Dibutyl ether (DBE) is a promising biofuel due to its high cetane number (~ 100) and high volumetric energy density (31.6 MJ/L). It could either be used directly in compression ignition engines or blended with other conventional or renewable fuels. Oxidation and pyrolysis kinetics of DBE are not well known, particularly at high pressures. In this work, we have experimentally investigated the chemical kinetics of DBE in three domains: (a) ignition delay time measurements in a rapid compression machine over T = 550 -650 K, P = 10, 20, 40 bar,  = 0.5, 1; (b) ignition delay time measurements in a shock tube over T = 900 -1300 K, P = 20, 40 bar,  = 0.5, 1; (c) laser-based carbon monoxide speciation measurements in a shock tube during DBE pyrolysis and oxidation over T = 1100 -1400 K, P = 20 bar. Pressure timehistories measured in RCM experiments exhibited unique 3-stage and 4-stage ignition behavior predominantly at fuel-lean conditions. Experimental data were compared with the predictions of two recent chemical kinetic models of DBE. Sensitivity analyses were carried out to identify key reactions which may have caused the discrepancy between experiments and simulations. It was found that the rate of decomposition of DBE may need to be revisited to improve the oxidative and pyrolytic predictions of DBE kinetic model.

Mid-infrared (MIR) laser sources are used in a number of applications such as remote sensing, air pollution monitoring, combustion diagnostics, and molecular spectroscopy. Here, we present our work on the development of a MIR laser source based on the difference frequency generation (DFG) process between an external-cavity quantum-cascade-laser tunable over 1750-1835 cm -1 (pump source) and a CO2 gas laser tunable over 921-1083 cm -1 (signal source). The DFG process was realized in a nonlinear, orientation-patterned GaAs crystal, and resulted in an idler spectral range between 667-865 cm -1 with a linewidth of ~2.3 MHz and an output power of up to ~31 µW. Exploiting the fine tunability of our DFG laser source, we performed high-resolution absorption measurements of ethylene (C2H4) and acetylene (C2H2).

No abstract

No abstract

No abstract