateleiras e o evaporador foi modelado como uma placa plana vertical com temperatura uniforme prescrita. O código numérico foi verificado parcialmente para problemas clássicos de convecção natural encontrados na literatura. Resultados experimentais preliminares para um refrigerador doméstico comercial de 350 l também foram levantados para a validação do código numérico. Após a validação do código numérico, as influências do posicionamento e temperatura do evaporador nos campos de temperatura e velocidade foram analisadas para três configurações do gabinete: gabinete sem gaveta de verdura, gabinete com gaveta de verdura e gabinete com gaveta de verdura com aberturas laterais. O modelo de gabinete com gaveta de verdura com aberturas laterais mostrou-se o mais adequado para estudar o problema. Nove posições do evaporador foram avaliadas, mostrando que o posicionamento na direção horizontal praticamente não influencia o campo de temperatura e velocidade do escoamento, enquanto que o posicionamento na direção vertical tem uma influencia significativa. Os campos de velocidade e temperatura e a carga térmica do evaporador...
A numerical study of the flow inside cabinets of domestic refrigerators working on natural convection regime is performed in this work using the Finite Volume Method as numerical procedure for solving the governing equations. The pressure-velocity coupling was solved using the algorithm SIMPLE–Semi Implicit Method for Pressure Linked Equations applied to a staggered mesh. The Power-Law scheme was used as interpolation function for the convective-diffusive terms, and the algorithm TDMA-Tri Diagonal Matrix Algorithm was used to solve the systems of algebraic equations. The model was applied to static refrigerator working in steady state with constant and uniform evaporator temperature. The cabinet was considered as an empty three-dimensional cavity without shelves and the evaporator was modeled as a vertical flat plate with prescribed uniform temperature. The numerical code was partially verified for classical natural convection problems usually found in the literature. Preliminary experimental results for a 350 l commercial domestic refrigerator were also obtained for validating the numerical code. After validating the numerical code, the influence of the positioning and temperature of the evaporator on the temperature and velocity fields were analyzed for three cabinet configurations: cabinet without vegetable drawer, cabinet with vegetable drawer, and cabinet with vegetable drawer presenting lateral openings. The model including the vegetable drawer with lateral openings showed to be the best model to study the problem. Nine evaporator positions were evaluated, showing that the positioning in the horizontal direction practically does not affect the temperature and velocity fields of the flow, while the vertical positioning has a significant effect on the results. The temperature and velocity... (Complete abstract click electronic access below)
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Kinoshita, Denise. "Simulação numérica da convecção natural no interior de um refrigerador doméstico /." Ilha Solteira : [s.n.], 2011. http://hdl.handle.net/11449/88860.
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Orientador: José Luiz GascheBanca: Cassio Roberto Macedo Maia
Banca: Sidnei José de Oliveira
Resumo: Neste trabalho realizou-se um estudo numérico do escoamento em gabinetes de refrigeradores domésticos operando em regime de convecção natural, usando-se o Método de Volumes Finitos. No procedmento numérico, o problema do acoplamento pressão-velocidade foi resolvido pelo algoritmo SIMPLE - Semi Implicit Method for Pressure Linked Equations para malha desencontrada. O esquema Power-Law foi utilizado como função de interpolação para os termos convectivo-difusivos e o TDMA-Tri Diagonal Matrix Algorithm foi usado para resolver os sistemas de equações algébricas. O gabinete do refrigerador foi modelado como uma cavidade tridimensional vazia sem prateleiras e o evaporador foi modelado como uma placa plana vertical com temperatura uniforme prescrita. O código numérico foi verificado parcialmente para problemas clássicos de convecção natural encontrados na literatura. Resultados experimentais preliminares para um refrigerador doméstico comercial de 350 l também foram levantados para a validação do código numérico. Após a validação do código numérico, as influências do posicionamento e temperatura do evaporador nos campos de temperatura e velocidade foram analisadas para três configurações do gabinete: gabinete sem gaveta de verdura, gabinete com gaveta de verdura e gabinete com gaveta de verdura com aberturas laterais. O modelo de gabinete com gaveta de verdura com aberturas laterais mostrou-se o mais adequado para estudar o problema. Nove posições do evaporador foram avaliadas, mostrando que o posicionamento na direção horizontal praticamente não influencia o campo de temperatura e velocidade do escoamento, enquanto que o posicionamento na direção vertical tem uma influencia significativa. Os campos de velocidade e temperatura e a carga térmica do evaporador... