Soot Reduction in Cookstoves due to Turbulent Mixing

Emissions from solid-fuel cookstoves, used by almost three billion people worldwide, create major issues for both human health and the environment. These emissions cause an estimated 4.3 million premature deaths annually and significantly contribute to environmental issues such as global climate change. One of the harmful emissions is soot and a promising option for reducing soot emissions from cookstoves is injecting air into the combustion chamber to increase turbulent mixing. Typically aerosol measurement systems are used to explore the effects of such modifications. However, these systems collect data relatively far away from the source, which makes it difficult to explore how the design modifications affect the actual flames. In this study, soot produced by a proxycookstove burner was measured in-situ using luminescence to explore the effects of different air injection modifications. The soot reduction trends were compared between different air injection angles and different air injection flow rates. Black carbon aerosol measurements were collected to compare with the values for in-situ soot and also to gain a quantitative value of black carbon produced in each case. It was found that overall trends appear to be consistent between the two measurement systems with all air injection modifications reducing black carbon over the baseline flame case and higher airflows proving to be more beneficial for soot reduction. Despite major differences in the amount of black carbon emitted from the flames recorded by the aerosol system, the luminosity intensity is similar for all cases, suggesting a significant increase in the soot oxidation with forced air flow. This indicates that the halo air injection systems are performing as desired, inducing turbulent mixing to reduce soot emissions.