低温余热驱动的ORC-VCR系统性能分析

Performance analysis of ORC-VCR system driven by low grade waste heat

建立低温余热驱动的有机朗肯循环耦合蒸汽压缩制冷循环系统(ORC-VCR)模型,为获取最高总系统制冷系数,在固定冷凝器露点温度及发生器和蒸发器泡点温度的条件下,对6种纯工质(R245fa,R227ea,R600,R600a,R1234yf,R134a)及2种非共沸混合工质(R227ea/R600a,R245fa/R600)的热力循环特性进行分析;同时分析了发生温度、冷凝温度及蒸发温度对子系统工质质量流量比及总系统制冷系数的影响。结果表明:在相同操作条件下,非共沸混合工质的总系统制冷系数优于纯工质。非共沸混合工质在某一组成下,滑移温度和总系统制冷系数均达到最高。在其他温度条件不变时,纯工质及非共沸混合工质的子系统工质质量流量比及总系统制冷系数均会随着发生温度及蒸发温度的升高而增大,随着冷凝温度的升高而减小。

The organic Rankine cycle coupled with vapor compression refrigeration cycle system(ORC-VCR)driven by low grade waste heat model was constructed,and the performance analysis of six pure fluids(R245fa,R227ea,R600,R600a,R1234yf and R134a)and two zeotropic mixtures(R227ea/R600a and R245fa/R600)was conducted to gain the highest whole system coefficient of performance(COP)under the fixed condensing dew point and evaporating bubble point.At the same time,the effects of boiling temperature,condensing temperature and evaporating temperature to the mass flow ratio of two subsystems and total coefficient of performance were also analyzed.The results show that the total COP of the zeotropic mixtures is higher than the pure fluids.Zeotropic mixtures′temperature glide and the total COP can reach to the maximum under a specific composition.Under the fixed temperature,the two subsystems′mass flow ratio and the total COP of six pure fluids and zeotropic mixtures increase with the increase of the boiling temperature and the evaporating temperature,but decrease with the increase of the condensing temperature.