Effect of sparger on injection cooling performance of cryogenic liquids.

Injection cooling is used for short term storage of cryogenic liquids by injection of a gas through the liquid. This causes liquid subcooling that reduces the boil off loss of liquid. Among various factors, sparger design (type, diameter of hole and number of holes) plays a significant role as it dictates the bubble dynamics in the liquid tank and thus the gas-liquid heat and mass transfer. This is the first work, to the best knowledge of the authors, on the sparger design in terms of the hole diameter and number of holes, on the cooling performance of such a system. Four types of sparger (single orifice, ring/spider, perforated plate and porous plate sparger) available commercially have been considered. A mathematical model of injection cooling based on lumped parameter approach has been developed and simulation was carried out to determine the effect of sparger design. Liquid subcooling was obtained for all the four types of spargers. It was observed that the rate of cooling increases with the decrease in sparger hole diameter. However, the effect of number of holes on liquid subcooling was found to be negligibly small.