Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
FLUID-STRUCTURE ANALYSIS OF PSHE HEAT EXCHANGER PLATES BY NUMERICAL APPROACH
Submission Author:
Damylle Donati , SC , Brazil
Co-Authors:
Damylle Donati, Rodrigo Santiago, Talita Possamai, Renato Oba
Presenter: Talita Possamai
doi://10.26678/ABCM.COBEM2021.COB2021-0868
Abstract
Heat exchangers are widely used devices in various industries due to their operating condition’s versatility in relation to temperature and pressure. In particular, in the oil and gas industry, the PSHE (Plate-Shell Heat Exchanger) model has been explored for combining the thermo-mechanical resistance of the shell-and-tube type exchangers and the compact size of the plate exchangers. Exposed to cyclic and intense thermo-mechanical loads, the model presents a need for investigation into the relationship between the flow of working fluids and the structural integrity of the device. This work addresses independent analysis in CFD and FEM as a tool of investigation for the FSI (Fluid-Structure Interaction) and aims to evaluate such interaction as to its real need in relation to hydrostatic structural analysis, as the quantitative importance of the loads generated by the flow facing the operation of the heat exchanger. Plates of Chevron angles of 45° were analyzed, in a simplified pack consisting of a pair of corrugated plates and a pair of rigid tops. Based on the evaluation of the fluid dynamic, Reynolds numbers between 1993 and 7529 were imposed as an initial condition for the flow, with an input temperature of 55 °C. Results of the fluid-structure coupling’s analysis with mechanical loads resulted in high variations in the maximum value of the stress field, but not in the maximum displacement value, in relation to the hydrostatic structural evaluation for the same range of pressure input. The behavior of both variables distributions, on the other hand, shows similarity between the two methods. Still, it was found that the analysis of the mechanical load in a single way is enough for the evaluation of the phenomenon for low numbers of Reynolds. Two are the critical regions where stress peaks occur in the exchanger. The first occurs among the points of contact between the plates reaching values above the material’s yield limit for loads higher than 10 bar. The tension drops dramatically - about ten times - in the region between points of contact. The second critical region occurs along the weld region, the region where there is the highest probability of failure, mainly due to the occurrence of cracks arising from the process of joining the plates. This region is located in opposite direction of the corrugations for low pressures getting to the parallel direction with the pressure increase. Normal plate displacement shows maximum values of only 5% of plate thickness, indicating system feedback between structural displacement and fluid dynamics is not required for low ranges of Reynolds number.
Keywords
PSHE, FSI, fluid-structure interaction (FSI), FEM, Heat exchanger, CFD
