NUMERICAL STUDY OF METHANE PYROLYSIS INSIDE A SINGLE-CHANNEL SHOCK WAVE REFORMER

Proceedings of ASME Turbo Expo 2022 Turbomachinery Technical Conference and Exposition

  1. School of Sustainable Energy Engineering, Simon Fraser University,Surrey, BC V3T 4B7, Canada

  2. Department of Mechanical Engineering, University of Bath, Claverton Down, Bath, Somerset BA2 7AY, United Kingdom

  3. New Wave Hydrogen, Inc., Gainesville, Florida, USA

  4. Department of Mechanical Engineering, California State Polytechnic University, Pomona, CA 91768-4062, USA

ABSTRACT

The paper describes a numerical investigation of the thermal decomposition of methane to hydrogen and carbon within a single-channel, four-port wave rotor using a three-dimensional (3-D), Reynolds-averaged Navier–Stokes (RANS) CFD model. This work is in support of the New Wave Hydrogen, Inc. ( NWH2) proprietary technology development. A Menter’s k ω SST turbulence is used for the closure of the mean momentum equations and is coupled to multispecies transport equations with a one-step finite-rate chemistry model. The kinetic model is validated based on a set of measurement data of a double-diaphragm shock tube case. To further examine the predictive accuracy of the numerical approach, the results of the 3-D single-channel wave rotor are compared with those of quasi-one-dimensional unsteady model that has been previously reported extensively in literature. It is observed that when the wave rotor channel is exposed to the high-pressure driven gas (HPDRVN) port, a secondary right-running shock wave is generated, which greatly energizes the flow around the HPDRVN port, resulting in large magnitudes of pressure and temperature; and consequently, the cracking of methane into hydrogen and carbon. The comparison between 1-D and 3-D simulation results indicate that the LPDRVN gas penetration is around 75% of the channel width in the case of 1-D, but is below 50% in the 3-D case. Furthermore, the conversion rate of methane in the 3-D case is one order of magnitude smaller than that in the 1-D case.

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