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: A numerical study of the flow inside cabinets of domestic refrigerators working on natural convection regime is performed in this work using the Finite Volume Method as numerical procedure for solving the governing equations. The pressure-velocity coupling was solved using the algorithm SIMPLE-Semi Implicit Method for Pressure Linked Equations applied to a staggered mesh. The Power-Law scheme was used as interpolation function for the convective-diffusive terms, and the algorithm TDMA-Tri Diagonal Matrix Algorithm was used to solve the systems of algebraic equations. The model was applied to static refrigerator working in steady state with constant and uniform evaporator temperature. The cabinet was considered as an empty three-dimensional cavity without shelves and the evaporator was modeled as a vertical flat plate with prescribed uniform temperature. The numerical code was partially verified for classical natural convection problems usually found in the literature. Preliminary experimental results for a 350 l commercial domestic refrigerator were also obtained for validating the numerical code. After validating the numerical code, the influence of the positioning and temperature of the evaporator on the temperature and velocity fields were analyzed for three cabinet configurations: cabinet without vegetable drawer, cabinet with vegetable drawer, and cabinet with vegetable drawer presenting lateral openings. The model including the vegetable drawer with lateral openings showed to be the best model to study the problem. Nine evaporator positions were evaluated, showing that the positioning in the horizontal direction practically does not affect the temperature and velocity fields of the flow, while the vertical positioning has a significant effect on the results. The temperature and velocity... (Complete abstract click electronic access below)
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Schaake, Katrin, and Sebastian Manzke. "Strömungssimulation und experimentelle Untersuchung für innovative Verflüssiger auf Basis neuartiger Rohre." Thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2009. http://nbn-resolving.de/urn:nbn:de:bsz:105-25345.
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In dieser Arbeit werden neuartige Flachrohre für die Verwendung als Rückwandverflüssiger in der Haushaltskältetechnik mit numerischen und dynamischen Simulationen sowie Experimenten untersucht. Dabei kommen unterschiedliche überströmte Längen sowie der Einfluss horizontaler Abstände auf den Wärmeübergang durch freie Konvektion zur Betrachtung. Realisiert wird die numerische Strömungssimulation mit der Software Fluent 3.6.26, wobei das RNG-k-epsilon- als Turbulenzmodell und diskrete Ordinaten zur zusätzlichen Modellierung des Strahlungswärmeübergangs verwendet werden. Zur Verifizierung werden experimentelle Untersuchungen mit natürlicher Konvektion durchgeführt. Ebenso kommt ein kompakter Verflüssiger bei erzwungener Konvektion zur experimentellen Analyse. Mit einem neuen Verflüssigermodell wird außerdem ein Haushaltskühlschrank in Modelica 2.2.1 dynamisch simuliert. Diese Arbeit zeigt, dass die Verwendung eines Flachrohrverflüssigers großes Potenzial einer konkurrenzfähigen Alternative zu konventionellen Verflüssigern besitztIn this work novel flat tubes used as rear panel condensers in the household refrigeration technology are examined with numerical and dynamic simulations as well as experiments. Therefore different overflowed lengths and the influence of horizontal spacing on the heat transfer by free convection are taken into consideration. The CFD calculations are realized with the software Fluent 3.6.26, where the RNG-k-epsilon turbulence model and discrete ordinates for an additional modelling of radiation heat transfer are applied. For the verification, experimental studies with natural convection are carried out. Likewise, a compact condenser is experimentally analysed in forced convection. With a new model for the liquefier a domestic refrigerator is also dynamically simulated in Modelica 2.2.1. This work shows that the use of a flat tube condenser has a great potential of a competitive alternative to conventional liquefiers
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Purdy, Julia Mary. "Thermal modelling of plate heat exchangers in natural convection solar domestic hot water systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0002/MQ36072.pdf.
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Bayer, Ozgur. "Simulation Of Refrigerated Space With Radiation." Phd thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610454/index.pdf.
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Performance of a refrigerator can be characterized with its ability to maintain a preset low temperature by spending the least amount of electricity. It is important to understand natural convection inside a refrigerator for optimizing its design for performance. Computational Fluid Dynamics (CFD) together with experiments is a very powerful tool for visualizing flow and temperature fields that are essential for understanding a phenomenon that involves both fluid and heat flow. In this aspect, simulations are performed for compartment and total refrigerator models using the package program Fluent which is based on finite volume method. An experimental study is performed to determine the constant wall temperature boundary conditions for the numerical models. Effect of radiation is also investigated by comparing the numerical study of a different full refrigerator model with a similar one in literature. While evaluating the radiation effect, convection boundary condition is selected by defining overall heat transfer coefficient between the ambient room air at a constant temperature and the inner surfaces of the walls. Based on assumptions, related heat transfer analyses are done using compartment and total refrigerator model analyses. Performing CFD simulations of a refrigerator cabinet for visualizing the flow and temperature fields which is the aim of the study is achieved and some observations that can be useful in design optimization are made.
