Comparative study on carbon monoxide stratification and thermal stratification in a horizontal channel fire

Abstract

Carbon monoxide (CO) stratification and its relationship with thermal stratification are quite important for dealing with issues related to building fire safety. This experimental study compares the CO stratification and thermal stratification in channel fires. The results show that the relationship between CO stratification and thermal stratification depends on heat loss intensity from smoke flow to walls. In the conditions with considerable amount of heat loss, the vertical gradients of CO volume concentration are smaller than those of temperature rise beneath the ceiling. However, in the conditions with negligible heat loss, the vertical profile of dimensionless CO volume concentration becomes similar with dimensionless temperature rise. The longitudinal ventilation, as a prevailing smoke control or ventilation method, has a strong effect on the relationship between CO stratification and thermal stratification. A larger longitudinal air flow velocity leads to smaller heat loss intensity from smoke flow to walls and thus a higher similarity between CO stratification and thermal stratification.