Spontaneous Ignition of n-Alkane Droplets with Various Volatility

Ignition delays of a cool flame (τ1) and a hot flame (τt) were measured experimentally for single n-decane, n-dodecane, n-tetradecane and n-hexadecane droplets, which have similar volatilities to common commercial hydrocarbon fuels, in hot air. Droplet diameter was 0.7 mm. Ambient pressure was 0.3 and 1.0 MPa. Ambient temperature was 550 K to 1000 K. Results show the similarity of the examined fuels in terms of reactivity of the low- and high-temperature reactions. Values of τ1 and τt were longer for fuels with lower volatility. Values of τ2 (=τt−τ1) were similar for examined fuels. Both the ignition limits of cool and hot flames were similar between fuels, but were slightly lower for less-volatile fuels.