Numerical simulation on shell side fluid flow and heat transfer in heat exchanger with trefoil-baffles

Heat exchangers with trefoil-baffle are a new type heat transfer device and are widely used in nuclear power system due to their special advantages, with the fluid flowing longitudinally on the shell side. In this study, to avoid the limitation of unit duct model, a whole model for the heat exchanger with trefoil-baffles is established including inlet and outlet nozzles. Based on the RNG k-e model, numerical simulation shell side fluid flow and heat transfer are conducted by using commercial CFD software FLUENT14.0. Characteristics of fluid flow and heat transfer performance on the shell side are analyzed. The results show that the fluid is fully developed after the first trefoil-baffle and the heat transfer coefficient and pressure drop vary periodically along the shell side. Fluid velocity increases gradually and the jet flow forms in the region near baffles. The secondary flow is also produced on two sides of baffles when the fluid flows through the trefoil-baffle. The jet flow and secondary flow can decrease the thickness of boundary layer and enhance the heat transfer.