Thesis (M.Sc.) - Cairo University - Faculty of Engineering - Department of Mechanical Power Engineering

Numerical simulations were implemented to study the effects of different baffle inclination angles on heat transfer and pressure drop of shell and tube heat exchangers with helical baffles. The simulations were carried out for five baffle inclination angles (25{u00B0}, 30{u00B0}, 35{u00B0}, 40{u00B0} and 45{u00B0}) by using periodic boundaries. The heat exchanger consists of 7 copper tubes, helical baffles, 600 mm length and shell diameter 90 mm. The helix angle of helical baffle will be changed from 25{u00B0} to 45{u00B0}. The shell and baffle of heat exchanger are made from aluminium and the tubes are made from copper. The working fluid for shell side and tube side of the heat exchanger is water liquid. The inlet mass flow rate of water in shell side will be changed from 1 Kg/s to 4 Kg/s and temperature is 353 K. The inlet mass flow rate in tube side is 0.05 Kg/s and temperature is 300 K. The simulation will show how the heat transfer and pressure change in the shell because of various helix angles. The flow pattern on the shell side of the heat exchanger with continuous helical baffles was forced to be rotated and helical because of the geometry of the continuous helical baffles, which leads to a great increment in heat transfer coefficient per unit pressure drop in the heat exchanger. The heat transfer rate and heat transfer coefficient increase with the increase of the baffle inclination angle Ü when Ü < 40{u00B0}. Whereas, the heat transfer rate and heat transfer coefficient decrease with the increase of the baffle inclination angle when Ü > 40{u00B0}. The pressure drop changes definitely with baffle inclination angle. The pressure drop decreases with the increase of the baffle inclination angle. The shell side heat transfer rate and heat transfer coefficient increase with the increase of the mass flow rate in shell side in same mass flow rate in tube side. The numerical results which are taken from solving simulation consist of modelling and meshing the geometry of shell and tube heat exchanger using CFD package ANSYS 16.0.

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