Experimental study on the spray cooling heat transfer performance and dimensionless correlations for ethylene glycol water solution

Abstract

With the increase of airborne electronic equipment heat dissipation, spray cooling with ethylene glycol as working fluid may be an effective way. In this paper, the influence of ethylene glycol mass fraction, mass flow rate, and nozzle inlet temperature on the spray cooling heat transfer performance are experimentally studied. Results show that the ethylene glycol mass fraction significantly affects the heat transfer performance. When the mass fraction increases from 0 to 100%, the maximum reduction of surface heat transfer coefficient is about to 58% at different heat flux. The increase of dynamic viscosity and the decrease of specific heat capacity and thermal conductivity are the direct cause, which significantly weaken heat transfer performance. As the nozzle inlet temperature rises from –2 to 50℃, the surface heat transfer coefficient increases gradually and tends to be stable. The evaporation intensity has the same trend with inlet temperature, and also evaporation is a non-negligible heat transfer form in spray cooling. In addition, a more widely applicable Nusselt number dimensionless correlation of ethylene glycol solution is proposed within the 10% error. The investigation in wider range of temperature and mass fraction will provide theoretical analysis and data support for the airborne application of spray cooling.