Study of Direct Contact Heat Transfer Characteristics from a Liquid Ice

对空气与液态冰的直接接触换热特性进行了实验研究。考察了溶液浓度、进气温度、液冰床高度、进气流量等因素对换热性能的影响。结果表明，入口风量对直接接触换热特性有较大影响，风量对总散热量的影响可能存在一个最佳条件。平均散热量与进气流量和进风温差与溶液初始浓度的平衡冻结温度之间具有良好的相关性。实验装置主要由实验段、冷却盐水循环回路和空气冷却系统组成。采用三相流态化空气作为直接接触换热的介质。空气是凉爽的…更多的是提前在气室中除湿。在流量、空气温度和湿度得到良好控制后，将其引入试验段。测试部分由测试贝塞尔、分配器和镇静部分组成。试验容器由内径150 mm、长330 mm的透明荧光管制成。为使试验段进口气流均匀，管口采用不锈钢网(20目)和尼龙布(200目)及分布器，将冰粒与设定温度和浓度的乙二醇液混合制成试验液冰。冰填充系数恒定为62%。将实验液体冰的初始高度设置为170 mm，对固-气-液三相流态化液体冰床的直接接触换热特性进行了实验研究。在本研究所涉及的参数范围内，可以得出以下结论：(1)散热量主要受进气流量、进风温度和溶液初始浓度的影响，而受液态冰床高度的影响不大。(2)总散热量随着空气流量的增加而减少，主要是由于壁面与液态冰之间的摩擦产热。=1.131 q_a^；1.127；删除^；1.248；更少

An experimental study has been performed to investigate the direct contact heat transfer characteristics between air and liquid ice. The effects of concentration of solution, inlet-air temperature, height of liquid-ice bed, and the flow rate of inle-air on the heat-removal performances were extensively examined. The results revealed that the flow rate of inlet-air exertes considerable effects on the direct contact heat transfer characteristics, and that there might be an optimum condition of the flow rate of air for total removed heat. The average heat removal rate was favorably correlated by the flow rate of inlt-air and the temperature difference between inlet-air and equilibrium freezing temperature of initial concentration of solution.The experimental apparatus fundamentally consists of test section, cooling-brine circulating loop, and air cooling system. The fluidization air for the three-phase fluidized bed was utilized as the medium of direct contact heat transfer. Air was coole … More d and dehuminided in the air chamber in advance. After both the flow rate and the temperature of air and humidity were favorably controlled, it was introduced to the test section. The test section consists of a test bessel, a distributor, and the calming section. The test vessel is made of transparent lucite tube which has dimensions of 150 mm in inner diameter and 330 mm in length. In order to obtain the uniform air flow at the inlet of test section, stainless mesh (20 mesh) and the Nylon cloth (200 mesh) along with the distributor were utilized at the inlet of the tube.The testing liquid ice was made up by mixing the fine ice particles and ethylene-glycol solution whose temperature and concentration were set in prescribed value. Ice packing factor was set constant at 62%. The initial height of the testing liquid ice h_b was set at 170 mm throu the experiments.Experiments were carried out to study the direct contact heat transfer characteristics of the solid-air-liquid three-phase fluidized liquid ice-bed. The following conclusions may be drawn within the parameters covered in the present study.(1) The heat removal rate is affected by the flow rate of inlet-air mostly and the temperature of inlet-air and initial concentration of solution, while it is little affected by the height of the liquid ice bed.(2) The total removed heat decreases as the flow rate of air increases owing to mainly the heat generation by the friction between the wall and liquid ice.(3) The average heat removal rate is correlated by the following equation within the deviation of <plus-minus>15DELTAh_<ave>=1.131 Q_a^<1.127>DELTAT^<1.248> Less