HEAT TRANSFER AND PRESSURE DROP ANALYSIS IN SHELL AND TUBE HEAT EXCHANGERS: SEGMENTAL BAFFLES DESIGN

Abstract

The aim of this study is to simulate and analyze the heat transfer and friction characteristics of shell and tube heat exchangers. Case Studies are made to decrease the pressure drop and to increase the heat transfer and the ratio of heat transfer and pressure drop in shell and tube type heat exchanger by tilting the baffle angle up to which we get the minimum pressure drop using different turbulence models. The optimum results are found at baffle tilting angle of 32ο and RNG k – ε turbulence model. The ratio of Nus / Eu deals with high heat transfer and low pressure drop and that is found at 32ο baffle angle 12% more than segmental baffle at 0ο baffle angle. Other studies are carried out using a set of CFD simulations for a single shell and single tube pass heat exchanger with a variable number of baffles and different values of baffle cutoff. The results are observed to be sensitive to the turbulence model selection. The results are observed to be sensitive to the turbulence model selection. The best turbulence model among the ones considered is determined by comparing the CFD results of heat transfer coefficient, outlet temperature and pressure drop with the Bell-Delaware method results. For two baffle cutoff values, the effect of the baffle spacing to shell diameter ratio on the heat exchanger performance is investigated by varying flow rate. All studies are carried out using commercial software for computational fluid dynamics (CFD) known as ANSYS CFX 16. The CFD modeling techniques solved the continuity, momentum and energy conservation equations in addition to RNG k – ε model equations for turbulence closure.