Enhancing the Efficiency of the Double-Tube Heat Exchanger by Using a Twisted Inner Tube

Abstract

This study utilized two double tube-type heat exchangers. The first exchanger employed a smooth inner tube, while the second one utilized a twisted inner tube. The shell was constructed of plastic (PVC), while the tube was made of copper with a length of 1000 mm, an outer diameter of 62.24 mm, a smooth tube inner diameter of 14.2 mm, and an equivalent diameter of 11.8 mm for the twisted tube. To minimize heat loss, the shell was insulated externally with a thermal insulator. A flow rate of 3 liters per minute of hot water was passed through a ring-shaped tunnel, with an inlet temperature of 63 °C, to enhance the heat exchanger's performance. The experimental results of the two heat exchangers (smooth and twisted inner tubes) were compared, and the use of water as the primary fluid led to improved performance. The twisted inner tube-type heat exchanger achieved a maximum efficiency of 0.33 at a volumetric flow rate of 5 liters per minute, while the maximum improvement in effectiveness was 65.71% at a volume flow rate of 3 liters per minute in the twisted inner tube-type heat exchanger.