Numerical Simulations of Shell and Tube Heat Exchanger with Segmental, Trefoil and Segmented Trefoil Baffles for Performance Comparison

Abstract

Shell and tube heat exchangers (STHX) are the most abundantly used heat exchangers in the industry. Baffles are the most important component involved in improving the thermohydraulic performance of STHXs. In this study, we propose a novel segmented trefoil baffle (STB) formed by imposing trefoil holes on segmental baffles (SGB). Numerical simulations have been conducted using ANSYS FLUENT 19.2 for SGBs, trefoil hole baffles (THB), and STBs at various mass flow rates to compare the heat transfer coefficients, pressure drop, thermohydraulic performance, and shell side flow distribution. Results indicate that for almost the same heat transfer coefficient, the pressure drop is significantly less for the STBs compared with the SGBs. A study of the flow field revealed that large dead zones, typical of SGBs, reduce significantly when STBs are used. Similarly, the recirculation zones, reported for THBs also decrease by incorporating the STBs. The thermohydraulic performance is enhanced by 41% and 235% compared to SGBs and THBs respectively by using the STBs. An increase in the number of baffles from 6 to 10 further enhanced the advantage of STBs over the segmental baffles from 41% to 57%. The inclusion of baffles to shell and tubes clearances does not affect the superior thermohydraulic performance of STBs over SGBs.