Study On Heat Transfer Of Spray And Falling Film Cooling For The Cylindrical Surface

Spray cooling is a very efficient cooling technology.At present,it is mainly used in heat dissipation of electronic components,and it is also widely used in aerospace and medicine.There are two main processes in spray cooling—droplets impingement cooling and falling film flow cooling.In the past decades,the research direction of researcher at home and abroad focused on the cooling mechanism of droplets impinging on the wall in spray process and the effect of the spray parameters on the spray cooling.However,the falling film cooling after spray is ingored.In this paper,cylindrical surface is selected as the research object,the heat transfer mechanism of spray cooling and falling film cooling is explored through the combination of visualization study and numerical simulation.Main tasks are as follows:(1)Design the experimental system and set up the spray cooling experimental table.The flow patterns of droplets and film under different spray distance and inclination angle are observed by high-speed camera,and the reasons of different results are analyzed.At the same time,Opencv is used to obtained the thickness of liquid film under different working conditions.(2)Through experiment and data processing,the heat transfer capability of spray cooling and falling film cooling is explored,and the cooling curve is obtained.The experimental conditions were designed.the spray distance,spray angle and spray pressure were taken as parameters.Heat transfer effect of different parameters on spray cooling and falling film cooling were obtained,providing guidance and suggestions for spray cooling design.(3)A reasonable numerical simulation model is established to calculate the spray cooling process.The simulation results are coMPared with the experimental results to verify the feasibility of the simulation model.Numerical simulation is used to calculate some parameters which can not be measured in the experiment,and the distribution of wall temperature and heat transfer coefficient in the spray is obtained.At the same time,the thickness distribution of the liquid film on the wall is obtained...