Experimental Evaluation of Heat Transfer Rate in Automobile Cooling System by Using Nanofluids

Abstract

The demand for more powerful engines in smaller hood spaces has created a problem of insufficient rates of heat dissipation in automotive radiators. Insufficient heat dissipation can result in the overheating of the engine, which leads to the breakdown of lubricating oil, metal weakening of engine parts, and significant wear between engine parts. To minimize the stress on the engine as a result of heat generation, automotive radiators must be redesigned to be more compact while still maintaining high levels of heat transfer performance. Moreover, this can be done without significant modification to the existing internal radiator structure, this can be done by increasing (i) heat transfer area, (ii) temperature, and (iii) heat transfer co-efficient. However, technologies have already reached their limit for the cases heat transfer area and temperature. Recently many researchers found that dispersing nano-sized particles into the liquids result in higher heat transfer co-efficient of these newly developed fluids called nanofluids compared to the traditional liquids. This kind of fluids are now of great interest not only for modifying heat transfer performance of fluids, but also for improving other different characteristics such as mass transfer and rheological properties of fluids. A major goal of the nanofluids project is to reduce the size and weight of the vehicle cooling systems by greater than 10% despite the cooling demands of higher power engines. Nanofluids enable the potential to allow higher temperature coolants and higher heat rejection in the automotive engines. It is estimated that a higher temperature radiator could reduce the radiator size approximately 30%. In this paper we have considered two nanofluids comprising of aluminium oxide and copper oxide in water mixture has been studied experimentally to compare their performance in automobile radiator. The study shows that for a particle volume concentration of 0.1%, both nano fluids show improvements in their performance over the base fluid. Comparison has been made on the basis of three important parameters; equal mass flow rate, equal air flow rate and equal radiator inlet temperature of coolant. For both nanofluids exhibit increase in heat transfer rate compared to base fluid.