Performance Analysis Of Air-cooled Absorption Refrigeration System And Structural Optimization Of Absorber

Recently, the lithium bromide absorption refrigeration technology as an important branch of refrigeration technology has attracted more and more attention in the world because of the large increase in electricity consumption of traditional vapor-compression cycles and the replacement of refrigerants. Air-cooled absorption system which is one of the most important ways to miniaturize H2O-LiBr absorption refrigeration system has become a research focus. High coolant temperature and low heat transfer coefficient in air-cooled absorption system seriously restrict the absorption effect of air-cooled absorber, which leads to the boost of temperature, concentration and pressure of lithium bromide solution, and further causes the large increase of heat source temperature and generator pressure and the decrease of thermal performance. In this paper, performance of double effect absorption system and absorber was analyzed based on numerical simulation results.Four lumped parameter models were developed for series system, counter series system, the system with parallel solution flow in which solution flow is distributed prior to low temperature solution heat exchanger and the system with parallel solution flow in which solution flow is distributed after low temperature solution heat exchanger respectively. The models were utilized to simulate and analyze various heat reservoir temperatures, evaporation temperatures, cooling air temperatures, high temperature solution heat exchanger and low temperature solution heat exchanger on the system's thermodynamic coefficient, heat exchange area and so on. The simulation result indicated that series system and the system with parallel solution flow in which solution flow is distributed prior to low temperature solution heat exchanger, are unfit for air-cooled absorber and condenser for low thermodynamic coefficient or high generator pressure; and solution heat exchangers are more important in the improvement of air-cooled system.A louvered fin was introduced to equip air-cooled absorber for performance improvement, and therefore an air-cooled plate type absorber as well as its simulated distributed parameter model was proposed in this paper. Through model of the absorber coupling with the lumped parameter model of the system with parallel solution flow in which solution flow is distributed after low temperature solution heat exchanger, the effect of fin pitch, fin width and louver pitch on the performance of absorber and system was analyzed, and the reasonable ranges of the above structural parameters were obtained.