孙会芹 韩昌亮 李泽宇 许麒澳 杨宇航 张欣悦

摘 要：为了揭示超临界甲烷热交换器的对流传热机理，建立了求解固体壁面导热和超临界甲烷对流传热耦合模型，分析了水平圆管内超临界甲烷非均匀流场的对流传热特性。结果表明：超临界甲烷受热过程中，Re随着主流体温度升高而单调增加，Pr出现了波峰和波谷双极值;受浮升力和重力的双重作用，圆管截面上超临界甲烷各项热物性均呈现“扭曲”和“分层”现象，并伴随着复杂的“二次环流”;圆管内壁温和内壁面热通量非均匀的分布特征，在圆管0°位置处达到最小值;对流传热系数峰值出现在拟临界温度附近，与管道压力相比，超临界甲烷对流传热特性受入口质量通量变化更为敏感。

关键词：超临界甲烷;圆管;非均匀;对流传热;二次环流

DOI：10.15938/j.jhust.2021.03.008

中图分类号： TE08

文献标志码： A

文章编号： 1007-2683（2021）03-0051-07

Non-uniform Flow Field of Convection Heat Transfer Characteristics

of Supercritical Methane in a Horizontal Tube

SUN Hui-qin1， HAN Chang-liang2， LI Ze-yu1， XU Qi-ao2， YANG Yu-hang1， ZHANG Xin-yue1

（1.School of Chemical and Environmental Engineering， Harbin University of Science and Technology， Harbin 150001， China;

2.School of Mechanical and Power Engineering， Harbin University of Science and Technology， Harbin 150080， China）

Abstract：In order to reveal the heat transfer mechanism of supercritical methane heat exchanger， a coupled model for solid wall heat conduction and convection supercritical methane is established， and the non-uniform flow field of convection heat transfer characteristics of supercritical methane are analysed. The results indicate that during the heating process， the Reynold number monotonously increases with the augment of bulk fluid temperature， and the Prandtl number has both the trough and peak values. Under the action of double effects of buoyancy and gravity， the thermal properties of methane on the tube cross section show the non-uniform “distortion” and “stratification” characteristics， accompanied by the complex “secondary flows” phenomenon. The non-uniform distributions of inner wall temperature and heat flux of circular tube are observed， and the minimum value is reached at 0° of tube. The peak of heat transfer coefficient appears near the critical temperature. Compared with the operating pressures， the heat transfer characteristics of supercritical methane are more sensitive to the mass fluxes.

Keywords：supercritical methane; circular tube; non-uniform; convection heat transfer; secondary flows

0 引 言

采用天然气（natural gas， NG）作为热源，可以有效减少煤和石油的消耗量[1-3]。NG是一种洁净且环保的清洁能源，主要成分是甲烷，含量超过90%左右[4]。为了提高NG领域换热设备的热效率，工程中普遍采用管道加压方式使其变为超临界甲烷进行换热。由于管道压力和主流体温度均高于甲烷临界点，使得超臨界甲烷热物性参数均随着主流体温度发生剧烈地变化[5]。与此同时，受重力和浮升力双重影响，管道截面上会出现非均匀“分层”和“二次环流”现象[6]。深入研究该流体动力学和热力学过程，对超临界甲烷热交换器的设计和高效运行至关重要。……