Enhancing Heat Exchanger Efficiency Using Computational Fluid Dynamics (CFD)Techniques

The aim of the present study was to assist in the development of increased thermal productivity of shell-and-tube type heat exchangers through computational fluid dynamics analysis along with design optimization of heat exchangers. Simulations were run for various Reynolds numbers between 5,000 and 30,000, using the standard k–ε turbulence model to evaluate how different conditions of flow and structural configurations affect a heat exchanger's overall performance. In addition, baffle spacing ratios and turbulence-inducing elements were tested to examine the effects of these parameters on heat transfer and pressure drop within the shell-and-tube heat exchangers. It was concluded that both increasing the number of baffles spacings along with the introduction of flow-disturbing elements would increase the convective heat transfer capabilities of the heat exchangers. Specifically, the Nusselt number and heat transfer coefficient were significantly increased due to the combination of the reduced baffle spacings and the controlled experimental flow disturbance, although frictional losses were also increased to a moderate degree. A baffle spacing of 0.3 times the shell diameter was found to have the best performance overall, producing approximately 10% greater thermal effectiveness compared to unmodified or poorly-baffled heat exchangers without incurring large hydraulic or legal penalties.