Ignition and combustion of n-heptane droplets in carbon dioxide enriched environments

The ignition process and burning characteristics of fiber-supported n-heptane fuel droplets in carbon dioxide enriched and varying pressure environments have been studied under normal gravity. Measured values of droplet burning rates, flame dimensions, broad-band radiant emission, and ignition times were compared to droplets burning in standard air conditions. The burning rate constants increased with increasing carbon dioxide concentration or pressure. For 21% ambient oxygen concentration ignition was achieved for carbon dioxide concentrations up to 46% with the remaining being nitrogen. The experimental burning rates were compared to existing theoretical models. A flammability map for n-heptane burning under normal gravity as a function of carbon dioxide concentration and pressure was also developed using these results.