Thermal Properties And Application Research Of New Low-temperature Phase Change Materials

The refrigeration equipment and cool storage technology which can make use of the lower valley electricity to achieve shifting electrical energy demand from peak period to off-peak period have been a hot topic in recent years. At present, cool storage technology is applied mainly in air-conditioning systems.The research on the low-temperature phase change cool storage materials and their application with phase change temperature below 0℃is still less. But the cool storage materials with which phase change temperature from 0℃to -60℃are tremendously demanded in the food, chemical, and cryogenic logistics, pharmaceuticals, beer, and many other industries. Therefore, for the large-scale application of the low-temperature storage technology in the future, the basic research and the basic physical properties research of low-temperature phase-change cool storage materials are very important. This paper focuses on developing the phase-change materials whose phase-change temperature is from 0℃to -60℃, and the phase-change latent heat is large. It can provide the basic data for the low-temperature cold storage, refrigerated transport, industry cold source applications and so on. And we try to apply it to the cold storage areas.In the experiment, we explore the method to find the eutectic concentration and the eutectic temperature by drawing the phase diagram by Differential Scanning Calorimetry (DSC). Eutectic concentration, eutectic temperature, latent heat and specific heat of NaHCO2-H2O, NaC6H5CO2-H2O, KC2H3O2-H2O, MgCl₂-H2O and so on are measured.On the basis of these studies, a critical method of eutectic system's comprehensive character with the fuzzy math is delivered by the latent heat, specific heat, thermal conductivity, density, and price of cool storage materials. The materials with the high coefficient of the comprehensive are screened out.Storage goals and helical coil are simulated by the FLUENT software. The temperature field is obtained and phase change interface position changed with time is also calculated. By comparison, heat exchanger efficiency of the direct evaporative helical coil is higher, and the storage capability is better at the same time. Helical coil is more suitable for refrigerator storage.Storage program of using low-temperature phase change cool storage materials in the cold storage is studied. 22%wt of MgCl₂ solution as phase change cool storage materials is used in cold storage of meat products. In the original mode of operation of cold storage, we build the appropriate storage system. Systems adopt the storage strategy according to electric power demand restrictions and some storage operation mode. Through economic analysis, investment payback period is about 2 years.