有机朗肯循环中工质泵对系统性能的影响

Influence of Working Fluid Pump on System Performance in Organic Rankine Cycle

针对有机朗肯循环中工质泵耗功对系统效率影响较大的问题,本文以R245fa为工质的发电系统为例,对在不同的工质泵效率下,是否考虑泵耗功时,系统性能随工况的变化进行分析计算。结果表明,是否考虑泵耗功对系统的第一定律效率有较大的影响,并且这一影响会随着膨胀机效率和工质泵效率的降低而更加明显;蒸发温度的升高同样会增大工质泵对第一定律效率的影响,而冷凝温度的变化则几乎不会引起工质泵对第一定律效率的影响。在蒸发温度为99℃、冷凝温度为35℃、膨胀机效率为0.7、泵效率为0.3的ORC系统中,不考虑泵耗功的系统第一定律效率为9.6%,考虑泵耗功的系统第一定律效率为8.5%,工质泵的耗功占膨胀机输出功的比例为12.5%。

Considering the question of energy consumption of working fluid pump have a huge impact on the system efficiency of organic Rankine cycle(ORC).This paper analysis the power generation system which using R245fa as working fluid,The system’s first law efficiency,mass flow rate and volume flow rate is calculated while with the variation of working condition at different pump efficiency.The results show that there is a huge influence on first law efficiency for whether considering energy consumption of working medium pump,this impact will enlarge with the efficiency decrease of expander and working medium pump;the system efficiency will get more influence by increase the evaporation temperature,but the condensation temperature don’t have this influence.While the evaporating temperature is 99℃,condensing temperature is 35℃,expander efficiency is 0.7,pump efficiency is 0.3,the first law efficiency is 9.6%when ignore pump power,the first law efficiency is 8.5%while pump power is considered.The energy consumption of pump have a ratio at 12.5%of expander power.