Heat Transfer Characteristic Analysis of Double Pipe Heat Exchanger With A Continuous Helical Baffle By Numerical Analysis

Abstract

In this paper, Three-dimensional computational fluid dynamics (CFD) simulations have been performed to study the annulus side laminar flow distribution, heat transfer characteristic, and pressure drop. This paper shows the effect of Reynolds number (Re), helical pitch and baffle height on Nusselt number (Nu), heat transfer coefficient, heat transfer rate, effectiveness & pressure drop of a double pipe heat exchanger with or without a continuous helical baffle. There are eight geometry was drawn by the design modeler such as pitch 102 mm, pitch 128mm, pitch 170mm, pitch 210mm, pitch 250mm with the pitch height 5mm & again for the pitch 102mm, spiral height 7mm, height 9mm, height 11mm. The outer diameter of the inner tube & inner diameter of the outer tube is fixed in all cases. The spiral was drawn 250 mm far from the inlet because the flow is fully developed after 250 mm. The inner pipe's outer surface is kept at a constant temperature of 340k. The temperature of the cold fluid is 293K. The outer tube’s the outside wall is kept adiabatic. The fully developed laminar flow passes through the annulus side with Reynolds numbers vary 700 to 1500.When the increases the pitch of the helical the Nusselt decreases. On the other hand, the Nusselt number increase while increasing helical height. If the comparison will take place between plain tube and helical tube the 78.53 % Nusselt number increases while using helical baffle for the pitch 102 mm & Reynolds number 1500. While using pitch 102 mm with a height of 11 mm instead of a plain tube the Nusselt number increases by 133.89 % for the Reynolds number 1500.When the increases the pitch of the helical the effectiveness decreases. On the other hand, the effectiveness increase while increasing helical height. When the increases the pitch of the helical the pressure drop decreases. On the other hand, the pressure drop increase while increasing helical height.