Fabrication of aluminum coatings via thermal evaporation technique for enhancement of pool boiling performance of R-600a

Abstract

In this study, thermal evaporation technique was scrutinized experimentally to fabricate Al coatings on plain aluminum heating surface and improve the pool boiling heat transfer (BHT) performance of R-600a. The Al coatings were fabricated by varying the coating thickness (100 nm, 150 nm, 200 nm and 250 nm). Pool BHT performance of R-600a on a plain aluminum and four Al coated heating surfaces (Al_100 nm, Al_150 nm, Al_200 nm and Al_250 nm) was investigated at a constant saturation temperature of 10 °C. All data were taken at heat fluxes ranging from 9.39 kW/m2 to 74.98 kW/m2. Decrement in the wall superheat was recorded with the increment in the coating thickness, and maximum decrement was observed for the surface with 250 nm thick coating. It was further observed that with the increment of the coating thickness, the HTC of the Al coated heating surfaces was increased than the plain aluminum heating surface. The maximum enhancement in HTC for the Al_250 nm heating surface was 51.62% higher than the plain aluminum heating surface.