In this study, flame structures, boiler efficiency and exhaust gas temperatures were investigated numerically at different thermal power and excess air ratio in a liquid fuelled boiler. Calculations were carried out at two dimensional axisymmetric conditions and Fluent was used as the computational fluid dynamics software. In all studies, the standard k-ε model was used for modelling the turbulent flow, the species transport model was used for modelling the combustion, and the pressurized swirl atomizer was used for modelling the injection. The calculations showed, that the droplet diameters after injection were reduced and droplets evaporated in a shorter period with increasing excess air. Exhaust gas temperatures were raised with the increasing boiler thermal power and excess air ratio. As expected, the higher flue gas temperature and excess air ratio showed lower boiler efficiency.
In this study, effect of heat sink geometries on the performance of a thermoelectric generator was researched. In this context, fins with different geometries (flat fin, square pin fin, hexagonal pin fin, circle pin fin) placed to aluminium heat sink and their effects on heat transfer and electricity generation were investigated numerically. Calculations were carried out according to three different hot surface temperatures and five different air velocities. As a result of this study, it was determined that the electrical output increased with the increase of air velocity and hot surface temperature in all geometries. The highest electrical outputs were obtained at 150 °C hot surface temperatures and 15000 Reynolds numbers, while the lowest electrical outputs were obtained at 50 °C hot surface temperatures and 5000 Reynolds numbers in all geometries. The best thermal and electrical performance was obtained with flat fin heat sink and the worst in the TEG system without heat sink. The highest power outputs of the flat fin heat sink and without heat sink TEG systems were 6.42 W and 1.12 W, respectively. In addition, the highest conversion efficiencies of the flat fin heat sink and without heat sink TEG systems were 14.94% and 5.54%, respectively.
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