Gotowe bibliografie tematyczne / PURE REFRIGERANTS

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Gotowa bibliografia na temat „PURE REFRIGERANTS”

Autor: Grafiati
Data publikacji: 11 września 2023

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Artykuły w czasopismach na temat "PURE REFRIGERANTS"

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Hsieh, Shou-Shing, i Chun-Jen Weng. "Nucleate Pool Boiling Heat Transfer Coefficients of Distilled Water (H2O) and R-134a/Oil Mixtures From Rib-Roughened Surfaces". Journal of Heat Transfer 119, nr 1 (1.02.1997): 142–51. http://dx.doi.org/10.1115/1.2824079.

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Measurements of pool-boiling heat transfer coefficients in distilled water and R-134a/oil mixtures with up to 10 percent (by weight) miscible EMKARATE RL refrigeration lubricant oil are extensively studied for a smooth tube and four rib-roughened tubes (rib pitch 39.4 mm, rib height 4 mm, rib width 15 mm, number of rib element 8, rib angle 30 deg–90 deg). Boiling data of pure refrigerants and oil mixtures, as well as the influences of heat flux level on heat transfer coefficient, are presented and discussed. A correlation is developed for predicting the heat transfer coefficient for both pure refrigerants and refrigerant-oil mixtures. Moreover, boiling visualizations were made to broaden our fundamental understanding of the pool boiling heat transfer mechanism for rib roughened surfaces with pure refrigerants and refrigerant-oil mixtures.
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Li, Hong. "Study on Alternative Refrigerants for Direct Expansion Solar Assisted Heat Pump System". Applied Mechanics and Materials 361-363 (sierpień 2013): 267–70. http://dx.doi.org/10.4028/www.scientific.net/amm.361-363.267.

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This paper reports the investigation results of the possibilities for using pure and mixed refrigerants as working fluids to replace R22 for the DX-SAHP systems. Firstly, pure refrigerants are compared in terms of COP, discharge temperature and mass flow rate. Comparison results show that R290 is the most promising alternative to R22. Secondly, two kinds of mixed refrigerants are investigated as well. It indicated that the mixed refrigerant R290/R22 with more R290 performs better than the others in terms of COP. Meanwhile, the mixed refrigerants produce relatively low discharge temperatures and proper mass flow rates can be created due to appropriate mixture in suitable mass proportion. Further investigation indicates that R290 and R290/R22 show better system performance with relatively high superheating temperatures.
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Chamra, L. M., i P. J. Mago. "Modelling of evaporation heat transfer of pure refrigerants and refrigerant mixtures in microfin tubes". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 221, nr 4 (1.04.2007): 443–47. http://dx.doi.org/10.1243/0954406jmes131.

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A semi-empirical model to predict the evaporation heat transfer of pure refrigerants and refrigerant mixtures flowing inside microfin tubes has been presented. The heat transfer coefficient correlation developed in the new model takes into account the nucleate boiling component and the forced convention component. The model was validated using a set of around 380 experimental data points compiled from published literature. Comparison shows that the model is capable of predicting evaporation heat transfer coefficients for different refrigerants and refrigerant mixtures within 10-25 per cent mean absolute deviation for the data sets.
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Wang, Qiang, Zhengyong Huang, Shucheng Ou i Ruiqiang Zhang. "The Energy Storage Properties of Refrigerants (R170, R134a, R143a, and R152a) in Mof-5 Nanoparticles: A Molecular Simulation Approach". Materials 12, nr 21 (31.10.2019): 3577. http://dx.doi.org/10.3390/ma12213577.

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The thermophysical properties of refrigerant can be modified via adding solid materials to it. In this paper, molecular simulations and thermodynamic calculations were employed to investigate the adsorption and energy storage of ethane (R170), 1,1,1,2-tetrafluoroethane (R134a), 1,1,1-trifluoroethane (R143a), and 1,1-difluoroethane (R152a) in metal organic framework (MOF)-5 nanoparticles. The results show that the fluorine atom in the refrigerants will strengthen the adsorption of refrigerants in MOF-5. However, the fluorine-free refrigerant, R170, owns larger enthalpy difference of desorption than the other refrigerants with fluorine under high pressure. The thermal energy storage capacity of the refrigerant/MOF-5 mixture is larger than that of the pure refrigerant at low pressure. Also, the negative enhancement of the energy storage property of the mixture is found in some cases when the refrigerant experiences phase transition.
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Yan, Fei, Qiang Wang, Shucheng Ou, Ruiqiang Zhang i Guoqiang Wang. "Molecular simulation study for adsorption and thermal energy storage analysis of refrigerants (R170, R161, R152a, and R143a) mixed with UIO-67 nanoparticles". Modern Physics Letters B 34, nr 30 (3.08.2020): 2050334. http://dx.doi.org/10.1142/s0217984920503340.

