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
A water-to-water high temperature heat pump was fested experimentally in this work. The inlet water temperature of evaporator was 40 ℃ and the inlet and outlet water temperature of condenser were 70 ℃and 80 ℃ respe...A water-to-water high temperature heat pump was fested experimentally in this work. The inlet water temperature of evaporator was 40 ℃ and the inlet and outlet water temperature of condenser were 70 ℃and 80 ℃ respectively. Almost no conveafioual refrigerant is proper for this high temperature working condition. R22/R141b was taken as heat pump working fluid firstly in this work and heat pump’s pressure performance is improved. Even though the highest cooling water temperature was about 80 ℃,the highest pressure was less than 2 5 MPa and compression ratio was less than 8, which could satisfy R22 compressor’s limits. The performance of system was characterized by refrigerant compositions, compressor RPM and water temperature change. It was found that the coefficient of performance reached its maxim of 2 5 when R22’s molar component was about 75%. If only the water temperature difference in evaporator Δ T E increased, the heating and refrigerating capacity all decreasd. However, the heating and refrigerating capacity all increased with water temperature difference in condenser Δ T C. Frequency of compressor had little influence on heat pump’s COP and working fluid’s (R22/R141b) composition if the compositions and working condition remained unchanged.展开更多
With more and more research being carried out to replace CFC and HCFC,some new green-refrigerant fluids are obtained,but those fluids are only used in some fixed-temperature fields,it limits the used in a bigger range...With more and more research being carried out to replace CFC and HCFC,some new green-refrigerant fluids are obtained,but those fluids are only used in some fixed-temperature fields,it limits the used in a bigger range of variable performance.According to this situation,theory etical and experimentsal’ conclusions are drawn in order to solve this problem in the paper.Non-azeotropic mixtures have temperature-gliding in phase change.CSD equation of state is used for theoretical calculation.Some mixtures that may be used in a bigger range of variable perfomance are found.Experiments are carried out in a refrigerant system.The mixtures S3 is recommended.展开更多
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.
文摘A water-to-water high temperature heat pump was fested experimentally in this work. The inlet water temperature of evaporator was 40 ℃ and the inlet and outlet water temperature of condenser were 70 ℃and 80 ℃ respectively. Almost no conveafioual refrigerant is proper for this high temperature working condition. R22/R141b was taken as heat pump working fluid firstly in this work and heat pump’s pressure performance is improved. Even though the highest cooling water temperature was about 80 ℃,the highest pressure was less than 2 5 MPa and compression ratio was less than 8, which could satisfy R22 compressor’s limits. The performance of system was characterized by refrigerant compositions, compressor RPM and water temperature change. It was found that the coefficient of performance reached its maxim of 2 5 when R22’s molar component was about 75%. If only the water temperature difference in evaporator Δ T E increased, the heating and refrigerating capacity all decreasd. However, the heating and refrigerating capacity all increased with water temperature difference in condenser Δ T C. Frequency of compressor had little influence on heat pump’s COP and working fluid’s (R22/R141b) composition if the compositions and working condition remained unchanged.
文摘With more and more research being carried out to replace CFC and HCFC,some new green-refrigerant fluids are obtained,but those fluids are only used in some fixed-temperature fields,it limits the used in a bigger range of variable performance.According to this situation,theory etical and experimentsal’ conclusions are drawn in order to solve this problem in the paper.Non-azeotropic mixtures have temperature-gliding in phase change.CSD equation of state is used for theoretical calculation.Some mixtures that may be used in a bigger range of variable perfomance are found.Experiments are carried out in a refrigerant system.The mixtures S3 is recommended.
