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Cleaner, Higher Efficiency Vehicles Using Plasmatrons †. Daniel R. Cohn Plasma Science and Fusion Center Massachusetts Institute of Technology Presentation to Fusion Power Associates Meeting Washington, D.C., Nov. 21, 2003

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Cleaner, Higher Efficiency Vehicles Using Plasmatrons †

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cleaner higher efficiency vehicles using plasmatrons

Cleaner, Higher Efficiency Vehicles Using Plasmatrons†

Daniel R. Cohn

Plasma Science and Fusion Center

Massachusetts Institute of Technology

Presentation to Fusion Power Associates Meeting

Washington, D.C., Nov. 21, 2003

†Research supported by Dept. of Energy Office of FreedomCAR and Vehicle Technologies and by ArvinMeritor

    • L. Bromberg
    • D.R. Cohn
    • A. Rabinovich
    • K Hadidi
    • N. Alexeev
    • A. Samokhin
    • J. Palaia
    • J. Heywood
    • J. Goldwitz
    • N. Margarit
    • G. Ziga
    • Major US automotive and heavy truck components manufacturer
    • Commercializing technology licensed from MIT
    • R. Smaling et. al.
lower emission higher efficiency gasoline engine
Lower Emission, Higher Efficiency Gasoline Engine


(e.g. 25%)

Hydrogen-rich gas (H2+CO)

Onboard PlasmatronFuelConverter

Ultra lean Burn Gasoline engine

Fuel Tank


(e.g. 75%)

  • Reduced pollutants (NOx)
  • Increased efficiency
uses of onboard hydrogen generation
Uses of Onboard Hydrogen Generation

 Gasoline Engine Cars And Other Light Duty Vehicles

 Hydrogen combusted along with gasoline in engine

 Lower emissions (from ultra lean operation)

 Higher efficiency (from ultra lean operation, higher compression ratio, strong turbocharging)

 Diesel Engine Trucks and Buses

 Use in exhaust aftertreatment system

 Facilitates attractive exhaust aftertreatment system for reduction of NOx (nitrogen oxides are a primary source of smog)

plasmatron reformer
Plasmatron Reformer

 Compact (e.g. 2 liter) device for onboard reforming of hydrocarbon fuels (gasoline, diesel, bio-oils, other fuels) into hydrogen-rich gas

 Reforming promoted by special electrical discharge

production of hydrogen rich gas from partial oxidation reforming
Production of Hydrogen Rich Gas From Partial Oxidation Reforming
  • Add sufficient oxygen from air to bind all carbon in fuel as CO;
  • For iso-octane (representative of gasoline):

C8H18 + 4 (O2 + 3.8 N2) --> 8 CO + 9 H2 + 15.2 N2

  • Reaction is mildly exothermic
    • ~ 15% of energy released in the reformation process
    • Relatively slow reaction
    • Difficult to provide effective reforming under transient conditions

Plasmatron Reformer

  • Provides continuous volumetric initiation of reforming reactions
    • Use of a special low current, high voltage distributed plasma
  • Advantages
    • Rapid startup and transient response
    • Relaxation or elimination of reforming catalyst requirements (conventional reformer catalyst vulnerability has been a major impediment)
    • Inhibits soot production
    • Compact
    • Efficient
    • Applicable to a wide range of fuels including difficult to process fuels (diesel, bio-oils)

Low current gasoline plasmatron




Plasma current


0.1 - 0.4







H2 flow rate




Plasma created in the a gas flow

  • Gas flow stretches the plasma
  • Plasma extinguishes and re-establishes (1 kHz)
  • Discharge over a large volume


plasmatron hydrogen enhanced turbocharged gasoline engines

Plasmatron Hydrogen Enhanced Turbocharged Gasoline Engines

Moderate fraction (20% - 30%) of gasoline converted into hydrogen-rich gas

Addition of hydrogen-rich gas improves both combustion stability resistance to knock (undesired detonation or “pinging”)

Increased knock resistance allows high compression ratio and strong turbocharging

