温湿度对空气源热泵相变蓄能除霜系统特性影响

Effect of air temperature and humidity on system defrosting characteristics of a PCM based air source heat pump

为明确空气温湿度对空气源热泵相变蓄能除霜系统除霜过程系统动态特性的影响,进行了室外环境温湿度对系统除霜特性影响的实验研究.结果表明,相变蓄能除霜可以有效保证除霜过程压缩机吸气压力0.35 MPa以上,高于系统低压保护设定值;温度一定时,随着室外空气湿度的增大除霜所需时间和除霜能耗逐渐增加;空气相对湿度一定时,除霜时间和除霜能耗随着空气温度的降低先增加后减少,其中-3℃工况下除霜时间最长和能耗最大.温湿度对除霜系统动态特性具有重要影响,相变蓄热器可有效提高空气源热泵除霜过程系统运行的可靠性,-3℃工况可选为设计除霜用相变蓄热器最不利工况.

The experiments were carried out to test the effect of air temperature and humidity on a novel PCM based reversed-cycle defrosting for air source heat pump（ASHP）,and the results showed that PCM based reversed-cycle defrosting method could keep the suction pressure of compressor higher than 0.35 MPa,which was father higher than the system＇s low suction protection pressure.The system＇s defrosting time and energy consumption increased with the relative humidity when air temperature was kept constant.Furthermore,the system＇s defrosting time and energy consumption increased first and then decreased with the decrease of air temperature,and the most defrosting time and energy were consumed when the outdoor air temperature was-3 ℃.It could be concluded that the air temperature and humidity affected the defrosting process greatly and the system＇s reliability was improved greatly because shutting down of ASHP unit due to low suction pressure protection during defrosting could be effectively avoided by the PCM based heat exchanger,and-3 ℃ working condition could be selected as the most adverse design condition for the PCM based heat exchanger when the relative humidity was constant because the most defrosting time and energy were needed.