Numerical Research Of Stream Analysis On Helical Baffles Heat Exchangers

The helical baffles heat exchanger is a upgraded shell-and-tube heat exchanger,the primary update is the replace of the original vertically amounted segmental baffles into the inclined installed sector baffles in the shell side.The change of the baffles could remarkably change the fluid flow pattern in the shell side and finally improve the performance of the heat exchanger.In this paper,the numerical simulations for helical baffles heat exchanger and segmental baffles heat exchanger with component clearance are performed to reveal the features of leakage streams and their effect on heat exchanger performance.Helical baffles heat exchanger models with four different angles and segmental baffles heat exchanger model were established and calculated via Gambit and Fluent software.The results reveal that the proportion of Stream B increases with the increase of the helix angle ? and the proportions of leakage streams decrease with the increase of ?.In both turbulent flow state and laminar flow state,with the rise of shell-side Reynolds number,the main stream B proportion decreases and the leakage streams proportion increases in segmental baffles heat exchanger,while stream B proportion increases and the leakage streams proportion decreases in helical baffles heat exchanger.The leakage streams proportion in segmental baffles heat exchanger is much bigger than that in helical baffles heat exchanger.The proportion of tube-baffle leakage stream A increases in radial direction.Both the proportion of stream A and baffle-shell leakage stream E fluctuate in the intermediate zone in axial direction.The heat exchanger with the 40° helix angle shows the best comprehensive heat transfer performance in turbulent state,and the heat exchanger with the 50° helix angle shows better comprehensive heat transfer performance in laminar flow state.The average values of heat transfer coefficient per pressure drop increase 2.3% when the baffle-shell clearance is blocked,while the comprehensive heat transfer performance of the model without tube-baffle clearance do not show to much difference with the normal helical baffles heat exchanger model.The pressure drop and heat transfer rate of helical baffles heat exchanger decrease with the increase of clearance size,while the leakage streams proportion increases with the increase of clearance size.The results of this paper could be of great significance in the optimal design and manufacture of helical baffles heat exchanger.