制冷剂充注量及毛细管长度对空气源热泵热水器性能的影响

Impact of refrigerant charge amount and capillary length on performance of air source heat pump water heater

对一台空气源热泵热水器进行制冷剂充注量和毛细管长度的性能匹配试验。试验结果表明:在试验所取的制冷剂充注量和毛细管长度范围内,随着制冷剂充注量增大,制热量和COP先增大后减小,功耗则不断增大;随着毛细管长度增大,制热量、功耗和COP均是先增大后减小;当系统在最佳匹配时,COP达到4.14 W/W。制冷剂充注量和毛细管长度对制热量的影响相对较大,对功耗的影响相对较小,当制冷剂充注量和毛细管长度发生变化时,在差异程度最大时,制热量的变化率比功耗的变化率分别高183.3%和82.4%;在制冷剂充注量较大时,COP会明显下降。当制冷剂充注量较大时,在运行前期的水温增长速率比制冷剂充注量较小时高,在运行后期(约60 min以后)反而比较低。

The performance matching experiments on one air source heat pump water heater under different refrigerant charge amounts and capillary lengths are carried out. The experimental results show that within the selected range of refrigerant charge amount and capillary length in the test, as the refrigerant charge amount increasing, the heating capacity and COP first increase then decrease, and the power consumption increases. As the capillary length increases, the heating capacity,power consumption and COP first increase then decrease. When the system is under the optimum matching, the COP reaches 4.14 W/W. The heating capacity is much sensitive to refrigerant charge amount and capillary length, while the power consumption is less sensitive to these two factors. When the refrigerant charge amount and capillary length change, the change rate of heating capacity is higher than those of power consumption by 183.3% and 82.4% respectively under the maxmium degree of difference. While, the COP decreases obviously under larger refrigerant charge amount. During the early operation time, the water heating velocity of system with larger refrigerant charge amount is higher than that with smaller refrigerant charge amount, while the situation is opposite during the late operation time （about after 60 minutes）.