二级再生氨—盐吸收制冷系统的改进与比较

Improvement of the Absorption Refrigeration System of Two-stage Generation with Ammonia-salt as Working Fluid

提出了二级再生氨-盐系统(系统1)的改进系统(系统2和系统3),将系统1和系统2、系统3的热力学模拟结果进行了分析比较。两种改进系统的最高操作压力都在0.2MPa以下,远低于系统1的最高操作压力。改进系统的操作性能都有显著提高,系统2的COP值升高幅度和循环倍率降低幅度都是最大,火用效率也有显著提高;系统3的COP值也有较大的提高,火用效率提高最为显著,但循环倍率反而较系统1明显升高。系统1和系统2均可在加热温度低于160℃时稳定操作,而系统3则适于加热温度高于160℃的情况。当被冷却系统需要在0℃以下的恒定温度下提供冷量时,适用系统1制冷。当物料需要在冷却水冷却后再逐渐降温至所需要的温度时,适用改进后的系统。

The two improved systems（SYSⅡ and SYSⅢ ） were proposed based on the system of two - stage generation with ammonia - salt as working fluid（SYS Ⅰ ）. Analyses and comparisons were performed on results of thermodynamic simulation for the three systems. The maximum operation pressures of the two improved systems are under 0.2MPa which are less than the pressure of SYSⅠ. The performances of the two improved systems increase obviously. For SYS Ⅱ, the improved extent of coefficient of performance（COP） and the reduced extent of circulation ratio（FR） are most, and the exergy efficiency （ηex） iS improved obviously. For SYSⅢ, the COP is higher and the increase of ηex is most obvious, but the FR increases compared with the FR for SYS Ⅰ. SYS Ⅰ and SYSⅡ can operate steadily at the heating temperature under 160℃ but the SYSⅢ is suitable at the heating temperature above 160℃. The SYS Ⅰ is suitable when the cooling temperature is constant under 0℃, and the two improved systems are suitable when the cooling temperature decreases gradually after cooling by cooling water.