电子膨胀阀的开度对变频除湿机低温工况下除湿性能的影响

The infl uence of electronic expansion valve opening on the dehumidifi cation performance of inverter dehumidifi ers under low-temperature operating conditions

在低温工况下,霜层容易在冷冻除湿机的蒸发盘管表面出现,从而恶化其除湿性能。为了提升冷冻除湿机在低温工况下的除湿性能,搭建了变频除湿机性能测试系统,通过实验研究了在低温工况下,压机频率和风机转速不同组合下,电子膨胀阀的开度对除湿系统运行参数、除湿性能以及结霜现象的影响。得出以下结论:电子膨胀阀开度的增大可以提高蒸发温度,使蒸发器最低温度点推迟到流程后半段,使霜层在冷凝水分布稀疏的区域首先出现,从而缓解结霜现象,提高除湿性能。并且当蒸发温度达到-4℃附近时,结霜覆盖率接近100%,蒸发盘管表面严重结霜,此时吸气压力也异常降低,达到0.2 MPa。实验结果表明,-4℃的蒸发温度和0.2 MPa的吸气压力可以作为除霜开始的一般判据。研究成果可以为冷冻除湿机在低温工况下的除湿性能提升提供优化方向和参考依据。

Under low-temperature operating conditions,frost layer is easy to appear on the evaporator coil surface of the refrigerated dehumidifier,thus its dehumidification performance is deteriorated.In order to improve the dehumidification performance of the refrigerated dehumidifier under low-temperature conditions,a variable-frequency dehumidifier performance test system was builded.The effect of the electronic expansion valve opening on the operating parameters,dehumidification performance,and frost phenomenon of the dehumidification system was experimentally investigated under low-temperature operating conditions with different combinations of compressor frequency and fan speed.The following conclusions were drawn:the increase in the electronic expansion valve opening can increase the evaporating temperature,so that the lowest temperature point of the evaporator is postponed to the second half of the process,and the frost layer appears first in areas with sparse condensate distribution,alleviating the frost phenomenon and improving the dehumidification performance.When the evaporating temperature reaches near-4℃,the frost covering rate is close to 100%,and the evaporator coil surface is seriously frosted,at the same time the suction pressure is abnormally lowered to 0.2 MPa.The experimental results shows,the evaporating temperature of-4℃and the suction pressure of 0.2 MPa can be used as a general criterion for the start of defrosting.The research results can provide optimization direction and reference basis for the dehumidification performance enhancement of refrigerated dehumidifier under low-temperature operating conditions.