Laminar Heat Transfer Augmentation through A Square Duct and Circular Tube Fitted with Twisted Tapes

Abstract

Experimental studies on friction factor and heat transfer characteristics for the laminar flow of ethylene glycol in a square duct fitted with twisted tapes of different twist ratios under nearly uniform wall temperature conditions are reported in this article. The Nusselt numbers were found to be 5.44–7.49 and 2.46–4.87 times that of plain square duct forced convection values based on constant flow rate and constant pumping power criteria, respectively, for y = 2.66. The augmented friction factor and Nusselt number for a square duct is about 1.9 and 2.10 times higher than that for an augmented circular tube.

Keywords:

• square duct
• heat transfer augmentation
• twisted tapes
• laminar flow
• twist ratio
• uniform wall temperature

Acknowledgments

This work was done by S. V. Patil as a part of his doctoral programme from July 2007 to July 2010 at the department of Chemical Engineering, Dr. Babasaheb Ambedkar Technological University, Lonere, under the guidance of Professor P. V. Vijay Babu. The authors are thankful to the authorities at Dr. Batu for providing all facilities necessary for completing this work.