Study On Dynamic Thermal Performance Of PCM Heat Storage Device In The Solar Water Heating System

In recent years, building energy efficiency is the basic trend of building development in China. In the building energy consumption, the account of heating energy consumption in winter is about 40% of the total building energy consumption. So reducing the energy consumption of winter heating is an effective method of building saving energy. Solar energy as a renewable energy has the advantages of rich resources and easy to use. Solar energy for building heating in winter can reduce heating consumption needed for conventional energy. Because solar heat flux is low and intermittent; developing highly efficient store-release heat equipment has an important effect to promote the application of solar heating systems and reduce energy consumption.Developing store-release device using phase-change heat storage technology is an effective way to solve the problems of the low heat flux and intermittent. The topic designs phase-change store-release heat storage which can store and release heat at the same time based on the theoretical developed and practice and shows the influence of phase-change store-release heat and enhanced heat transfer technology on the device thermal performance. It gives the curve of the thermal performance to promote application and development of solar energy heating system.The device uses Na₂S₂O₃·5H₂O as store-release media and is done lots of experiment to the melting and solidification of the device in the solar heating system. The study founds that phase-change store-release heat storage runs 1.5h experiment and it increases about 2MJ energy which is about 4.5% of total store energy. Comparing with the store or release system, it can take full advantage of solar heat in the evening to maximize the use of solar energy. Experimental studies media, the internal device structure, operating conditions to the device heat performance. It gives optimized design and operating conditions which uses Na₂S₂O₃·5H₂O as store-release media, adds metal mesh between the heat exchange tubes, keeps the hot temperature of collector water and heating water. The conditions can improve the efficiency of device which store heat and release/store heat efficiency improves 35% and 10%.The study also uses Fluent to simulate store-release process of simplified model of device and the software simulates heat performance curve and expression of the device in optimal conditions. The curve shows store heat and release/store heat efficiency increase with the store heat energy. That is the more store heat, the better of the device heat performance which is verified by the the experiment results. In the paper, it gives the design process to the phase-change store-release device using the heat performance curve so that it can prove the application and development of solar heating systems.