Experimental study on the heat transfer performance of the two-phase spray cooling of Liquefied natural gas

Abstract

To improve the heat dissipation capability of future aircraft, the design of thermal management systems using cryogenic fuels has become one of the trending research directions in recent years. This study explores the feasibility of using liquefied natural gas (LNG) for spray cooling applications. An LNG spray cooling experimental system is constructed. The influence of spray flow rate, spray height, and surface roughness on spray heat transfer characteristics are discussed. Results show that LNG's critical heat flux (CHF) increases with flow rate (61.6 % higher at 0.3 kg/min than at 0.12 kg/min) and decreases with spray height (43.4 % higher at 11.5 mm compared to 31.5 mm). Surface roughness also enhances heat transfer, with a 12.4 % higher CHF observed on rough surface. The maximum CHF of 341 W/cm² of all experimental results is obtained with the surface sanded by P120 sandpaper at the spray height of 21.5 mm and the spray flow rate of 0.25 kg/min. Dimensionless correlation for LNG spray cooling is proposed as a function of Reynolds, Prandtl, Weber, and Jacob numbers. The experiments of water spray cooling using the same nozzle are also investigated to compare the differences in heat transfer capacity and application prospects of water and LNG.