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Björk, Erik. "Energy Efficiency Improvements in Household Refrigeration Cooling Systems." Doctoral thesis, KTH, Tillämpad termodynamik och kylteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-93061.
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This thesis is based on eight articles all related to the characteristics of the cooling system and plate evaporator of a household refrigerator. Through these articles, knowledge is provided that can be used to increase the operational efficiency in household refrigeration. Papers A, B and C focus on heat transfer and pressure drop in a commonly used free convection evaporator – the plate evaporator. Applicable correlations are suggested on how to estimate the air side heat transfer, the refrigerant side pressure drop and the refrigerant side heat transfer. Papers D, E and F hold a unique experimental study of the refrigerant charge distribution in the cooling system at transient and steady state conditions. From this cyclic losses are identified and estimated and ways to overcome them are suggested. In paper G the topic “charging and throttling” is investigated in an unparalleled experimental study based on more than 600 data points at different quantities of charge and expansions device capacities. It results in recommendations on how to optimize the capillary tube length and the quantity of refrigerant charge. Finally, Paper H holds a thermographic study of the overall cooling system operating at transient conditions. Overall, a potential to lower the energy use by as much as 25 % was identified in the refrigerator studied. About 10 % was found on the evaporator’s air side. 1-2 % was identified as losses related to the edge effect of the evaporator plate. About 8 % was estimated to be cyclic losses. About 5 % was found in cycle length optimization. It is believed that most of these findings are of general interest for the whole field of household refrigeration even though the results come from one type of refrigerator. Suggestions of simple means to reduce the losses without increasing the unit price are provided within the thesisQC 20120411
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Avina, John. "The modeling of a natural convection heat exchanger in a solar domestic hot water system." 1995. http://catalog.hathitrust.org/api/volumes/oclc/33083188.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 1995.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 233-234).
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Murray, Robynne. "SIMULTANEOUS CHARGING AND DISCHARGING OF A LATENT HEAT ENERGY STORAGE SYSTEM FOR USE WITH SOLAR DOMESTIC HOT WATER." 2012. http://hdl.handle.net/10222/15169.
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Sensible energy storage for solar domestic hot water (SDHW) systems is space consuming and heavy. Latent heat energy storage systems (LHESSs) offer a solution to this problem. However, the functionality of a LHESS during simultaneous charging/discharging, an operating mode encountered when used with a SDHW, had not been studied experimentally.
A small scale vertical cylindrical LHESS, with dodecanoic acid as the phase change material (PCM), was studied during separate and simultaneous charging/discharging. Natural convection was found to have a strong influence during melting, but not during solidification. During simultaneous operation heat transfer was limited by the high thermal resistance of the solid PCM. However, when the PCM was melted, direct heat transfer occurred between the hot and cold heat transfer fluids, indicating the significance of the PCM phase on heat transfer in the system. The results of this research will lead to more optimally designed LHESS for use with SDHW.
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Ashwin, T. R. "CFD Studies Of Pulse Tube Refrigerators." Thesis, 2010. http://etd.iisc.ernet.in/handle/2005/1849.
