Developing Al@GNPs composite coating for pool boiling applications by combining mechanical milling, screen printing and sintering methods

4

ABSTRACT

Due to ever growing ‘demand of the energy’ and for the capability to remove large quantities of heat from the heating surface, pool boiling heat transfer becomes the main attraction for research in search of finding the efficient means for transferring heat. Following this trend, the present study also investigated the pool boiling performance of refrigerants, mainly, pure refrigerant (R-134a) and natural refrigerant (R-600a), on the plain aluminium and two graphene nanoplatelets (GNPs) reinforced aluminium matrix composite (Al@GNPs) coated aluminium heating surface with different thickness (50 ± 5 µm and 125 ± 6 µm), which were synthesised by the help of a three-step technique involving mechanical milling, screen printing and sintering process on the plane aluminium surface. The test is conducted at a saturation temperature of 10°C and heat fluxes ranging from 8.28 kW/m² to 75.61 kW/m^2. Test results of R-134a and R-600a were compared. It is observed that thicker Al@GNPs composite coated surface showed better HTC but with reduced ‘onset of nucleate boiling’ (ONB) wall superheat than the plain Al surface.

KEYWORDS:

• Graphene-nano-platelets (GNP)
• onset of nucleate boiling (ONB)
• R-134a
• R-600a
• screen printing
• wall superheat

Nomenclature

Table

Acknowledgments

This experimental work was performed in the Phase Change Heat Transfer Laboratory, Mechanical Engineering Department, NIT Agartala, India. This Laboratory was developed under the DST-FIST Project. It is further acknowledged the help extended by the Mechanical Engineering Department, BITS Pilani, India, in this work.

Disclosure statement

No potential conflict of interest was reported by the author(s).