effect on performance of engine by … · plasmatron fuel reformer. water electrolysis: water...

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Int. J. Mech. Eng. & Rob. Res. 2013 Suryakant Sharma et al., 2013

EFFECT ON PERFORMANCE OF ENGINE BYINJECTING HYDROGEN

Suryakant Sharma1*, Deepak Bhardwaj1 and Vinay Kumar1

*Corresponding Author: Suryakant Sharma,[email protected]

The principle of this type of combustion is to addition of hydrogen gas to the combustion reactionsof either compression or spark ignition engines. The addition of hydrogen has been shown todecrease the formation of NOx, CO and unburnt hydrocarbons. Studies have shown that addedhydrogen in percentages as low as 5-10% of the hydrocarbon fuel can reduce that hydrocarbonfuel consumption. The theory behind this concept is that the addition of hydrogen can increasethe lean operation limit, improve the lean burn ability, and decrease burning time. To apply thismethod to an engine a source of hydrogen is needed. At this time the simplest option would beto carry a tank of hydrogen. Research is being conducted to allow the hydrogen to be reformedfrom the vehicles hydrocarbon fuel supply or produce hydrogen from electrolysis of water. In thefuture, better methods could be developed for storing hydrogen in the vehicle or production ofhydrogen on-board the vehicle.

Keywords: Combustion reactions, Engine Performance, Injecting Hydrogen

INTRODUCTIONCombustion of fossil fuels has caused serious

problems to the environment and the

geopolitical climate of the world. The main

negative effects on the environment by fossil

fuel combustion are emissions of NOx, CO,

CO2, and unburnt hydrocarbons. The main

negative effect of burning fossil fuel on the

geopolitical climate is the lack in supply of these

fuels and the effect pollution has on politics.

ISSN 2278 – 0149 www.ijmerr.comVol. 2, No. 3, July 2013

© 2013 IJMERR. All Rights Reserved

Int. J. Mech. Eng. & Rob. Res. 2013

1 Bhiwani Institute of Technology and Science, Sarsa Ghogra, Rohtak Road, Bhiwani, Haryana-127021

There are several possible solutions to

alleviate the problems of using fossil fuels, but

most of them would require years of further

development and additional infrastructure.

This paper will look at a method of

improving fossil fuel combustion that could be

implemented without a large investment. This

method involves burning hydrogen gas along

with hydrocarbon fuels in engines.

Research Paper

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THEORYIn order to properly understand the effect ofadding hydrogen to enrich hydrocarboncombustion it is important to understand thebasics of how an internal combustion cycleworks. Figure 1 shows a diagram of a four-stroke engine.

rotation of the crankshaft. At the end of thepower stroke the exhaust valve opens.

In the exhaust stroke the rotation of thecrankshaft causes the piston to move uppushing the exhaust out the open exhaustvalve. At the end of the exhaust stroke theexhaust valve closes. The cycle is then readyto repeat.

In the experimentation and performanceanalysis of an engine several parameters areneeded to quantify the results. Some of theseparameters include air/fuel ratio, equivalenceratio, power, thermal eff iciency, fuelconsumption and emissions.

The emissions of an engine are determinedby the operating conditions of the engine. Themain emissions of an engine are nitrogenoxidizes, carbon oxides and unburnthydrocarbons.

NOx: Nitrogen oxidizes are generally formedat high temperatures when N

2 is oxidized in

air. Typically, if combustion temperature andresidence time are minimized and theappropriate amount of air is used NOemissions will be small.

O2� O + O

O + N2 NO + N

N + O2 NO + O

CO and CO2: Carbon dioxide is the product

of complete combustion. If sufficient oxygen ispresent then CO will be oxidized to CO

2.

Carbon monoxide emissions are more likelyto occur during rich mixture conditions .

Unburnt Hydrocarbon: Unburnt hydrocarbonsare created due to several conditions in thecombustion process. In regions of the flame

Figure 1: Four StrokeInternal Combustion Engine

The four stroke engine cycle is made up offour phases: induction, compression, power,exhaust.

