相变材料与热边界相对位置对环形单元熔化传热影响规律的数值分析

在保证相变材料质量与加热面尺寸一定的条件下,分别设计外环加热与内环加热2种环形相变单元,采用焓-多孔介质模型对相变传热过程进行模拟,并通过实验验证该文数值计算方法的正确性。在此基础上,针对22种单元进行65、75、85℃这3种定壁温边界下的数值模拟,对其熔化速率和典型位置温度进行对比分析。研究结果表明:在3种温度边界条件下,外环加热单元与内环加热单元熔化分数随时间变化曲线均存在交点,随温度的升高熔化分数交点分别为90%、88%及84%。在交点以下,内环加热设计方案中的相变材料融化更快,在交点以上则结果相反。边界温度升高对外环加热单元底部相变材料温升影响最大,其在相变材料完全熔化时间上优势更明显。

NUMERICAL ANALYSIS OF INFLUENCE OF RELATIVE POSITION OF PHASE CHANGE MATERIAL AND THERMAL BOUNDARY ON MELTING CHARACTERISTICS OF ANNULAR UNIT

Two kinds of annular phase change units were designed which have the same mass of phase change material and heating surface size. The enthalpy-porous medium model was used to simulate the phase change heat transfer process,and the correctness of the numerical calculation method was verified by experiments. The melting performance of two kinds of units at 65 ℃,75 ℃ and 85 ℃ was simulated,and the temperature of the typical positions was monitored. The research results indicated that under the three temperature boundary conditions,the melting fraction of the outer ring heating unit and the inner ring heating unit existed with the time curve,and the melting fraction was 90%,88% and 84%,respectively with the temperature increasing. Phase change material with inner ring heating design scheme melt faster below the intersection,while the outer ring heating design scheme was slower above the intersection.The increase of the boundary temperature has the greatest influence on the temperature rise of the phase change material at the bottom of the outer ring heating unit,and which is more obvious on total melting time of phase change material.