Numerical analysis of generation of Colburn j and friction f factor for the pin fins of a compact heat exchanger using CFD approach

Abstract

A Compact Heat Exchanger has a large heat transfer area per unit volume, which is achieved by utilizing extremely high-density fins. A pin fin is one of the most frequently used fins because of its advantages such as minimal pressure drop and ease of fabrication by adjusting geometric parameters such as fin height (h), fin spacing (a), fin back pitch (b), and fin diameter (d). A numerical examination was carried out on a pin fin to develop a correlation between the Colburn-j factor and friction f factor. The study was conducted for a large range of Reynolds (Re) values, encompassing both laminar (Re 200–2000) and turbulent regions (Re 2500–15000). ANSYS Fluent was used to conduct the CFD-based numerical analysis, with air at 300 K as the working fluid. The Colburn j factor and friction f factor data were acquired in this numerical study for various Reynolds numbers, as well as non-dimensional geometrical characteristics such as the fin diameter-to-fin spacing ratio (d/a), fin diameter-to-fin back pitch ratio (d/b), and fin diameter-to-fin height ratio (d/h) values. These data were validated using available experimental data from open literature. The correlations of the Colburn j factor and friction f factor were determined over a wide range of Reynolds numbers as well as the geometric characteristics of the pin fins, spanning the complete operational range of Compact Heat Exchangers for Aerospace and other applications.