Reduction of a phosphorus oxide and acid reaction set

The addition of small amounts of phosphine combustion products (phosphorus oxides and acids) to water vapor has been found to result in a faster relaxation rate of OH to its equilibrium density following H2O photolysis. This article describes the systematic construction of a reaction model of 162 phosphorus reactions among 17 phosphorus-containing species. Those reactions that contribute to the reestablishment of equilibrium following the perturbation of the system by H2O photolysis or by an increase in temperature are identified. A thermodynamic free energy function is used to quantify the rate of system relaxation back to equilibrium for a series of 36 reaction conditions covering a temperature range of 1500 to 3000 K, a gas density range of 5 × 10−7 to 5 × 10−5 mol/cm3 and a fuel equivalence ratio of 0.8 to 1.2.