Modeling a stratified downdraft wood gasifier with primary and secondary air entry

► A mathematical model of an open-core downdraft gasifier for wood is developed. ► Dual air entry is simulated: primary air (top) and secondary air (inside the bed). ► The reaction front structure varies with percentage and position of secondary air. ► Char and tar conversion is improved by dual air distribution. ► Good quantitative agreement is obtained between predictions and measurements.