Performance Evaluation of an Automobile Radiator using CuO/Glycerol based Nanocoolant

Abstract

The ever-increasing trend of energy consumption along with the miniaturization of equipment has led to the discovery of a new class of heat transfer fluids called nanofluids, having extraordinary thermo-physical properties. These nanofluids are colloidal suspensions of nanoparticles in the conventional base fluid such as water, EG, glycerol, etc. In this study, experimental investigation on the heat transfer performance of automobile radiator using DI water, EG based coolant, and glycerol solution along with the CuO/glycerol nanocoolant has been carried out. The overall heat transfer coefficient has been calculated by using the conventional LMTD method. The copper oxide (CuO) nanoparticles are added to the base fluid in three different concentrations of 0.5%, 1.0%, and 1.5% by vol. along with 0.5 wt. % of SDS (sodium dodecyl sulfate) as a surfactant. SDS has been used to achieve homogeneous suspension of nanoparticles in the base fluid with longer stability. The coolant side Reynolds number is varied from 25 to 325 while that of the air side is kept constant at 190. The inlet liquid temperature is kept constant at 60C and care has been taken to keep the ambient conditions constant at 20C DBT and 45% RH. Overall, experiments have been conducted on six coolant flow rates (1, 2, 4, 6, 8, 12 lpm) and four nanocoolants of different concentrations (0.0%, 0.5%, 1.0% and 1.5% by vol.). The effects of these parameters have been studied on temperature drop, heat transfer rate, Nusselt number, convective heat transfer coefficient, and overall heat transfer coefficient for both the coolant and the air side heat transfer. Results show that enhancement of up to 32.5% can be achieved in overall heat transfer coefficient (tube side) using CuO/glycerol nanofluid of 1.5% by vol. conc. However, enhancements of up to 15.3% and 22.2% respectively were observed when the lower concentrations of 0.5% and 1.0% by vol. were used. Moreover, the effect of nanoparticle concentration has also been studied on the pumping power, where the increase is found to be more at lower coolant flow rates and reduced towards higher coolant flow rates.