致冷和热泵系统中闪蒸阀的损失

Exergy Losses at Flash Valves in Refrigeration & Heat Pump Systems

在计算致冷和热泵系统中闪蒸阀的(火用)损失时,由于焓、熵数据稍有不一致,就对结果带来很大的影响。为解决此问题,本文导出了一个“计算模型”,即在闪蒸前先让冷的致冷剂用来过冷饱和液体,使闪蒸阀的部分(火用)消耗转移至过冷器,而过冷器的(火用)损计算就不需用熵数据,即使原始数据较差,本模型也能给出较正确的结果。 对液体乙烯和丙烯系统的闪蒸阀,以文献数据、不同的状态方程和本模型作了验证计算。结果证明模型是可行的。

Small inconsistencies in enthalpy / entropy data can lead to erroneous exergy-loss calculations for flash valves in refrigeration or heat pump systems.lt is shown that this problem can be circumvented by a 'calculational model' in which the cold refrigerant is used to subcool the saturated liquid prior to flash. This transposes exergy consumption from the flash valve to the subcooler, where it can be calculated without the need for entropy values.Thus, even with 'poor'data, such a model gives accurate exergy loss values. Exergy losses at liquid ethylene and propylene flash valves are calculated from literature data, several ASPEN PLUS equations of state, and two models which use subcoolers.