采用分流过冷的跨临界CO2冷热联供系统性能

为了探索不借助外力即可实现跨临界CO₂冷热联供系统循环中工质过冷的方法，本文提出了三种采用系统循环内部工质分流实现过冷的跨临界CO₂循环系统形式，建立了系统循环热力学模型，通过模拟计算分析不同工况下系统性能变化规律。结果表明：在蒸发器与节流阀间分流的系统方案不会提高系统的性能；在气体冷却器与过冷器间分流的系统方案与在过冷器与节流阀间分流的系统方案对系统性能提升的效果相同，相对于在蒸发器与节流阀间分流的系统方案，综合循环性能系数（coefficient of performance，COP）最大可提高17.62%；采用分流过冷会提高压缩机的吸气压力，当气体冷却器出口CO₂温度确定时，存在最佳的排气压力使综合COP最高。因此，采用合理的分流过冷循环系统可以使跨临界CO₂冷热联供系统仅依靠自身循环实现过冷并提升系统性能。

Performance of transcritical CO2 combined cooling and heating system with split flow cooling

In order to explore the ways realizing subcooling in transcritical CO₂ combined cooling and heating system without external assistance, three types of transcritical system with split flow cooling were proposed, and the thermodynamic model of the systems were established. The system performance changes under different working conditions were analyzed by simulation calculation. The results showed that the system scheme of split flow between evaporator and throttle valve could not improve the system performance. The split flow between the gas cooler and the subcooler, and the split flow between the subcooler and the throttle valve had the same effect on improving system performance, and comprehensive COP(coefficient of performance) can be increased by 17.62%. The use of split flow cooling will increase the suction pressure of the compressor. When the temperature of CO₂ at the outlet of the gas cooler was determined, there was an optimal discharge pressure to maximize the comprehensive COP. A reasonable scheme of split flow cooling system could be used as an effective means to realize CO₂ subcooling in transcritical system and improve system performance only by self-circulation.