CO_2跨临界制冷循环系统性能评价及分析

Performance Evaluation and Exergy Analysis on Transcritical CO_2 Refrigeration Cycles

通过用分析方法对CO2 跨临界制冷循环带节流阀和带膨胀机系统进行分析 ,发现节流阀的损失较大 ,用膨胀机代替节流阀后 ,可使这部分损失降低 ,提高系统效率。在带膨胀机的系统中 ,主要损失发生在气体冷却器、压缩机和膨胀机 ,其中高压侧压力、气体冷却器出口温度以及蒸发温度对各部件的损失和效率都有不同程度的影响 ,在优化系统设计时应综合考虑这些参数。用分析方法对系统性能进行评价 。

An exergy analysis method is applied to investigate the performance of transcritical carbon dioxide refrigeration cycles with a throttling valve and an expansion turbine.It is found that the exergy loss of throttling valve is very large, but the exergy loss in this process can be decreased and the exergy efficiency of the system can be improved after replacing it by an expansion turbine.In the system with an expansion turbine, greater percentages of exergy losses take place in the gas cooler, compressor and expansion turbine. And the heat rejection pressures, outlet temperatures of gas cooler and evaporating temperatures have different effects on the exergy loss in each component and on the exergy efficiency of the cycle. So these parameters should be taken into account comprehensively in the system design and optimization.Exergy analysis is a powerful tool for the performance evaluation of the system and shows the direction for potential improvement.