Experimental and numerical investigations of nanofluids performance in a compact minichannel plate heat exchanger

Three nanofluids comprising of aluminum oxide, copper oxide and silicon dioxide nanoparticles in ethylene glycol and water mixture have been studied theoretically to compare their performance in a compact minichannel plate heat exchanger (PHE). The study shows that for a dilute particle volumetric concentration of 1%, all the nanofluids show improvements in their performance over the base fluid. Comparisons have been made on the basis of three important parameters; equal mass flow rate, equal heat transfer rate and equal pumping power in the PHE. For each of these cases, all three nanofluids exhibit increase in convective heat transfer coefficient, reduction in the volumetric flow rate and reduction in the pumping power requirement for the same amount of heat transfer in the PHE. On the cold fluid side of the heat exchanger, a coolant, HFE-7000, has been studied, which has the potential for application in extremely low temperatures, but has not been investigated widely in the literature. Experimental data measured from a minichannel PHE in a test loop using water as the base fluid have validated the test apparatus with excellent agreement of predicted heat transfer rate and the overall heat transfer coefficient with the experimental values. From experiments on a 0.5% aluminum oxide nanofluid, preliminary correlations for the Nusselt number and the friction factor for nanofluid flow in a PHE has been derived. This apparatus will be useful to test different kinds of nanofluids to ultimately determine the effects of parameters such as: volumetric concentration, particle size and base fluid properties on thermal and fluid dynamic performance of nanofluids in compact heat exchangers.