Experimental study on heat transfer performance of spray cooling on high heat flux rail surface

Lack of the principle of selecting the best spray cooling parameters will be detrimental to the effective thermal management of the high heat flux electromagnetic rail. This paper conducted experimental study on the heat transfer characteristics and cooling effect of spray cooling on a high heat flux vertical rail surface, an experimental system was designed and built, and the main influencing factors on the cooling effect of the rail were experimentally studied. the results showed that with the increasing spray distance, the critical heat flux (CHF), average heat flux (AHF) and integrated heat transfer coefficient (IHTC) all increased first and then decreased, while the average temperature of rail surface gradually decreased. When the spray increased to 25 cm, the CHF, AHF and IHTC reached the maximum value of 241.69 W/cm², 44.10 W/(cm² K) and 14007.02 W/(m² K), while the average surface temperature (AST) of rail reached the minimum value of 55.77 ℃. With the increase of spray angle, the CHF, AHF and IHTC shown a trend of first increasing and then decreasing, while the AST of rail shown a trend of first decreasing and then increasing. The best cooling effect can be obtained at the spray angle of 0°. As the cooling water pressure at the nozzle inlet increased, the CHF, AHF and IHTC all shown a gradually increasing trend, while the AST of rail shown a gradually decreasing trend. When the cooling water pressure increased to 0.5 MPa, the CHF, AHF and IHTC reached the maximum value, while the AST reached the lowest value. The results have a positive guiding significance for improving the spray cooling effect of the high heat flux rail surface.