The Research Of Low-temperature Eutectic Salt

Developing cold energy storage technology is an important measure to decrease the electrical energy demand between peak and off-peak period,and the power of refrigeration system.At present,cool storage system is applied mainly to air-conditioning in buildings.However,the research and data in temperature from-60～0 ℃ is not enough.As the demand for this technology is high in industry,the low temperature cold storage research is important.PCMs(Phase Change Material)in-60～0℃,i.e.,NaCl solution,MgCl2 solution,CaCl2 solution,K2CO3 solution,Al(NO3)3 solution are chosen as the research materials.Some basic thermophysical properties of them are tested,and certain applications of these PCMs in the high-low temperature alternate process are designed.And what results have been gotten are shown as below:Firstly,the mass concentration of eutectic point,freezing point and degree of subcooling of NaCl solution,MgCl2 solution,CaCl2 solution,K2CO3 solution,Al(NO3)3 solution are tested,and the liquid density,solid density and their ratio,corrosion to metal,stability of NaCl eutectic salt solution,MgCl2 eutectic salt solution,CaCl2 eutectic salt solution,K2CO3 eutectic salt solution,Al(NO3)3 eutectic salt solution are tested.Above of them provide basic thermophysical parameters for engineering applications.Secondly,the experiment and numerical simulation of solidification process in the cool storage tube are researched,and a design for improvement of heat transfer in tubes is given by numerical simulated.Besides,the effects on improving heat transfer with fin’s sectional area,fin’s thickness and high ratio and fin’s number are studied by numerical simulation.Finally,a cool storage tank for a high-low temperature alternate process is designed with NaCl solution as PCM.Thus,refrigerating units’ operating power in high-low temperature alternate process is balanced and the capacity of refrigerating units is reduced through adding cool storage tanks.