Laminar burning velocity of liquefied petroleum gas mixtures

This thesis reports experimental and theoretical studies of the laminar burning velocity of liquefied petroleum gas (LPG) measured using the constant volume bomb method. The test rig designed at Loughborough University was a rigid and spherical chamber with central ignition. The LPG gas used in this study is a mixture of propane and n-butane with volume percentage of n-butane ranging from 0 to 100. The laminar burning velocities of the LPG/air mixtures have been determined over a range of equivalence ratios (0.7 to 1.4), unburnt gas pressures and temperatures (0.5 to 37 bar and 293 to 530 K respectively). With the measured pressure/time history in the constant volume combustion chamber, a new combustion model, which was developed based on a commonly used two-zone combustion model, was used to determine the laminar burning velocity. To obtain a more accurate value of the laminar burning velocity, the assumptions in the two-zone combustion model were analysed, and two effects were considered in the new combustion model, i.e. the effect of flame thickness and the effect of temperature gradient in the burnt gas zone. [Continues.]