温度极化对带有膜热交换器的溴化锂吸收式制冷系统性能的影响分析

摘要

The forming mechanism of temperature polarization in the membrane distillation is explained. And a mathematic model of heat and mass transfer in the membrane heat exchanger is developed and validated by means of experimental data in the existing literatures. The difference of temperature between the bulk solution and membrane wall and the distribution of temperature polarization coefficient (TPC) along the tube length are analyzed. Under the conditions of different heat source temperature and the inlet temperature of cooling water and freezing water, the effect of temperature polarization to the coefficient of performance (COP) of the membrane heat exchanger lithium bromide absorption refrigeration system is discussed. The results show that, the decrease rate of COP increases with the increasing of heat source temperature and decreases with the increasing of cooling water inlet temperature, while it is essentially constant with the change of freezing water inlet temperature.%本文阐述了膜蒸馏过程中温度极化现象的形成机理，建立了膜热交换器传热传质数学模型并借助文献实验数据进行了验证，分析了膜热交换器中主体溶液温度和膜处温度的差异及温度极化系数（TPC）沿管长的分布规律，探讨了不同热源温度、冷却水和冷冻水进口温度下温度极化现象对小型溴化锂吸收式制冷系统性能系数（COP）的影响。结果表明：温度极化对 COP 的减小率随着热源温度的升高而升高，随着冷却水进口温度的升高而降低，且在冷冻水进口温度变化的情况下，温度极化对COP的减小率基本不变。