ZigZag微通道内S-CO_2流动传热性能分析

以超临界二氧化碳(S-CO_2)为工质,对其在Zig Zag半圆形横截面微通道内湍流状态下流动传热性能进行数值计算,分析了Zig Zag角度θ、单位周期流道轴向长度P对传热与流动阻力的影响。结果表明,流体在Zig Zag微通道内流动,在流道拐弯处有旋涡产生,导致流通面积减少,流体主流速度急剧增大并冲刷换热壁面,使边界层减薄或破坏,并且该位置附近湍动能急剧增大,增强了流体的扰动与混合,促进了能量传递,强化了换热;随着Zig Zag角度θ增大,微通道内传热性能提高而流动阻力急剧增大;随着单位周期流道轴向长度P增大,传热性能与流动阻力均下降;在文中所述计算条件下,θ=15°,P=15 mm时Zig Zag微通道内S-CO_2耦合传热综合传热性能最优。

Numerical Analysis of S-CO_2 Flow Heat Transfer in ZigZag Microchannel

With supercritical CO 2 as the working medium,the flow heat transfer performance of it in semi-circular ZigZag microchannel under turbulent state was numerically investigated,and the effects of ZigZag angle θ and axial length P of unit periodic channel on heat transfer and flow resistance were analyzed.The simulation results show that the fluid flows in the ZigZag microchannel,and there appears vortex at the bent location of the channel,which causes the decrease of flow area,the main stream velocity of the fluid increase sharply and scours the heat transfer wall,which makes boundary layer thinner and destroyed,and the turbulence kinetic energy near this location increase sharply,which strengthens the disturbance and mixing of the fluid,promotes energy transfer and strengthens heat transfer;with the increase of the ZigZag angle θ,heat transfer performance is increased,and flow resistance is sharply increased;with the increase of axial length P of the channel in a unit period,both the heat transfer performance and flow resistance are reduced;under the calculation conditions given in this paper,when θ=15° and P =15 mm,the overall heat transfer performance for S-CO 2 coupled heat transfer in the ZigZag microchannel is optimal.