Pool boiling of R-134a refrigerant over a thin film aluminum nanostructured coated surface

Experimental investigation of nucleate pool boiling heat transfer analysis of R-134a is carried out on a bare copper surface and over a 50, 100, 150 and 200 nm thickness aluminum nanostructured coated surfaces at 10 degrees C and 15 degrees C saturation temperature. Thin film aluminum nanocoating on the polished copper surface is produced by using Thermal Evaporation Physical Vapor Deposition Technique. The coated surfaces are distinguished with the film thickness, roughness by 2D profilometer, imaging by scanning electron microscopy (SEM) and existing of coating material by energy dispersive X-ray spectroscopy (EDX). The effects of thin film aluminum nanocoating over a bare copper surface with increasing heat flux is thoroughly examined. It is observed that maximum enhancement in heat transfer coefficient at 150 nm thickness of thin film aluminum nanocoated surface is about 2.49 times and 2.81 times compared to copper surface over a heat flux range of 6-90 kW m(-2) at 10 degrees C and 15 degrees C saturation temperatures respectively. Coated surfaces showed a steady increment in heat transfer coefficient values with the increase in the heat flux values. About 26.8% augmentation in heat transfer coefficient of bare copper surface is observed at 15 degrees C saturation temperature compared to 10 degrees C saturation temperature. The heat transfer coefficient values of bare copper surface are validated with Rohsenow and Cooper correlations of nucleate boiling and agreed well with measured data with a standard deviation of +/- 9%, +/- 13.5% for both correlations at 10 degrees C and 15 degrees C saturation temperatures respectively. Copyright (C) 2022 Elsevier Ltd. All rights reserved.