工质对的过量焓对吸收式制冷系数的影响

Effect of Excess Enthalpy on Absorption Refrigeration Efficiency

针对高效吸收式制冷工质对的筛选问题,为了寻求一个新的突破口来提高吸收式制冷系数,对单级吸收式制冷系统中工质对的循环和能量转移过程进行了理论分析。通过将溶液焓“拆分”为溶质焓、溶剂焓和过量焓,发现过量焓可以影响吸收式制冷的制冷系数,并且既可以有利于亦可以抑制吸收式制冷的制冷系数;通过对比分析100%和0%两种极端回热换热器工况下的制冷系数,发现过量焓对吸收式制冷的影响与回热换热器的效率相关。为定量分析过量焓对制冷系数的影响,对H2O/LiBr、R134a/[HMIM][Tf2N]和R1234yf/[HMIM][BF4]3种工质对的吸收式制冷系统进行热力学模拟,结果表明:回热换热器效率较高时,由于过量焓的作用,R1234yf/[HMIM][BF4]的制冷系数将反高于H2O/LiBr。

To obtain a breakthrough in selecting high-efficient working pairs for absorption refrigeration,the energy diversion along with the working pair circulation in a single-stage absorption refrigeration system is investigated.By regarding solution enthalpy as the sum of excess enthalpy,solute enthalpy and solvent enthalpy,it is found that the excess enthalpy exerts either positive or negative effect on the performance coefficient.Moreover,comparison between the systems with a 100%or 0%efficiency heat recovery exchanger implies that the excess enthalpy effect is related with the heat recovery exchanger efficiency.Subsequently,system simulations for H2O/LiBr,R134a/[HMIM][Tf2N]and R1234yf/[HMIM][BF4]show that the higher efficiency of heat recovery exchanger and the excess enthalpy effect together lead R1234yf/[HMIM][BF4]to acquire a higher coefficient of performance than H 2O/LiBr.