Experimental study on hydro-thermal behavior of water, ethylene glycol-based Cu/Ni bi-metallic nanofluid in an air-finned cross-flow heat exchanger
摘要
In the current study, overall heat transfer coefficient of water and ethylene glycol (60DW:40EG)-based bi-metallic nanoparticles in a cross-flow heat exchanger has been evaluated under the laminar flow regime. The effect of concentration in the range of 0.25, 0.5 and 1.0 vol.% of stabilized Cu-Ni/ (60DW:40EG) nanofluid has been measured with variation in flow rate in the segment of 12–15 LPM. The air-cooled cross-flow heat exchanger consisted of 2 rows of vertical aluminum tubes, and each row contained 76 tubes. Multi-louvered fins are inaugurated on the outer surface of the tubes, and air with different velocities (3.16, 4.26, 5.33 and 6.22 m s–1) is allowed to pass through them. In addition, the hot working fluid is permitted to enter into the radiator at different temperatures, viz. 50, 60 and 70 °C. The result demonstrates that the waterside Nusselt number gets enhanced by 4.262% and 11.92% with an increase in Reynolds number at 0.25 and 0.5 vol.% concentration, respectively. The friction factor is enhanced by 52.631%, 26.315% and 15.789% for 1.0%, 0.5% and 0.25% nanofluid concentration, respectively. However, drops in friction factor by 35.578% at 0.25, 38.636% at 0.5 and 29.916% at 1.0 vol% have been observed when the Reynolds number increases from 144 to 180. On the air side, the maximum improvement in Nusselt number by 51.91% with 1.0% vol. concentration of nanofluid is observed and that of Colburn factor of air gets enhanced by 16.439%, 24.657% and 41.096% for 0.25%, 0.5% and 1.0% concentration of nanofluid. The effectiveness of the heat exchanger shows a significant rise to 75.29% with 1.0% vol. nanofluid concentration, whereas that is 68.05% using base fluid.