Study of Direct Contact Heat Transfer Characteristics from a Liquid Ice

对空气与液态冰直接接触换热特性进行了实验研究。考察了溶液浓度、入口空气温度、液冰床高度和入口空气流量等因素对系统除热性能的影响。结果表明，入口空气流量对直接接触换热特性有很大影响，对于总排热量而言，存在一个最佳空气流量条件。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。三相流化床的流化空气被用作直接接触传热的介质。空气很凉爽 关于我们 并在气室中预先脱腐。在对空气的流速、温度和湿度进行良好控制后，将其引入试验段。测试部分由测试贝塞尔、分配器和平静部分组成。试验容器由内径为150 mm、长为330 mm的透明有机玻璃管制成。为了使试验段入口处气流均匀，在管道入口处采用不锈钢网（20目）和尼龙布（200目）沿着分布，将细冰粒与设定温度和浓度的乙二醇溶液混合制成试验液冰。冰填充系数设定为恒定的62%。通过实验将试验液冰的初始高度h B设定为170 mm，对固-气-液三相流化液冰床的直接接触传热特性进行了实验研究。在本研究所涉参数范围内，可得出以下结论。(1)除热率主要受进气流量、进气温度和溶液初始浓度的影响，而受液冰床高度的影响较小。(2)随着空气流量的增加，总的去除热量减少，这主要是由于壁与液态冰之间的摩擦产生的热量。(3)平均热移除速率通过以下方程在<plus-minus>15 Δ h_<ave>=1.131 Q_a^<1.127>Δ T ^的偏差内关联<1.248>，

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