【摘要】 为了揭示大型印刷电路板换热器的流动传热特性，重点研究集箱结构的均流性能，将换热器芯体简化为多孔介质模型并对完整的冷热板片进行建模和数值模拟，以研究交叉流对大型换热板片传热性能的影响。研究结果如下：第一，换热芯体表面的速度均匀性随相对动压增大而降低。在常规运行参数下，换热芯体表面的速度均匀性指数为99.85%，其对应的相对动压参数约为3.3%。当相对动压小于30%时，Z型和U型进出口结构条件下的流动均匀性无显著差异。当相对动压大于30%时，U型结构的均流性能优于Z型结构。第二，短管横截面积不变时，增加短管的数量可提高芯体表面速度分布均匀性，但对换热器总体压降无显著影响。第三，随着大型换热板片的长宽比增大，交叉流所占的区域降低，换热器换热性能提高。当换热板片长宽比大于2.63，可获得与纯逆流相近的换热器效率。综上所述，大型印刷电路板换热器芯体表面的速度均匀性与相对动压密切相关，实际运行条件下的相对动压值很小，芯体表面的速度较为均匀；大型换热板片的交叉流区域占比可高达50%，提高换热板片的长宽比有助于改善换热器总体传热效率。更多还原

【Abstract】 In order to reveal the thermal-hydraulic characteristics of large-scale printed circuit heat exchangers, the heat transfer core is simplified as the porous media to study the influences of inlet and outlet structure on the flow distribution,and the one complete pair of cold and hot plates is modeled to investigate the effects of cross flow on the overall heat transfer performance. The obtained results are as follows: first, the velocity uniformity at the surface of the core increases with the relative dynamic pressure. At the conventional operation parameters, the velocity uniformity index is around 99.85%, and its corresponding relative dynamic pressure is about 3.3%. When the relative dynamic pressure is below 30%,the flow uniformities of the Z-shaped and U-shaped structures are similar. When the relative dynamic pressure is above30%, the U-shaped structure performs better than the Z-shaped structure in flow uniformity. Second, the flow uniformity will be improved but the pressure drop will hardly be affected by increasing the number of short tubes with the cross section area of short tubes unchanged. Third, the cross flow area will be reduced by increasing the length-width ratio of heat exchanger plates, leading to the improvement of the heat exchanger efficiency. When the plate length-width ratio is above 2.63, the efficiency will be close to that of the pure counter flow. The results reveal that the velocity uniformity at the core surface of large-scale printed circuit heat exchanger is closely related to the relative dynamic pressure. Under common operational conditions, the relative dynamic pressure has a small value, indicating that the velocity distribution is rather uniform. The cross flow area can occupy nearly 50% of the total heat transfer area for large-scale plates, and the overall heat transfer efficiency can be improved by increasing the plate length-width ratio.更多还原