翼型结构对印刷电路板换热器流动与换热特性影响

Effect of airfoil structure on flow and heat transfer characteristics of printed circuit heat exchanger

印刷电路板换热器(PCHE)作为超临界二氧化碳(S-CO_(2))布雷顿循环中的重要设备,其性能会影响系统的效率。为了提高翼型PCHE性能,探究翼型翅片结构对其流动与换热性能的影响。本工作针对S-CO_(2)布雷顿循环系统中的高温回热器,采用数值模拟的方法,选用S-CO_(2)为传热工质。通过对3种不同结构的NACA0020的翼型翅片通道的流动与换热性能进行比较,研究翼型翅片最大厚度在弦长上的位置参数对换热器的性能影响,并从热工水力性能、综合性指标、整体流动性、局部性能等方面分析了变化规律。结果表明,在翼型翅片结构中保持相对厚度不变的情况下,随着翼型翅片最大厚度在弦长上越接近翼型前缘的位置,其换热性能也会随之提高。其中NACA0020-20的翼型翅片通道在选定的工况条件下,j因子和Nu比其他两种翼型翅片通道大2.7%~8.8%和2.7%~8%,并且该翼型翅片结构可以有效地减小边界层所带来的影响,提高了其PCHE的换热性能,其综合性能更是优于其他两种翼型翅片。研究结果对于翼型PCHE的结构设计和性能优化提供了一定的依据。

The performance of the printed circuit heat exchanger(PCHE),an important component in the supercritical carbon dioxide(S-CO_(2))Brayton cycle,affects the efficiency of the system.This study aims to improve the performance of airfoil PCHE by investigating the effect of the airfoil-fin structure on its flow and heat transfer performance.Herein,for the high-temperature return heaters in the S-CO_(2)Brayton cycle system,a numerical simulation method is used,with S-CO_(2) selected as the heat transfer medium.By comparing the flow and heat transfer performance of the airfoil-fin channels of NACA0020 with three different structures,we study the influence of the positional parameter of the maximum thickness of the airfoil fins on the chord length on the performance of the heat exchanger and analyze the rule of change in terms of the thermo-hydraulic performance,comprehensive indexes,overall fluidity,local performance,etc.Results show that the heat transfer performance increases as the maximum thickness of the airfoil fins approaches the leading edge of the airfoil along the chord length while maintaining a constant relative thickness in the airfoil-fin structure.Compared to the other two airfoil-fin channels,the airfoil-fin channel of NACA0020-20 exhibits a larger j factor and Nu of 2.7%-8.8% and 2.7%-8%,respectively,under the selected operating conditions.This airfoil-fin structure can effectively reduce the influence of the boundary layer and improve the heat transfer performance in the PCHE.Overall,its performance is even better than the other two airfoil fins.These results provide a certain basis for the structural design and performance optimization of the airfoil PCHE.