Evaluation of Using Al2O3/EG and TiO2/EG Nanofluids as Coolants in the Double-tube Heat Exchanger

In the present paper, Al2O3/EG and TiO2/EG nanofluids with volume concentration of up to 10% have been used as coolants in a double-tube heat exchanger under laminar flow conditions. Thermal conductivity is an important parameter in the field of nanofluid heat transfer. Therefore, this paper presents two experimental models to predict the thermal conductivity of nanofluids. Based on these models, heat transfer relation between the hot solvent and nanofluid coolants has been investigated theoretically, as the first step. Because nanofluid coolants radiate the same amount of heat, they can be used in the heat exchanger to optimize the heat transfer area and the flow rate of the coolant. The results proved that as the probability of collision between nanoparticles and the heat exchanger wall increases, due to using higher concentration of coolants, the total heat transfer coefficient increases. Consequently, in this paper, heat transfer coefficient, total heat transfer coefficient, friction factor, pressure drop and pumping power for Al2O3/EG and TiO2/EG nanofluid coolants in the double-tube heat exchanger are calculated.