Hydrogen in internal combustion engines- NASA investigation

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Results from 1977 investigation into the use of hydrogen on demand for use in internal combustion engines.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.gov/19770016170.pdf

This investigation concluded there was a significant reduction in emissions and a decrease in the total energy consumption of a multicylinder piston engine running on gasoline (petrol) and a hydrogen-gasoline mixture.

Hydrogen

The results was show to extend the efficient lean operating range of gasoline by adding hydrogen.  Both botted hydrogen and hydrogen produced by a methanol steam reformer were used and compared to results from all gasoline.

The results were used to explain the advantages of adding hydrogen to gasoline as to a method of extending the lean operating range.   The minimum –energy –consumption equivalence ratio  was extended to leaner conditions by adding hydrogen while the minimum energy consumption did not change  – showing that more usable energy was provided.   All emission levels decreased at the leaner conditions and there was a significantly  increased flame speed and reduced engine lag over all equivalence ratios   (60 cm/sec increase to 120 cm/sec at low RPM         to              110 cm/sec increase to 150 cm/sec at high RPM)

  • It was shown that pure hydrogen injection produced the same results as for hydrogen produced from the methanol reformer process
  • The minimum-energy-consumption equivalence ratio decreased from 0.79 to 0.67….. an 18 % reduction
  • Oxides of nitrogen production are appreciably lower for hydrogen / gasoline mixture . Gasoline with reformed hydrogen from methanol have higher NOx  emissions as the reformer must produce gas at a high enough temperature to prevent water and methanol condensation and the higher inlet temperature can cause higher peak combustion temperatures and therefore higher NOx emissions
  • Whilst there are limitations of using the methanol reformation process , with proper design and catalyst selection to produce the hydrogen it is a possible way to use the energy lost in exhaust gases to produce hydrogen as an interesting supplementary or alternative fuel source..

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