Net efficiency increase of up to 30%

Engine efficiency can be substantially increased by

Ultra lean burn (high air/fuel ratio)

High compression ratio

Strong turbocharging (allows for engine downsizing)


Gasoline engine testing at MIT

  • Hydrogen enhanced combustion stability allows very lean burn (high air to fuel ratio) without misfire
  • Naturally aspirated (no turbocharging) with conventional compression ratio
  • Ultralean operation increases efficiency 15% and decreases NOx by a factor of 50

Leaner operation


Leaner operation


Lean burn characteristics of a gasoline engine enriched with hydrogen rich gas from a plasmatron fuel reformer

E. Tully and J.B. Heywood

MIT Dept. of Mechanical Engineering and Sloan Automobile Laboratory


high compression ratio high boosted operation through improved knock resistance
High Compression Ratio, High Boosted Operation through Improved Knock Resistance
  • Recent experimental studies at MIT Sloan Automobile laboratory show that knock resistance is substantially improved by addition of hydrogen rich gas to gasoline
    • Octane rating number (ORN) has been increased by 20 ORN when 25% of fuel energy is from hydrogen-rich gas (for reference, the octane rating number difference between regular and premium gasoline is 6)
  • The combination of enhanced knock resistance and enhanced combustion stability are projected to increase gross engine efficiency by a factor of up to 1.4 and net efficiency by up to 1.3
status and prospects plasmatron hydrogen enhanced turbocharged gasoline engines
Status and Prospects Plasmatron hydrogen enhanced turbocharged gasoline engines
  • Tests on engines in the laboratory
  • Ultimate goal is up to 30% increase in net efficiency with further decreased emissions from already low emissions
  • Could be economically attractive:
    • Additional cost projected to be around $1,000 including the cost of the turbocharger
    • Pay back time from fuel savings significantly less than life of vehicle
  • Next step involves vehicle tests by ArvinMeritor team

Diesel Engine Emissions Aftertreatment Concept

Normal Operation


Small side

stream of

diesel fuel

Exhaust from

engine (Oxygen rich)


rich gas








Clean exhaust

Clean exhaust

Advantages of regeneration with H2-rich gas:

  • Greater operating temperature range (down to about 130 C)
  • Greater regeneration effectiveness (fuel penalty decreased by a factor of 2)
  • Reduced sulfur effects on system
h2 assisted nox trap test set up
H2-Assisted NOx Trap: Test Set-up



Fuel Reformer



NOx Trap A

To Tailpipe

Brake Valve


NOx Trap B

Switching Valve

nox adsorption comparison bus road load same fuel penalty
NOx Adsorption Comparison – Bus Road Load Same Fuel Penalty

Plasmatron hydrogen regeneration

Diesel regeneration

bus h2 assisted nox trap installation
Bus H2-Assisted NOx Trap Installation

Fuel Reformer Box

NOx Trap: 21L/leg

Access Door

prospects diesel exhaust treatment
Prospects Diesel Exhaust Treatment
  • EPA requirements demand implementation of effective exhaust aftertreatment system in heavy trucks and buses in 2007-2010 time frame
    • Present heavy vehicles use no exhaust aftertreatment
  • Plasmatron hydrogen enhanced NOx trap aftertreatment is one of the most promising technologies to meet this need
  • Onboard plasmatron hydrogen generation could improve efficiency and reduce emissions of both gasoline and diesel engine vehicles
  • The environmental and economic attractiveness of plasmatron enhanced turbocharged gasoline engine vehicles could facilitate widespread use. Widespread use could result in a significant impact on average fuel efficiency
  • If average fuel efficiency of US fleet of cars and light duty vehicles is increased by 20%, yearly fuel savings would be 25 billion gallons of gasoline (equivalent to 70% of oil presently imported from the Middle East)
summary continued
Summary (continued)
  • Use of onboard hydrogen generation for improving internal combustion engine vehicles could provide substantial impact much sooner than use of hydrogen fuel cells
  • Could be first step towards longer term vision of hydrogen fuel cell vehicles. Next step could be use of a small amount of stored hydrogen.