微重力下管内凝结换热性能的研究

为了预测失重条件下航天飞行器中冷凝器的传热性能，提出了一种研究微重力场中管内凝结换热过程的方法，建立了管内环状流域层流凝结换热的数理模型。改变重力加速度ｇ值进行仿真计算，随着ｇ值的减小，凝结液膜变厚，使凝结换热恶化，例如在相同冷却条件下，当进口蒸气Ｒｅ数为１０４时，ｇ＝０和ｇ＝９．８ｍ／ｓ２环境下的平均冷凝Ｎｕ将降低３０％。并以重力场中垂直管内凝结换热的实验结果对模型进行了间接的检验。给出了预测零重力环境中管内平均凝结换热系数的准则关联式，可供航天器热控系统的热分

Study of condensation heat transfer inside a tube in microgravity

To calculate the heat transfer performance of condensers in space capsule under zero gravity, this paper introduces a method for studying condensation heat transfer inside a tube in a microgravity environment. The model assumes laminar flow in the condensate film and an annular flow pattern. The local heat transfer coefficient is then calculated for gravitational acceleration, g , from 0 to 9.8 m/s 2 , with the reduce of g , the condensate film thickness is increased, condensation heat transfer has worsended. For example, under same cooling conditons when Re is equal to 10 4, Nu in 0 g according to Nu in 1 g has reduced by 30%. The model was tested indirectly by experimentally measuring condensation heat transfer inside a vertical tube in a normal gravity environment. The formulas about calculating average condensation heat transfer coefficient inside a tube in zero gravity environment are introduced. It can apply to thermal analyses of the thermal control system of space capsule.