Oxidation of C1-C5 Alkane Quinternary Natural Gas Mixtures at High Pressures

Rapid compression machine (RCM) and shock-tube facilities have been employed to study the oxidation of natural gas blends at high pressure and intermediate to high temperatures. The use of both types of facilities allows a broad temperature envelope to be investigated and therefore encompasses the complete range applicable to gas turbines. A detailed chemical kinetic mechanism has been developed to simulate these results and will be used to approximate similar fuels. Mixtures of CH4/C2H6/C3H8/n-C4H10/n-C5H12 have been studied in the temperature range 630-1550 K, in the pressure range 8-30 bar, and at equivalence ratios of 0.5, 1.0, and 2.0 in air. For shock-tube experiments, the diluent gas was nitrogen, whereas in the RCM experiments the diluent gas composition ranged from pure nitrogen (at lower temperatures) to pure argon (at the highest temperatures). In addition, the combustion chamber in the RCM was fitted with a thermostat and heating tape to control and vary the initial temperature thereby varying the compressed gas temperature. Because the time-scale of a rapid compression machine experiment is so long, heat losses are significant. Thus, a series of nonreactive experiments were performed in order to account for the heat loss associated with each mixture composition and pressure.