小型有机朗肯循环系统中工质泵的效率

对小型有机朗肯循环系统中工质泵的性能进行了实验研究,建立了应用R245fa工质的小型工质泵性能研究试验台,针对容积型工质泵的效率展开实验研究,对工质泵出口压力、进出口压差和系统质量流量分别进行控制,获得了工质泵等熵效率随上述3个变量的变化曲线.实验结果表明,在蒸发温度75℃、冷凝温度11℃条件下,有机朗肯循环系统中工质泵的等熵效率范围为15%~47%,随着系统质量流量的增大和工质泵进出口压差的增加,工质泵等熵效率升高,且受到系统质量流量的影响较大.实验证实了有机朗肯循环系统中工质泵的实际运行效率比以往模拟、理论计算研究中应用的工程经验值低.依据本研究实验结果,工质泵等熵效率宜取平均值30%;基于理论循环等熵过程的分析,泵功占膨胀机输出功的比例约为8%,而实际过程中,综合考虑泵的效率、电机效率、膨胀机机械效率,其比值可达到12%以上.

Efficiency of working fluid pump in a small-scale organic Rankine cycle system

The isentropic efficiency of the working fluid pump in a small-scale power system of organic Rankine cycle (ORC) was experimentally studied under designed variable conditions. The selection and principle of the working fluid pump were focused. A small-scale power system of ORC using R245fa as working fluid was established. The volume type working fluid pump was chosen. The pressure difference of pump inlet and outlet pressure and the mass flowrate of system were controlled respectively. The experimental results showed that, the ORC system working fluid pump's isentropic efficiency was about 15% to 47% under the condition that evaporation temperature is 75℃ and condensing temperature is 11℃. The pressure difference between the inlet and outlet of the working fluid pump increased with the increase of mass flowrate of system. The isentropic efficiency increased, and largerly affected by the mass flowrate. The experiments confirmed that the estimation efficiency of the working fluid pump in the ORC system is much lower than that of the previously value used in simulation, calculation and industrial applications. The experimental working fluid pump isentropic efficiency of the average value of 30% is more appropriate. From isentropic aspect, the ratio of pump power for expander to output power should be 8%. For the actual process, the ratio should be greater than 12% by considering the efficiency of the pump and the motor.