变工况条件下单螺杆膨胀机膨胀比的实验研究

Experimental Study on the Expansion Ratio of Single Screw Expanders under Variable Working Conditions

摘要: 在中低温余热回收利用中，有机朗肯循环被认为是具有较大潜力的技术方向。膨胀机作为有机朗肯循环的输出动力设备起着至关重要的作用，而单螺杆膨胀机由于其独特的结构和工作特性使得其在节能和可再生能源利用领域具有较好的应用前景。除了膨胀机效率，膨胀比是膨胀机另一个重要的性能参数，其对有机朗肯循环系统的热效率影响很大。本文通过对本实验室设计的单螺杆膨胀机样机进行实验研究，分析了单螺杆膨胀机内、外膨胀比随工况的变化规律。实验结果发现，内膨胀比随着转速的增加逐渐增大，外膨胀比则逐渐下降。单螺杆膨胀机内、外膨胀比都随着进气压力的增加而增加。当进气压力区间为0.4~0.65 MPa时，外膨胀比变化范围为3.26~3.73，内膨胀比变化范围为4.8~8.0。可以发现，单螺杆膨胀机内膨胀比受工况的影响较大，外膨胀比受背压影响，但变化幅度较小。

Abstract: In the recovery utilization of medium and low temperature waste heat, the organic Rankine cycle (ORC) is regarded as the most potential technique. The expander plays an important role as the output power equipment of the ORC, and the single screw expander has a great prospect due to its unique structure and working characteristics. In addition to the expander efficiency, the expansion ratio is another important performance parameter of the expander, which has a great influence on the thermal efficiency of the ORC system. Based on the experimental study of the single screw expander in this laboratory, the change of the internal and external expansion ratio of single screw expander is analyzed. The experimental results show that the expansion ratio increases with the increase of rotational speed, and the external expansion ratio decreases gradually. The internal and external expansion ratio of single screw expander increases with the increasing of inlet pressure. When the inlet pressure interval is 0.4~0.65 MPa, the external expansion ratio is 3.26~3.73, and the internal expansion ratio is 4.8~8.0. It can be found that the effects of internal expansion ratio of single screw expander on the working condition larger than external expansion ratio, while the latter is affected by the back pressure, but the variation is small.