喷气增焓空气源热泵补气量对系统性能的影响

Effect of Vapor-injection Mass on System Performance Air-source Heat Pump with Enhanced Vapor Injection

空气源热泵在较低的环境温度下会产生压比大、排气温度高、循环性能差等现象,喷气增焓EVI(enhanced vapor injection)技术可以改善空气源热泵在低温下的运行特性。本文首先建立了EVI空气源热泵的数值仿真模型,并搭建了实验台对仿真实验数据进行验证并在此模型的基础上对带EVI的空气源热泵系统的补气运行特性进行了数值模拟。结果表明:带EVI的空气源热泵系统存在最佳相对补气量,可使系统运行最优,当环境温度低于-6℃时,最佳补气量为8%~10%;当环境温度为-6~0℃时,最佳补气量为5%~8%;当环境温度高于0℃时,最佳补气量为4%~5%。在最佳补气量下,各个工况的相对补气压力在0.7~0.9之间。在最佳补气参数条件下,系统制热量最高提升33%,能效最高提升31%。

Air-source heat pumps suffer from many problems such as high pressure ratio, high discharge temperature, and poor performance at low temperature. The enhanced vapor injection(EVI) technology can improve the performance of an air-source heat pump at low temperature. This study sets up a numerical simulation model of an air-source heat pump system to investigate with the effect of EVI. A test bed is designed to verify the simulation model. The performance of the air-source heat pump with EVI is simulated based on the model. The results demonstrate that an optimal relative vapor-injection mass exists that achieves the highest system energy efficiency. The best range of relative vapor-injection mass is 8%-10% for the best heating performance when the environment temperature is lower than-6 ℃. The best range of relative vapor-injection mass is 5%-8% when the environment temperature is from-6 to 0 ℃. The best range of relative vapor-injection mass is 4%-5% when the environment temperature is higher than 0 ℃. The corresponding optimal relative vapor-injection pressure is between 0.7 and 0.9. The heating capacity increases by 33%, and the coefficient of performance increases by 31% under optimal air-injection parameters.