LAUSR

The heat transfer performance of the air–water double pipe heat exchanger (HE) was experimentally investigated. Segmental baffles with semi-circular perforations were introduced in the annular side of HE. Each baffle contains semi-circular fins. Air was used as a working fluid in the annular while, water for the inner tube. Seven different air Reynold’s numbers range from 2700 to 4000 were selected. While water side Reynold’s number fixed at 34,159. Three different semi-circular perforation diameters were studied (30, 25, and 20 mm) to investigate their effect on HE thermal performance. The Nu number, overall heat transfer coefficient, friction factor, and thermal performance factor (TPF) were calculated. Also, compassion for the baffled and un-baffled pipe was done. It was observed that the thermal performance of the baffled pipe HE was better than the un-baffled one. The average overall heat transfer coefficient increases by 29.7%, 62%, and 80.6% by using perforated baffles with 30, 25, and 20 mm perforation diameters. The TPF of the heat exchanger with all studied perforated baffles cases is above unity and the best thermal performance obtained by using baffles was with 20 mm perforation diameter.