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The performance evaluation and parametric studies of an Inertance Tube Pulse Tube Refrigerator (IPTR) are performed for different length-to-diameter ratios, with the Computational Fluid Dynamics (CFD) package FLUENT. The integrated model consists of individual models of the components, namely, the compressor, compressor cooler, regenerator, cold heat exchanger, pulse tube, warm heat exchanger, inertance tube and the reservoir. The formulation consists of the governing equations expressing the conservation of mass, momentum and energy with axi-symmetry assumption and relations for the variable thermophysical properties of the working medium and the regenerator matrix, and friction factor and heat transfer coefficients in oscillatory flows. The local thermal non-equilibrium of the gas and the matrix is taken into account for the modeling of heat exchangers and the regenerator which are treated as porous zones. In addition, the wall thickness of the components is also accounted for. Dynamic meshing is used to model the compressor zone. The heat interaction between pulse tube wall and the oscillating gas, leading to surface heat pumping, is quantified. The axial heat conduction is found to reduce the overall performance. The thermal non-equilibrium results in a higher cold heat exchanger temperature due to inefficiencies. The dynamic characteristics of pulse tube are analyzed by introducing a time constant. The study is extended to other types of PTRs, namely, the Orifice type Pulse Tube Refrigerator (OPTR), Double Inlet type Pulse Tube Refrigerator (DIPTR) and a PTR with parallel combination of inertance tube and orifice (OIPTR). The focus of the second phase of analysis is the pulse tube region. The oscillatory flow and temperature fields in an open-ended pipe driven by a time-wise sinusoidally varying pressure at one end and subjected to an ambient-to-cryogenic temperature difference across the ends, is numerically studied both with and without the inclusion of buoyancy effects. Conjugate effects arising out of the interaction of oscillatory flow with heat conduction in the pipe wall are taken into account by considering a finite thickness wall with an insulated exterior surface. Parametric studies are conducted with frequencies in the range 5-15 Hz for an end-to-end temperature difference of 200 K. As the pressure amplitude increases, the temperature difference between the wall and the fluid decreases due to mixing at the cold end. The pressure amplitude and the frequency have negligible effect on the time averaged Nusselt number. The effect of buoyancy is studied for hot side up and cold side up configurations. It is found that the time averaged Nusselt number does not change significantly with orientation or Rayleigh number. Sharp changes in Nusselt number and velocity profiles and an increase in energy transfer through solid and gas were observed when natural convection comes into play with hot end placed down. Cooldown experiments are conducted on a preliminary experimental setup. Comparison of the numerical and experimental cooldown curves disclosed a number of areas where improvement is required, primarily the leakage past the piston and the design of the heat exchangers. The setup is being improved to bring out a second and improved version for attaining the lower cold heat exchanger temperature.
Conference papers on the topic "Domestic refrigerator - Natural convection"
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Zhang, Chaolei, and Yongsheng Lian. "Numerical Investigation of Heat Transfer and Flow Field in Domestic Refrigerators." In ASME 2013 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fedsm2013-16039.
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Air circulation and temperature distribution inside a domestic refrigerator chamber are two important factors in refrigerator design. They are critical for food quality control and energy saving and are affected by natural/forced convection, radiation and layout of the stored food. Knowledge about the actual air flow and temperature distributions inside a refrigerator is required to improve temperature homogeneity and reduce energy consumption. In present work we numerically study the air circulation and the heat transfer phenomena in a domestic frost-free refrigerator. The inner compartment, the evaporator and the outside thermal insulation foam are considered. The conjugate heat transfer problem is studied by solving the unsteady laminar Navier-Stokes equations using a finite volume method. The Boussinesq approximation is used to model the natural convection. The discrete ordinate method is adopted to take into account the radiation heat transfer between the cold back evaporator and warm surfaces to further understand the impact of radiation. The accuracy of the numerical methods is verified through grid sensitivity analysis and comparison with available numerical and experimental data. Comparisons are made with and without radiation. Our simulations show that radiation significantly changes the temperature distribution and air circulation pattern. The effects of shelf and food stored on the temperature distribution and air circulation are also studied by comparing three configurations: empty refrigerator, empty refrigerator with shelves and loaded refrigerator with food.
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Cruickshank, Cynthia A., and Stephen J. Harrison. "Experimental Characterization of a Natural Convection Heat Exchanger for Solar Domestic Hot Water Systems." In ASME 2006 International Solar Energy Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/isec2006-99130.
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To predict the long-term performance of solar domestic hot water (SDHW) systems requires computational models that can characterize the systems under a range of operating conditions. The development of detailed fundamental models that suitably describe the operation of systems with natural convection heat exchangers is, however, difficult and time consuming. The fact that the natural convection flow through the heat exchanger is intrinsically self-controlling and temperature dependent complicates the analysis. One approach to modeling this type of system is to use performance characteristics, empirically derived from experimental data, to predict the performance of the heat exchanger under typical operating conditions. Unfortunately, a significant number of tests may be required to characterize the full operation of the device. This paper presents a simplified test method that was developed to allow pre-configured SDHW systems that use natural convection heat exchangers, to be characterized. The results of this test method produce performance coefficients for simple empirical expressions that describe the fluid flow and heat transfer in the heat-exchange loop. These empirically derived coefficients are an input to a general simulation routine that allows overall system performance to be determined for various loads and climatic conditions. In this paper, data is presented for a typical heat exchanger under a range of operational conditions.
