Research On Spray Cooling Technology Of High Heat Flux Laser Medium

Spray cooling is promising due to its high heat transfer coefficient,low flow-rate,compact structure,no boiling hysteresis,and no contact thermal resistance.It has advantages in laser technology,microelectronics,aerospace technology,national defense and other fields.This article focuses on the requirements of high heat flux laser media for efficient heat dissipation and temperature control.Through numerical simulation and experimental research methods,the effects of multiple factors on spray cooling heat transfer performance and temperature control are explored,including the following contents:1)The research status of spray cooling at home and abroad was investigated,and introduced the cooling mechanism,heat transfer characteristics and application prospects of high heat flux laser media in detail.2)According to the research content and purpose,an open single nozzle spray cooling visualization experimental platform was designed.The equipment and device design were introduced in detail that used in the experimental platform,which includes the design of simulated heat source,the selection of cooling medium and atomizing nozzle,the design of spray chamber,and the design and selection of liquid supply system component,and the selection of data measurement and acquisition system component.3)A three-dimensional geometric model of spray cooling was established,and the Discrete Phase Model(based on Euler-Lagrange)was used to conduct detailed simulation analysis of the spray cooling flow field and heat source surface cooling.Simulation results indicated that under certain conditions,spray cooling only occurs in the single-phase region,and when the spray height changes within the range of(5?30 mm),there is an optimal spray height(10 mm),which can achieve the lowest surface temperature of the heat source and the best surface temperature uniformity.When the opening angle of the nozzle is fixed at 60°,the spray height H is 10 mm,the simulated heat source surface heat flux is 30 W/cm2,and the flow rate of working fluid increased in the range of(150?300 mL/min),the surface temperature of the simulated heat source decreased,which can improve spray cooling heat exchange performance,and promote the temperature uniformity of the simulated heat source surface.4)A visualization experiment platform of open single nozzle spray was designed and established by using the deionized water as cooling medium.The spray cooling heat transfer coefficient and cooling uniformity effect in the single-phase region were obtained at different heat flux(16?110 W/cm2),flow rates(200?300 mL/min)and spray height(15?25 mm).It is concluded from the experimental results that the cooling efficiency and temperature uniformity were significantly affected by the spray height and flow rate under different heat flux.When the spray height is reduced,the surface temperature of the heat source decreases,the convective heat transfer coefficient increases,and the heat transfer performance of spray cooling is enhanced.Increasing the working flow rates can reduce the surface temperature of the heat source,but leads to the decrease of the heat transfer coefficient accordingly.The maximal heat transfer coefficient of 5.53 W/(cm2·K)was got at the spray height of 15 mm and flow rates of 250 mL/min,while the temperature uniformity could be greater than 0.6?.