Abstract:
Development of smart heating surfaces to enhance the performance of pool boiling heat transfer (BHT) has great significance in pool boiling applications. This paper presents the results of a study of improved pool BHT performance of R-134a on horizontal Al surfaces with microporous coating (diameter = 9 mm) at saturation temperature. Microporous Al coatings were fabricated by electrodeposition using AlCl3/urea ionic liquid (IL). The effect of various electrolyte temperatures (30°C, 40°C, 50°C, and 60°C) on the morphology, microstructure, porosity, thickness, and surface roughness of Al coatings was investigated. The pool BHT experiments were performed for increase in the heat flux, varying from 9.51 kW/m2 to 75.14 kW/m2. For the microporous Al coating electrodeposited at an electrolyte bath temperature of 30°C, 40°C, 50°C, and 60°C, the heat transfer coefficient (HTC) value was increased by 58%, 75%, 92%, and 109%, respectively, compared with the bare Al surface. The differences in the HTC augmentation for Al-coated surfaces can be explained by variations in the thickness of the microporous structure and in their surface characteristics such as porosity and surface roughness.