Impact of Surface Wettability on Flash Spray Cooling at Low Pressure: An Experimental Study

The influence of the surface wettability and pressure on the flash spray cooling was experimentally investigated with the lab-built test platform.The surface modification of red-copper via chemical route reduced its water contact-angle from 94.9° to 38.1°.The preliminary results show that the surface wettability and pressure had a major impact.To be specific,the vaporization on the control/modified Cu-surfaces went through 4 distinctive stages:including the deposition of water film,vigorous vaporization,formation/sustaining and shrinking of the triple-phase interface line.The surface temperature of modified Cu decreased much faster than that of the control sample;as the pressure decreased,the vaporization rate rapidly increased,resulting in a lower final equilibrium temperature.When it comes to the lowest temperature cooled by flash spray,the optimized pressure was 1.9 kPa,depending little on the initial temperature of sprayed distilled-water.