封闭空间内纵向外翅片管结构参数对传热的影响

对封闭空间内的竖直纵向外翅片管在翅片长度、翅片夹角及基管壁温改变时的自然对流条件下的换热特性进行了三维数值研究。结果表明翅片管的单位质量散热量随翅片长度的增加而增大。在翅片长度一定时,其最大值大多出现在翅片夹角60°左右;在基管壁温升高时,对流占据比重出现极大值;在考虑翅片夹角对换热影响的基础上引入量纲1因子,依据65种算例结果拟合出竖直纵向外翅片管自然对流换热准则关系式,准则式与计算结果偏差平均为3.53%。

Heat transfer characteristic of longitudinal externally-finned tube in closed space

A three-dimensional numerical study was carried out to investigate effects of fin angle,fin length,and tube wall temperature in natural convection on heat transfer enhancement for a longitudinal externally-finned tube placed vertically in a closed space.The numerical results show that the heat transfer rate per unit mass increases with fin length.The maximum heat transfer rate per unit mass occurs when the fin angle is about 60° for all the fin angles investigated.With increasing tube wall temperature,the maximum ratio of the natural convection occurs in the temperature range studied.In order to consider the effect of fin angle on heat transfer enhancement,the dimensionless factor d/H is introduced.The natural convection heat transfer criterion of longitudinal externally-finned tube in vertical is fitted based on 65 computational cases and the mean error is 3.53% between the criterion and simulations.