Abstract
In this study, a theoretical model of the hot and cold fluid flow, heat transfer, and thermal stress coupling in a baffle plate heat exchanger is established, and numerical simulation is carried out. The flow field in the heat exchanger and the deformation of the heat exchange tube bundles in the baffle plate heat exchanger are studied. The optimization effect of the diversion grid on the flow field at the inlet of the variable section is emphasized. The influence of grid arrangement on the flow field and the performance of the tube bundles are analyzed and discussed. The results show that the backflow situation can be effectively improved and the vortex intensity in the straight section of the cold fluid inlet can be greatly reduced by adding the grid. The deformation of the heat exchange tube bundles illustrates the maximum deformation with 1.39 mm at the position of the strongest backflow. The deformation can be reduced by 26% due to the arrangement of the diversion grid, which is helpful to improve the safety of the device.
Highlights
Speaking, heat transfer enhancement can be divided into passive enhancement and active enhancement
As can be seen from the figure, the straight pipe between the trumpet and the heat exchanger has the strongest backflow and the largest vortex intensity, owing to the fact that the position is close to the tube bundle inside the heat exchanger
In order to avoid the fluid backflow on the heat exchange performance and mechanical properties of heat exchange tube bundles, it is necessary to arrange a diversion device in the trumpet section of the cold fluid inlet to optimize the fluid diversion
Summary
Heat transfer enhancement can be divided into passive enhancement and active enhancement. Baffle enhancement is very important to improve the shell side heat transfer of the heat exchanger, which is widely used because it can achieve a high heat transfer film coefficient at the shell side, with advantages of simple structure, easy production, and installation, but it has retention area and have disadvantages of easy scaling on the shell side and a great pressure drop along the way. The flow field uniformity inside the heat exchanger is generally improved by installing a diversion device to enhance the heat exchange effect in engineering applications (Long, 2014). There is no slip boundary on the inner wall of the heat exchanger, both sides of the heat exchange tube bundle and baffle plate. Respectively, on both sides of the heat exchange tube bundle and baffle plate, and the coupling boundary is adopted. The specific heat capacity, viscosity, thermal conductivity, and other physical parameters of the fluid are related to the temperature of the fluid and are calculated according to the widely used direct calculation method proposed by Xu (1999)
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