Experimental study on heat transfer characteristics of CNTs/Al 2 O 3 nanofluids in personal cooling system based on thermoelectric refrigeration

Nanofluids have been considered as one of the most promising working fluids to significantly enhance heat transfer in a variety of applications. This paper presents experimental study on the heat transfer characteristics of Carbon Nanotube (CNTs) and Al 2 O 3 nanofluids in a natural circulation loop for a personal cooling system based on thermoelectric cooler. The nanofluids are prepared by CNTs or Al 2 O 3 in the base fluid. In the experimental system, the nanofluid flows into the heat exchanger filled with high porosity metal foam, and is cooled by a thermoelectric cooler. The nanofluid then flows into the heat transfer coil by natural circulation, thereby absorbing heat released from a human body, which flows into the heat exchanger again to complete a natural circulation. The heat transfer characteristics for CNTs and Al 2 O 3 nanofluids with deionized water as the base fluid are experimentally determined and compared with those of deionized water obtained by the experimental system under the identical conditions. The effects of some factors, such as the particle sizes, volume fractions, and cooling temperatures, on the heat transfer characteristics of nanofluids are experimentally studied. The mechanism for the heat transfer enhancement of nanofluids in the personal cooling system is explored in detail. The obtained results may be useful to the development and practical operation of personal cooling system based on thermoelectric refrigeration.