An experimental investigation of hydrodynamic and heat transfer characteristics of surfactant-water solution and CNT nanofluid in a helical coil-based heat exchanger

Abstract

Nanofluids are gaining attention due to their excellent heat transfer characteristics as compared to conventional basefluids. In this study, CNT nanofluid was prepared using double distilled water (as basefluid) and mixed surfactant (a mixture of surfactant SDBS and GA) keeping the Surfactant/CNT ratio 1. Hydrodynamics as well as heat transfer characteristics of water, surfactant-water solution and CNT nanofluid were investigated in coil tube heat exchanger. Thermo-physical properties of surfactant-water solution and CNT nanofluid were also examined. Results showed no difference in viscosity of surfactant-water solution in comparison to water but a slight increment in density of the surfactant-water solution compared to water. Also, it was found that friction factor was increased with increase in Reynolds number for water, surfactant-water solution and CNT nanofluid. The overall heat transfer coefficient was 62.62% higher for CNT nanofluid at 5000 Reynolds number as compared to water. No enhancement was observed in heat transfer coefficient for surfactant-water solution in comparison to water. These results concluded that CNT nanoparticles play a major role to enhance the heat transfer rate of nanofluid in contrast to water.