| Under today’s situation of the shortage of energy, countries around the world try to find solutions positively. Policies encourage to accelerate scientific and technological innovation, and dissolve energy-saving in culture, called for a national energy-saving. Solar energy as a new energy has many potential to be developed and used. Solar water heating system is one of the most common way of solar energy utilization. But due to the solar energy is intermittent, the use of solar energy hot water system restricted by climate, therefore, need to match the electric auxiliary heating.In this paper, the solar energy storage plan combining the phase change materials(PCM) with water is proposed. First of all, on the basis of summarizing the predecessors’ research, the PCM species, PCM phase transition temperature range,and the kinds of PCM storage unit structure is chosen and designed to determine the physical structure and heat transfer form.And then to build mathematical model of water tank, and simulate through the Matlab platform, contrast the situation of adding different amount of PCM.Simulation results show that adding PCM can increase the heat storage ability of water tank, and delay the water temperature. The plan is applied in conventional solar energy system associated with electric auxiliary heat, which offers heat water in 24 hours. The results show that the water temperature fluctuation is smaller in the system with PCM, which means that the PCM causes an effect as "chipping peak off and filling valley up". This effect on water temperature is beneficial for the system, since the heat loss and the electric auxiliary heat consumption are reduced, resulting in the electricity saving rate up to 22%.This paper also makes a comparative study for the application of application in different parts. The results found in the rich solar energy resources region, the power saving would be more; and in regions where the average outdoor temperature is higher, the heat loss would be reduced. But overall, the phase change energy storage of solar energy hot water system is applicabled in the areas where solar energy hot water system is original used.At the end, this paper explores the optimized PCM parameters including phase change temperature and the PCM volume fraction. The influence that PCM melting temperature and volume fraction have on the performance of the energy storage system is analyzed and the selection range is provided. |
