Värmeöverföring mellan två zoner i en bubblande fluidiserad bädd

Sammanfattning: In this Master's thesis, the heat transfer between two zones in a bubbling fluidized bed and the resultant temperature field were examined using a laminar Eulerian-Eulerian two-fluid model in computational fluid dynamics. The purpose was to estimate the thermal potential to multi-stage a combined heat and power boiler by integration therein of a communicating gasification reactor, which utilizes heat from the combustion, and to analyze how different construction parameters influence the homogeneity of the gas temperature field. The virtual set-up consisted of a reactor zone, partially separated from a combustion zone by an impermeable wall, leaving a gap below the wall through which heat could be transferred from the combustion zone to the reactor zone, mostly by means of particulate transport. Effects on the gas temperature field from all combinations of two different gap heights and two different separating wall thicknesses, i.e. four subcases, were investigated. Excluding the region within two decimeters of the Dirichlet boundaries, the maximum temperature differences in the symmetry plane of the domains were found to be less than 15°C for all four subcases. The smallest such maximum temperature difference was obtained in the subcase where the gap height was 450 mm and the separating wall thickness was 20 mm, below 9°C.