微细流道形式对超临界LNG流动换热性能影响研究

Study on the Effect of Micro Channels on Micro Channels Flow and Heat Transfer of Supercritical LNG

广泛应用的超临界液化天然气(LNG)换热器内部由许多微细流道构成,不同结构和尺度的微细通道对超临界LNG流动换热性能有着重要影响。通过耦合超临界LNG热物性模型、湍流模型、传热模型,建立了微细通道内超临界LNG流动换热计算方法。分别建立直流道、S型流道、Z型流道,讨论了不同尺度的不同流道形式在不同温度和流速条件下的流动特性和换热性能。结果表明,在相同入口流量和压力条件下,随着流道截面尺寸和压力的增大,微细通道压降降低,换热系数增大,换热性能提高。在相同压力下,随着流道内超临界LNG流量的增大,微细通道压降增加,换热系数增大,换热性能有一定提高但会降低可流动性。S型微细通道较直流道和Z型流道有较小的压降和较大的换热系数,具有较优的流动和换热特性。

The widely used supercritical liquefied natural gas (LNG) heat exchanger is composed of many mi-cro channels. The micro channels of different structures and sizes have important influence on the heat transfer performance of supercritical LNG flow. Through coupling the thermo-physical proper-ty model, turbulence model and heat transfer model of supercritical LNG, the numerical method in predicting flow and heat transfer of supercritical LNG flow in micro channels was established. The straight channel, S channel and Z channel were established respectively, and the flow characteris-tics and heat transfer performance of different flow channel forms at different temperature and flow rate were discussed. The results show that, under the same inlet flow and pressure conditions, the pressure drop of the micro channel decreases, the heat transfer coefficient increases and the heat transfer performance improves with the increase of the flow section size and pressure. Under the same pressure, with the increase of the supercritical LNG flow in the flow channel, the pressure drop of the micro channel increases, and the heat transfer coefficient increases. The heat transfer per-formance is improved, but the fluidity is reduced. Compared with the straight channel and the Z channel, the S-type micro channel has smaller pressure drop and larger heat transfer coefficient, and so has better flow and heat transfer characteristics.