Abstract
Microscopic balance equations of mass, energy and exergy were derived for a deodorization system using soil cover. Applying the balance equations to the practical case of the system, concentration of an odorous gas component and temperature were simulated, and the contents of exergy dissipation and their variation with time and location were discussed. There are six kinds of irreversible processes in this system, that is, heat conduction, mass transfer, frictional loss due to viscosity, dissolution or volatilization of odorous gas components, evaporation or condensation of water, and chemical decomposition of odorous gas components. These processes are accompanied by the exergy dissipation Ed1, Ed2, Ed3, Ed4, Ed5, and Ed6, respectively. Of all the six kinds of exergy dissipation, Ed3 is exclusively greater than the others. According to the results of the vertical distribution of the dissipation terms, it is found that heat conduction (Ed1) and evaporation or condensation (Ed5) occur mainly near the top and bottom parts of the soil bed, frictional loss due to viscosity of gas (Ed3) occurs near the top part, and dissolution or volatilization of odorous gas components (Ed4) occurs uniformly in the soil bed. The microscopic exergy analysis presented here is useful in understanding the temporal and spatial variations of irreversible processes occurring in the system, and therefore useful in considering the effective utilization of the system.
