Experimental investigation of enhanced cooling performance with the use of hybrid nanofluid for automotive application

Abstract

The hybrid nanofluids exhibit remarkable thermal performance as coolant in automobile radiators. Hybrid nanofluid predominantly improves the heat transfer performance as compared to conventional coolants. Therefore, the present research work is focused on the hybrid nanofluids as coolant for automobile radiator. Due to improved heat transfer rate of hybrid nanofluid, the overall size of automobile radiator can be reduced. The heat transfer characteristics of Multi Walled Carbon Nanotubes (MWCNT)-Copper Oxide (CuO)/deionized water and Graphene/deionized water nanofluids were analyzed experimentally compared with deionized water. The experimental work aimed to find thermo physical properties such as thermal conductivity, specific heat capacity, and density of hybrid nanofluids. The concentrations of MWCNT-CuO and Graphene nanofluid were varied from 0.05 to 0.15wt%. Significant improvement in the stability was observed by magnetic stirring and ultra-sonication process with the Sodium dodecyl sulphate (SDS) surfactant. The effect of SDS surfactant on stability of MWCNT/CuO and Graphene nanofluid experimentally investigated. Effect of coolant flow rate on heat transfer rate is studied experimentally by varying coolant flow rate (3-7 lit/min) for different temperature (50°C to 80°C) conditions.Based on the experimental observations it was noticed that the Nusselt number of the hybrid nanofluid is linear relationship with the nanocoolant flow rate and a highest Nusselt number of 37.7 was observed at 0.1 %wt and 7 lit/min nanocoolant flow rate at 80°C inlet temperature. It was observed that aqueous based MWCNT-CuO hybrid nanofluid enhanced the convective heat transfer coefficient by 295% as compared to conventional base fluid at 80°C and 7 lit/min nanocoolant flow rate. It was also observed that the convective heat transfer coefficient for MWCNT-CuO/Deionized water hybrid nanofluid is 30% more than graphene based nanofluid at higher operating temperature (80°C) and higher coolant flow rate (7 lit/min). Further experiments were conducted at higher mass flow rates and temperature to investigate the maximum heat transfer ability of Graphene-CuO and MWCNT-CuO hybrid nanofluids as a feasible nanocoolant for automotive application.