Experimental Research On Heat Transfer Performance And Surface Temperature Uniformity In Array Spray Cooling

Due to the integration and the power density of electronic devices increase continuously at expense of increasing thermal dissipation, the traditional cooling methods has been difficult to meet the requirements of the heat dissipation. Compared with other technologies, spray cooling technology is a promising in the future, for its high heat capacity, excellent ability of temperature control, the advantages of small working fluid has attracted the great attention of researchers in the heat transfer field. At present, a lot of research about spray cooling has been focused on heat transfer mechanism of basic research on the small size of the single or two nozzles. Based on the spray cooling engineering application background, the paper design standard modular coolers and explore heat transfer characteristics of boiling region on the large surface of nozzle array. The main research work is as follows:(1)The enclosed spray cooling system is established for R134a and R407c are used as the working fluid. Then the nozzle atomization characteristics are calculated analyzed. The results show that R407c Suater diameter of atomized droplets is less than R134a under the same condition. And the Suater diameter will be smaller with the increase of the spray pressure drop.(2)The array spray modular coolers are completed by designing arrangement of nozzle array, calculating the optimal spray height and optimizing the structure of cooling fluid flow. Then the uniformity of spray nozzle array is tested.(3)In this paper, enclosed spray cooling system as the experimental platform, the array spray cooling heat transfer characteristics and its major influence factors such as spray flow, inlet temperature, spray pressure, working fluid and surface microstructure are studied. The heat transfer ability is enhanced as spray flow rate and pressure result in an increase in the droplet number; The high inlet temperature of working fluid result in enhancement in the boiling heat transfer; Rib structure improve the heat transfer performance; The heat transfer performance of R407c is superior to R134a. Then the influence factors that affect non-uniform temperature distribution are researched. The surface temperature distribution of the free flow region tends to be more uniform under the array spray. The increase of flow can improve the distribution of temperature.(4)Optimizing the performance parameters and testing modular cooler heat transfer characteristics. The tests show that modular coolers can offer the ability to remove the heat flux of 170w/cm2 and maintain a lower temperature on the surface and the difference in temperature is 1.55℃ in the width direction; Offering the ability to remove the heat flux exceed 127w/cm2 and maintaining uneven temperature less than 0.6℃ in the width direction with spray inlet temperature above 12℃ and the pressure difference of import and export within 3.5 Bar.