单螺杆膨胀机在有机朗肯循环系统中的性能研究

Performance Study on Single-screw Expander in Organic Rankine Cycle System

对于有机朗肯循环(Organic Rankine cycle,ORC)系统,膨胀机的选择对系统性能的影响至关重要。单螺杆膨胀机作为一种新型的容积式膨胀机,非常适用于中小型ORC系统。为了研究单螺杆膨胀机在ORC系统中的性能,搭建完成以烟气为热源、R123为循环工质的ORC系统试验台。通过改变单螺杆膨胀机的输出转矩和背压以及有机工质的蒸汽干度,获得单螺杆膨胀机相应性能的变化,并得到单螺杆膨胀机的最大输出功率为5.46 k W,最大总效率和容积效率分别为48.7%和80%。试验结果表明,在热源不变的条件下,单螺杆膨胀机的膨胀比随着转矩的增加、干度的增加而增加,而随着背压的增加而降低;容积效率随着转矩的增加和干度的增加均为下降;单螺杆膨胀机的总效率随着背压和干度的增加而降低,而随着转矩的增加先增加而降低。

The selection of expanders for organic Rankine cycle （ORC）systems is very important, because it affects the performance of the system significantly. Single-screw expander is a new type of volume-type expanders, which is very suitable for medium/small scale ORC systems. In order to investigate the performance of single-screw expander in an ORC system, an experimental system is set up which is used high temperature gas as heat source and R123 as working fluid. By adjusting the torque and back pressure of single-screw expander and the vapor dryness of working fluid, the performance of single-screw expander has been obtained. The power output of single-screw expander is 5.46 kW, and the total efficiency and volume efficiency are 48.7% and 80%, respectively. The results shown that under the same heat resource, the expander ratio of single-screw expander increased with the risings of torque and dryness, but it decreased with the increase of back pressure; the volume efficiency decreased with increases of torque and dryness; and the total efficiency of single-screw of expander decreased with increases of back pressure and dryness, and with increase of torque, it increased at first and then decreased after the maximum is gotten.