Hydrogen fuel injection

Hydrogen fuel injection, or HFI, is a system to reduce exhaust emissions of internal combustion engines and improve fuel economy. HFI systems work by injecting hydrogen as a combustion enhancement into the intake manifold of an internal combustion engine to achieve these benefits. A small amount of hydrogen added to the intake air-fuel charge enhances the flame velocity and thus permits the engine to operate with leaner air-to-fuel mixture than otherwise possible. The result is lower pollution with more power and better mileage.

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A simplified single-step combustion reaction is represented as: [FUEL] + [HYDROGEN] + [AIR] → HC + CO + CO₂ + H₂O + NOx

For incomplete combustion, the above results in exhaust products including unburned hydrocarbons (HC) and carbon monoxide (CO). The NOx is formed mainly from the combustion air, and is highly temperature-dependent.

Research in the 1970s examined hydrogen enhanced gasoline in lean combustion.^[1] John Houseman and D.J Cerini of the Jet Propulsion Laboratory produced a report for the Society of Automotive Engineers titled "On-Board Hydrogen Generator for a Partial Hydrogen Injection Internal Combustion Engine", and F.W. Hoehn and M.W. Dowy, also of the Jet Propulsion Lab, prepared a report for the 9th Intersociety Energy Conversion Engineering Conference, titled "Feasibility Demonstration of a Road Vehicle Fueled with Hydrogen Enriched Gasoline."

In 2003 Tsolakis et al. of the University of Birmingham showed that "partial replacement of the hydrocarbon fuel by hydrogen combined with EGR resulted in simultaneous reductions of smoke and nitrogen oxides emissions (NO,) without significant changes to engine efficiency".^[2] Similar results have been presented by a team of scientists from Zhejiang University, China, which found that "a little amount of hydrogen supplemented to the gasoline-air mixture can extend the flammability of the mixture... improving the economy and emissions of engines".^[3]

Commercially, Canadian Hydrogen Energy Company, LTD, produces an HFI system which generates hydrogen during vehicle operation by electrolysis of water (from an onboard storage tank) using power from the vehicle's electrical system.^[4]

References

1. ^ Houseman J, "Lean Combustion of Hydrogen Gasoline Mixtures". Abstracts of papers of the American Chemical Society (169): 6-6 1975. (meeting abstract)
   • Hoehn FW, Baisley RL, Dowdy MW, "Advances In Ultralean Combustion Technology Using Hydrogren-Enriched Gasoline", IEEE Transactions on Aerospace and Electronic Systems 11 (5): 958-958 1975. (meeting abstract)
2. ^ Tsolakis A, Megaritis A, Wyszynski ML, "Application of exhaust gas fuel reforming in compression ignition engines fueled by diesel and biodiesel fuel mixtures" Energy & Fuels 17 (6): 1464-1473 NOV-DEC 2003.
3. ^ Li JD, Guo LS, Du TS, "Formation and restraint of toxic emissions in hydrogen-gasoline mixture fueled engines". International Journal of Hydrogen Energy 23 (10): 971-975 OCT 1998.
4. ^ Stephen Leahy (15 November 2005). Truckers Choose Hydrogen Power. Accessed 2007-05-03.