CO2跨临界循环带膨胀压缩机系统热力学分析

膨胀压缩机是一种膨胀功回收装置，膨胀机的膨胀功全部用于提供给辅助压缩机作为输入功，以驱动压缩机完成压缩过程。膨胀压缩机在系统中可以与主压缩机串联和并联，由于布置形式不同，则压缩机的流量和压比改变，导致系统循环性能系数也发生变化。本文利用简单的压缩机模型，对CO2跨临界循环带膨胀压缩机的两种不同布置系统形式进行了分析，并在理想等熵情况和考虑压缩机和膨胀机效率情况下进行了对比，得出串联模式系统的中间压力不能达到系统最优中间压力，串联模式系统COP总是高于并联模式系统。

THERMODYNAMIC ANALYSIS OF CO2 TRANSCRITICAL CYCLE WITH AN EXPRESSOR

The EXPRESSOR (expander-compressor) is used for expansion work recovery. The ex pander supplies the energy to drive the assistant compresso r to implement the compression process. The EXPRESSOR can be in parallel and in series with the main compressor respectively. The mass flow rate and the compres sion ratio of the expander-compressor are affected by its location, and so is t h e efficiency. Provides an energy efficiency study for CO_2 cycle by c omparing two compression processes with an EXPRESSOR. Two different locations of an EXPRESSOR in the cycle are investigated by using simplified com pressor model. The comparison is implemented respectively under the ideal isoen tr opic condition and the situation that the efficiencies of compressor and expande r are taken into account. It is indicated that the intermediate pressure of the s eries model cannot reach the optimum value. Based on the model calculations, the efficiency of the serial model is always higher than the parallel model.