Thermodynamic Analysis Of Ammonia-water Solution Desorption And Absorption Compression Refrigeration Cycle

As the continued refinement of our understanding of environmental protection, the CFC and HCFC refrigerants are to be constrained or substituted. In the last years, there has been a great resurgence of interest in ammonia refrigeration systems for its environmentally friendly. However the conventional ammonia vapor compression refrigeration system has a lower safety and the COP (coefficient of performance) of conventional ammonia solution absorption refrigeration systems is relatively smaller because of its complicated system and bulky equipment. In order to overcome the disadvantages of ammonia refrigeration systems, a lot of studies have been done and new ammonia refrigeration system models have been proposed. In this paper, a new refrigeration cycle, ammonia-water solution desorption and absorption compression refrigeration cycle(ADAR cycle) was studied on the base of the above, including comprehensive thermodynamic calculation and analysis, corrective method, and tests of crucial equipment.ADAR cycle combines ammonia compression refrigeration cycle and ammonia absorption refrigeration cycle, which takes desorption and absorption processes instead of evaporation and condensation processes in traditional refrigeration cycle. In addition, the rising liquid film on surface of a horizontal tube evaporation process has been used in the desoiption process of ADAR cycle. The above-mentioned makes ADAR cycle superior in safety and efficiency.In this paper, a thermodynamic calculation program on ADAR cycle has been developed to simulation the cycle. By analyzing the ADAR cycle on the base of first law of thermodynamics, the performance change trends of this cycle under different temperatures of desorption process and absorption process, solution concentration, degassing range, and working pressures were obtained. The comparison between ADAR cycle and ammonia compression refrigeration cycle shows that ADAR cycle has a better performance under lower cold source inlet temperatures (<6℃). The exergy analysis on the base of second law of thermodynamics shows that, the desorber, absorber, and solution heat exchanger have a larger exergy loss, which designates the energy saving trend. And the exergy loss rate of ADAR cycle (58.38%) is lower than that of ammonia compression refrigeration cycle (66.01%), which shows the further advantage of ADAR cycle. In addition, the tests show the feasibilities of desorption process using rising liquid film on surface of a horizontal tube.