微通道内超临界LNG变物性流动传热数值模拟

Numerical simulation of heat transfer of supercritical LNG fluid with variable physical properties in microchannels

跨临界LNG在临界点附近物性变化剧烈,采用数值模拟方法研究了直通道和Zigzag型微通道内超临界LNG变物性和常物性对流动传热性能,分析了LNG跨临界变物性和常物性的偏差。研究结果表明,在Re为9 816、16 956、24 164和31 390时,直通道定物性和变物性的对流传热系数偏差为1.95%、-3.37%、-6.48%和-9.11%。Zigzag通道的变物性和定物性对流传热系数偏差为-0.11%、-5.47%、-7.84%和-5.83%。Zigzag对流传热系数按节距周期性变化。靠近半圆角位置涡的增大对传热有良好的强化作用。在直通道和Zigzag通道中,变物性的压降比定物性更小,但摩擦因子f比定物性更大。在Zigzag通道中物性对摩擦因子f的影响可以忽略。

The physical properties of transcritical LNG vary significantly near the critical point.The flow and heat transfer performance of supercritical LNG with variable and constant physical properties in straight channels and Zigzag type microchannels were studied by numerical simulation method,and the deviation between LNG transcritical variable and constant physical properties was analyzed.The research results indicate that the deviation of convective heat transfer coefficients between the constant and variable properties of the straight channel are 1.95%,-3.37%,-6.48%,and-9.11%and the deviation of the Zigzag channel is-0.11%,-5.47%,-7.84%,and-5.83%.The convective heat transfer coefficient of Zigzag varies periodically according to the pitch.The increase of vortices near the semicircle angle has a good strengthening effect on heat transfer.In the straight channel and Zigzag channel,the pressure drop of variable physical properties is smaller than that of constant physical properties,but the friction factor f is greater than that of constant physical properties.The influence of physical prop-erties on f in the Zigzag channel can be ignored.