The vapor compression heat pump is considered as the best option for aerospace thermal control system.The heat exchanger in vapor compression heat pump is a component that is greatly influenced by the cosmic environme...The vapor compression heat pump is considered as the best option for aerospace thermal control system.The heat exchanger in vapor compression heat pump is a component that is greatly influenced by the cosmic environment.Lubricating oil enters heat pump system with a refrigerant under microgravity,and the entrance of the lubricant increases the complexity of the flow.In this work,FLUENT software was used to study the flow and lubricant deposition of a two-phase mixture of lubricant POE RL 68H and refrigerant R134a in a heat exchanger without the consideration of phase-change heat transfer.The functional relationships between the oil film thickness and the proportion of lubricating oil,the gravitational acceleration,the inlet flow velocity,and the placement directions of the two phases of oil in the heat exchanger were established.The results demonstrate that with the increase of the gravitational acceleration and the lubricating oil content,the thickness of the oil film will exhibit an S-type change in line with the Boltzmann function,and the amount of lubricating oil deposition will increase.With the increase of the flow velocity,the thickness of the oil film will exhibit an exponential decline.展开更多
A new-type multiple-source heat pump cycle with two-stage compression was established on the basis of the problems of similarly existing heat pumps.The equivalent temperature levels of typical evaporators are applied ...A new-type multiple-source heat pump cycle with two-stage compression was established on the basis of the problems of similarly existing heat pumps.The equivalent temperature levels of typical evaporators are applied to the different heat sources of the proposed cycle,and the high-temperature heat sources are shown to enhance vapor injection.Then,the mathematical model and prototype are developed,and the results from experimental simulation and validation showed that the solar collector can improve the heating performance of the proposed heat pump system.In the middle-temperature heating period,the outdoor temperature is less than-25℃,and the average coefficient of performance(COP)value of the proposed heat pump was 4.2,which was greater than the COPs of conventional ground source heat pumps.展开更多
基金financially supported by the National Nature Science Foundation of China(No.51906116)Inner Mongolia Autonomous Region Science and Technology Plan Project(No.2021GG0253)+1 种基金Nature Science Foundation of Inner Mongolia(No.2019BS05007)Nature Science Foundation of School(No.BS201918)。
文摘The vapor compression heat pump is considered as the best option for aerospace thermal control system.The heat exchanger in vapor compression heat pump is a component that is greatly influenced by the cosmic environment.Lubricating oil enters heat pump system with a refrigerant under microgravity,and the entrance of the lubricant increases the complexity of the flow.In this work,FLUENT software was used to study the flow and lubricant deposition of a two-phase mixture of lubricant POE RL 68H and refrigerant R134a in a heat exchanger without the consideration of phase-change heat transfer.The functional relationships between the oil film thickness and the proportion of lubricating oil,the gravitational acceleration,the inlet flow velocity,and the placement directions of the two phases of oil in the heat exchanger were established.The results demonstrate that with the increase of the gravitational acceleration and the lubricating oil content,the thickness of the oil film will exhibit an S-type change in line with the Boltzmann function,and the amount of lubricating oil deposition will increase.With the increase of the flow velocity,the thickness of the oil film will exhibit an exponential decline.
基金supported by the Natural Science Foundation of Beijing Municipality(3172040)National Natural Science Foundation(51736008)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA21050600)
文摘A new-type multiple-source heat pump cycle with two-stage compression was established on the basis of the problems of similarly existing heat pumps.The equivalent temperature levels of typical evaporators are applied to the different heat sources of the proposed cycle,and the high-temperature heat sources are shown to enhance vapor injection.Then,the mathematical model and prototype are developed,and the results from experimental simulation and validation showed that the solar collector can improve the heating performance of the proposed heat pump system.In the middle-temperature heating period,the outdoor temperature is less than-25℃,and the average coefficient of performance(COP)value of the proposed heat pump was 4.2,which was greater than the COPs of conventional ground source heat pumps.