Induction: In the induction stroke the intakevalve opens and the piston moves down pullingin air or air/fuel.

Compression: In the compression strokeboth valves close and the piston moves upcompressing the air mixture. Near the top ofthe stroke the spark plug fires or fuel is injected.

In the power stroke the fuel burns causingthe pressure and temperature to rise drivingthe piston downward. This generates the

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near the surfaces of the combustion chamber

the heat lost through the chamber wall is greater

than the heated needed to sustain a flame. This

condition causes areas of quenched flame

where hydrocarbons are left unburnt.

The combustion chamber often has gap that

do not allow a flame to propagate. These

areas allow for bui ldup of unburnt

Hydrocarbons.

During conditions where the engine is

operating at part- load and reduced speed

combustion is often incomplete. This is

because the combustion velocity is too slow

to allow the entire combustion charge to burn

before it is expelled during the exhaust stroke.

To prevent unburnt hydrocarbon emissions,

lean mixture conditions and extended

residence time at high temperature are

beneficial.

HYDROGENHydrogen holds significant promise as a

supplemental fuel to improve the performance

and emissions of spark ignit ion and

compression ignition engines.

Hydrogen has the ability to burn at extremely

lean equivalence ratios. Hydrogen will burn at

mixtures seven times leaner than gasoline and

five times leaner than methane.

The flame velocity of hydrogen is much faster

than other fuels allowing oxidation with less

heat transfer to the surroundings. This

improves thermal efficiencies. Efficiencies are

also improved because hydrogen has a very

small gap quenching distance allowing fuel to

burn more completely. The only drawback to

hydrogen is that even though its lower heatvalue is greater than other hydrocarbon fuelsit is less dense therefore a volume of hydrogencontains less energy .

APPLICATIONThe setup for introducing hydrogen into theengine involves a hydrogen source, tanks oron-board processor and metering equipmentto measure various combustion parameters.This process can be applied to both sparkignition engines and compression ignitionengines.

Figure 2: Sample Setup

Spark Ignition: Spark ignition engines canbe either fueled by liquid fuels or gaseousfuels. Propane and methane are the gaseousfuels and gasoline and ethanol are the liquidfuels commonly used. It can be seen inAppendix A that gaseous fuels and liquid fuelshave different properties and react differentlyto hydrogen addition, but both still benefit fromhydrogen addition.

Various methods have been used tointroduce hydrogen into the engine. In one

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study, hydrogen was mixed with air andcompressed in a cylinder before introductioninto the engine. In studies using gaseous fuelshydrogen flow rate is matched with the primaryfuel in-order to achieve the desired percentageof hydrogen enrichment . The ultimate designfor hydrogen introduction into an engine wouldbe using a computer control system that wouldvary hydrogen percentage, equivalence ratioand throttle with the vehicles gas pedal foroptimal running conditions .

Compression Ignition: Compressionignition engines can be fueled with standarddiesel, biodiesel or straight vegetable oil.These engines have two options for introducinghydrogen into the combustion process.Hydrogen can be inducted with air into theintake manifold or it can be directly injectedinto the cylinder similar to the diesel fuel .

HYDROGEN ENRICHEDCOMBUSTIONThermal efficiency generally is increased withthe introduction of hydrogen into an engine butit must be properly tuned in-order to gain thesebenefits. Results also seem to vary dependingon the fuel used. A properly tuned compressionengine will increase in thermal efficiency athigh loads for hydrogen mass percent of about8%. For an engine to have optimal thermalefficiency the timing must be retarded toaccount for hydrogen fast burn velocity.Thermal efficiency is related to fuelconsumption with the addition of hydrogen inall of the studies fuel consumption decreased

Figure 3 shows the effect of hydrogenaddition on the efficiency of a compressionignition engine. This figure shows the effect ofhydrogen addition on thermal efficiency at two

different load settings for diesel fuel and RSOMoil. Figure 4 shows the effect of hydrogenaddition on reduction in fuel consumption. Thisfigure shows that with increased hydrogenaddition fuel consumption decreases.

