On the increase in carbon monoxide production during the activation of water mist spray on a fire

Abstract

The paper presents an experimental study on carbon monoxide production during water mist spray activation. The fire source is a circular propane gas burner with diameters between 0.15 and 0.25 m, and corresponding to the heat release rates for complete combustion between 3.7 and 40.2 kW. The water mist nozzle, with an orifice diameter of 0.69 mm, was positioned at 1 m above the fire source and delivered water flow rates between 0.15 and 0.80 L/min. The whole assembly was under a hood to collect and analyze the combustion products and, more specifically, determine carbon monoxide (CO) yields before and during the application of a water spray. The experimental results show that CO yields can increase by up to 45 times during water spray activation. A two-step reaction model with finite-rate chemistry for CO oxidization was examined using the Fire Dynamics Simulator (FDS 6.8.0) to determine the dependence of CO yields on water spray application. The FDS simulations show qualitatively promising results in capturing the experimental trends.