A simplified model for understanding natural convection driven biomass cooking stoves—Part 1: Setup and baseline validation

Abstract

It is estimated that half the world's population cooks over an open biomass fire; improved biomass cooking stove programs have the potential to impact indoor air quality, deforestation, climate change, and quality of life on a global scale. The majority of these cooking stoves operate in a natural convection mode (being driven by chimney effect buoyant fluid forces). Simplified theories for understanding the behavior of this unexpectedly complex combustion system, along with practical engineering tools to inform its design, are markedly lacking. A simplified model of the fundamental stove physics is developed for predicting bulk flow rate, temperature, and excess air ratio based on stove geometry (chimney height, chimney area, viscous and heat release losses) and the firepower (as established by the stove operator). These parameters are intended to be fundamental inputs for future work understanding and improving biomass cook stove emissions and heat transfer. Experimental validation is performed and the simplified model is shown to be accurate and applicable to typical stove operation. Carbon monoxide and particulate matter emissions data have been recorded in conjunction with the validation data. The initial results are presented and indicate that the excess air ratio is a promising tool for reducing carbon monoxide emissions.