Real-time combustion rate of wood charcoal in the heating fire basin: Direct measurement and its correlation to CO emissions

Abstract

Previous studies of solid fuel emissions in household stoves focused more on emission measurements of the overall combustion process instead of the dynamic burning rate and its connection to the emissions. This study put forward a measurement system to monitor the dynamic fuel burning rate and emission rate directly, and explored their relationships during different combustion phases. Experiments were conducted using two types of wood charcoal consumed in a small open pan (i.e. fire basin) used commonly for space heating in rural China. The measured real-time CO emission rate (ER_CO), fuel burning rate (BR_F), and calculated carbon burning rate (BR_C) all rose and then subsided as the combustion progressed. The relationships between ER_CO and BR_F and between ER_CO and BR_C were different for the two charcoals during a phase with rising carbon content in the combusted fuel (Phase I), likely because moisture evaporation and volatile matter release were the dominant processes and the reaction was complex during this phase. ER_CO and BR_F or BR_C had linear relationships during a phase with stable carbon content in the combusted fuel (Phase II) for the two charcoals, which may be generalized to other solid fuels, because this phase is associated to fixed carbon dominating phase which usually exist during solid fuel combustion. The study presented a novel measurement approach to the combustion properties of solid fuels. The results implied that a complex relationship between the combustion and pollutant emissions existed in Phase I, and presented the possibility of estimating the fuel burning rate based on emission measurements in Phase II, or vice versa.

Keywords: Carbon burning rate; Carbon monoxide; Emission rate; Fuel burning rate; Linear relationship; Measurement system.