Hydrogen fuel enhancement
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/* Hydrogen injection */ More info, another link.
[[Image:HCNG.CNG.Bar chart emissions levels.gif|thumb|HCNG -CNG emission]]
'''Hydrogen fuel enhancement''' is a term used to describe the supplementation of an [[internal combustion engine]] (ICE) with hydrogen to improve fuel efficiency<ref name="SI" /> and power. By supplementing an engine's normal fuel with hydrogen / compressed natural gas blends (H2CNG or HCNG), the [[Exhaust gas|exhaust emission]]s of the ICE can be dramatically improved.<ref name="NG"/><ref>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.</ref> Hydrogen injection is similar to both [[propane injection]] and [[nitrous|nitrous oxide injection]], but since hydrogen is a fuel source, the ICE will react in some ways similar to a [[hydrogen car]]'s engine.
==HCNG==
[[hydrogen|H]][[Compressed natural gas|CNG]] (or H2CNG) is a mixture of [[compressed natural gas]] and 4-9 percent [[hydrogen]] by energy.<ref>[http://www.eere.energy.gov/afdc/fuels/natural_gas_blends.html DOE HCNG]</ref> Hydrogen contents
of less than 50% in the HCNG blend have leakage and flammability risks similar to those of CNG alone. With the hydrogen being part of the mixture, there are no special precautions needed to avoid [[hydrogen embrittlement]] of the materials
coming in contact with the mixture.<ref>[http://www.metro.net/projects_programs/atvc/1108%20HCNG%20TECHNOLOGY.pdf HCNG and hydrogen embrittlement]</ref>. HCNG stations can be found at [[Hynor]] ([[Norway]]) and the [[BC hydrogen highway]] in [[Canada]].
==Hydrogen injection==
Automotive fuel enhancement systems inject either a [[hydrogen]]-rich mixture, or pure hydrogen into the [[Manifold (automotive engineering)|intake manifold]] of the engine. In some cases, this is combined with air/fuel ratio and timing modifications<ref>[http://www.ntpefs.com/idaho_national_laboratory_hydrogen_study.html Idaho national laboratory on fuel enhancement]</ref>. A small amount of hydrogen added to the [[intake]] air-fuel charge permits the engine to operate with [[Lean burn|leaner]] air-to-fuel mixture than otherwise possible.<ref name="H"/> As the air/fuel mix approaches 30:1 the temperature of combustion substantially decreases effectively mitigating [[nitrogen oxide|NO<sub>x</sub>]] production.<ref name="H"/>
Under idle conditions power is only required for extraneous components other than the drive train, therefore fuel consumption can be minimized. A 50% reduction in gasoline consumption at idle was reported by numerically analyzing the effect of hydrogen enriched gasoline on the performance, emissions and fuel consumption of a small spark-ignition engine.<ref name="HEG">{{cite journal
| title = Performance and Fuel Consumption Estimation of a Hydrogen Enriched Gasoline Engine at Part-Load Operation
| journal = SAE Technical Paper Series
| issue = 2002-01-2196 | pages = p. 4–5
| author = G. Fontana, E. Galloni, E. Jannelli and M. Minutillo |date=January, 2002}}</ref>
Under most loads near [[Stoichiometry|stoichiometric]] air/fuel mixtures are still required for normal acceleration, although under idle conditions, reduced loads and moderate acceleration hydrogen addition in combination with lean burn engine conditions can guarantee a regular running of the engine with many advantages in terms of emissions levels and fuel consumption.<ref name="numerical"/>
Increases in engine efficiency are more dominant than the energy loss incurred in generating hydrogen.<ref name="H"/> This is specifically with regard to use of a [[hydrogen reformer]]. Overall computational analysis has marked the possibility of operating with high air overabundance (lean or ultra-lean mixtures) without a substantial performance decrease but with great advantages on pollution emissions and fuel consumption.<ref name="HEG"/>
Overall comparing the properties of hydrogen and gasoline, it is possible to underline the possibilities, for hydrogen fueled engines of operating with very lean (or ultra-lean) mixtures,<ref name="PC">{{cite journal
| title = Performance characteristics of a Hydrogen Fueled SI Engine using Timed Manifold Injection
| journal = Int. J. Hydrogen Energy
| issue = vol 16, pp. 115-117, 1991
| author = Mathur H.B., Das L.M.
