过热度振荡对变制冷剂流量系统性能的影响

The Effect of Hunting of Superheated Temperature on the Performance of a Variable Refrigerant Flow Refrigeration System

在变制冷剂流量制冷循环中,通常控制蒸发器出口过热度尽可能小来提高蒸发器换热面积的利用率,但过热度过低会诱发制冷系统的振荡。本文分别对变制冷剂流量制冷系统在过热度振荡段和过热度稳定段进行了试验,试验结果表明：（1）压缩机容积效率和等熵压缩效率的振荡幅度和振荡周期变化相似;（2）随着过热度的增大,系统制冷量和COP先缓慢减小。当过热度大于最小稳定过热度后,制冷量和COP的减小幅度变大;（3）当过热度增大时,压缩机容积效率在0-4 K范围内先大幅减小,后逐渐增加,在4-6 K时又逐渐减小,其在制冷量对应的最小稳定过热度附近具有最大值;（4）当系统过热度达到最小稳定过热度时,系统各项性能处于最佳状态。压缩机排气温度与过热度几乎呈线性关系,可以通过排气温度与过热度的关系,将系统控制在最小稳定过热度处。

The superheated temperature of variable refrigerant flow are usually controlled as lower as possible to enhance the use of heat exchange area of evaporator. However,the system will be hunting when superheated temperature at lower level. The hunting and stabilization of superheated temperature are experimental studied. It could be concluded by analyzed the result that the hun-ting amplitude and period of volume efficiency and isentropic efficiency of compressor are similar. Moreover, with the increasing of superheated temperature, the refrigerating capacity and COP gradually decrease at first, and the range of decrease are larger when superheated temperature reach to the minimum stability superheated temperature. Furthermore,at the range of 0 -4 K,the volume efficiency sharply falls and then increases,and at 4 -6 K,it gradually decreases again, which means the maximum of volume effi-ciency exist at the minimum stability superheated temperature corresponding to the refrigerating capacity. There has linear relation between the discharge temperature of compressor and superheated temperature, which makes controlling to the minimum stability superheated temperature to be possible.