Study On The Performance Of Solar Photovoltaic Refrigerator System

Solar energy being researched and developed by various countries around the globe is a renewable resource attached with great importance at present. Solar photovoltaic power generation has been applied in our daily life. With improvement of people’s living standard and life quality, the most extensively used refrigerator has occupied more and more percentage in construction energy consumption. Hence, solar photovoltaic refrigerators attracted much attention and were researched by people. Solar photovoltaic refrigerator systems take solar energy as source power and possess great advantages over regular household refrigerators. It can be applied in preserving food or medicines and used in remote electricity-insufficient area without polluting the environment. This thesis takes the weather conditions of Kunming as background to research the performance of system characteristics of solar photovoltaic AC refrigerators through the following works:1. This thesis explained the present research and development situation of solar photovoltaic refrigerator system, analyzed advantages of photovoltaic refrigerator systems, introduced formation of photovoltaic refrigerators as well as functions and relevant parameters of various parts, selected models of system parts, designed and established a set of solar photovoltaic AC refrigerator systems with voltage of 24 V and consisting of photovoltaic components, controller, inverter, accumulator and regular refrigerator. This thesis also established theoretical models for important system parts.2. The thesis carried out experiment research and analysis of working performance in fine day, cloudy day or overcast day of Kunming. The consequence indicated this system was mainly powered by photovoltaic components in fine day. It took 60 minutes for the freezing chamber to fall below 0℃ and 180 minutes for refrigerating chamber to fall below 5℃. Moreover, the voltage of the accumulator was boosted by 1.6 V and the running rate of the refrigerator is 38%. In cloudy day, the refrigerator was alternatively powered by photovoltaic components and accumulators. It took 50 minutes for the freezing chamber to fall below 0 and 130 minutes for refrigerating chamber to be lowered to 5℃.In addition, the voltage of the accumulator was reduced to 1.5 V and the running rate of the refrigerator was 36%. In overcast day, the voltage of the accumulator was reduced to 1.9 V and the running rate of the refrigerator was 32%. Furthermore, in this system, temperature of the refrigerator freezing chamber could be lowered to-22℃ and that of the refrigerating chamber could be lowered to 0-7℃, which can meet the refrigerating needs of Kunming.3. In order to verify the accuracy of the theoretical model of this system, the thesis took test data of cloudy day as the experiment sample. The final research showed the outcome of the theoretical model established by thesis was basically the same with the test outcome and its error stayed within 10%. This thesis put forward the performance of solar cells and attenuation property of accumulator capacity should be taken into consideration during design of photovoltaic AC refrigerator systems. According to the requirements for time limit, we should spare certain time for solar cells and accumulators, so as to extend the life span of photovoltaic AC refrigerator systems.4. This thesis conducted relevant experiment research of idle load and loads of different mass. The outcome indicated it took 75 minutes for the freezing chamber of this system to fall below 0℃ in idle load condition and 150 minutes for the refrigerating chamber to be lowered below 5℃ After operating for 210 minutes, the refrigerator could proceed to stable operation stage and its running rate could achieve 28%. In case of 10 MJ of accumulative irradiance, it respectively took 791 minutes, 1151 minutes and 1232 minutes for the freezing chamber to fall below-20℃ in the load conditions of 5kg, 6kg and 7kg. In case of stable operation, the refrigerator system showed running rates like 38.5%, 42.8% and 46.7%, accumulative energy consumption like 1.1k W·h, 1.9k W·h and 2.1k W·h, and COP like 0.24, 0.29 and 0.34. Based on this, we should consider the proper load of the refrigerator instead of overload, so as to extend the life span of refrigerators.The conclusion made by this thesis based on the solar photovoltaic AC refrigerator system displays certain representativeness, which means the conclusion is also applicable to other similar photovoltaic AC refrigerating systems and offers reference basis for further research and application of photovoltaic AC refrigerating systems.