Investigation of Thermohydraulic Performance of Multiple Tube Pass Heat Exchanger with Baffles

Abstract

Shell side design and analysis of a small shell and tube heat exchanger with baffles and two tube passes is reported. The effect of different baffle spacing on parameters such as heat transfer, Number of Transfer units (NTU) and pressure drops was studied using numerical and experimental techniques to identify the inter baffle spacing for optimal thermohydraulic performance. Contrary to earlier studies in this area, both the shell and tube fluids along with channels were modeled for multiple tube passes; besides conduction effects along the baffle were also considered. Segmented baffles with a baffle cut of 20% were simulated in ANSYS for multiple inlet temperatures. Turbulence was modeled using the realizable k-ε scheme while the Bell-Delaware method was employed for pressure drops. Increase in heat transfer was observed when the number of baffles was increased, but an inter baffle spacing ratio of 0.41 was identified to be the optimal for thermohydraulic performance. Experimental investigation conducted to gauge the reliability of the results displayed a close match showing that the current numerical methodology can be used to design and assess industrial heat exchangers with segmented baffles and multiple tube passes.