Part II: Computational studies on a pulverised fuel stove

Abstract

This paper presents computational and analytical studies made on the pulverised fuel stove reported in part I (Dixit CSB, Paul PJ, Mukunda HS. Experimental studies on a pulverised fuel stove. Biomass and Bioenergy, to be published). An analysis has been carried out on the condensed phase thermal profile with moving pyrolysis front for this stove. This unsteady thermal analysis that accounts for moving pyrolysis front has provided the predictions for the rate of movement of the pyrolysis front. The comparison of the predicted temperature profiles and pyrolysis front movement rates with the measured data is excellent. The single port configuration was computationally analysed with an aim to understand the aero-thermo-chemical behaviour of the stove operation in combustion and gasification modes. The g-phase of tangential entry stove was subjected to a three-dimensional analysis using a commercial CFD code CFX TASCflow with combustion modelled using single step overall reaction. It was possible to obtain combustion and gasification modes of stove operation computationally also by varying the fuel release pattern. A fuel release pattern biased towards the bottom of the port as seen in the experiments, when used for the calculations, resulted in gasification mode operation while uniform fuel release pattern induced combustion mode operation. Comparison of g-phase temperature profiles in combustion mode seems satisfactory. The comparison of g-phase temperature profiles in the gasification mode appears intriguing. An explanation for the behaviour is sought in faster hydrogen combustion compared to carbon monoxide, something not accounted for in the calculations with single step chemistry.