Emission factors of domestic coal-burning braziers

We present experimental results of emission factors from a suite of domestic coal-burning braziers (lab fabricated and field collected) that span the possible range of real-world uses in the Highveld region of South Africa. The conventional bottom-lit updraft (BLUD) method and the top-lit updraft (TLUD) method were evaluated using coal particle sizes between 20 mm and 40 mm. Emission factors of CO₂, CO and NO_x were in the range of 98-102 g/MJ, 4.1-6.4 g/MJ and 75-195 mg/MJ, respectively. Particulate matter (PM_2.5 and PM₁₀) emissions were in the range 1.3-3.3 g/MJ for the BLUD method and 0.2-0.7 g/MJ for the TLUD method, for both field and lab-designed stoves. When employing the TLUD method, emission factors of PM_2.5/PM₁₀ reduced by up to 80% compared with those when using the BLUD method. Results showed the influence of ventilation rates on emission factors, which reduced by ∼50% from low to high ventilation rates. For energy-specific emission rates, the combined (3-h) PM10 emission rates were in the range of 0.0028-0.0120 g/s, while the combined average CO emission rates were in the range of 0.20- 0.26 g/s, with CO₂ emission rates in the range of 0.54-0.64 g/s. The reported emission factors from coal braziers provide the first comprehensive, systematic set of emission factors for this source category, and fill a major gap in previous efforts to conduct dispersion modelling of South African Highveld air quality.