Influence of helix angle on the performance of shell-and-tube heat exchanger with continuous helical baffle

摘要

In the present study, three-dimensional numerical simulation of three shell-and-tube heat exchangers (STHXs) with similar dimensions but different baffle configurations is carried out using finite element method. A comparative study is performed to analyze the performance of shell-and-tube heat exchanger with continuous helical baffle (STHXsHB) of different helix angles (Φ = 25.52°, 17.66° and 10.81°) based on the simulation results. Different helix angles are obtained with the variation of helical baffle pitch length, considering helix revolutions of 1 turn, 1.5 turns and 2.5 turns, which eventually create baffles with Φ = 25.52°, 17.66° and 10.81° respectively. At first, validation of the mathematical model is performed by comparing the shell side average Nusselt number with the available experimental data. Reasonably good agreement is obtained and the reasons causing the discrepancy are analyzed. Simulation results for three models of STHXsHB are obtained in terms of shell side heat transfer coefficient, pressure drop and energy efficiency (heat transfer coefficient per unit pressure drop) as a function of mass flow rate of oil. The comparative study shows that STHXsHB with helix angle, Φ = 25.52° has the highest energy efficiency among the three configurations of STHXs for the same shell-side mass flow rate. However, with decreasing helix angle, performance of STHXsHB deteriorates.