Effect of Absorber Temperature on the Performance of the Intermittent Ammonia Absorption Refrigeration System

For the importance of the refrigeration devices in the rural areas which is far away from the electricity grids, and due to importance of the medical toxins and the perishable agricultural products in these areas, research must be conducted on absorption refrigeration devices operated by solar energy so as to improve and increase efficiency and make maximum utilization from it in this field. The objective of this project is to carry out a study on an intermittent absorption refrigeration device which consist of two vessels: the first one acts as a generator during the generation cycle and as an absorber in the absorption cycle. The second vessel acts as a receiver during the generation cycle and as an evaporator in the absorption cycle. The device uses aquaammonia solution where ammonia acts as a refrigerant and the water acts as an absorbent. The research contains literature review on absorption refrigeration field, explains the types of intermittent and continuous absorption refrigeration devices, and the main differences between the absorption and mechanical refrigeration. It also explains the ammonia properties in homogeneous binary mixtures. Two experimental tests were conducted: In the first test the absorber temperature was kept at 18oC, and in the second test the absorber temperature was kept at 11oC.The objective of these tests is to study the effect of the absorber temperature variation on the coefficient of performance of the absorption refrigeration device, when all other parameters are constant like condenser temperature, mass flow rate of the absorber cooling water and mass of water contained in the evaporator. The results of the experiments were discussed, and the change in pressure and temperature versus the time curves were drawn. Also graphs representing the performance of the absorption refrigeration device during generation and absorption cycles were shown. From the experimental results the coefficient of performance of the intermittent absorption refrigeration device in the first test (when the absorber temperature was about 18oC) was found to be equal to 0.0035 and in the second test (when the absorber temperature was about 11oC) was found to be equal to 0.013. This indicates that: when the absorber temperature is decreased, the coefficient of performance of the absorption refrigeration device is increase