Hydrogen: Primary or Supplementary Fuel for Automotive Engines

Hydrogen, gasoline, and mixtures thereof were compared as fuels for lean-burn engines. Hydrogen for the mixed fuels tests was generated by partial oxidation of gasoline. Hydrogen combustion yielded the highest thermal efficiency at any NO_x level. Gasoline yielded the second highest thermal efficiency for NO_x levels greater than or approximately equal to two gm/mi. For lower NO_x levels and high vehicle inertia weights, progressively more hydrogen supplementation was the second most efficient system. For vehicle inertia weights below 5000 lbm (2300 kg), the statutory NO_x standard (0.4 gm/mi) could be met with one lb/hr (0.13 g/s) hydrogen supplementation.