Numerical Simulation of Helical Coil Tube in Tube Heat Exchanger with Baffles

Abstract

The project aims at studying the effect of providing baffles in helical coil tube in tube heat exchanger. A three dimensional helical coil tube in tube heat exchanger with number of turns equal to two and which consist of three ring shaped baffles which are placed in annular space between two helical tubes is considered for study. The main aim of providing baffle is to increase the turbulence and thereby increase the convection and the baffle also provides support and helps to maintain two coils concentric. The geometry was modelled using Ansys design modeler. The hot fluid flows through the inner tube and cold fluid flows through annular space. The fluid considered is water. The analysis is done using Ansys fluent. The heat transfer in helical coil heat exchanger is analysed by varying the flow rate of hot fluid and flow rate of cold fluid is kept constant. The laminar and turbulent flow cases are studied. K–e model is used to model the turbulence in the flow and the flow is analysed for counter flow heat exchanger setup. The variation of Nusselt number values with the change in Reynolds number of hot fluid is plotted. By varying the thickness of baffle in helical coil tube in tube heat exchanger the variation of Nusselt number with the variation of Reynolds number of hot fluid is studied. The coil diameter of the helical coil is also varied to study the effect for both laminar and turbulent flow. The D/d ratio is varied from 10 to 25 in steps of 5