Experimental Investigations on Heat Transfer Enhancement in Double Pipe Heat Exchanger Using PT-SCA and PTT-SCA Twisted Insert Profile

Abstract

The continuous rise in the price of energy and the materials has necessitated industries to gear-up their efforts in modifying the heat exchangers for higher outputs. The proposed work on heat exchanger considers technical aspects such as heat transfer modes, pressure-drops, long-lasting performance along with economic aspects. The compactness in size and minimizing energy requirement is significant in the design of tubes for improved heat transfer. In heat exchanging devices, the heat transfer rate could be enhanced by generating disturbance in the fluid flow thereby breaking the thermal boundary layers that hinder effective heat exchange. But such a process would require increased pumping power. Hence, this work attempts to achieve improved heat transfer rate in a double pipe heat exchanger (DPHE) of counter-flow type that consumes economical pumping power and involves a technique in which inserts of varied profiles are used to disrupt the flow in the tube. The different types of insert profiles used include Plain Tape (PT), Plain Tape Step-Cut Arc (PT-SCA), and Plain Twisted Tape Step-Cut Arc (PTT-SCA) to study their performance in heat exchange rate. The effect of an insert is that the heat transfer surface gets enlarged for convection and creation of turbulence in the fluid flow, both contribute for increased heat transfer. PTT-SCA insert provided the higher thermal enhancement for DPHE.