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Generally, with the help of adding solid materials, the thermophysical behaviors of refrigerant can be modified. In this work, four kinds of organic refrigerants (i.e. ethane R170, 1-fluoroethane R161, 1,1-difluoroethane R152a, and 1,1,1-trifluoroethane R143a) mixed with metal–organic framework UIO-67 nanoparticles are selected as the objects, their thermodynamic energy, adsorption, desorption heat, and energy storage properties are investigated by means of molecular simulations and thermodynamic calculations. The simulation method and calculation details are elaborated. The results illustrate that the relationship between the change of thermodynamic energy and the temperature is linear, and the adsorption of refrigerants in UIO-67 can be reinforced owing to the fluorine atom in the refrigerants. However, R170, the fluorine-free refrigerant, has greater enthalpy variation of desorption than the other three refrigerants containing fluorine atom under some pressures. The thermal energy storage capacity of the refrigerant/UIO-67 mixture is greater than that of the pure refrigerant at low pressure. Meantime, as the refrigerant undergoes phase transition, the weakened improvement of the energy storage property of the refrigerant/UIO-67 mixture is found in some cases. This work can not only enrich the content of researches about metal–organic heat carrier nanofluids (MOHCs), but also provide guidance for the performance improvement and practical application of organic refrigerants.
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Saleh, Bahaa, Ayman A. Aly, Mishal Alsehli, Ashraf Elfasakhany i Mohamed M. Bassuoni. "Performance Analysis and Working Fluid Selection for Single and Two Stages Vapor Compression Refrigeration Cycles". Processes 8, nr 9 (20.08.2020): 1017. http://dx.doi.org/10.3390/pr8091017.

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Screening for alternative refrigerants with high energy efficiency and low environmental impacts is one of the highest challenges of the refrigeration sector. This paper investigates the performance and refrigerant screening for single and two stages vapor compression refrigeration cycles. Several pure hydrocarbons, hydrofluorocarbons, hydrofluoroolefins, fluorinated ethers, and binary azeotropic mixtures are proposed as alternative refrigerants to substitute R22 and R134a due to their environmental impacts. The BACKONE equation of state is used to compute the thermodynamic properties of the candidates. The results show that the maximum coefficients of performance (COP) for single and two stage cycles using pure substances are achieved using cyclopentane with values of 4.14 and 4.35, respectively. On the other side, the maximum COP for the two cycles using azeotropic mixtures is accomplished using R134a + RE170 with values of 3.96 and 4.27, respectively. The two-stage cycle presents gain in COP between 5.1% and 19.6% compared with the single-stage cycle based on the used refrigerant. From the obtained results, among all investigated refrigerants, cyclopentane is the most suitable refrigerant for the two cycles from the viewpoint of energy efficiency. However, extra cautions should be taken due to its flammability.
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Soujoudi, Ray, i Randall Manteufel. "Thermodynamic performance of ammonia in liquefied natural gas precooling cycle". Thermal Science, nr 00 (2021): 72. http://dx.doi.org/10.2298/tsci201227072s.

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The selection of proper refrigerants for natural gas liquefaction processes play a key role in cycle?s efficiency. Mixed refrigerants have been proven to improve cycle?s exergy efficiency over single pure refrigerant. However, the future of some of these refrigerants with higher global warming potential index (GWPI) are unknown due to the continuous restriction being enforced by the energy and environmental agencies over the past few decades. This study examines the benefits and drawbacks of mixing ammonia, a refrigerant with zero GWPI and a high occupational safety characteristic, with lighter hydrocarbon refrigerants such as methane and ethane as a mixed refrigerant in a natural gas liquefaction?s precooling cycle. Results showed, presence of ammonia in mixed refrigerant not only saved in capital cost due to the smaller footprint of plant and smaller cold box, it also lowers the plants precooling operation expense by reducing the required compression power needed for the precooling cycle up to 16.2%. The results of exergy analyses showed that by reducing the molar concentration of more pollutant refrigerant methane and replacing it with ammonia enhanced the cycle?s efficiency by 4.3% and lowered the heat exchanger total exergy loss up to 47.9 [kW.kgLNG-1].
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Chamra, L. M., P. J. Mago, M.-O. Tan i C.-C. Kung. "Modelling of evaporation and condensation pressure drop in microfin tubes". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 219, nr 1 (1.01.2005): 61–70. http://dx.doi.org/10.1243/095440605x8306.

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A semi-empirical model to predict the pressure drop of pure refrigerants and refrigerant mixtures in microfin tubes for both condensation and evaporation is presented. The new pressure-drop model is based on an existing smooth-tube correlation. The model was validated using experimental data compiled from published literature and this showed that the model is capable of predicting pressure drops for different refrigerants and refrigerant mixtures within 10–25 per cent mean absolute deviation. This model can be employed in micro-fin tubes with fin heights from 0.1 to 0.38 mm, helix angles from 0 to 30°, and mass flux ranges up to 600 kg/m2 s.
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Morales-Espejel, Guillermo E., Hans H. Wallin, Rudolf Hauleitner i Magnus Arvidsson. "Progress in rolling bearing technology for refrigerant compressors". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, nr 16 (21.08.2017): 2948–61. http://dx.doi.org/10.1177/0954406217725772.

