Ramakrishna N. Hegde
Department of Automobile Engineering, Srinivas
Institute of Technology, Mangaluru, Karnataka, India 575029
Shankara Murthy.H. M
Department of Mechanical Engineering, Sahyadri College of Engineering & Management, Mangaluru, Karnataka, India
Heat exchangers are used in diverse processes ranging from conversion, utilization and recovery of thermal energy in various industrial, commercial & domestic applications. In order to transport the desired energy rate with cost and size effectiveness, a combined augmentation technique could be considered as one among many options. The present work aims to investigate heat transfer augmentation using a combination of propeller type metallic turbulators/normal twisted inserts (with different twist ratios TR = 20, 13.3, 9.8) and volume concentrations (0.05%, 0.1%, 0.15%) of Graphene Oxide (GO) nanofluid, for Reynolds number ranging from 500 to 5000. Experimental investigation reveals significant rise in heat transfer to the extent of 6.26% with the twisted insert having a twist ratio of 13.3, and 8.72% using propeller turbulators fitted with ten propellers in 0.15% by volume of nanofluid. The combined heat transfer augmentation technique yielded a maximum 3.25 times higher rate when compared to using only GO-water nanofluid without any inserts; using nanofluid further enhanced heat transfer by 2.56%, with a small pressure drop of 6.03%.