CaCl2--LiBr(1.35:1)/H2O工质对的热物性及应用

围绕以LiBr/H2O为工质对的单级太阳能吸收式制冷循环因对太阳能集热温度要求高而难以实现应用的问题,提出了CaCl2-LiBr(1.35:1)/H2O(CaCl2与LiBr的质量比为1.35:1)新型工质对,系统地测定了其结晶温度、饱和蒸气压、密度和黏度,并与LiBr/H2 O进行了比较.结果表明,采用CaCl2-LiBr(1.35:1)/H2 O作为太阳能单级吸收式制冷循环的工质对,在同一制冷工况条件下,其发生温度,即太阳能集热温度比采用LiBr/H2 O的情况低6.2℃.另外,采用浸泡法测试了碳钢、316L不锈钢和紫铜在CaCl2-LiBr(1.35:1)/H2 O中的腐蚀速率,结果表明316L不锈钢和紫铜的腐蚀性非常小,可满足实际工程应用的要求.

Thermophysical properties and applications of CaCl2--LiBr(1. 35:1)/H2 O as a working pair

Absorption refrigeration is an ideal way to utilize solar energy in summer. For a single-stage solar-driven refrigeration cycle based on the typical working pair of LiBr/H2 O, the required generation temperature is up to 88. 0℃, which is too high for the commonly used flat plate solar collectors or vacuum glass tube solar collectors. Thus far, this problem has been addressed via two meth-ods:(1) using high-temperature solar collectors and (2) applying a two-stage absorption refrigeration cycle. In literature, a study per-taining to the former was conducted on the performance and economic feasibility of a 100 kW single-stage solar-driven absorption air conditioning system using heat pipe vacuum tube solar collectors, and another study pertaining to the latter was conducted on the per-formance and economic feasibility of a 100 kW two-stage solar energy absorption refrigeration air conditioning system using flat-plate so-lar collectors. Their results show that the system cost is high for the former and that the system cost is high and the coefficient of per-formance is low for the latter. In addition, the results show that the latter system is complicated. Thus, there are currently few commer-cial applications for the solar-driven absorption refrigeration system. In this study, a new method has been proposed that can address the existing problem, i. e. , the required generation temperature is too high for flat plate solar collectors or vacuum glass tube solar col-lectors in a solar-driven single-stage refrigeration cycle, using a new working pair instead of LiBr/H2 O. In this study, it is found that CaCl2/H2 O has an absorption characteristic benefitting refrigeration, although its absorption ability is limited owing to its relatively low solubility. Based on CaCl2/H2O, a new working pair of CaCl2-LiBr(1. 35:1)/H2O has been proposed. The crystallization tempera-ture, saturated vapor pressure, density, and viscosity of this working pair were systematically measured, and the results show that the required solar collector temperature or the generation temperature of CaCl2-LiBr(1. 35:1)/H2 O for a single-stage absorption refrigera-tion cycle is 6. 2℃ lower than that of LiBr/H2 O under the same refrigeration conditions. In addition, the corrosion rates of the carbon steel, 316L stainless steel, and copper in CaCl2-LiBr(1. 35:1)/H2 O were measured with a weight loss method, and the results show that the corrosion rates of 316L and copper are sufficiently low for practical applications.