Figure 3: Variation of Thermal EfficiencyWith Hydrogen Mass Share

Figure 4: Reduction in Fuel ConsumptionWith Increase in Hydrogen Addition

Hydrogen addition gives the engine theability to be operated in the very lean mixtureregion. Lean mixtures allow for complete

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combustion decreasing carbon monoxideemissions .

Unburned hydrocarbon emissions arereduced because hydrogen allows leanmixtures. They are also reduced because highflame velocity and small quenching distanceof hydrogen promote complete combustion.Figures 5 and 6 show that hydrogen additionallows the engine to be operated with leanmixtures which reduce CO and hydrocarbonemissions.

The addition of hydrogen increasescombustion temperatures therefore creatingconditions where it is easier for NOx to form ifproper tuning is not utilized. Several studieshave shown that if mixtures are made lean andspark timing is retarded NOx can be reducedto a point below normal hydrocarboncombustion. Figure 8 shows the reduction ofNOx with increasing lean mixtures.

Figures 7 and 8 compare the effect onemissions of the addition of 70 g/h of hydrogen

Figure 5: Effect of H2 Addition onJatropha Oil Combustion CO Emissions

Figure 6: Effect of H2 Addition on NaturalGas Combustion Hydrocarbon Emissions

Figure 7: Emission BeforeHydrogen Addition

Figure 8: Emission AfterHydrogen Addition

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to an engine running at 3000 RPM. For thesefigures it can be seen that emissions aresignificantly reduced by the addition ofhydrogen.

HYDROGEN PRODUCTIONThe greatest limitations to using hydrogen forfuel enrichment are the cost and difficulty ofproduction and storage. Currently, there arethree main options for producing hydrogen forfuel enrichment. These options are:

• Producing hydrogen from electrolysis orreforming at a f ixed location andcompressing the hydrogen for storage onthe vehicle in tanks.

• Producing hydrogen, on-board by a fuelreformer and introducing the hydrogen asneeded from the vehicles hydrocarbon fuelsupply.

• Producing hydrogen, on-board, from waterusing electrolysis powered by the vehiclesalternator.

Compressed Hydrogen: Compressedhydrogen is probably the simplest but mostcostly method for using hydrogen for fuelenrichment. The hydrogen must be generatedoff the vehicle, compressed and stored on thevehicle. All these steps require a great deal ofcost.

Fuel Reformer: A fuel reformer usesplasmatrons, electrical gas heaters, which usethe conductivity of gases at high temperatureto convert the liquid fuel to a hydrogen-rich gas.Plasmatron fuel reformers have been shownto increase engine efficiency by as much as35% . Figure 9 shows a sample diagram of aplasmatron fuel reformer. Table 1 shows typical

operating parameters of a low currentplasmatron fuel reformer.

Water Electrolysis: Water electrolysis is theprocess of passing an electric current throughwater breaking the bonds of the watermolecule to produce hydrogen and oxygengases. Water electrolysis products have been

Power 50-300 W

Current 15-120 mA

H2 Flow Rate 30-50 1/min

Height 25 cm

Volume 2 l

Weight 3 Kg

Table 1: Operating Parameters of a LowCurrent Plasmatron Fuel Reformer

Maximum gas supply 20 l/h

Cathode electrode Carbon

Anode electrode Platinum

Electrolysis voltage 90 V

Electrolysis Current 3 A

Water Normal tap water

Water tank volume 2.5 l

Water consumption 100 ml/250 km

Water supply control Electronically controlled

Water temperature range 45-50oC

Cooling Water cooled

Dimensions 150 x 140 x 135 mm

Weight 2 kg

Table 2: Technical Specification for theKocaeli Electrolysis Unit

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shown to have a significant improvement onperformance and emission when comparedto adding hydrogen alone.

The University of Windsor in Canadaconducted a simulation of adding electrolysisproducts of 2 parts hydrogen to 1 part oxygen.This study used the CHEMKIN kineticsimulation software. It was found that adding10% hydrogen and oxygen was equivalent toadding 20% hydrogen alone in reduction ofemission and improvement of performance .