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The paper describes the latest technological solutions in rolling bearings (ball and roller) used in refrigerant compressors. First, the numerous tribological challenges faced by rolling contacts in a lubricant environment made of oil and refrigerant mixture are discussed. It is followed by a description of the even tougher conditions derived by the replacement of the more chemically stable pre-Montreal and pre-Kyoto Protocol refrigerants by the new generation of more environmental friendly refrigerants. In these conditions, rolling bearings are expected to suffer from surface distress and sometimes corrosion fatigue. Thus, attempts to model these conditions by using advanced tribological models are described. Finally, descriptions of different solutions in rolling bearings in refrigerant compressors facing challenges in lubrication and bearing life are described, all the way from traditional oil–refrigerant mixture lubrication up to the latest innovation related to oil-free lubrication, namely the pure refrigerant lubrication.
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Hasheer, Shaik Mohammad, i Kolla Srinivas. "Performance Comparison of a Low GWP Refrigerants as Alternatives to R134a in a Refrigerator with and without Liquid-Suction Heat Exchanger". Materials Science Forum 969 (sierpień 2019): 343–48. http://dx.doi.org/10.4028/www.scientific.net/msf.969.343.

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The usage of refrigerators and air conditioners are more prevalent in a domestic environment now-a-days. Improving the efficiency of these devices can be considered as an important step to reduce their energy consumption. Currently, in India, most refrigerators work with HFC-134a as a refrigerant. The GWP value of HFC-134a is around 1430.Therefore, there is a greater demand to replace HFCs with low GWP refrigerants. In this document, the comparison of the performance of a refrigerator without fluid intake heat exchanger (LSHX) with low GWP refrigerants and the results are compared with HFC-134a performed. The low GWP refrigerants used in the test are: hydrocarbon-propane (R290) and isobutane (R600a), the pure hydrocarbons are HFC-134a and HFC-152a and the refrigerants are hydrofluoroolefins 1234yf and 1234ze (E). All have been tested without making changes in the system. The entire examination was carried out in the same system under the same working conditions.
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Rozprawy doktorskie na temat "PURE REFRIGERANTS"

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Rabah, Ali A. "Flow boiling of pure refrigerants and binary refrigerant mixtures in a horizontal tube". [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969263775.

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Rabah, Ali A. [Verfasser]. "Flow boiling of pure refrigerants and binary refrigerant mixtures in a horizontal tube / Ali A Rabah". Aachen : Shaker, 2003. http://d-nb.info/1179039882/34.

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Hassan, Mohamed Abdel-Rahman Mohamed. "Flow boiling of pure and oil contaminated carbon dioxide as refrigerant : with focus on heat transfer and pressure drop /". Online version, 2004. http://bibpurl.oclc.org/web/31435.

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Faverani, Leonardo Perez [UNESP]. "Estudo in vitro das alterações na superfície do titânio comercialmente puro e da liga de titânio Ti -6Al-4V submetida a diferentes tratamentos". Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/88943.

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Made available in DSpace on 2014-06-11T19:23:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-17Bitstream added on 2014-06-13T18:51:03Z : No. of bitstreams: 1 faverani_lp_me_araca.pdf: 585353 bytes, checksum: 55ba5a6198999b7b032f65483a4c39b6 (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação para o Desenvolvimento da UNESP (FUNDUNESP)
Proposição: Neste estudo nós investigamos o efeito dos peróxidos de carbamida a 16% e a 35%, peróxido de hidrogênio 35% e refrigerante de Cola, nas modificações da superfície do titânio comercialmente puro (Ti-cp) e liga Ti-6Al-4V. Materiais e Métodos: Setenta e dois discos de Ti (8 mm de diâmetro, 2 mm de espessura) foram utilizados e divididos em 18 grupos (n = 4) em função do tratamento das soluções e o tipo de Ti. Os espécimes foram mecanicamente polidos utilizando procedimentos metalográficos padrão. Os espécimes foram imersos em 3 ml de peróxido de carbamida a 16% e a 35%, em peróxido de hidrogênio 35% e ao refrigerante de Cola, 4 horas por dia (mantidos secos ou imersos em saliva artificial nas 20 horas restantes), durante 15 dias. Os espécimes do grupo controle foram imersos apenas em saliva artificial ao longo dos 15 dias. A rugosidade de superfícies e a topografia do Ti foram examinados por meio da microscopia de força atômica (AFM) e microscopia eletrônica de varredura (MEV). As modificações químicas das superfícies Ti foram avaliadas por meio da espectroscopia de energia dispersiva (EDS). Os dados foram analisados pela ANOVA de três fatores e o teste de Tukey foi utilizado como técnica post-hoc (α =.05). Resultados: Os grupos imersos em peróxido de hidrogênio 35% apresentaram a maior rugosidade (P <0,05), seguido pelos peróxidos de carbamida, com maiores valores para o Ticp, porém sem alterações quando associados ou não à saliva artificial. Estes valores foram estatisticamente superiores aos observados no início e no grupo controle. O refrigerante de Cola não alterou a rugosidade de superfície de ambos os tipos de Ti (P> 0,05). A MEV e a AFM mostraram maiores alterações...
Purpose: In this study we investigated the effect of 16% and 35% carbamide peroxides, 35% hydrogen peroxides and cola soft drink, on the surface modifications of commercially-pure titanium (cp-Ti) and Ti-6Al-4V alloy. Materials and Methods: Seventy-two Ti discs (8-mm diameter, 2-mm thickness) were used and divided into 18 groups (n=4) as a function of solution treatments and Ti type. Samples were mechanically polished using standard metallographic procedures. Samples were immersed into 3 ml of 16% and 35% carbamide peroxides, 35% hydrogen peroxide and cola soft drink at 4 hours per day (kept dried or immersed in artificial saliva in the remaining 20 hours) during 15 days. Control samples were immersed just in artificial saliva throughout the 15 days. Ti surfaces roughness and topography were examined using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The chemical modifications of Ti surfaces were evaluated through energy dispersive spectroscopy (EDS). Data were analyzed by 3-way ANOVA, Tukey’s tests were further used as post-hoc techniques (α=.05). Results: Groups immersed in 35% hydrogen peroxide exhibited the greatest surface roughness (P<.05), followed by the carbamide peroxides regardless of Ti type and association or not with artificial saliva. Ticp exhibited greater surface roughness than Ti-6Al-4V alloy. These values were statistically higher than those observed at baseline and in control group. Cola soft drink did not change the surface roughness of both Ti types (P>.05). The SEM and AFM images of Ti surfaces showed higher surface changes for the samples immersed in 16% and 35% carbamide peroxides, and 35% hydrogen peroxide, with greater visible alteration for Ticp. These groups promoted the formation of crevices and pitting on the Ti surfaces. No detectable chemical... (Complete abstract click electronic access below)
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Faverani, Leonardo Perez. "Estudo in vitro das alterações na superfície do titânio comercialmente puro e da liga de titânio Ti -6Al-4V submetida a diferentes tratamentos /". Araçatuba : [s.n.], 2012. http://hdl.handle.net/11449/88943.

