Enhanced condensation with active methods

Abstract

Condensation of low surface tension fluids is important in liquefied natural gas processing and refrigeration systems. Current state of the art low surface energy low hysteresis coatings are not able to achieve dropwise condensation below 10 mN/m. Surface acoustic waves are proposed as an active method to shed thin condensate films to reduce their thermal resistance and improve heat transfer coefficients. Interdigitated electrode patterns were fabricated on piezoelectric LiNbO3 wafers and SAW waves were generated with RF voltages in the 12.5 - 100 MHz regime. These were tested in the in-house condensation rig with Ethanol, Pentane, Hexane and Perfluorohexane. Heat transfer coefficients showed more than 2X improvement over standard filmwise condensation. Further, the effect of refrigerant side heat transfer enhancement in a condenser operating in a vapor compression refrigeration cycle is studied as a potential application.