In a second study, conducted by theUniversity of Winsor an experimental methodwas developed to simulate the effects ofadding electrolysis products to an engine. Dueto the danger of compressing a mixture ofhydrogen and oxygen, a tank with 98% air, 2%hydrogen and 1% oxygen was prepared. Thismixture was then used to test the effect ofelectrolysis products. It was found that thismixture gave the same benefits of hydrogenalone and that the oxygen did not affectperformance .

Performance of a commercial electrolysisunit that produces 6.7 ml/s at 169 W wasassumed as the baseline for on-boardhydrogen production . It was assumed thatelectrolysis products contain only hydrogenand oxygen, no radicals. Also, no timingadjustments were made in this setup tooptimize performance. This study concludedthat an electrolysis unit would not provideenough performance increase to offset theenergy required to run the electrolysis process.Figure 9 shows the University of Windsorestimation of the ability of an electrolysis unitto provide hydrogen to enrich combustion .

In contrast to the findings of the Universityof Windsor study, Kocaeli University replicateda patent for an electrolysis system to providehydrogen and oxygen for combustionenrichment. This unit is made of a cylindricalcarbon cathode surrounding a platinum rodanode. This unit was supplied 90 V at 3 A and

Figure 9: Low Current PlasmatronFuel Reformer

Figure 10: The Power Requirement forElectrolysis and the Power Gained fromthe Engine Through Hydrogen Addition

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produced about 20 L/h . Figure 11 shows adiagram of Kocaeli University’s hydrogenenrichment setup.

From these two studies there appears tobe a discrepancy between the theoreticalmodeled results and actual experimentsconducted with electrolysis units in vehicles.Either the experiments were not conductedaccurately or there is an error in theassumptions of the models for waterelectrolysis products effect on engines.

Further testing should be conducted onactual electrolysis units in engines. Althoughsome is not highly scientific, there is a largeamount of performance data on electrolyticgas production and its effects on engineperformance, particularly improvement in fuelconsumption from “backyard engineers”.Searches on YouTube and Yahoo Groups suchas “Hydroxy” and “Watercar” reveal that manypeople have installed water electrolysis units,better known as “hydrogen boosters”, on theirvehicles and are achieving fuel consumptionimprovements ranging from 25% to 40%.Several high performance units are evenachieving results as high as 50% to 100%.There needs to be a complete investigation ofthese claims and this technology beforediscounting these results.

Theories on Efficient Electrolysis: Duringthe 1970’s professor and inventor Yull Browndesigned an electrolysis power torch for usein welding operations. This electrolysis unitwas designed to pass the molecular hydrogenand oxygen output through an electric arc.Brown states in his patents that the electric arcsplits the molecular hydrogen and oxygen intoatomic hydrogen and oxygen radicals. Whenthese atomic radicals are combusted therepurportedly is an additional 218,000 cal pergram mole released than is normally assumedto be released when molecular hydrogen andoxygen are combusted.

Figure 11: Electrolysis Unit

This system was tested on four vehicles, fuel

consumption and emissions were measured.

Table 3 displays the results for this test. It was

shown that using this system to add electrolysis

products to the engine increased fuel economy

by 25-40%. The emissions, for these cars,

were also tested and were reduced from

between 40-50% depending on engine type.

There was no noticeable reduction in the

performance of these vehicles.

Vehicle % Increase Fuel Economy

1993 Volvo 940 43%

1996 Mercedes 280 36%

1992 Fiat Kartal 26%

1992 Fiat Dogan 33%

Table 3: Electrolysis Test Results

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Electrolytic gas, often referred to as“Brown’s Gas”, has several interestingproperties that have been observed andutilized. “Brown’s Gas” can be generatedwithout the need to separate the hydrogen andoxygen therefore, the electrical resistancebetween the anode and cathode can beminimized and electrolytic velocity can bemaximized. Another interesting effect ofcombustion of the gas is that it burnsimplosively. This implosive burning is likely dueto atomic hydrogen and oxygen being present.Studies suggest that implosion will only occurwhen there is less than 5% air in the mixtureotherwise explosion occurs.

