The Development of Sensitive Diagnostics for Formaldehyde ( CH2O) and Formyl (HCO) and their Use in Shock Tube Studies of Reaction Rate Coefficients

Stanford University, Stanford CA

Investigators

Abstract

Reaction involving formaldehyde (CH2O) and formyl (HCO) radical lie on the primary oxidation pathway for methane and other funds, but there are still large uncertainties in the high-temperature rate coefficients of key reactions involving these species. This uncertainty stems largely from instability to measure CH2O and HCO with sufficient sensitivity. To address this situation, sensitive optimal diagnostics to measure CH2O and HCO are developed and used to measure important rate coefficients from shock-tube studies. Formaldehyde is measured using vacuum ultraviolet (VUV) lamp absorption at 174 nm. Formyl is measured using frequency modulation (FM) laser absorption at 614 nm. These techniques are applied to the investigation of several elementary reactions in shock-tube studies and species concentration time-history databases from pyrolysis and oxidation experiments.