Effect Of N-butanol Addition Research Articles

Effects of n-Butanol Addition on the Combustion Characteristics of n-Heptane Counterflow Diffusion Flame at Elevated Pressure

This study focused on the effects of n-butanol addition on the combustion characteristics of n-heptane counterflow diffusion flame under pressures of 1, 3, and 5 atm by a detailed kinetic simulation. The added n-butanol volume fraction ranged from 0 to 50%. The mass averaged velocity of fuel streams was selected to ensure momentum flux balance and was approximately constant for the investigated flames. Flame structures and mole fraction profiles impacted by n-butanol addition for major species, free radicals, and intermediate species were analyzed by concentrating on the formations of soot precursors and oxygenated air pollutants. The results showed that with the addition of n-butanol, the flame temperature decreased and the formation of the main soot precursors such as C2H2 and C6H6 was inhibited. This can be attributed to the reduced rate of production of these species. The flame temperature increased significantly, and the profile moved towards the fuel side with the increasing pressure. Moreover, the production of C2H2 and C6H6 was observably promoted as the pressure increased. The concentrations of free radical H, O, and OH decreased significantly as the pressure increased but slightly decreased with the increasing n-butanol addition, which might have been caused by the chemical effect of n-butanol.

Effect of n-butanol addition on the burning rate and soot characteristics during combustion of single droplets of diesel–biodiesel blends

The effect of n-butanol addition on the burning rate and soot characteristics of single droplets of diesel–biodiesel blends was systematically studied. A single droplet of a diesel–biodiesel-n-butanol mixture of approximately 1 mm in diameter was suspended on a silicon carbide fibre and burned in air at 973 K in an electrically heated tube furnace. The droplet size during combustion was continuously recorded using a colour CCD camera and the burning rate based on the d2 law was determined. The soot intensity as indicated by theKLfactor and flame temperature were estimated from the CCD camera spectrum data using a two-colour pyrometry technique. Soot particles were also sampled using a thermophoreric deposition probe and characterised using a high resolution transmission electron microscope (TEM) for particle size and morphology. The results showed that n-butanol addition increased the burning rate of diesel–biodiesel blends, reduced the KL factor, being more profound with increasing n-butanol addition. The temperatures of the flames surrounding the fuel droplets with and without n-butanol addition showed little differences. The mean diameter of primary soot particles decreased and the particle size distribution shifted towards a smaller size range with n-butanol addition. At low levels of n-butanol addition the soot particles consisted of predominantly amorphous carbon, however, became progressively more graphitic in the inner structure with increasing n-butanol addition.

Effects of n-butanol addition on sooting tendency and formation of C1 –C2 primary intermediates of n-heptane/air mixture in a micro flow reactor with a controlled temperature profile

ABSTRACTEffects of n-butanol addition on the sooting tendency and formations of C1 and C2 primary intermediates of n-heptane/air mixtures were studied in a micro flow reactor with a controlled temperature profile. Sooting tendency was investigated over equivalence ratios of 1.5–4.0 at a maximum wall temperature of 1300 K. Experimental observations indicated two types of flames: a flame alone (type I) or a flame with soot (type II). The critical sooting equivalence ratio, at which the flame switched from type I to type II, increased with the increase of butanol content in the fuel blend. Results show that the sooting tendency of n-heptane decreases as the amount of n-butanol is increased.Computational results obtained using the Chemical Reaction Engineering and Chemical Kinetics mechanism show fair agreement with measurement results obtained at equivalence ratio of 2.0 and the maximum wall temperature of 1166 K. The validity in initial-stage reaction progress of existing mechanisms was examined.

Performance and emissions of a reactivity controlled light-duty diesel engine fueled with n-butanol-diesel and gasoline

Reactivity Controlled Compression Ignition can be extended over a wide spectrum of fuels and is anticipated as a promising strategy in meeting current and future emission regulations. In this study, the effect of n-butanol addition on combustion characteristics and emissions in a reactivity controlled engine was investigated experimentally. Different ratios of butanol-diesel blends at different settings of EGR and premixed ratios were applied to a light duty diesel engine. The butanol-diesel blends were directly injected into the combustion chamber while gasoline was injected at the intake port. Combustion phasing was maintained at 2.7 °CA for all of test points by adjusting fuel injection timing. The results showed that start of combustion delayed by n-butanol addition, so direct injection timing should be retarded to keep constant the combustion phasing. By increasing n-butanol fraction in the mixture from 0% to 40%, the optimum value of premixed ratio has decreased from 85% to 70%. The addition of n-butanol has reduced CO emission while HC emission has increased due to higher latent heat of vaporization of the alcohol fuel. The incorporation of an EGR unit in the experimental setup has improved the engine’s thermal efficiency but of little effect on the optimum premixed fuel ratio.

Experimental and kinetic investigation on soot formation of n-butanol-gasoline blends in laminar coflow diffusion flames

Bio-butanol has been considered to be an important alternative fuel to reduce soot emissions from gasoline engines, and it has the potential to overcome the disadvantages brought by low-carbon alcohols. In this study, the effect of n-butanol addition on soot formation in gasoline laminar diffusion flame is investigated respectively under the same fuel flow and the same carbon flow. The soot volume fraction distributions in the flames are measured using the two-color laser induced incandescence (TC-LII) technique. Furthermore, the But-TRF-PAH mechanism is constructed and used to simulate the formation and oxidation of soot precursors in the CHEMKIN zero-dimensional constant pressure reactor. The experimental results showed that n-Butanol addition can significantly reduce the soot formation, and the measured peak and average soot volume fraction both decrease linearly with the increasing n-butanol ratio. For a given n-butanol ratio, the reduction of soot under the same carbon flow (SCF) condition is only slightly smaller than that under the same fuel flow (SFF) condition, which indicates that the decreasing carbon mass flow due to n-butanol addition has little contribution to soot reduction. The simulated results showed that benzene is mainly produced via C6H5CH3+H=A1+CH3, and is mainly consumed via A1 + OH = A1- + H2O and A1 + CH3 = A1- + CH4. The production pathways of PAH is consistent for the toluene reference fuels (TRF) and n-butanol/TRF blends. The ratio of benzene accounts for toluene consumption is essentially constant, about 1/4. Thus, the n-butanol addition reducing the soot is mainly due to the dilution of the amount of aromatics (toluene in TRF) in gasoline. Furthermore, the amount of OH and HO2 radicals increases with increasing n-butanol ratio, which have an important indirect effect on the soot precursors formation.

