Study On The Heating And Air Conditioning System Driven By Medium-temperature Solar Energy

Solar energy as a renewable energy has great prospects and market, its development and effective utilization has been given more and more attention. In the fields of solar energy heat utilization, not only including hot water supply system by the solar energy, but also including the heating and air conditioning systems by solar energy.In this paper, a double-effect absorption of heating and air conditioning system driven by medium-temperature solar energy is put forward. Through the medium-temperature solar collectors, the system collect solar heat, and the medium-temperature heat is stored in heat storage device at the same time. This system can realize refrigeration in summer, heating in winter and provide domestic hot water all the year round. When need refrigeration in summer, the medium-temperature stored in the heat storage device drive absorption refrigerating unit realize refrigeration; through the regulation of automatic control system, the system can realize heating of the end user in winter. In addition, the system also add an auxiliary heat storage device, when the solar energy is rich and the storage temperature meet the setting temperature, excess heat can be stored in the auxiliary heat storage device in case of lack of sunlight or rainy days.By the method of theoretical calculation, the single-effect and the double-effect absorption refrigeration are calculated, respectively. In addition, the coefficient of performance of the three different heating and air conditioning system put forward in this paper are calculated and analyzed. The calculation results show that the double-effect absorption refrigerator has higher coefficient of performance than single-effect absorption refrigerator, and the former is about 1.6 times of the latter. And the coefficient of performance of double-effect refrigeration system driven by medium-temperature of solar energy can up to 0.564, which is 1.3 times than the single-effect system driven by medium-temperature of solar energy.Second, the solar collector area required was calculated for different system. The results show that the solar collector area required by the single-effect absorption refrigeration system driven by medium-temperature solar collectors decreases about 10.9% than the solar collector area required by the single-effect absorption refrigeration system driven by low-temperature solar collectors. The solar collector area required by the double-effect absorption refrigeration system driven by medium-temperature solar collectors decreases about 61.9% than the solar collector area required by the single-effect absorption refrigeration system driven by medium-temperature solar collectors.Thirdly, the working condition of refrigeration of double-effect absorption refrigeration heating air conditioning system driven by medium-temperature solar energy is modeled and simulated by using TRNSYS simulation software. A preliminary study analyzes the influence of the unit COP and the refrigerating capacity of double-effect absorption refrigeration system by external conditions, such as the inlet temperature and flow rate of heat source, the inlet temperature and flow rate of cooling water, the outlet temperature and flow rate of the chilled water. The results show that to increase the refrigerating capacity and COP of the system should raise the inlet temperature and flow rate of heat source appropriately, and if the temperature of heat source every raise 10℃, the refrigerating capacity can increase about 21.5%; With the increasing temperature of cooling water, the refrigerating capacity and COP of the system are decreased gradually, and if the inlet temperature of cooling water every raise 1 ℃, the refrigerating capacity will reduce about 7%, but increase the flow rate of cooling water can improve the refrigerating capacity and COP; To increase the refrigerating capacity and COP of the system can improve the outlet temperature of chilled water, and if the inlet temperature of chilled water every raise 1℃, refrigerating capacity can increase about 4.4%, but only improve the flow rate of chilled water has small effect on the refrigerating capacity and COP of the system.Finally, taking a specific project in Ji’nan for an example, in view of the condensed water recycling equipment set in the system, the amount of condensation water is calculated, when adopt fan-coil unit plus fresh air system at the end of the form. Moreover, the influence of condensed water recycling equipment on the supplement of cooling tower in the system is analyzed. On this basis, the amount of condensation water in the city of four different areas in China are calculated and analyzed. The results show that the recycling and utilization of condensed water is suitable for south China, which has higher temperature and larger relative humidity. What’s more, the recycling of condensation water saves water resources as well as cold quantity, which promote the practical application and further application of the double-effect absorption refrigeration system driven by medium-temperature solar energy in different regions, especially in the south of the high relative humidity.