Flow characteristics of liquid nitrogen through solid-cone pressure swirl nozzles

Liquid nitrogen spray cooling is receiving increasing attention due to its promising potential in cryogenic cooling applications. In this study, an experimental apparatus of liquid nitrogen spray cooling system was built. The influence of injection pressure, difference on the flow characteristics of liquid nitrogen through solid-cone pressure swirl nozzles was investigated and compared with that of water. It is found that the mass flow rate of water is much larger than that of liquid nitrogen in the whole range of injection pressure difference. The discharge coefficient of liquid nitrogen increases as the injection pressure difference increases. Contrarily, a slight decreasing trend in the discharge coefficient is observed for water. At low injection pressure differences, the orifice diameter presents a significant influence on the discharge coefficient. The nozzle with a larger orifice diameter exhibits a larger discharge coefficient. As the injection pressure difference increases, the influence of orifice diameter reduces. A discharge coefficient correlation for liquid nitrogen was developed based on the experimental data. In this correlation, the influence of gas-liquid phase change in the nozzle was taken into consideration. The results show that the proposed correlation exhibits a good agreement with the experimental data. (C) 2016 Elsevier Ltd. All rights reserved.