Measurements of the laminar burning velocity for mixtures of methanol and air from a constant-volume vessel using a multizone model

Abstract

A novel multiple burned gas zone model has been used to determine the temperature distribution within the burned gas and the relationship between the pressure rise and the mass fraction burned in a constant-volume vessel. This computation allows for the variation in heat capacity of the constituents and solves the equilibrium combustion equation for the 10 major species: N 2, O 2, H 2, CO, CO 2, H 2O, O, H, NO, and OH. A constant-volume spherical vessel has been used for measuring burning rates for liquid fuels at elevated initial temperatures and pressures. A heating system and a mixing system were installed for measurements at elevated initial temperatures and for preparing mixtures of liquid fuels. The test facility has been used for generating reproducible data for both gaseous and liquid fuels. Using the multizone model, the laminar burning velocity has been found for mixtures of methanol–air with initial temperatures of 293.15 and 425 K, initial pressures of 0.5, 1.0, 2.0, and 3.5 bar, and equivalence ratios of 0.8 to 1.6. The laminar burning velocities were fitted to a seven-term equation to describe the effects of stoichiometry, pressure, and temperature. The burning velocities for methanol–air have been compared with earlier measurements; the values obtained from the present study give very good agreement with the recently reported data of Davis and Law for ambient pressure and temperature. Cellular flames were found to exist in some test runs and the conditions of its onset are reported.