| date=1991
}}</ref> obtaining interesting fuel economy and emissions reductions.<ref name="numerical"/> The concept of hydrogen enriched gasoline as a fuel for internal combustion engines has a greater interest than pure hydrogen powered engines because it involves fewer modifications to the engines and their fueling systems.<ref name="numerical"/>
Hydrogen fuel enhancement from [[electrolysis]] of water can produce fuel efficiency improvements on the order of 4% and similar modest reductions in emissions, and is currently in use in Canada.<ref>http://www.etvcanada.com/F/data/PDF_CHEC.pdf</ref><ref>[http://www.wired.com/news/technology/0,69529-0.html Wired magazine: Truckers Choose Hydrogen Power]</ref>
==Engine Control==
[[Electronic control unit|ECU]] or carburetor modifications are required to establish lean or ultra [[lean burn]] engine conditions.<ref name="NG"/><ref name="H"/>
==Research==
A simplified single-step combustion reaction is represented as:
: [FUEL] + [HYDROGEN] + [AIR] → HC + CO + CO<sub>2</sub> + H<sub>2</sub>O + NO<sub>x</sub>
===1975===
Research in 1975 examined hydrogen enhanced gasoline in [[Carburetor#Carburetor adjustment|lean]] combustion.<ref name="H">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)</ref> 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."<ref name="H"/>
===2002===
Research done in 2002 shows that the "addition of hydrogen to natural gas increases the burn rate and extends the [[lean burn]]-limit".<ref name="NG"/> Also concluded was that "hydrogen addition lowers HC emissions", and with properly "retarded ignition timing" also reduces NO<sub>x</sub> emissions.<ref name="NG">{{cite journal
| title = Hydrogen Addition For Improved Lean Burn Capability of Slow and Fast Natural Gas Combustion Chambers | journal = SAE Technical Paper Series | issue = 2002-01-2686 | pages = p. 7–8 | author = Per Tunestal, Magnus Christensen, Patrik Einewall, Tobias Andersson, and Bengt Johansson |date=January, 2002}}</ref>
Further research in 2002 achieved results showing "a reduction of NO<sub>x</sub> and CO<sub>2</sub> emissions", by modeling an on-board hydrogen reformer and "varying the efficiency".<ref name="numerical"/> The research was specifically a "numerical investigation" done to "forsee performances, exhaust emissions, and fuel consumption of a small, multi valve, spark ignition engine fueled by hydrogen enriched gasoline".<ref name="numerical">{{cite journal
| title = Performance and Fuel Consumption Estimation of a Hydrogen Enriched Gasoline Engine at Part-Load Operation | journal = SAE Technical Paper Series | issue = 2002-01-2196 | pages = p. 4–5 | author = G. Fontana, E. Galloni, E. Jannelli and M. Minutillo |date=January, 2002}}</ref>
===2003===
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<sub>x</sub>) without significant changes to engine efficiency".<ref name="R">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.</ref> 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".<ref>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.</ref>
===2004===
Test results in 2004 show "that the H<sub>2</sub>-rich reformate gas was an excellent NO<sub>x</sub> reductant, and can out perform raw Diesel fuel as a reductant in a wide range of operating conditions".<ref name="Red">{{cite journal
| title = NO<sub>x</sub> Trap Regeneration with an On-Board Hydrogen Generation Device | journal = SAE Technical Paper Series | issue = 2004-01-0582 | pages = pp. 6–7 | author = Yougen Kong, Sam Crane, Palak Patel and Bill Taylor |date=January, 2004}}</ref> This is referring to Diesel fuel being used in excess, as a reductant, to cool the combustion reaction, which indeed has a mitigating effect on NO<sub>x</sub> production.
In 2004 research was conducted concluding that an "SI engine system fueled by gasoline and hydrogen rich reformate gas have been demonstrated" to achieve a "dramatic reduction of pollution emissions".<ref name="SI">{{cite journal
| title = Advanced Emissions and Fuel Economy Control Using Combined Injection of Gasoline and Hydrogen in SI-Engines | journal = SAE Technical Paper Series | issue = 2004-01-1270 | pages = p. 11–12 | author = Thorsten Allgeier, Martin Klenk and Tilo Landenfeld |date=January, 2004}}</ref> This was achieved by "extending [[EGR]] operation" in addition to consuming "gasoline and hydrogen rich reformate".<ref name="SI"/> Emissions results show that "HC-emissions as well as NO<sub>x</sub>-emissions could be reduced to near zero".<ref name="SI"/> Overall a 3.5% reduction in CO<sub>2</sub> emissions was achieved during the "FTP test cycle".<ref name="SI"/> The research also concluded that the exhaust aftertreatment system can be simplified, "resulting in cost reduction for the catalysts".<ref name="SI"/>
==Government==
To date, Hydrogen fuel enhancement products have not been specifically addressed by the [[EPA]]. No research devices or commercial products have reports available as per the "Motor Vehicle Aftermarket Retrofit Device Evaluation Program."<ref>[http://www.epa.gov/otaq/consumer/reports.htm See list of devices tested under EPA Gas Saving and Emission Reduction Devices Evaluation]</ref> In general there are no references available for the US Government addressing the concept of hydrogen fuel enhancement.
==References==
<references />
[[Category:Petroleum products]]
[[Category:Engine fuel system technology]]
[[Category:Hydrogen technologies]]
[[Category:Energy conservation]]
[[es:Hydrogen Fuel Injection]]
[[fr:Enrichissement hydrogène du carburant]]