单级/复叠双制式热泵干燥系统设计与试验研究

Design and Experimental Study of a Heat Pump Dryer with Dual Models of Single Stage and Cascade Cycles

提出了一种单级/复叠双制式热泵干燥系统,通过不同模式的切换适应环境温度变化对系统制热量的影响,保障干燥系统的供热需求,同时利用干燥空气的循环加热可提高干燥室的供风温度。在此基础上,进一步开发了单级/复叠双制式热泵样机,并设计出相应的试验系统,根据试验结果对单级/复叠双制式热泵样机的变工况性能进行分析与讨论,结果表明:相同环境温度时,复叠模式的最高供风温度明显高于单级模式,两者差值随环境温度升高而减小;相同环境温度时,复叠模式制热量与能耗都高于单级模式,且两者能耗的差值随环境温度升高而增大;随着环境温度的增大,复叠模式的COP存在最优值,而单级模式的COP逐渐升高;高温级压缩机不同模式下运行压比差异较大,系统设计时需要合理选型。

This paper proposes a single stage/cascade double mode heat pump drying system, which can adapt to the temperature variation of environment and then satisfy the drying system’s heating demand. Meanwhile the maximum temperature of drying air can be elevated using cyclic heating. Moreover, a prototype of the single stage/cascade double mode heat pump is developed and an experimental study is carried out. On the basis of experimental results, the performance variation of the heat pump at different modes and operating condition is analyzed. According to the results, it can be concluded that the maximum drying air temperature of cascade mode is higher than that of single stage with the same environment temperature and its difference decreased with the environment temperature. At the same environment temperature, both the heating capacity and power consumption of cascade mode are larger than single stage and the difference of power consumption increased with the environment temperature. With the increase of environment temperature, there existed a maximum COP of cascade mode and the COP of single stage kept increasing. The pressure ratio of the high stage compressor varied greatly at different operating mode and its selection should be reasonable.