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Orientador: Wirley Gonçalves Assunção
Coorientador: Valentim Adelino Ricardo Barão
Banca: Idelmo Rangel Garcia Júnior
Banca: Cláudio Maldonado Pastori
Resumo: Proposição: Neste estudo nós investigamos o efeito dos peróxidos de carbamida a 16% e a 35%, peróxido de hidrogênio 35% e refrigerante de Cola, nas modificações da superfície do titânio comercialmente puro (Ti-cp) e liga Ti-6Al-4V. Materiais e Métodos: Setenta e dois discos de Ti (8 mm de diâmetro, 2 mm de espessura) foram utilizados e divididos em 18 grupos (n = 4) em função do tratamento das soluções e o tipo de Ti. Os espécimes foram mecanicamente polidos utilizando procedimentos metalográficos padrão. Os espécimes foram imersos em 3 ml de peróxido de carbamida a 16% e a 35%, em peróxido de hidrogênio 35% e ao refrigerante de Cola, 4 horas por dia (mantidos secos ou imersos em saliva artificial nas 20 horas restantes), durante 15 dias. Os espécimes do grupo controle foram imersos apenas em saliva artificial ao longo dos 15 dias. A rugosidade de superfícies e a topografia do Ti foram examinados por meio da microscopia de força atômica (AFM) e microscopia eletrônica de varredura (MEV). As modificações químicas das superfícies Ti foram avaliadas por meio da espectroscopia de energia dispersiva (EDS). Os dados foram analisados pela ANOVA de três fatores e o teste de Tukey foi utilizado como técnica post-hoc (α =.05). Resultados: Os grupos imersos em peróxido de hidrogênio 35% apresentaram a maior rugosidade (P <0,05), seguido pelos peróxidos de carbamida, com maiores valores para o Ticp, porém sem alterações quando associados ou não à saliva artificial. Estes valores foram estatisticamente superiores aos observados no início e no grupo controle. O refrigerante de Cola não alterou a rugosidade de superfície de ambos os tipos de Ti (P> 0,05). A MEV e a AFM mostraram maiores alterações... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Purpose: In this study we investigated the effect of 16% and 35% carbamide peroxides, 35% hydrogen peroxides and cola soft drink, on the surface modifications of commercially-pure titanium (cp-Ti) and Ti-6Al-4V alloy. Materials and Methods: Seventy-two Ti discs (8-mm diameter, 2-mm thickness) were used and divided into 18 groups (n=4) as a function of solution treatments and Ti type. Samples were mechanically polished using standard metallographic procedures. Samples were immersed into 3 ml of 16% and 35% carbamide peroxides, 35% hydrogen peroxide and cola soft drink at 4 hours per day (kept dried or immersed in artificial saliva in the remaining 20 hours) during 15 days. Control samples were immersed just in artificial saliva throughout the 15 days. Ti surfaces roughness and topography were examined using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The chemical modifications of Ti surfaces were evaluated through energy dispersive spectroscopy (EDS). Data were analyzed by 3-way ANOVA, Tukey's tests were further used as post-hoc techniques (α=.05). Results: Groups immersed in 35% hydrogen peroxide exhibited the greatest surface roughness (P<.05), followed by the carbamide peroxides regardless of Ti type and association or not with artificial saliva. Ticp exhibited greater surface roughness than Ti-6Al-4V alloy. These values were statistically higher than those observed at baseline and in control group. Cola soft drink did not change the surface roughness of both Ti types (P>.05). The SEM and AFM images of Ti surfaces showed higher surface changes for the samples immersed in 16% and 35% carbamide peroxides, and 35% hydrogen peroxide, with greater visible alteration for Ticp. These groups promoted the formation of crevices and pitting on the Ti surfaces. No detectable chemical... (Complete abstract click electronic access below)
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Rabah, Ali A. [Verfasser]. "Flow boiling of pure refrigerants and binary refrigerant mixtures in a horizontal tube / von Ali A. Rabah". 2003. http://nbn-resolving.de/urn:nbn:de:gbv:089-3662516277.

