Experimental investigation of enhanced heat transfer of a car radiator using ZnO nanoparticles in H₂O–ethylene glycol mixture

Water is mainly used in moving vehicles as a coolant to remove the engine’s heat mostly through forced convection heat transfer. However, mixtures of water and anti-freezing materials like ethylene glycol (EG) are also used as coolant. In the present research work, a mixture of EG and water (50:50) mixed with ZnO nanoparticle, called nanofluid, is utilized in a car radiator. Different volume concentrations of ZnO nanoparticles (0.01%, 0.02%, 0.03% and 0.04%) have been added in base fluid. It has been observed that overall heat transfer coefficient and heat transfer rate enhanced with different volume concentrations by mixing ZnO particle in base fluid, while flow rate varied in a range of 4–12 LPM (litre per minute). A maximum enhancement in heat transfer rate up to 36% has been observed experimentally at 0.04% volume concentration of ZnO nanoparticle. Greater heat transfer rate has been observed at low flow rate, i.e. at 4 LPM and 6 LPM, as compared to higher flow rate, and contribution of inlet temperature is found to be minimum in transferring the heat.