Dynamic relationships between real-time fuel moisture content and combustion-emission-performance characteristics of wood pellets in a top-lit updraft cookstove

Abstract

Fuel moisture content (FMC) has an essential impact on the performance of biomass combustion. FMC typically changes during the burning process; therefore, considering only the initial FMC is inadequate for understanding clean combustion and emission control. An on-line FMC monitoring method was employed by measuring relative humidity of emissions to determine the real-time effect of FMC on modified combustion efficiency (MCE) and emission factors (EFs) of pollutants from a typical top-lit updraft cookstove fueled with wood pellets. The results obtained from a complete 16-h combustion sequence showed an overall decreasing trend of FMC, consequently increasing combustion temperature and MCE. Flaming combustion appeared in a high-power phase where the EFs of carbon monoxide (CO) and fine particulate matter (PM2.5) decreased while real-time FMC decreased from 3.5% to 2.1% (wet basis). Smoldering combustion was generally dominant in a low-power phase where EFs of CO and nitric oxide (NO) decreased, while PM2.5 increased with real-time FMC decreasing from 6.3% to 4.9% (wet basis). This paper can provide meaningful information for modeling biomass burning, quantifying pollutant emissions and understanding related impacts on the residential sector.