Hydrogen Production via Plasma Reformers

The potential for efficient production of hydrogen-rich gas from hydrocarbon fuels using thermal plasmas has been investigated both analytically and experimentally. Thermodynamic analysis shows that the most efficient production of hydrogen from hydrocarbons can be achieved by partial oxidation (lambda = 0.25); at optimal conditions, the availability of the output fuel mixture is 83 percent of the input availability. Chemical kinetic analyses of the partial oxidation of methane in plasma reactors, using both plug flow reactor and perfectly stirred reactor models, indicates that for residence times of less than 500 milliseconds, the minimum achievable energy input per amount of hydrogen produced ranges from 40 to 50 MJ per kg hydrogen. This corresponds to a thermodynamic efficiency of approximately 75 percent. An experimental plasma reformer has been constructed and initial tests have been performed using methane as the fuel molecule. The plasmatron has demonstrated startup and response times on the order of hundreds of milliseconds or less and gas heating efficiencies of over 80 percent. Observed hydrogen output is approximately 50 percent of the predicted values; this is presumed to be due to heat losses in the reactor and will be addressed in future reformer designs. The system shows promise for use as a load-following, inline fuel reformer for fuel cells and other power systems. Thesis Supervisor: Simone Hochgreb Title: Assistant Professor of Mechanical Engineering