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Tracy, T., J. C. Ordonez, and J. V. C. Vargas. "First and Second Law Thermodynamic Analysis of a Domestic Scale Trigeneration System." In ASME 2007 Energy Sustainability Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/es2007-36184.
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The potential use of small-scale trigeneration systems in domestic homes, especially for emergency use in the event of a hurricane or natural disaster where electricity and useful power are at a premium, is increasing. They have the ability to produce both useful thermal energy and electricity from a single source of fuel such as gasoline, natural gas, or other alternate fuel. However, small-scale systems present some technological challenges in order to achieve a significant increase in efficiency over conventional systems. This paper addresses the fundamental question of the splitting of a hot exhaust into two heat recovery heat exchangers that are part of a trigeneration system. We consider a system which produces electricity, refrigeration, and hot water by recovering waste energy from a reciprocating internal combustion engine. First and second law analyses were performed on the refrigerator and water heating heat exchangers and on the overall system. An optimal splitting of the available hot exhaust stream between the refrigerator and the hot water heat exchangers is identified. The thermodynamic optima is sharp and robust with respect to the variation of refrigerant and water inlet temperatures.
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Botello-Arredondo, Israel, Abel Hernandez-Guerrero, Marino Pen˜a-Taveras, Victor Miranda-Razo, and Cuauhtemoc Rubio-Arana. "Natural Convection in an Air-Filled Cubical Enclosure With a Protruding Heat Sink: Application to a Thermoelectric Refrigerator." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11271.
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The present study evaluates the effects of a protruding heat sink located on one of the vertical walls of a cubic cavity, with a free convective laminar regimen. The best of three locations for the heat sink will be determined with the analysis of the velocity and temperature fields in the cavity. An optimal operation condition is required since the cavity will contain medical products with a specific temperature range. Three different locations for the heat sink, (in the +Y direction), are to be studied: 1/3 H, 1/2 H and 2/3 H, where H is the height of the cavity, for different values of Rayleigh Number 103<Ra<106. The heat exchange occurs between the heat sink and the isothermal walls. The results obtained show that it is recommended to place the heat sink at the position H/2. This configuration presented the best behavior of the fluid, dynamically and thermally. The results will be used for a further and more completed numerical analysis, and to determine the thermoelectric refrigerator parameters for a later experimental study with a prototype.
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Fang, Z. C. "Numerical Analysis and Experimental Study on Natural Convection in the Sample Enclosure Cooled by a G-M Refrigerator." In ADVANCES IN CRYOGENIC ENGINEERING: Transactions of the Cryogenic Engineering Conference - CEC. AIP, 2006. http://dx.doi.org/10.1063/1.2202413.
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Boetcher, S. K. S., F. A. Kulacki, and Jane H. Davidson. "Use of a Shroud and Baffle to Improve Natural Convection to Immersed Heat Exchangers." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22924.
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Optimizing heat transfer during the charge and discharge of thermal stores is crucial for high performance of solar thermal systems for domestic and commercial applications. This study models a sensible water storage tank for which charge and discharge are accomplished using a heat exchanger immersed in the storage fluid. The objective is to investigate the use of a baffle and shroud as a means to improve convective heat transfer and thermal stratification. The immersed heat exchanger is modeled as a two-dimensional isothermal cylinder which is situated near the top of a storage tank with adiabatic walls. Transient numerical simulations of the discharge process are obtained for 105 < RaD < 107. An adiabatic shroud and baffle whose geometry is parametrically varied is placed around and below the cylinder. Transient Nusselt numbers are calculated for different baffle-shroud geometries and Rayleigh numbers. Results indicate that a long baffle with a high shroud height is optimal.
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Devore, Nathan, Henry Yip, and Jinny Rhee. "Domestic Hot Water Storage Tank: Design and Analysis for Improving Thermal Stratification." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-88350.
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Experimental designs for a solar domestic hot water storage system were built in efforts to maximize thermal stratification within the tank. A stratified thermal store has been shown by prior literature to maximize temperature of the hot water drawn from the tank while simultaneously increasing the temperature delta required for effective heat transfer from the solar panels, thereby improving the annual performance of domestic solar hot water heating systems (DSHWH) by 30%–60%. Our design incorporates partitions, thermal diodes, and a coiled heat exchanger enclosed in an annulus. The thermal diodes are passive devices that promote natural convection currents of hot water upwards, while inhibiting reverse flow and mixing. Several variations of heat exchanger coils, diodes and partitions were simulated using ANSYS Computational Fluid Dynamics, and benchmarked using experimental data. The results revealed that the optimum design incorporated two partitions separated by a specific distance with four diodes for each partition. In addition, it was discovered that varying the length and diameter of the thermal diodes greatly affected the temperature distribution. The thermal diodes and partitions were used to maintain stratification for long periods of time by facilitating natural convective currents and taking advantage of the buoyancy effect. The results of the experiment and simulations proved that incorporating these elements into the design can greatly improve the thermal performance and temperature stratification of a domestic hot water storage tank.