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Swanepoel, Wayne. "Wet compression versus dry compression in refrigeration cycles working with pure or non-azeotropic refrigerant mixtures for air-conditioners". Thesis, 2012. http://hdl.handle.net/10210/6097.

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M.Ing.
Wet compression versus dry compression in refrigeration cycles working with pure refrigerants or non-azeotropic mixtures is investigated in this paper. In total 34 pure refrigerants as well as 31 non-azeotropic binary mixtures are considered. This resulted in approximately 300 different mixtures being analysed. The pure refrigerants and refrigerant mixtures were analysed for one cooling application, namely that of spatial air conditioning at an evaporating temperature of 7°C, and a condensing temperature of 50°C. The investigation was conducted with cycle analyses calculating performances at different wet and dry compressor inlet values. Use was made of thermodynamic refrigerant properties calculated from a computer database. It was concluded that for both pure and non-azeotropic refrigerants analysed, all those with re-entrant saturation vapour lines produce better cooling COP's when the refrigerant is superheated before entering the compressor. Only a few of the refrigerants with bell-shaped T-s curves consistently produce higher cooling COP's when wet compression is used. However, their cooling capacities decreased while the compressor displacement rates increased. It was concluded that in general dry compression is more favourable than wet compression. From the exceptions that do exist, some manage to produce relatively high COP c 's while retaining competitive cooling capacities. A by-product of this study is that, from the vast amount of refrigerant mixtures analysed, valuable knowledge was gathered regarding refrigerants not commonly used in the applications considered.
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Vorster, Paul Philip Jacobus. "Wet compression versus dry compression in heat pumps working with pure refrigerants or non-azeotropic mixtures for different heating applications". Thesis, 2012. http://hdl.handle.net/10210/7627.

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M.Ing.
Wet compression versus dry compression in heat pumps working with pure refrigerants or nonazeotropic mixtures is investigated in this paper. In total 34 pure refrigerants as well as 31 nonazeotropic binary mixtures at different concentrations are considered. This resulted in approximately 300 different mixtures being analysed. The pure refrigerants were analysed for three different heating applications found in practice: the heating of swimming pool water, heating air for interior space heating, and the heating of water for domestic use. The investigation was conducted with cycle analyses calculating performances at different wet and dry compressor inlet values. Use was made of thermodynamic refrigerant properties calculated from a computer database. It was concluded that for both pure and non-azeotropic refrigerants analysed, all those with re-entrant saturation vapour lines produce better heating COP's when the refrigerant is superheated before entering the compressor. Only a few of the refrigerants with bell-shaped T-s curves, consistently produce higher heating COP's when wet compression is used. However, their heating capacities decreased while the compressor displacement rates increased. It was concluded that in general dry compression is more favourable than wet compression. From the few exceptions that do exist, some manage to produce very high COPh's while retaining competitive heating capacities. A by-product of this study is that, from the vast amount of refrigerant mixtures analysed, valuable knowledge was gathered regarding refrigerants not commonly used in the applications considered
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SANGADE, NIKHIL VASANT. "PERFORMANCE EVALUATION OF MULTI EVAPORATOR VAPOUR COMPRESSION REFRIGERATION SYSTEM WITH LIQUID-VAPOUR HEAT EXCHANGER AND FLASH CHAMBER USING ALTERNATIVE PURE REFRIGERANTS". Thesis, 2016. http://dspace.dtu.ac.in:8080/jspui/handle/repository/15374.

