Measurement of Laminar Flame Speed and Flammability Limits of a Biodiesel Surrogate

摘要

Laminar flame speed of a newly developed biodiesel surrogate, 1,3-dimethoxyoctane, has been experimentally determined at standard atmospheric pressure and 433 K using a spherical combustion chamber. The 29 L combustion chamber has two pairs of fused silica windows for optical access and is also equipped with 4 pairs of axial fans for generating isotropic turbulence, which is used here to prepare homogeneous combustible mixtures of fuel and air. Schlieren technique was used to visualize and document the temporal evolution of the outwardly propagated spherical 1,3-dimethoxyoctane/air flame. An in-house developed Matlab code was employed for postprocessing of the flame front images and determining the time histories of its radius. Validation of the experimental setup and methodology was achieved by measuring the laminar flame speed of n-heptane/air mixtures at atmospheric pressure and 353 K, and compared with published reports. The results revealed that the proposed biodiesel surrogate, 1,3-dimethoxyoctane, has an overall flame speed comparable to that of published biodiesel surrogates. Furthermore, the flammability limits of the newly developed biodiesel surrogate were similar to those of gaseous hydrocarbons (e.g., methane, ethane) and higher than those of liquid fuels (e.g., gasoline, diesel).