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Sultana, Tanzeen, Graham L. Morrison, Siddarth Bhardwaj, and Gary Rosengarten. "Heat Loss Characteristics of a Roof Integrated Solar Micro-Concentrating Collector." In ASME 2011 5th International Conference on Energy Sustainability. ASMEDC, 2011. http://dx.doi.org/10.1115/es2011-54254.
Full textAbstract:
Concentrating solar thermal systems offer a promising method for large scale solar energy collection. It is feasible to use concentrating solar thermal systems for rooftop applications such as domestic hot water, industrial process heat and solar air conditioning for commercial, industrial and institutional buildings. This paper describes the thermal performance of a new low-cost solar thermal micro-concentrating collector (MCT), which uses linear Fresnel reflector technology and is designed to operate at temperatures up to 220°C. The modules of this collector system are approximately 3 meters long by 1 meter wide and 0.3 meters high. The objective of the study is to optimize the design to maximise the overall thermal efficiency. The absorber is contained in a sealed enclosure to minimise convective losses. The main heat losses are due to natural convection inside the enclosure and radiation heat transfer from the absorber tube. In this paper we present the results of a computational investigation of radiation and convection heat transfer in order to understand the heat loss mechanisms. A computational model for the prototype collector has been developed using ANSYS-CFX, a commercial computational fluid dynamics software package. Radiation and convection heat loss has been investigated as a function of absorber temperature. Preliminary ray trace simulation has been performed using SolTRACE and optical efficiency has been evaluated. Finally, the MCT collector efficiency is also evaluated.
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Luttrell, Jeff, and Dereje Agonafer. "Solar Assisted Household Clothes Dryer." In ASME 2010 4th International Conference on Energy Sustainability. ASMEDC, 2010. http://dx.doi.org/10.1115/es2010-90095.
Full textAbstract:
Energy savings for domestic appliances have been an emphasis for several years. The efficiencies of several appliances have improved dramatically as a result of this attention. Refrigerator, water heater, and washing machine energy consumptions have been reduced. One appliance has not experienced significant improvement, the clothes dryer. Typical household clothes dryers use large amounts of electricity or natural gas to heat air that is circulated with the clothes. The energy to heat the air is a function of the amount of air and heat needed to remove moisture from the clothes. Using solar heat to augment or replace the other energy sources can provide significant energy savings. Conventional house construction includes features which collect and concentrate solar energy in the air occupying the attic space. Typical home design provides a roof which functions as a large area solar energy collector. Many roofing materials have solar absorption of 80% or more. Insulation of the roof decking is uncommon so that absorbed solar heat conducts through and heats the attic air. Through simple, low-cost ducting and minor modification of a clothes dryer air inlet, this energy resource becomes available for use. This study evaluates the potential energy savings of using solar-heated attic air as a clothes dryer air source. Considering house construction as well as seasonal and regional climate variations, attic air can augment and may fully replace utility energy as the heat source for drying air during daylight hours when solar energy is incident on the roof. The energy savings can be up to 3.5 kilowatt hours (or the heating equivalent for natural gas) for each dryer load.
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Cruickshank, Cynthia A., and Stephen J. Harrison. "Comparison of Multi-Tank and Large Single Tank Thermal Storages for Solar DHW Applications." In ASME 2007 Energy Sustainability Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/es2007-36213.
Full textAbstract:
The performance of a multi-tank water storage was studied by experiment and computer simulation. The unit investigated consisted of three 270 L storage tanks connected in series and was charged through individual side-arm, natural convection heat exchangers. Laboratory tests were conducted on a specially instrumented prototype to characterize its performance in terms of temperature stratification, heat transfer and energy storage rates. Based on these tests, a computer model of a complete multi-tank solar thermal system was created. With this model, the performance of a multi-unit storage was compared to a single-tank system of equal total storage volume for a multi-family solar domestic hot water (SDHW) system application. Data were produced for two U.S. locations representative of differing climatic locations. Results show that a reasonably insulated multi-tank system can be used in place of a large single tank with only a small reduction in delivered solar energy.