Energy Policy
Moslem Akbari Vakilabadi; Sadegh Nikbakht Naserabad; Alireza Binesh
Abstract
In this paper, it is determined exactly how much of the loss of exergy in a specify component is concerning the own component and how much of the exergy loss is due to the effects of the rest of the components on that component. In this new method of exergy analysis, at first, the exergy loss in a component ...
Read More
In this paper, it is determined exactly how much of the loss of exergy in a specify component is concerning the own component and how much of the exergy loss is due to the effects of the rest of the components on that component. In this new method of exergy analysis, at first, the exergy loss in a component is classified as avoid. /unavoid categories. With this classification, it is possible to understand what quantity of the exergy loss of a component is eliminated by optimizing that component and how much of the exergy dissipation can never be eliminated and is related to the nature of the component. In the next classification, by categorizing the exergy loss into endo./exo., we can find out how much of the exergy destruction is due to the non-optimality of other components and has nothing to do with the component itself. Finally, the categories are divided into avoid-endo, unavoid-endo, avoid-exo and avoid-enxo. By performing this new method, the results demonstrate that the highest exergy destruction (1.976 MW) happens in the evaporator, 68% of which is unavoid-endo. exergy loss. The highest avoid. exergy loss relates to low pressure turbine (0.5791 MW). It is shown that optimizing of surrounding components of deaerator, economizers, and evaporators has a greater effect on decreasing the exergy dissipation of these own components, and the most Avoid. exergy destruction is in heat exchangers, pumps, condensers, turbines, expansion valves, reheaters, and superheaters.
Biomass Energy Sources
M. Akbari Vakilabadi; A.R. Binesh; M. Monfared
Abstract
A mathematical model has been investigated to predict the effect of hydrodynamic forces, especially thermophoretic forces on micro organic particles in counter-flow combustion in this research. Hydrodynamic forces change the velocity and concentration of evaporative organic particles moving toward the ...
Read More
A mathematical model has been investigated to predict the effect of hydrodynamic forces, especially thermophoretic forces on micro organic particles in counter-flow combustion in this research. Hydrodynamic forces change the velocity and concentration of evaporative organic particles moving toward the flame and they make a particle-free distance above the flame surface. Particle evaporation creates a thrust force that affects the velocity of the particles, which can be ignored compared to other hydrodynamic forces. Also, the temperature difference between the particles, the interaction of the particles on each other is neglected.The distance between the inlet nozzle and the flame surface is divided into four zones to investigate the dynamic behavior of particles in the flame front that in each case, the dynamic particles equations are written and the effect of thermophoretic force, weight force, drag force and buoyant force are analyzed on the particles and as a result, the velocity and concentration profiles of the particles are obtained in terms of distance from the flame front at different strain rates and with different particle diameters. The particles concentration of above the flame front increases with the balance of these forces, which the increasing the particles accumulation above the flame decreases the combustibility of particles in the flame front. Then, the length of the particle-free zone is extracted under the influence of different strain rates at different temperatures. As the flame surface approaches, the temperature gradient rises and the thermophoretic force increases. Accordingly, heavier particles accumulate closer to the flame surface.