R404A在Y形翅水平管外的降膜蒸发换热特性

Falling film evaporation heat transfer performance of R404A outside horizontal Y-type fin tubes

为探究R404A在Y形翅水平强化管外降膜蒸发换热特性,分别在喷淋密度Γ=0.039~0.056 kg/(m·s)、蒸发温度t=5~20℃、热流密度q=15~35 kW/m~2的实验条件下对其进行降膜蒸发实验。采用热阻分离法和改进的Wilson-Gnielinski图解法对实验数据进行处理,得到管外传热系数,并探究了各参数变化对其换热性能的影响。根据实验结果设计了正交试验,分析得出,热流密度对其降膜蒸发传热系数影响最大,喷淋密度的影响紧随其后,蒸发温度的影响最小。当Γ=0.0465 kg/(m·s)、t=20℃、q=20 kW/m~2时对应的降膜蒸发传热系数最高。采用量纲一分析及多元非线性回归方法对Y形翅水平管降膜蒸发传热关联式进行了拟合。

In order to explore the falling film evaporation heat transfer performance of R404 A outside the enhanced horizontal Y-type fin tube,carries out the falling film evaporation experiment,under the experimental conditions of the spray densityΓ=0.039~0.056 kg/(m·s),evaporation temperature t=5~20℃,and heat flux density q=15~35 kW/m~2.Applies the thermal resistance separation method and the modified Wilson-Gnielinski graphic method to process the experimental data to obtain the heat transfer coefficient outside the tube,and investigates the influence of various parameters on the heat transfer performance.According to the experimental results,designs the orthogonal test.The results indicate that the heat flux density has the greatest influence on the heat transfer coefficient of the falling film of the tube,followed by the spray density and the evaporation temperature.Under the condition ofΓ=0.0465 kg/(m·s),t=20℃,q=20 kW/m~2,the corresponding falling film evaporation heat transfer coefficient is the highest.Uses the dimensionless analysis and multivariate nonlinear regression methods to fit the falling film evaporation heat transfer correlation equation of the tube.