Nucleate pool boiling heat transfer data of the HFC23/CFC13 system have been systematically measured in a wide range of pressures and heat fluxes. The experimental results are also compared with the measured data of R...Nucleate pool boiling heat transfer data of the HFC23/CFC13 system have been systematically measured in a wide range of pressures and heat fluxes. The experimental results are also compared with the measured data of R508A and R508B. It is found that the heat transfer coefficient of R503 （HFC23/CFC13=0.511/0.489） is higher than that of R508A and R508B. Furthermore, the measured data were compared with the predicted results with three well-known correlations. Correlation by Fujita and Tsutsui can provide acceptable results. Most of the data fall within ±20% of this correlation.展开更多
Using near-azeotropic refrigerant R410A as the working fluid, the experimental studies on the horizontal micro-fin tubes were conducted. Several factors affecting heat transfer coefficients were analyzed, and the char...Using near-azeotropic refrigerant R410A as the working fluid, the experimental studies on the horizontal micro-fin tubes were conducted. Several factors affecting heat transfer coefficients were analyzed, and the characteristics of flow boiling of the refrigerant in the horizontal micro-fin tubes were discussed. The local heat transfer coefficients increase with mass flux, heat flux and quality. And the heat transfer enhancement factor of those testing tubes is about 1.6 to 2.2.展开更多
In order to improve the convective boiling heat transfer of R410A,the micro-fin tube was used to enhance heat transfer.The experimental studies on the horizontal micro-fin tube and smooth tube were conducted by using ...In order to improve the convective boiling heat transfer of R410A,the micro-fin tube was used to enhance heat transfer.The experimental studies on the horizontal micro-fin tube and smooth tube were conducted by using R410A as the working fluid.Several factors affecting heat transfer coefficients were analyzed, such as mass flux, heat flux, and quality.The circumferential wall temperature variation of the testing tubes with R410A as the working fluid was observed and analyzed.The heat transfer enhancement factor of the micro-fin tube against the smooth tube was about 1.6 to 2.2.The preliminary experiment data were useful for further research.展开更多
With the increasing environmental concern on global warming, hydrofluoro-olefin (HFOs), possessing low GWP, has attracted great attention of many researchers recently. In this study, non-azeotropic mixtures composed o...With the increasing environmental concern on global warming, hydrofluoro-olefin (HFOs), possessing low GWP, has attracted great attention of many researchers recently. In this study, non-azeotropic mixtures composed of HFOs (HFO-1234yf, HFO-1234ze(z), HFO-1234ze(e) and HFO-1234zf) are developed to substitute for HFC-134a and CFC-114 in air-conditioning and high-temperature heat pump systems, respectively. The cycle performances were evaluated by an improved theoretical cy-cle evaluation methodology. The results showed that all the mixtures proposed herein were favorable refrigerants with excel-lent thermodynamic cycle performances. M1A presented lower discharge temperature and pressure ratio and higher COPc than that of HFC-134a. The volumetric cooling capacity was similar to HFC-134a. It can be served as a good environmentally friendly alternative to replace HFC-134a. M3H delivered similar discharge temperature as CFC-114 did. And the COPh was 3% higher. It exhibits excellent cycle performance in high-temperature heat pump and is a promising refrigerant to substitute for CFC-114. And the gliding temperature differences enable them to exhibit better coefficient of performance by matching the sink/source temperature in practice. Because the toxicity, flammability and other properties are not investigated in detail, ex-tensive toxicity and flammability testing needs to be conducted before they are used in a particular application.展开更多
基金This project is supported by the National Natural Science Foundation of China under the contract number of 50576102.
文摘Nucleate pool boiling heat transfer data of the HFC23/CFC13 system have been systematically measured in a wide range of pressures and heat fluxes. The experimental results are also compared with the measured data of R508A and R508B. It is found that the heat transfer coefficient of R503 （HFC23/CFC13=0.511/0.489） is higher than that of R508A and R508B. Furthermore, the measured data were compared with the predicted results with three well-known correlations. Correlation by Fujita and Tsutsui can provide acceptable results. Most of the data fall within ±20% of this correlation.
基金Shanghai Leading Academic Discipline Project(No.T0503)
文摘Using near-azeotropic refrigerant R410A as the working fluid, the experimental studies on the horizontal micro-fin tubes were conducted. Several factors affecting heat transfer coefficients were analyzed, and the characteristics of flow boiling of the refrigerant in the horizontal micro-fin tubes were discussed. The local heat transfer coefficients increase with mass flux, heat flux and quality. And the heat transfer enhancement factor of those testing tubes is about 1.6 to 2.2.
文摘In order to improve the convective boiling heat transfer of R410A,the micro-fin tube was used to enhance heat transfer.The experimental studies on the horizontal micro-fin tube and smooth tube were conducted by using R410A as the working fluid.Several factors affecting heat transfer coefficients were analyzed, such as mass flux, heat flux, and quality.The circumferential wall temperature variation of the testing tubes with R410A as the working fluid was observed and analyzed.The heat transfer enhancement factor of the micro-fin tube against the smooth tube was about 1.6 to 2.2.The preliminary experiment data were useful for further research.
基金supported by the National Natural Science Foundation of China (Grant No. 50976079)Science and Technology Support Key Project of Tianjin (Grant No. 10ZCKFGX01700)
文摘With the increasing environmental concern on global warming, hydrofluoro-olefin (HFOs), possessing low GWP, has attracted great attention of many researchers recently. In this study, non-azeotropic mixtures composed of HFOs (HFO-1234yf, HFO-1234ze(z), HFO-1234ze(e) and HFO-1234zf) are developed to substitute for HFC-134a and CFC-114 in air-conditioning and high-temperature heat pump systems, respectively. The cycle performances were evaluated by an improved theoretical cy-cle evaluation methodology. The results showed that all the mixtures proposed herein were favorable refrigerants with excel-lent thermodynamic cycle performances. M1A presented lower discharge temperature and pressure ratio and higher COPc than that of HFC-134a. The volumetric cooling capacity was similar to HFC-134a. It can be served as a good environmentally friendly alternative to replace HFC-134a. M3H delivered similar discharge temperature as CFC-114 did. And the COPh was 3% higher. It exhibits excellent cycle performance in high-temperature heat pump and is a promising refrigerant to substitute for CFC-114. And the gliding temperature differences enable them to exhibit better coefficient of performance by matching the sink/source temperature in practice. Because the toxicity, flammability and other properties are not investigated in detail, ex-tensive toxicity and flammability testing needs to be conducted before they are used in a particular application.
