Numerical assessment of hydraulic behavior and thermal efficiency of multiphase hybrid nanofluid in a shell-and-tube heat exchanger with inclined baffles

Improving the thermo-hydraulic performance of shell-and-tube heat exchangers (STHE) has always been the focus of researchers due to their wide applications in recent decades. This numerical study investigates the hydraulic behavior and thermal efficiency of turbulent multiphase flow of Fe3O4_MWCNT/water hybrid nano fluid (HN) in a shell-and-tube heat exchangers (STHE). The Reynolds number (Re) is 5000, 7500, 10000, and 12500 and the volume fraction of nanoparticles (f) is 0, 2, and 4%. Numerical simulations are conducted using the k-e turbulence model, two-phase mixture model, finite volume method (FVM), and PISO algorithm. The maximum value of the friction coefficient (FC) is 1.45, which corresponds to a baffle angle of 180 degrees, f = 4%, and Re = 5000. As the baffle angle is enhanced, the value of the average Nusselt number (Nuave) is intensified for all cases. The maximum value of the performance evaluation criteria (PEC) is about 1.55, which is related to a baffle angle of 180 degrees and Re = 7500. For all the examined situations, the value of PEC is greater than one, indicating the effectiveness of the application of nanofluid and baffles at different angles. Hence, it is recommended to utilize baffles. The maximum value of thermal efficiency is about 37%, which occurs when the baffle angle is180 degrees, f = 4%, and Re = 5000.