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Parametric investigation of energy and exergy analysis of multi-evaporators at different temperatures with individual expansion valve and individual compressor using flash chamber and liquid vapour heat exchanger is carried out for R134A, R142B, R152A, R600 and R1234YF as alternative refrigerants. In engineering equation solver, a computational model is developed for these systems, simple multi-evaporator system and improved one system. The present investigation has been done for evaporator-I in the range -120C to -200C, evaporator-II in the range 10C to 40C and condenser in the range 350C to 550C. Performance parameters like exergetic efficiency, the coefficient of performance and exergy destruction ratio are calculated over these ranges and compared for these refrigerants. The performance comparison of the simple multi-evaporator system and improved system for dairy plant application, COP improves by 16.99%, 15.97%, 15.88%, 16.24% and 18.41% for refrigerants R134A, R142B, R152A, R600 and R1234YF respectively in multi-evaporator system with flash chamber and LVHE. Exergy efficiency improves by 16.98%, 15.97%, 15.87%, 16.22% and 18.36% for refrigerants R134A, R142B, R152A, R600 and R1234YF respectively in multi-evaporator system with flash chamber and LVHE. Due to additional components in basic system, flash chamber and LVHE, exergy destruction in multi-evaporator system increases. EDR % increases by 20.37%, 16.84%, 14.74%, 18.66% and 24.92% for refrigerants R134A, R142B, R152A, R600 and R1234YF respectively in multi-evaporator system with flash chamber and LVHE. The corresponding values of input energy consumed for expansion valve, evaporator and compressor are varied between 7% to 18%, 11% to 22% and 18 % to 24 % respectively. From the point of enery-exergy analysis, R142B is best among all five selected refrigerants as total exergy destruction of all components is always less for R142B than that of all others and R142B refrigerant has higher COP and Exergetic efficiency in this modified system. Also, R142B has least EDR in this analysis. Though R142B have highest COP and exergetic efficiency among all refrigerants, it is not recommended due to its GWP 2400, which is highest among all. Second best refrigerant R600 has only GWP 3. Hence it is recommended over R142B in dairy plant application.
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Kukreja, Rajeev. "Study of condensation characteristics of pure and mixtures of HFC refrigerants in horizontal tubes with micro-fins". Thesis, 2010. http://localhost:8080/iit/handle/2074/5247.

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Książki na temat "PURE REFRIGERANTS"

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International Institute of Refrigeration. Commission B1., red. Propriétés thermophysiques des frigorigènes purs ou en mélange: Compte rendu de la réunion de la Commission B1 = Thermophysical properties of pure substances and mixtures for refrigeration : proceedings of the meeting of Commission B1, (March 5-7, 1990). Paris, France: Institut international du froid, 1990.

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Części książek na temat "PURE REFRIGERANTS"

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Meyer, J. P. "Evaluation of Energy Efficient and Environmentally Acceptable Pure and Zeotropic Refrigerants in Air-Conditioning and Refrigeration". W Energy and the Environment, 239–46. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4593-0_21.

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Al-Nadawi, Ayad Khudhair. "Distributed parameters modeling for heat exchangers using pure and zeotropic blend refrigerants". W Advanced Analytic and Control Techniques for Thermal Systems with Heat Exchangers, 49–129. Elsevier, 2020. http://dx.doi.org/10.1016/b978-0-12-819422-5.00003-7.

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Sun, Z. H., M. Q. Gong, Y. F. Qi, E. C. Luo i J. F. Wu. "Experimental investigation on pool boiling heat transfer of pure refrigerants and binary mixtures". W Proceedings of the Twentieth International Cryogenic Engineering Conference (ICEC20), 821–24. Elsevier, 2005. http://dx.doi.org/10.1016/b978-008044559-5/50197-6.

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Koyama, Sh, J. Yu, S. Momoki, T. Fujii i H. Honda. "Forced Convective Flow Boiling Heat Transfer of Pure Refrigerants Inside a Horizontal Microfin Tube". W Convective Flow Boiling, 137–42. CRC Press, 2019. http://dx.doi.org/10.1201/9780367812089-16.

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Greco, Adriana. "Convective Boiling Heat Transfer of Pure and Mixed Refrigerants within Plain Horizontal Tubes: An Experimental Study". W Advances in Multiphase Flow and Heat Transfer (Volume 2), 216–303. BENTHAM SCIENCE PUBLISHERS, 2009. http://dx.doi.org/10.2174/978160805094910901010216.

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Greco, Adriana. "Convective Boiling Heat Transfer of Pure and Mixed Refrigerants within Plain Horizontal Tubes: An Experimental Study". W Advances in Multiphase Flow and Heat Transfer (Volume 2), 216–303. BENTHAM SCIENCE PUBLISHERS, 2012. http://dx.doi.org/10.2174/978160805094910902010216.

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Lee, Inkyu, Kyungjae Tak, Wonsub Lim, Kwangho Choi, i Il Moon. "Optimization of Pure-Refrigerant Cycle Compressing Ratio on C3-MR Process". W Computer Aided Chemical Engineering, 1472–76. Elsevier, 2012. http://dx.doi.org/10.1016/b978-0-444-59506-5.50125-5.

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Sumardi, K., E. T. Berman i M. Mutaufiq. "Performance investigation of an air-cooled chiller system using pure hydrocarbons as refrigerant". W Regionalization and Harmonization in TVET, 293–96. Routledge, 2017. http://dx.doi.org/10.1201/9781315166568-62.

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Streszczenia konferencji na temat "PURE REFRIGERANTS"

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Dalkilic¸, Ahmet Selim, i Somchai Wongwises. "Comparison of Various Alternative Refrigerants for Vapour Compression Refrigeration Systems". W ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44267.

