Experimental investigation on dimensionless numbers and heat transfer in nanocompositefluid shell and tube heat exchanger

In the present study, the thermal performance of horizontal shell and tube heat exchanger with a new TiO2–Ag/Distilled water nanocompositefluid in comparison with conventional coolant water is experimentally investigated. Thermal conductivity of 0.2 vol% TiO2–Ag/distilled water is about 17% higher than water at 60 °C. The tube flow Reynolds number is decreased, while the Prandtl number is increased due to the increase in viscosity of the nanocompositefluid. Consequently, the Nusselt number difference between nanocompositefluid, and water is reduced and the difference decreases with the increase in the tube flow rate. For nanocompositefluid, the tube side heat transfer coefficient is 13.43%, the overall heat transfer coefficient is 12.16%, and heat transfer rate is 18.4% higher than base fluid water at a shell fluid flow rate of 6 lpm at 60 °C and tube fluid flow rate of 4 lpm at 35 °C. The enhancement in heat transfer with nanocompositefluid is higher mainly due to its enhanced thermal conductivity. The pumping power is 1.95 times higher for nanocompositefluid for the same volume flow rate. But, for the same heat load, the required volume flow rate of nanocompositefluid and the size of heat exchanger are reduced, and pumping power penalty is also reduced. Thus, the present experimental study ascertains that TiO2–Ag/distilled water nanocompositefluid has the potential to improve the thermal performance of the heat exchanger and reduce the cost of heat exchanger by reducing the size of the heat exchanger for the same heat capacity.