Effect of Using A Double Coil Tube with Modified Pitch on The Overall Heat Transfer Rate

Abstract

The goal of this work was to design a simple and cost-effective technique for improving the performance of heat exchangers, and the emphasis was on the experimental side while not neglecting the necessity of validating our findings with theoretical results using CFD. A new method was used to enhance the heat transfer inside the heat exchanger by using a coil with modified steps, as the published papers did not previously address this method, which proved its effectiveness. For varied coil pitches, the numerical findings were in good agreement with the experimentally obtained results, with an error rate of less than 8%. To compare results and confirm effective correlation between pitch changes, a double coil tube is manufactured with a fixed pitch and a double coil tube with modified pitches, while maintaining the basic design parameters of tube diameter ( ), shell diameter ( ), height of shell ( ), and coil height ( ) in order to try to increase the overall heat transfer coefficient and heat transfer. This new design enhanced heat transfer and total heat transfer coefficient at Reynolds number (400< <2000), with a 22% improvement in overall heat transfer coefficient. The new design of the coil (modified pitch) also gave an improvement in the flow distribution, which generated a higher secondary flow than the traditional pitch coil.

Keywords

• Double coil heat exchanger
• CFD
• Coil pitch
• Dean vortices
• Reynolds number
• Overall heat transfer coefficient Pitch