Experimental analysis of heat transfer and friction factor of nanofluid as a coolant in a corrugated plate heat exchanger

Effects of nanofluid (Al2O3 in water 2,3 and 4 vol.%) and water as coolants on heat transfer, frictional losses, and exergy loss in a counter flow corrugated plate heat exchanger were experimentally investigated. The required properties of the nanofluid were measured. It was observed that the heat transfer characteristics improve with increase in Reynolds- and Peclet-number and with decrease in nanofluid concentration. For a given heat load, the required pumping power increased with increase in nanofluid concentration. Both power consumption and heat transfer rates were lower for water in comparison to the nanofluid for flow rates of 2-5 lpm for hot and cold fluids. Further, for a given heat load the nanofluid required lower flow rate but suffered higher pressure drop than that for water. For a given pumping power more heat could be removed by the nanofluids relative to water, though the maximum heat transfer rate was found with the lowest concentration of nanofluids. The non-dimensional exergy loss was found to remain constant for water. Among the four coolants considered for experiment, the non-dimensional exergy loss was lowest with 2 vol.% nanofluid for a coolant flow rate up to 3.7 lpm beyond which water gave the least value. Correlation equations were obtained for Nusselt number and friction factor for both water and the nanofluid. (C) 2011 Elsevier Inc. All rights reserved.