Effect of Oxygen on the Burning Behavior of Liquid and Solid Fuels in a Large-Scale Calorimeter

The purpose of this experimental study was two-fold: first, to explore and understand the effects of oxygen availability on the combustion of liquid and solid fuels; second, to provide data for comparison with CFD models. Experiments were conducted in the controlled-atmosphere calorimeter of IRSN, called CADUCEE, varying the oxygen concentration in the oxidizing stream and the size of the fire. Polymethylmethacrylate (PMMA) and heptane were used as fuels. Results are found to be in good agreement with the literature data. As the oxygen level decreases, the mass loss rate and flame heat feedback decrease, as well as the flame height and maximum flame temperature, for both fuels whatever the sample size. For heptane pool fires, temperature measurements in the liquid layer reveal a decrease in heat transfer at the fuel surface and inside the fuel with the oxygen molar fraction. For PMMA, the radiative and convective contributions to the total heat flux remain nearly constant, with about 65% and 35% respectively, regardless of sample size and oxygen concentration.