Airside Heat Transfer and Pressure Drop on the Spiral Finned-Tube Compact Heat Exchanger with Sharp Turns

Abstract

This study aims to examine the airside heat transfer and pressure drop on the outer surface of a spiral finned-tube compact heat exchanger with sharp turns. The heat exchanger is made of a tube with sharp turns with an inside and outside diameter, namely 0.02, and 0.022 m. The length of the heat exchanger is 0.3 m with a turn length of 0.082 m and the total length of the heat exchanger is 6 m. The heat exchanger fins are made of aluminum with a thickness of 0.0003 m and the fin diameter is 0.042 m. The fin pitch of the heat exchanger tested was varied, namely 0.01, 0.02, 0.03, 0.05, and 0.07 m. Water is heated by a heater to a temperature of 80 ℃ and then circulated into the heat exchanger with a mass flow rate of 0.39 kg/s. The air inlet temperature is constant, and the air outlet temperature is measured using a thermocouple. The air velocity was varied, namely 2.4, 2.8, and 3.4 m/s. The results showed that to some extent the smaller the pitch between the fins, the higher the heat transfer rate. While the pressure drop is being higher as the pitch between the fins decreases. Heat exchanger with a pitch of 0.02 m produced the highest heat transfer rate compared to other configurations. The pressure drop in the heat exchanger with a pitch of 0.02 m is also lower than that at a pitch of 0.01 m. These results indicate the optimum fin pitch for this study is 0.02 m, where the high heat transfer rate with the low-pressure drop is more effective for industrial thermal system applications.