Experimental study for Effect of hydrogen on laminar burning velocity for different fuel blendsBy M.Sc. student Ahmed Sh. Yousif SupervisorProf. Haroun Ak. Shahad1Increasing concern over the fossil fuel shortage and pollution of air, the requirement for alternative fuels for Internal Combustion Engines (ICEs) has been a major concern for the researchers. The need for a sustainable energy system has lead researchers to study the combustion process and alternative fuels , several studies have been conducted on this fuel since the 1930s for hydrogen as an alternative fuel . In particular, comprehending the combustion performance of hydrogen at varying equivalence ratios, and volumetric percentages with other fuels is essential to optimize engine operations. Introduction2Introduction3This study investigates the effect of hydrogen blend injected with fuel into a constant volume combustion chamber (CVCC) on the laminar burning velocity. The properties studied include flame structure, flame front speed, chamber pressure , Laminar burning velocities, Markstein lengths, Zeldovich number , Lewis number and flame thickness. Aim of the StudyThe aim of this study is to investigate laminar flame speed based on fuel composition with air. The main objective will be to determine the effect of hydrogen with fuel percentage on burning velocity. Different fuels will be tested using differing percentages by volume composition to determine the optimal ratio of fuel to air. An optimal ratio will be defined as being the ratio that results in the fastest flame speed.

5Fuels Liquefied petroleum gas (LPG) LPG consists mainly of butane and propane as one of the main energy sources used for domestic and commercial applications, LPG has advantages such as :-A high heating value ("calorific value") 46.1 MJ/kgEmissions from LPG vehicles are lower . hydrocarbon (HC) emissions as 40% lower, carbon monoxide (CO) as 60% lower and a virtual absence of sulphur, leading to cleaner burning.Because it burns in the engine in the gaseous phase, LPG results in less corrosion and engine wear than does gasoline.Its high octane rating (105) enables it to burn more completely than does gasoline, . With less carbon buildup, spark plugs often last longerstable flame and low processing cost.can be liquefied in a low pressure range of 0.7 to 0.8MPa at atmospheric pressure6Fuels

Hydrogen Hydrogen (H2) another well-known clean fuel ,at standard temperature and pressure, hydrogen is a colorless, odorless, tasteless, non-toxic, nonmetallic, highly combustible diatomic gas has high flame speed (200cm/sec), wide flammability range will burn in air at a very wide range of concentrations between 4% and 75% by volume, low minimum ignition energy, and no emissions of HC or CO2. Recent studies on internal combustion engines with hydrogen enriched fuels showed that hydrogen addition could increase engine thermal efficiency, improve lean burn capability and mitigate the global warming problem .the temperature of spontaneous ignition in air, is 500 C .However, hydrogen flame can be rather unstable during operation because of its extremely light weight and special combustion characteristics. Also, because of its low density and light molar weight, hydrogen has very low volumetric heating value.

Burning Velocity and Flame Speed8Flame SpeedThe flame speed is the measured rate of expansion of the flame front in a combustion reaction.

Flame can be divided into premixed and non- premixed (diffusion ) according to the mixing with oxider and each can be divided into laminar and turbulent according to flow regime.9Laminar Burning VelocityThe burning velocity (Su) is defined as the velocity at which unburned gases move through the combustion wave in the direction normal to the wave surface.

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Experimental Work12Experimental SetupThe study of flame propagation subject needs Rainbow Schlieren Deflectometer systems because of the short period available for measurement, which is not longer than few milliseconds.The experimental apparatus consists mainly of the following units: combustion chamber and ignition unitmixture preparing unitRainbow Schlieren Deflectometer unit

13The MixerH2tankfueltankAir compressorC.CSpark plugA.C. powertransformerPush ButtonCombustion Chamber and Ignition Unit

The present work is using a cylindrical shape with (190mm) inner diameter; (250mm) length , (10 mm) wall thickness , (20 mm) thickness upper and lower flange, made of solid iron to resist the high pressure that occur during the combustion .These flanges are joined with the combustion chamber by 16 hex bolt (M16 ) for each flange. Two pressure-resisting quartz windows ( 80 mm) are installed on the two sides of the combustion chamber by flange to allow the combustion process optically accessibleA temperature and pressure recorder are used To produce a powerful spark in the spark Plug , a DC power is produced from a transformer connected to AC power line (220 V AC). The transformer (2*7.5 KV HOSEL ) output is 14KV the peakmixture preparing unit The main purpose of preparing the mixture in the mixer rather than in the combustion chamber is to increase the total pressure of the mixture and then increase the partial pressure of hydrocarbon fuel and hydrogen so that the reading will be more accurate . The calculation for the mixing will be obey to Gibbs Dalton Law The MixerH2tankfueltankAir compressorto the combustion chamberVacuum gauge Total pressure gauge 16Rainbow Schlieren Deflectometer Unit

There are 3 methods to visualize the flow in the Schlieren technology Rainbow Schlieren Deflectometer Single concave mirror method Z- type mirror methodStill working on this method to get the perfect way to visualize the flameMethod of Measurements and procedure18Laminar Burning Velocity Measurement Methods The heat flux method needs to determine the heat loss as a function of the inlet velocity and to extrapolate the results to zero heat loss to get the adiabatic burning velocity This method utilizes the prototypical propagating spherical or half spherical flame configuration and has drawn particular attention due to its simple flame configuration, well-defined flame stretch rate and well controlled experiment . .Its done by creating stretch stabilized twin flames. This method can establish different flame configurations, but it is difficult to draw a clear flame front and to stabilize the flame under the high-pressure conditions and its not the most accurate 19Burning Velocity Measurement techniques 20H2 + 0.5(O2 + 3:76N2) H2O + 0.5 * 3:76N2 CnHm + (n+m/4)(O2 + 3:76N2) nCO2 +m/2 H2O + (n+m/4) * 3:76N2(F/A )st= 1 / [ X%h2 * 0.5 (1+3.76) +( 1-X%h2)*(n+m/4)(1+3.76) ]Mixture can be expressed as {(1 - X% )CnHm + X% H2} and airDalton's law state that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gasesP total = P1+p2+p3 ..Pn Pfuel /Ptotal = Nfuel /NtotalAnalytical MethodAnalytical Methodexample 10%H2 +90% LPG (60%C3H8 +40%C4H10) for =1 ,Pf=0.1 bar T=298 K 0.1 H2 +0.54 C3H8 +0.36 C4H10 + (x) / (O2 + 3:76N2) aCO2 +bH2O + (x/ ) * 3:76N2Experimental work plan laminar burning speeds and flame structures of spherically expanding flames of the mixtures in a constant volume cylindrical chamber.. Burning velocity will be as the following Type of fuel in this study we will use LPG , Propane , acetylene , Methane ( if available !!!) Blends of hydrogen from 0-100 percent use for each fuelEquivalence ratios from 0.4 to 1.4according to the flammability limits for each blends Initial pressure the range pressure of 0.52.0atm,P= 2 atm100%90%80%70%60%50%40%30%20%10%0%0.40.60.811.21.4P= 1.5 atm100%90%80%70%60%50%40%30%20%10%0%X%H20.40.60.811.21.4P= 0.5 atm100%90%80%70%60%50%40%30%20%10%0%X%H20.40.60.811.21.4P= 2.0 atm100%90%80%70%60%50%40%30%20%10%0%X%H20.40.60.811.21.4P= 1.0 atm100%90%80%70%60%50%40%30%20%10%0%X%H20.40.60.811.21.4Thank You

BabylonUniversity April , 29th , 2015MechanicalAhmedEngineering LPG