Analysis of thermal and composition distributions inside a methane thermal decomposition reactor using experiments and simulation

A methane thermal decomposition reactor and its compressible, multi-component, non-isothermal, computational fluid dynamics model were developed. Experimental methane conversion rates are determined at temperatures below 1300 K, for pure methane at varying flow rates, an industrially relevant range rarely studied. The experimental data is used with a least-square parameter estimation framework to determine the reaction rate and activation energy. Only a reaction model with forward and backward rate constants is shown to achieve excellent agreement between numerical and experimental results at all tested conditions. The model is used to study temperature, density, and composition inside the reactor and to assess the validity of commonly used plug flow and negligible gravitational effect assumptions. Results show that: (a) in a 28 mm diameter reactor, radial effects can cause up to 12% errors at high flow rates and 1295 K; and, (b) a minimum flow rate of 0.05 SLPM is needed to prevent gravitational effects. • An experimental methane thermal decomposition reactor was constructed. • Conversion values measured at multiple operating temperatures and flow rates. • A 3D, CFD reactor model developed and validated with experimental results. • Forward and backward rate parameters estimated by least-square optimization. • Radial and gravitational effects are studied using the CFD model.