R410a双级制冷循环性能研究

Performance research on R410a two-stage refrigeration cycle

基于两级节流、中间完全冷却的R410a双级制冷循环,建立了热力学模型并进行了性能分析。结果表明,随着双级循环中间压力的升高,系统制冷量和耗功均降低,系统COP先升高后降低,系统存在最优中间压力,并且对应最优中间压力存在最优中间温度。与单级循环相比,双级循环的高压级压缩机排气温度低于单级循环的排气温度,约低35.47℃,双级循环系统COP提高了约7.41%。[火用]分析表明,蒸发器[火用]损失最大,约占总[火用]损失的42.78%,其次,冷凝器[火用]损失占32.50%;压缩机[火用]损失最小,约为16.70%,其中,低压级压缩机[火用]损失比高压级压缩机高约28.60%。由双级循环中膨胀机代替节流阀循环的分析得出,膨胀机循环性能COP比节流阀提高了约42.24%,[火用]损失降低约23.74%,膨胀机循环无论在参数优化还是性能改善方面,均比节流阀循环具有一定优势。

A thermodynamic model was developed and evaluated for the R410 a two-stage refrigeration cycle with two-stage throttling and intermediate complete cooling. The results show that as the intermediate pressure of the two-stage cycle increases, the system’s cooling capacity and power consumption decrease, the COP of the system grows and subsequently falls, the system has the optimal intermediate pressure, and the optimal intermediate temperature corresponds to the optimal intermediate pressure. The exhaust temperature of the high-pressure compressor of the two-stage cycle is about 35.47 ℃ lower than that of the single-stage cycle, and the COP is approximately increased by 7.41%. The exergy analysis shows that the exergy loss of evaporator is the largest, accounting for 42.78% of the total loss, followed by the exergy loss of condenser, accounting for 32.50%. The compressor exergy loss is the smallest, about 16.70%, among which the exergy loss of low-pressure stage compressor is about 28.60% higher than that of high-pressure stage compressor. The analysis for the expander replacing the throttle valve cycle in a two-stage cycle reveals that the COP of the expander is about 42.24% higher than that of the throttle valve and the exergy loss is approximately 23.74% lower. In terms of parameter optimization and performance enhancement, the expander cycle is better than the throttle valve cycle.