基于蒸汽压缩技术的热泵蒸汽系统热力性能分析

Performance analysis of heat pump steam system based on vapor compression technology

热泵蒸汽技术相比电锅炉及燃煤、燃气锅炉制取蒸汽,具有更高的一次能源利用效率,并且不产生CO2和NOx,符合我国节能环保发展战略。本文提出一种基于蒸汽压缩技术的热泵蒸汽系统,采用两级冷凝直接制取低压蒸汽,再通过蒸汽压缩升压至0.7MPa。并基于EES软件建立数值模型,分析冷凝温度Tcond、蒸发温度Tevap、经济器温度Tecon、喷气率βg对冷媒压缩机功耗Wrefri、蒸汽压缩机功耗Wvapor和系统能效系数COP的影响。结果如下:基于蒸汽压缩的热泵蒸汽系统,制取165℃的饱和蒸汽,在Tevap为50℃、Tcond为93℃时,系统COP为2.996,制取1t蒸汽消耗功率仅为247k W·h;系统COP随Tevap的升高逐渐增大,但是Tevap的升高需要更高的热源温度;蒸发温度不变时,系统存在最佳的Tcond、中间冷却温度Tecon和喷气率βg,当蒸发温度Tevap为50℃,最佳冷凝温度Tcond为93℃时,最佳经济器温度Tecon为65℃,最佳喷气率βg为0.13。

Heat pump steam technology has higher primary energy utilization efficiency,and does not produce CO2 and NOx,compared with electric boilers,coal-fired boilers and gas-fired boilers,which are in line with China’s energy-saving and environmental protection development strategy.This paper presented a heat pump steam engine based on vapor compression technology,which produced low pressure vapor by two-stage condensation and then boost to 0.7 MPa by using vapor compressor.A mathematical model has been developed using the EES software.The effects of condensation temperature(Tcond),economizer temperature (Tecon),evaporation temperature (Tevap) on the refrigerant compressor power consumption (Wrefc),vapor compressor power consumption (Wvapc),the coefficient of performance (COP)were studied in detail.The results showed that the heat pump steam engine based on vapor compression technology obtain a COP of 2.996 under Tevapis 50℃and Tcondis 93℃.The power consumption is 247k W·h for producing 1ton saturated steam of 165℃.The COP increases gradually with the increase of Tevap,but it requires a higher temperature heat source.There exists a highest COP with the optimum Tcond,Tecon,βg,when Tevapis 50℃,they are 93℃,65℃and 0.13,respectively.