Determination of Optimum Concentration of Nanofluid for Process Intensification of Heat Transfer Using Corrugated Plate Type Heat Exchanger
Abstract In this study cooling of hot water is taken up using a compact heat exchanger such as corrugated plate type heat exchanger and with utility fluid as a nanofluid prepared from mixing Al2O3 in water. In general a monotonic increase of 30 % to 70 % in overall heat transfer coefficient is observed for increase in nanofluid concentration as well as its flow rate. An optimum concentration of nanofluid is hence not possible to be found as heat transfer coefficient exhibited a monotonic trend. But there is a penalty for using nanofluid of higher concentrations in heat exchangers in the form of additional hydraulic power required to supply the nanofluid due its higher viscosity. Hence, as a novel approach, a target temperature drop of 15 °C for hot fluid (with constant flow rate) is assumed and the minimum critical flow rate of cold nanofluid of various concentrations required for achieving this is determined using simulation. For such a critical flow rate at various nanofluid concentrations, the determined hydraulic power (product of pressure drop and flow rate) exhibited a global minimum around 0.75 % volume concentration of Al2O3 in water. Thus this article presents the process intensification procedure for the heat exchangers using nanofluids as heat transfer enhancement option.