R. Sivaramakrishnan

A shock-tube study of the high-pressure thermal decomposition of benzene

ABSTRACT The high-temperature, high-pressure pyrolysis of the prototype aromatic, benzene, has been studied behind reflected shock waves in the UIC High Pressure Single Pulse Shock Tube. Three sets of experiments were performed at nominal pressures of 30 and 50 bars in the high temperature regime from 1200–1800 K. Stable species sampled from the shock tube were analyzed offline using gas chromatographic techniques. The present data set was simulated using the three most recent models, two of the models developed and validated against high-temperature benzene pyrolysis shock-tube data for stable species profiles as well as H atom production rates and the third model, a “work-in-progress” model from our laboratory aimed at resolving the high-pressure combustion of primary aromatics such as benzene and toluene. The simulations reflect the complexities and uncertainties involved not only in describing the primary decay steps but also the subsequent high-temperature secondary chemistry for even the simplest aromatic molecule, benzene.

Elevated pressure thermal experiments and modeling studies on the water-gas shift reaction

The water-gas shift reaction influences the chemistry between the postcombustion gases of a rocket and the rockets graphite nozzle. The rockets operating pressures (70-600 atm) exceed those for existing water-gas shift reaction data, and further study of the chemistry under similar conditions is essential for optimum rocket design. To investigate chemical kinetic effects at the pertinent pressure and temperature regime, experiments were performed using the University of Illinois at Chicago high-pressure shock-tube facility with experimental temperatures ranging from 1200-2100 K and pressures ranging from 194-490 atm with reaction times averaging 1.17 ms. Initial mole fractions of H 2 O and CO were varied from 115-983 ppm (0.0002-0.003 mol/L). The experimental data have been compared with predictions from a comprehensive model for synthesis gas (CO/H 2 /CO 2 ) combustion and a reduced four-step model with the chemistry relevant to the water-gas shift reaction. The rate coefficients at our elevated pressure and temperature conditions were found to be pressure independent when compared with prior lower temperature 1 atm measurements.