Experimental investigation on heat transfer performance of Fe2O3/water nanofluid in an air-finned heat exchanger

In this paper, the overall heat transfer coefficient of water based iron oxide nanofluid in a compact air-cooled heat exchanger has been measured experimentally under laminar flow conditions. The concentrations of 0.15, 0.4 and 0.65 vol.% of stabilized Fe2O3/water nanofluid have been examined with variation of flow rates in the range of 0.2–0.5 m3/h. For better dispersion of iron (III) oxide nanoparticles in water, 0.8 wt% polyethylene glycol has been added and pH has been adjusted to 11.1. The air-cooled heat exchanger is consisted of 34 vertical tubes with stadium-shaped cross section and air makes a cross flow through the tube bank with variable flow rates ranging from 740 to 1009 m3/h. Also, hot working fluid enters the heat exchanger at different temperatures including 50, 65, and 80 °C. The results demonstrate that increasing the nanofluid flow rate and concentration and the air Reynolds number can improve the overall heat transfer coefficient and heat transfer rate whereas enhancing the inlet temperature has a negative effect on the overall heat transfer coefficient and a positive effect on the heat transfer rate. Meanwhile, the maximum enhancements of the overall heat transfer coefficient and heat transfer rate compared with base fluid (distilled water) are respectively equal to 13% and 11.5% which is occurred at the concentration of 0.65 vol.%. •Overall heat transfer coefficient in the car radiator measured experimentally.•Nanofluids showed greater heat transfer performance compared with water.•Increasing liquid and air Re increases the overall heat transfer coefficient.•Increasing the inlet liquid temperature decreases the overall heat transfer coefficient.