【作者】 唐娟；

【导师】 李夔宁；

【作者基本信息】 重庆大学 ， 制冷与低温工程， 2007， 硕士

【摘要】 可利用电网低谷电实现电网“移峰填谷”的制冷设备及相应的蓄冷技术成为近年来蓄能领域的国际性热门课题,而目前蓄冷技术的研究和应用主要集中在空调领域,国内外对0℃以下的低温相变蓄冷材料及其应用的研究还比较少。但在食品、化工、低温物流、医药、啤酒等众多行业,对于0℃～-60℃温度范围的蓄冷有着巨大的需求。因此,进行低温相变蓄冷材料的基础研究,测定其基本的热物理性质,对于以后低温蓄冷技术的大规模应用,显得尤为重要。本文围绕研制出相变温度为0℃～-60℃,相变潜热大的低温相变蓄冷材料系列,为蓄冷材料在低温贮存、冷藏运输、工业冷源等领域的应用提供基础数据,并试图将其应用到冷库领域。在实验研究中,探索出利用DSC绘相图寻找共晶浓度、共晶温度的方法,测得甲酸钠、苯甲酸钠、乙酸钾、乙酸钠等有机盐溶液的共晶浓度、共晶温度、相变潜热,同时对其比热进行了测量。在上述研究基础上,对低温相变蓄冷材料的相变潜热、比热、导热系数、密度,蓄冷材料的价格等方面进行一级模糊数学综合分析,对其进行综合评价,筛选出综合性能指数大,即相变温度为0℃～-60℃,具有高相变潜热值的有机、无机蓄冷材料。利用FLUENT软件对间接蓄冷（蓄冷球）和直接蒸发式蓄冷（螺旋盘管）进行数值模拟研究,得到凝固过程中不同时刻蓄冷体内蓄冷材料的温度场及固液相比例。通过比较,直接蒸发式螺旋盘管换热效率高,在相同时间内蓄冷能力强,适合用于冷库蓄冷。研究低温相变蓄冷材料在冷库蓄冷的方案,将综合性能指数较高的22%wt的MgCl₂溶液作为相变蓄冷材料,运用到肉食品冷库低温间蓄冷中,在原冷库运行模式的基础上建立了相应的蓄冷系统,系统采用了按电功率需求限制进行蓄冷策略,和部分蓄冷运行方式,并通过经济分析,得到投资回收期约为2年左右。更多还原

【Abstract】 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.更多还原