Abstract:

This paper experimentally studied the influence of lithium bromide concentration on the coefficient of performance (COP) of the ternary working fluid ammonia-water absorption refrigeration system (AARS) under different working conditions. The huge rectifier and low COP are two main shortcomings that limits the usage of AARS. The lithium bromide, as the third working fluid, can shift the vapor-liquid equilibrium (VLE) state of ammonia-water binary solution, and the ammonia concentration in vapor phases can be elevated to reduce the distillation thermal load. An AARS experiment platform was established to research the influence of lithium bromide on COP. The lithium bromide concentrations in the ternary working fluid were set to 5%, 10%, 15%, and 20%. The generation temperatures ranged from 90℃ to 130℃, evaporation temperature ranged from -19℃ to -4℃, cooling water temperature ranged from 22℃ to 33℃. The experiment results showed that lithium bromide can promote COP compared with the binary system and 15% is the optimum lithium bromide concentration in the ternary working fluid. The COP can reach 0.408, 0.410 and 0.412 when the generation temperature, evaporation temperature and cooling water temperature are 130℃, -4℃ and 22℃. As a consequence, applying ammonia-water-lithium bromide ternary working fluid in ammonia absorption refrigeration system can improve the heat utilization efficiency and promote COP of AARS directly.

Key words: absorption, experimental validation, economic, refrigeration, ammonia-water-lithium bromide

摘要：

通过试验研究了使用氨-水-溴化锂三元工质对氨吸收式制冷性能的影响。根据现有研究，工质中溴化锂的质量分数设定为5%、10%、15%和20%，试验中发生温度设定为90～130℃，蒸发温度设定为-19～-4℃，冷却水温度设定为22～33℃。通过试验发现，溴化锂质量分数在15%时对COP提升效果最好，发生温度在130℃时性能系数可以达到0.408，蒸发温度在-4℃时性能系数可达0.410，冷却水温度在22℃时性能系数可以达到0.412；而且添加三元工质可以减小精馏能耗且充分利用低品位热能，因此采用氨-水-溴化锂三元工质可以在高效利用热能情况下改善氨吸收式制冷系统的劣势。

关键词: 吸收, 试验验证, 经济, 制冷, 氨-水-溴化锂