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Single-stage vapour compression refrigeration system was compared with an actual vapour compression cycle, single-stage process with internal heat exchanger, and a two-stage process with economiser using the refrigerants of HCFC-22, CFC-502 and their alternatives such as HFC-134a, HFC-32, HFC-152a, HFC-404A, HFC-407C, HFC-507, HFC-410A. A theoretical performance study on a cascade refrigeration system was performed using two refrigeration cycles connected through the heat exchanger in the middle working as the evaporator for the high pressurized cycle and condenser for the low pressurized cycle. Other performance study was performed using a two-stage cascade refrigeration system having low and high pressure compressors connected through the mixing chamber in the middle. The condensation temperatures were between 30 and 50 °C, evaporation temperatures were between −50 °C and 5 °C and heat exchanger and economiser temperatures were kept as constant for the comparisons. Some of the alternative refrigerants’ coefficients of performance values are found to be higher than their base traditional pure refrigerants. The effects of the main parameters of performance analysis such as refrigerant type, degree of subcooling, and superheating on the performance coefficient, refrigerant charge rate and volumetric refrigeration capacity are investigated for various operating conditions as case studies.
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Avsec, Jurij, i Milan Marcic. "The calculation of the thermophysical properties for pure refrigerants and their mixtures". W 33rd Thermophysics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1999. http://dx.doi.org/10.2514/6.1999-3676.

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Inoue, Norihiro, Masao Goto i Satish G. Kandlikar. "Flow Boiling Heat Transfer With Binary and Ternary Mixtures in Microfin Tubes". W ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-1275.

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Abstract An experimental setup was designed and fabricated to test the flow boiling heat transfer performance of microfin tubes. Five microfin tubes were tested with pure refrigerants. Two tubes were selected for further testing with binary and ternary refrigerant mixtures. This paper reports the data for these two microfin tubes employing R22, R410A (mixture of 50% by weight of R32 and 50% of R125) and R407C (ternary mixture of 23 wt. % R32, 25 wt. % R125, and 52 wt. % R134a). A correlation scheme is presented for the heat transfer coefficient of mixtures in microfin tubes. In general, it is observed that the heat transfer performance of binary mixture R410A in microfin tubes is similar to pure R22; however, the performance of the ternary mixture R407C is lower than that with pure R22.
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Field, Brandon S., i Pega Hrnjak. "Visualization of Two-Phase Refrigerant and Refrigerant-Oil Flow in a Microchannel". W ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43471.

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Visualizations of adiabatic two-phase refrigerant flow in a glass channel of diameter 0.5 mm have been made for three refrigerants: R134a, Propane (R290), and Ammonia (R717), representing a wide span of fluid properties, which covers most of the refrigerants commercially in use. In these visualizations four flow regimes were observed: bubble-slug, slug, slug-annular, and annular. These flow regimes were compared to various flow maps, including some developed for small channels. Flow visualizations were also made with mixtures of R134a and 68-weight POE oil at oil circulation rates of approximately 0.5, 1.5 and 3 percent. This is of interest when considering refrigeration systems, which have a small percentage of oil in circulation that travels through system and through the heat exchangers. When the refrigerant is in a liquid state, this presents little variation in fluid properties, because the concentration is so small. However, when the refrigerant is partly vapor, the oil concentration in the remaining liquid can have significant effect on the fluid properties. In addition, the saturation temperature and pressure of the oil-refrigerant mixture changes with concentration, where a single-phase vapor is never observed in flows of oil-refrigerant mixtures, even at temperatures exceeding the saturation temperature of the pure mixture. This effect is known as “apparent superheat”.
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Jung, Dongsoo, Chong-Bo Kim, Kil-Hong Song i Jun-Kang Lee. "Pool Boiling Heat Transfer Coefficients of Alternative Refrigerants". W ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-1014.

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Abstract Nucleate pool boiling heat transfer coefficients (HTCs) of 14 refrigerants are measured from a 19mm o.d. plain copper tube heated by a cartridge heater. All measurements are carried out in the pool temperature of 4∼25°C and in the heat flux of 10∼80kW/m2. Test results show that HTCs of R32, R125, R143a, R152a, and R410A are higher than those of R22. Especially, R32 showed the highest HTCs among all the refrigerants tested. As for R22 alternatives, HTCs of R410A are 50% higher than those of R22 while those of R407C are very similar to those of R22. It is also found that some of the popular pool boiling heat transfer correlations in the literature failed to predict the HTCs of newly developed alternative refrigerants. Hence, a dimensionless analysis is carried out in an attempt to develop a general correlation for all HTCs of pure refrigerants. Thus developed correlation showed an excellent agreement with all experimental data showing a mean deviation of 5.5%.
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Greco, Adriana, Rita Mastrullo, Alfonso W. Mauro i Giuseppe P. Vanoli. "Two Phase Pressure Drops for Refrigerants: A Statistical Comparison Among Experimental Data and Correlations". W ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95817.

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A 962 points database for refrigerants two-phase flows by Greco A. and Vanoli G.P. was statistically compared to four widely used prediction methods by Lockhart and Martinelli, Chawla, Theissing and Mu¨ller-Steinhagen and Heck in order to determine the best one. The experimental points are in a wide range of operating conditions for six pure or mixed refrigerants (R134a, R22, R407C, R507A, R410A and R404A) during evaporation in a smooth horizontal tube of 6 m length and 6 mm ID.
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Rohlin, Peter. "Heat Transfer Coefficients of Zeotropic Refrigerant Mixtures and Their Pure Components in Horizontal Flow Boiling: An Experimental Study". W ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-1011.

