The Influence Of Nozzle Group Droplet Atomization Characteristics On Enhanced Heat Transfer

Spray cooling technology,as a kind of high heat flux cooling and phase change cooling technology,has been widely used in electronic device cooling,natural gas humidification and other fields.However,the traditional single nozzle can no longer meet the increasing demand of atomizing flow field and heat transfer effec t,so it is necessary to optimize the nozzle combination.Droplet velocity,diameter,concentration and other parameters are important factors to determine the atomization effect of the nozzle group,and the atomization effect of the nozzle group can direc tly affect the cooling of the hot wall.At present,the existing studies on atomization and heat transfer of nozzle group are mainly based on experiments,and there are few studies on the mechanism of atomization characteristics of nozzle group on heat transfer enhancement.So based on the number of different nozzle group as the research object,through the Fluent software export of droplet through the nozzle jet and movement in the computational domain to carry on the numerical simulation,the nozzle press ure,Angle,distance,quantity of atomized droplet velocity,velocity distribution,diameter,diameter distribution and the influence of the atomization characteristics such as the concentration of DPM are analyzed,It provides theoretical support for the study of atomization cooling mechanism of different number of nozzles.The simulation results show that when the nozzle pressure increases,droplet velocity increases,droplet diameter decreases,and droplet flux increases.When the nozzle inclination Angle increases,droplet velocity decreases,droplet diameter decreases,and droplet concentration distribution becomes more concentrated.With the increase of nozzle spacing,the interference is weakened,the droplet velocity increases,and the droplet diameter decreases.The number of nozzles increases,the droplet velocity increases,the droplet diameter decreases slightly,and the droplet concentration increases significantly.Combined with the atomization characteristics of the nozzle group,the atomization cooling effect of the nozzle group was analyzed from four aspects: hot wall temperature,liquid film temperature,liquid film thickness and heat transfer coefficient of the hot wall.Through analysis,it is found that with the increase of pressure,the liquid film thickness becomes thinner,the average wall temperature decreases and the heat transfer coefficient increases.When the tilt Angle changes to30°,the average temperature of the wall surface is the lowest and the heat transfer coefficient is the highest.When the tilt Angle is 15°,the heat transfer effect is the worst.With the increase of spacing,the average wall temperature decreases and the heat transfer coefficient increases.When the number of nozzles is 3,the average wall temperature is the highest and the heat transfer coefficient is the minimum.When the number of spray groups is 4,the heat transfer effect is the most ideal.According to the orthogonal test method,the influence of various factors on the heat transfer effect of nozzle group is as follows: pressure > inclination > spacing > number of nozzles.When the pressure of the nozzle group is 2.0 MPa,the inclination Angle is 30°,the distance between the nozzles is 10 mm,and the number of nozzles is 4,the heat transfer effect of the nozzle group is the best.