变截面半圆通道内超临界二氧化碳热工水力性能研究

Study on thermal hydraulic performance of supercritical carbon dioxide in semi-circular channel with variable cross-section

建立了不同半圆通道的数学和物理模型,并通过与实验数据的比较,验证了所建立模型的准确性。研究了超临界二氧化碳(S-CO_(2))在等截面半圆通道、渐扩型和渐缩型通道内的热工水力换热性能,并分析了不同通道和压力对S-CO_(2)在变截面半圆通道内的热工水力性能的影响。结果表明:相较于均匀截面半圆通道,渐扩型通道恶化传热,渐缩型通道强化传热;入口和出口半径比为1.0:0.5的渐缩型半圆通道的总体换热系数最大提升了39.93%,流动传热综合性能评价因子PEC最大为1.346;当压力越靠近临界压力或热通量较低时,传热性能越高。最后,从场协同性和湍动能分布的角度解释了渐缩型变截面通道强化传热的原因。研究结果可为S-CO_(2)循环系统冷却器的设计与优化提供新的思路和理论指导。

The mathematical and physical models of different semicircular channels are established,and the accuracy of the numerical models is verified by comparing with the experimental data.The thermal and hydraulic heat transfer performance of supercritical carbon dioxide(S-CO_(2))in uniform cross-section semicircular tube,diverging tube and converging tube is studied,and the influence of different channels and pressures on the thermal and hydraulic performance of S-CO_(2) in a semi-circular tube with variable cross-section is calculated and analyzed.The results show that,compared with the uniform cross-section semicircular tube,the diverging tube deteriorates heat transfer,the converging tube enhances heat transfer.The overall heat transfer coefficient of converging semicircular tube with the inlet and outlet radius ratio of 1.0:0.5 increases by 39.93%,and the maximum evaluation factor PEC of flow heat transfer comprehensive performance is 1.346.When the pressure is closer to the critical pressure or the heat flux is low,the heat transfer performance is higher.Finally,the reason why the converging tube with variable cross-section can enhance heat transfer is explained from the perspective of field coordination and turbulent kinetic energy distribution.The research results can provide new ideas and theoretical guidance for the design and optimization of coolers in S-CO_(2) circulation system.