Evaporation of Al₂O₃-water nanofluids in an externally micro-grooved evaporator

Nanofluid is a mixture of liquid and solid phase nano-sized particles that shows a high thermal conductivity compared to its base fluid. With micro-grooves being a good method to increase the surface area for heat transfer, there is potential for nanofluid together with microgrooves to improve the performance of cooling systems. This article aims to study the effect of an externally micro-grooved surface on evaporation of aqueous nanofluids and discuss its potential application. In order to prepare a stable nanofluid, the duration time required for ultrasonication, which is a common technique in the preparation process of nanofluid, was first investigated. Next, experiments were conducted to investigate the effect of the micro-grooved surface on the evaporation rate of the nanofluids under different environmental conditions. Results show that the advantage of the enhanced thermal properties of nanofluids can only be manifested by the presence of micro-grooves. The use of a heat exchanger with nanofluids together with micro-grooves shows a better heat transfer performance than a heat exchanger without micro-grooves using water as the coolant. The enhancement is dependent on the vapor pressure and the largest improvement can be up to 44.6%.