跨临界CO_(2)双级压缩空气源热泵循环的高级分析

Advanced exergy analysis of transcritical CO_(2) two-stage compressed air-source heat pump cycle

目前以自然工质CO_(2)为制冷剂的空气源热泵具有十分优良的应用前景,为挖掘其节能潜力,本文改进了常规的㶲分析评价方法,采用高级㶲分析方法对跨临界CO_(2)双级压缩空气源热泵循环进行了深入研究。结果表明:系统的可避免内因㶲损占比为46.88%,这一部分㶲损可通过改进系统部件性能避免;从高级㶲分析角度,低压压缩机、高压压缩机和膨胀机具有最高的优化优先级;高压压缩机的㶲损占总㶲损的25.37%,对高压压缩机进行优化可明显提升系统性能;蒸发器的㶲损全部为自身因素导致的内因㶲损;节流阀的外因㶲损和可避免㶲损为负值,可通过更换其他节流设备提高系统性能;系统存在对应最高㶲效率的最优高压压力,高压压力从8.00 MPa增大到10.00 MPa时,高压压缩机的可避免内因㶲损增大了1.96%。

At present,the air-source heat pump with natural refrigerant CO_(2) has a very good application prospect.In order to tap its energy saving potential,the conventional exergy analysis method has been improved,and an advanced exergy analysis method has been adopted to further study the cycle of a transcritical CO_(2) two-stage compressed air-source heat pump.The results show that the proportion of the avoidable endogenous exergy loss of the system is 46.88%,which can be avoided by improving the system component performance.From the angle of advanced exergy analysis,the proportion of the low pressure compressor,the proportion of the high pressure compressor and the proportion of the expander have the highest optimization priority.The exergy loss of the proportion of the high pressure compressor accounts for 25.37%of the total exergy loss,and the optimization of the proportion of the high pressure compressor can significantly improve the system performance.The exergy loss of the evaporator is all caused by internal factors.The exogenous exergy loss and the proportion of the avoidable exergy loss of the throttle valve are negative,and the system performance can be improved by replacing other throttling equipment.There is an optimal high pressure corresponding to the highest exergy efficiency in the system.When the high pressure increases from 8 MPa to 10 MPa,the avoidable endogenous exergy loss of the proportion of the high pressure compressor increases by 1.96%.