When radical atoms of hydrogen andoxygen are bonded they form what is called

crystall izing -bonds. These -bondsgenerate -far infrared rays. These -farinfrared rays create a strong gravitational cavitythat causes the substances to focus inwardwhen burning. It has been observed that thiseffect produces a burning temperature ofBrown’s Gas in the range of more than 6000°Cwhile normal hydrogen’s burning temperatureis in the range of 2700°C .

Brown’s Gas has been used for manyunique processes. It can be used for weldingmetals and ceramics.

Brown’s gas incinerators are used to burnatomic waste the radioactive rays are reduceto 1/3-1/20 of their original strength.

CONCLUSIONInjection of hydrogen into the combustionprocess has been shown to:

1. Increase thermal efficiency and decreasefuel consumption.

2. Decrease carbon monoxide and unburnthydrocarbon emissions.

3. Increase NOx emissions unless propertiming and mixture adjustments are used.

4. The challenge to using hydrogen as asupplemental fuel is the storage andgeneration of hydrogen.

5. Use of electrolysis of water to createhydrogen to enrich combustion should becompletely experimentally investigatedbefore dismissing it as ineffective.

REFERENCES1. Andrea T D et al. (2003), “Investigating

combustion enhancement and emissionsreduction with the addition of 2H

2 + O

2 to

Figure 12: Yull Brown's Electrolysis Unit

Figure 13: Hydrogen Passing Through Arc

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a SI engine”, SAE Paper, 2003320011.

2. Andrea T et al. (2004), “The addition ofHydrogen to a Gasoline-Fuelled SIEngine”, Int J Hydrogen Energy, Vol. 29,pp. 1541-1552.

3. Bauer C and Forest T (2001), “Effect ofHydrogen Addition on the Performanceof Methane-Fueled Vehicles”, Part I:Effect on S.I. Engine performance, Int JHydrogen Energy, Vol. 26, pp. 55-70.

4. Bauer C and Forest T (2001), “Effect ofHydrogen Addition on the Performanceof Methane-Fueled Vehicles”, Part II:Driving Cycle Simulation, Int J HydrogenEnergy, Vol. 26, pp. 71-90.

5. Bromberg L et al. (2001), “Emissionsreductions using hydrogen fromplasmatron fuel converters”, Int JHydrogen Energy, Vol. 26, pp. 1115-1121.

6. Choi G et al. (2005), “Performance andEmissions Characteristics of a HydrogenEnriched LPG Internal CombustionEngine at 1400 RPM”, Int J HydrogenEnergy, Vol. 30, pp. 77-82.

7. Dulger Z and Ozcelik K (2000), “FuelEconomy Improvement by on BoardElectrolytic Hydrogen Production”, Int JHydrogen Energy, Vol. 25, pp. 895-897.

8. Kumar M et al. (2003), “Use of Hydrogento Enhance the Performance of aVegetable Oil Fuelled CompressionIgnition Engine”, Int J Hydrogen Energy,Vol. 28,pp. 1143-1154.

9. Ma F et al.(2007), “Experimental Studyon Thermal Efficiency and EmissionCharacteristics of a Lean Burn HydrogenEnriched Natural Gas Engine”, Int JHydrogen Energy, doi: 10.1016/j.ijhydene.2007.07.048

10. Park et al. (2005), “Vitrification ofmunicipal solid waste incinerator fly ashusing Brown’s Gas”, Energy & Fuels, Vol.19, pp. 258-262.

11. Saravannan N et al. (2007),“Experimental investigation of hydrogenport fuel injection in DI diesel engine”, IntJ Hydrogen Energy, doi :10.1016/j.ijhydene.2007.03.036

12. Uykur C et al. (2001), “Effects of additionof electrolysis products on methane/airpremixed laminar combustion”, Int JHydrogen Energy, Vol. 26, pp. 265-273.

13. Wang J et al. (2007), “CombustionBehaviors of a Direct-Injection EngineOperating on Various Fractions of NaturalGas- Hydrogen Blends”, Int J HydrogenEnergy, Vol. 32, pp. 3555-3564.

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