无量纲力对超临界氢气在U形管内传热的影响
Effect of dimensionless force on heat transfer of supercritical hydrogen in U-shaped tube
高月 1张丽 2海笑 1李洋 1杨帆 1李鹏飞 1王长顺1
作者信息
- 1. 辽宁石油化工大学石油天然气工程学院,辽宁 抚顺 113001
- 2. 辽宁石油化工大学机械工程学院,辽宁 抚顺 113001
- 折叠
摘要
针对发动机换热器的冷却问题,开展了超临界压力下氢气在竖直管和U形管内流动传热特性研究.采用数值方法研究了压力和质量流率对管道换热的影响,从而得到换热规律,深入讨论弯管段的换热机理,分析了无量纲力对换热的影响.结果表明:压力贴近拟临界或质量流率增大均会增加对流换热系数,产生换热强化;U形管的弯管段可有效强化换热,在θ=90°附近达到峰值;入口直管段存在浮升力作用,但当压力高于 2.0 MPa时,由于密度差影响,浮升力作用在弯管段后可忽略;由二次流引起的迪恩涡是强化弯管段换热性能的主要因素,其中对入口段的影响显著弱于出口段.
Abstract
Against the cooling problem of engine heat exchangers,the flow and heat transfer characteristics of hydrogen in vertical and U-shaped tubes at supercritical pressures are studied.The influence of pressure and mass flow rate on heat transfer of the pipeline is studied by numerical method,and the heat transfer law is obtained.The heat transfer mechanism of the elbow section is discussed in depth,and the effect of dimensionless force on heat transfer is analyzed.The results show that,the closer the pressure is to the quasi-critical or when the mass flow rate increases,the convective heat transfer coefficient will increase,resulting in heat transfer enhancement.The bend section of the U-shaped tube can enhance heat transfer effectively,reaching a peak near θ=90°.There is a buoyancy effect in the straight pipe section at the inlet,but when the pressure is higher than 2.0 MPa,the buoyancy effect can be ignored after the hydrogen flows through the elbow section due to the influence of density difference.The Dean vortex caused by the secondary flow is the main factor to enhance the heat transfer performance of the elbow section,and the influence on the inlet section is significantly weaker than that on the outlet section.
关键词
氢气/超临界流体/U形管/传热特性/迪恩涡Key words
hydrogen/supercritical fluid/U-shaped tube/heat transfer characteristics/Dean vortex引用本文复制引用
出版年
2024
国家科技期刊平台
NSTL
万方数据