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Abstract The paper deals with an experimental study of flow boiling heat transfer coefficients in horizontal tubes. The experiments are performed in an electrically heated thermosiphon loop with two different evaporator tube diameters. Measurements are performed with constant heat flux along the tube and at relatively low heat and mass fluxes. The gravitational forces will influence the flow pattern and incomplete wetting of the tube walls will occur in a great part of the measurements. The tests are performed with the pure substances R22, R142b, R32 and R134a as well as several mixtures of R22/R142b and R32/R134a. The two tube dimensions tested have quite different behavior in spite of having the same length and refrigerant distribution system. A Chen-type correlation is chosen to predict the local heat transfer coefficients. The influences on the heat transfer coefficient of incomplete wetting are correlated by correcting the enhancement factor by a function of the Froude number. The correlations obtained for the two tube diameters and with pure refrigerants are then used as basis for the evaluation of the refrigerant mixture tests. The degradation of the heat transfer coefficient for mixtures is discussed. The measured mixture heat transfer coefficients are well estimated by using Jung’s correlation for mixtures, if Jung’s enhancement factor is replaced by the enhancement factors evaluated from the tests and the real mixture transport properties are used or by the theoretically approached correlation by Granryd.
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Xia, Jiaxi, Jiangfeng Wang, Pan Zhao i Dai Yiping. "Performance Analysis and Comparison Study of Transcritical Power Cycles Using CO2-Based Mixtures as Working Fluids". W ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57132.

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CO2 in a transcritical CO2 cycle can not easily be condensed due to its low critical temperature (304.15K). In order to increase the critical temperature of working fluid, an effective method is to blend CO2 with other refrigerants to achieve a higher critical temperature. In this study, a transcritical power cycle using CO2-based mixtures which blend CO2 with other refrigerants as working fluids is investigated under heat source. Mathematical models are established to simulate the transcritical power cycle using different CO2-based mixtures under MATLAB® software environment. A parametric analysis is conducted under steady-state conditions for different CO2-based mixtures. In addition, a parametric optimization is carried out to obtain the optimal design parameters, and the comparisons of the transcritical power cycle using different CO2-based mixtures and pure CO2 are conducted. The results show that a raise in critical temperature can be achieved by using CO2-based mixtures, and CO2-based mixtures with R32 and R22 can also obtain better thermodynamic performance than pure CO2 in transcritical power cycle. What’s more, the condenser area needed by CO2-based mixture is smaller than pure CO2.
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Tavakol, Mohsen, i Maziar Shafaee. "CFD Study on Supersonic Ejectors Used for Suction of Two Different Gases". W ASME 2015 9th International Conference on Energy Sustainability collocated with the ASME 2015 Power Conference, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/es2015-49577.

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In ejector refrigeration cycles, ejector working fluids include various refrigerants with different properties. In some cases, ejector works with mixture of two different refrigerants; that each refrigerant have distinct properties. The purpose of this paper is to evaluate the performance of an ejector used for suction of a mixture of air and water vapor. In this regard, the ejector performance was numerically studied under the operating condition that a mixture of air and steam with variable mass fractions, were sucked into the ejector. With the help of numerical simulation, various conditions for two perfect gas streams of air and water vapor were investigated. Initially, the numerical simulation was carried out for the case that pure water vapor was considered as the working fluid of ejector. After validation of initial case with experimental data, numerical method was expanded for a specific case that, water vapor was considered as the working fluid of motive flow and a mixture of air and water vapor was considered for suction flow. Numerical simulations were done for different mass fraction of air and water vapor for suction flow mixture. Results indicated that, variations of the mass fraction of air in suction flow, leads to obvious changes in ejector performance. Also, it was observed that the increment of suction flow pressure, leads to increment of the ejector performance sensitivity to variations of suction flow mass fraction.
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García-Valladares, O., C. D. Pérez-Segarra i A. Oliva. "Numerical Simulation of Capillary-Tube Behaviour Working With Pure and Mixed Refrigerants Under Adiabatic and Non-Adiabatic Flow Conditions". W ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/htd-24220.

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Abstract A detailed numerical method for analysing the thermal and fluid-dynamic behaviour of capillary tube expansion devices working with pure refrigerants and mixtures has been developed by means of a one-dimensional analysis of the governing equations (continuity, momentum and energy). Metastable both liquid and two-phase regions have been taken into account. The discretized governing equations are coupled using an implicit step by step method. In order to minimise computational cost, a special treatment has been implemented to solve the control volume that contains transition between regions and a special mesh distribution has been used. All the flow variables together with the thermophysical properties are evaluated at each point of the grid in which the domain is discretized. The numerical model allows analysis of aspects such as geometry, type of fluid, critical or non-critical flow conditions, metastable regions, adiabatic or non-adiabatic capillary tubes and transient aspects. The accuracy of the detailed simulation model is demonstrated by comparison with experimental data from the technical literature for adiabatic capillary tubes and also for concentric capillary tube-suction line heat exchanger.
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Raporty organizacyjne na temat "PURE REFRIGERANTS"

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Ross, Howard D. An investigation of horizontal flow boiling of pure and mixed refrigerants. Gaithersburg, MD: National Bureau of Standards, 1986. http://dx.doi.org/10.6028/nbs.ir.86-3450.

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