A Study of Heat-Transfer Performance of Insulation Material Available in Cold Climates With De-Frosting Function

通过实验研究了风速、风温和冷壁温度对玻璃棉隔热层热流特性、蓄热含水率和当量导热系数的影响。试验材料为高1000 mm、深300 mm、厚100 mm、密度16 kg/m~3的玻璃棉。为了测量玻璃棉内部的温度，在材料中安装了6个C-A热电偶。冷却壁由3 mm厚的铜板组成。通过将温控盐水从设置在冷壁背面的管子的喷嘴孔中铺开，使冷却壁面温度保持均匀。INS…之间的清枪实弹冷壁厚度为20 mm。房间的温度由电热水器统一控制，湿度由加湿器控制。结果和讨论在本研究的参数范围内可以得出以下结果。(1)玻璃棉中储存的水分含量随着间隙内气流速度的增加而减少。当空气温度为5℃，冷壁温度为-15℃时，U=1.0m/S的蓄热含水率约为U=0.2m/S时的1/3。(2)玻璃棉的热流特性随风温的变化明显，在T_a=5℃时，热流密度随风速的增大而单调增加，而在T_a=10℃时，热流密度随风速的增大而单调下降。(3)等效导热系数行为受气流温度的影响较大，低温气流使等效导热系数随风速的增大而增大。(4)在本系统中，进风温度是一个可以显著控制玻璃棉换热特性的重要参数。(5)需要进行额外的研究，以使用实际的进口空气温度来更准确地确定通过冷却壁和保温层之间的净空的气流的影响。较少

An experimental investigation has been conducted to determine the effect of air velocity, air temperature, and cooled-wall temperature on the heat-flow characteristics through the glass-wool insulation, the storaged moisture content, and the equivalent thermal conductivity.A. Experimental Apparatus and Arocedures The present experimental apparatus consists of test section, air circulating system, cooled-brine circulating system, temperature-compensating room, and associated instrumentations. Glass wool of 1000 mm in hight, 300 mm in depth, 100 mm in thickness with 16 kg/m^3 in density was used as a testing material. To measure the temperature within the glass wool, 6 C-A thermocouples were installed into the material. The cooled wall was made up of copper plate 3 mm in thickness. Temperature of the cooled-wall surface was maintained uniformly by spreading the temperature-controlled brine from the nozzle holes of the pipe set at just backside of the wall. The clear-lance between the ins … More ulation and the cooled wall was 20 mm. Temperature of the room was uniformly kept by use of electric heaters, while the humidity of the room was controlled by a humidifier.B. Results and Discussion The following results may be drawn within the parameters covered in the present study. (1) The stored moisture content within a glass wool decreases with an increase in air-flow velocity in the clearance. For air temperature of 5 C and cooled-wall temperature of -15 C, the storaged moisture content at U = 1.0 m/s is about 1/3 times as large as that at U = 0.2 m/s. (2) The heat-flux characteristics through the glass wool change markedly with the value of air-flow temperature; for T_a= 5 C the heat flux increases monotonically with increasing air velo-city, while for T_a= 10 C the heat flux decreases monotonically with increasing air velocity. (3) The equivalent thermal conductivity behavior is influenced peculiarly on the air-flow temperature; low temperature air flow causes an increase of the equivalent thermal conductivity with an increase in air velocity. (4) Inlet air temperature is a most important parameter which may controll markedly the heat-transfer characteristics through the glass wool in the present system. (5) An additional study is required to more exactly determine the effect of the air flow through the clearlance between the cooled wall and the insulation using an actual inlet air temperature. Less