Design And Research Of Spray Cooling System On The High Heat Flux Density Condition

Spray cooling is a new Liquid-cooled type cooling technology,which is currently the most promising cooling way in the high power solid laser device cooling field. It has the advantages of high thermal efficiency, the low demand of working medium, the uniform heat dissipation, along with the complex heat transfer mechanism.Based on the analysis of the working principle of spray cooling system, a open water spray cooling system is built and the influences such as the heating power, spray pressure, spray height on the heat transfer performances of the spray cooling system are investigated. The thesis has the following major contents and results:1)When water is employed as the cooling agents, the heat transfer coefficient of the system can be 1.55-2.12 W/cm2·K, which is high than that of the other cooling system.2)The influence factor of heating power has hardly effect on the performance of heat transfer coefficient while no phase transition of the water occurs. Besides, heat transfer coefficient can be improved with the increasing of spray pressure, while pressure changed from 5bar to 6bar, heat transfer coefficient has improved 7.5%, pressure changed from 7bar to 8bar, heat transfer coefficient has improved 1.4%, the pressure larger, the gain lesser.3) With no phase transition of the water occurs, while spray height reducing from 27mm to 20mm,13mm, the heat transfer coefficient has decreased 2.2%,1.1%; spray height raised from 27mm to 34mm, it decreases 10.2%. This result shows that there exists a best spray height.4)The heat transfer coefficient can be much improved with phase transition of the water, heat transfer coefficient can be maximum improved about 14%, and in this process, heat-removed capacity of the water per unit flow is improved.Way to enhance the heat transfer coefficient of the system given as below:l)In order to promote the phase transition with high heat transfer coefficient, Spray height control and the heating power adjusting method can be used with the considering of the lowest temperature limit of the heat sink surface.2)The method of increasing the spray pressure and adjusting the spray height can be used to improve the heat transfer coefficient while no phase transition of the water occurs.This work offers an effective reference for the application and development of the spray cooling system in the field of high heat flux density condition.