超临界LNG在新型船用换热器冷通道内流动换热特性研究

Research on flow heat transfer characteristics of supercritical LNG in the cold passage of a new marine heat exchanger

本文在新型换热器冷通道内,对超临界状态下LNG的对流换热过程进行数值模拟,分别研究入口温度、入口质量流量和壁面热流密度对超临界甲烷流动与换热特性的影响,提出一种在直通道中加入凹槽结构的强化换热模型。首先采用Ansys Space Claim对换热通道进行几何建模,再使用Siemens STAR-CCM+仿真软件对模型进行网格划分和求解。研究发现:局部对流换热系数随着入口温度的升高有所降低,努塞尔数变化趋势与局部对流换热系数变化趋势大致相同,在斜通道内,超临界LNG具有更好的换热性能;当通道入口质量流量和壁面热流密度增加时,局部对流换热系数也随之增大;凹槽结构对换热器换热性能有较大的提升,对综合性能的提升较小。

In this paper, the convective heat transfer process of liquefied natural gas(LNG) in supercritical state is numerically simulated in the cold passage of a new type heat exchanger, this paper studied the inlet temperature and inlet mass flow rate and wall heat flux density on the influence of supercritical methane flow and heat transfer characteristics, and puts forward a direct way to add a groove structure of strengthening heat transfer model. In this paper, Ansys Space Claim was first used for geometric modeling of heat transfer channel, and Siemens STAR-CCM+ simulation software was used for grid division and solution of the model. It is found that the local convective heat transfer coefficient decreases with the increase of inlet temperature, the change trend of Nusselt number is roughly the same as that of local convective heat transfer coefficient;In inclined channel, supercritical LNG has better heat transfer performance;The local convective heat transfer coefficient increases with the increase of inlet mass flow and wall heat flux. The groove structure has a great improvement on the heat exchange performance of the heat exchanger and a small improvement on the comprehensive performance.