宽温区空气源热泵热水机性能实验研究

Experimental Study on the Performance of Air-source Heat Pump Water Heater over Wide-range Temperature Conditions

本文基于一台直流调速卧式涡旋压缩机(双级压缩),结合闪蒸式中间腔补气冷却和双级节流技术,试制了一台5 HP专用于严寒、寒冷地区供暖的宽温区空气源热泵热水机(DCAHP),并在多种测试工况下对其制热性能进行了实验研究。实验结果表明:DCAHP实现了宽温区可靠制热,其名义制热量为16 548 W,制热EER为3. 0;在室外干球温度为-20. 0℃的条件下,其最大制热量可达11 278 W,制热EER为1. 6。研究发现,热力膨胀阀感温包与压缩机吸气口的距离/蒸发器单元传热管长大于7/200后,阀能力衰减剧烈,且压缩机输入功率下降了19%;若模块化蒸发器面积增加1倍,DCAHP在低温环境的制热能力可提升18%;设置冷冻油充注量精细调节装置,DCAHP的制热能效比最高可提升50%。

Vapor compression air-source heat pump(VCASHP) systems have been widely applied due to their simple structure and low initial cost. However,there are a series of problems when a VCASHP system is operated for space or water heating in cold regions. For example,with a decline of ambient temperature,the decreased heating capacity of the VCASHP system may be insufficient with respect to the consumer’s requirement. Furthermore,its rising compression ratio may lead to an extremely high discharge temperature,resulting in shutting down. Therefore,a great deal of previous research into VCASHP systems has been carried out to address such problems. Nevertheless,the articles concentrated on VCASHP units with direct current(DC) speed regulation are scarce. In the present work,an airsource heat pump water heater(5 HP) integrating flash-injection cooling,two-stage throttling,and DC speed regulation(DCAHP) that can be applied to cold and/or severely cold regions over wide-range temperature conditions,is proposed and studied experimentally. The results indicate that the proposed DCAHP performs well over a wide range of temperature conditions and reaches the heating capacity of 16548 W and 11 278 W when the ambient dry bulb temperature is 7. 0 ℃ and-20. 0 ℃,respectively. Furthermore,the heating energy efficiency ratio(EER) of the proposed DCAHP reached 3. 0 and 1. 6 individually. Specifically,the compressor input power tends to be reduced by 19% if the dimensionless distance between the thermometer of the expansion valve and the inlet of compressor/the tube length of evaporator unit heat transfer is greater than 7/200;however,the valve capacity decline will be inevitable. While the area of evaporator was doubled,the heating capacity of the DCAHP rose by 18% at low ambient temperatures. In addition,the energy efficiency ratio of the DCAHP can be maximally enhanced by 50%.