Performance and emission characteristics of papaya seed oil methyl ester–n-butanol–diesel blends on a stationary direct-injection CI engine

ABSTRACTCurrently, atmospheric pollution and increased energy needs delineate the importance of alternate sources of fuels. In this current study, the performance and emission characteristics of papaya seed methyl ester (PSME) blended with diesel are studied at varying loads. PSME is blended at 5, 10 and 15% into the fuel and, in addition to that, a 10% concentration of n-butanol is also blended. The blends showed promising results where the CO, HC and smoke emissions were reduced significantly by addition of n-butanol despite the higher viscosity of papaya seed oil. Also, the effect of n-butanol addition was high in blends with lower concentration of biodiesels. Their effect was found to be predominant at medium operating loads rather than at lower and higher loads. In addition to that, PSME increased the brake thermal efficiency (BTE), exhaust gas temperature (EGT) and NOx emissions.

Extraction and characterization of waste plastic oil (WPO) with the effect of n-butanol addition on the performance and emissions of a DI diesel engine fueled with WPO/diesel blends

With growing global energy demands, recovering energy from waste plastic presents an attractive avenue to explore as it promotes recycling. Oil synthesized from waste plastic can be excellent fuel for diesel engines but yields higher carcinogenic smoke emissions and poor performance than fossil diesel (D). This study demonstrates the extraction and characterization of waste plastic oil (WPO) obtained by pyrolysis in a laboratory scale batch reactor and later sets out to investigate the effects of adding a renewable oxygenated component in the form of n-butanol (B), a naturally occurring biofuel. Three ternary blends, D50-WPO40-B10, D50-WPO30-B20 and D50-WCO20-B30 were strategically prepared to utilize both a recycled component (WPO by up to 40%) and a renewable component (n-butanol by up to 30%). The performance and emissions of DI diesel engine when fueled with these blends was then analyzed in comparison with both neat WPO and diesel operation. Results indicated that n-butanol addition presented lower smoke emissions and higher HC emissions when compared to diesel. Addition of 10% n-butanol by vol. to WPO/ULSD blend reduced NOx emissions favorably when compared to both WPO and diesel. However NOx emissions were higher than the corresponding WPO case for higher volume n-butanol blends. Brake thermal efficiency (BTE) of the engine increased with increasing n-butanol fraction in the blends when compared to WPO. Fuel consumption of ternary blends was found to be better than WPO. D50-WPO40-B10 blend presented less NOx and smoke emissions with improvement in engine performance when compared to diesel. Study revealed that n-butanol could be a viable additive for diesel engines operating with WPO extracted from mixed waste plastic.

Explosion characteristics of n-butanol/iso-octane-air mixtures

N-butanol is a promising alternative fuel for automobile whose explosion characteristics should be a major focus before widely used. Unfortunately, limit researches focusing on its explosion characteristics have been launched until now. In this study, the effects of n-butanol addition on the explosive characteristics of iso-octane-air mixtures with various concentrations and initial pressures and temperatures were experimentally investigated and analysed on the basis of combustion pressure history. The explosion pressure pexp and the maximum explosion pressure pmax, the maximum rate of pressure rise (dp/dt)max, the deflagration index KG, and combustion duration tc as well as flame development period td, were examined. Results show that with the increase of n-butanol blending ratio, explosion pressure does not change, while explosion duration is decreased, so the maximum rate of pressure rise is increased. It was found that pressure curves of rich mixtures oscillate in the vicinity of pressure peak at elevated pressures, and the pressure oscillation greatly shortens the explosion duration and increases the maximum rate of pressure rise. In addition, with the increase of n-butanol blending ratio, the pressure oscillation intensity is decreased.

Effect of the n-butanol addition on propargyl radical issued from the combustion of benzene

A global kinetic model was constructed from the combination of two existing and broadly validated kinetic schemes for benzene and butanol. Then the combined model, which was able to predict the combustion behavior of benzene-butanol fuel mixtures, was implemented in the PREMIX code in conjunction with CHEMKIN II in order to investigate the effect of n-butanol addition on the formation-depletion of propargil radical C3H3, which is known to be soot precursor, in fuel-rich n-butanol-benzene flames. It was treated the dependence of the soot precursor amounts on n-butanol percentage in the fuel mixture. Then was considered the causes of the variation of this species mole fractions with benzene replacement percentage by oxygenate additive. The principal objective of the current study was to obtain fundamental understanding of the mechanisms through which the oxygenate compound affects the soot precursor amounts. It was found that n-butanol-benzene fuel mixture displayed lower propargyl radical concentrations as compared to the pure benzene flame.

Autoignition response of n-butanol and its blends with primary reference fuel constituents of gasoline

We study the influence of blending n-butanol on the ignition delay times of n-heptane and iso-octane, the primary reference fuels for gasoline. The ignition delay times are measured using a rapid compression machine, with an emphasis on the low-to-intermediate temperature conditions. The experiments are conducted at equivalence ratios of 0.4 and 1.0, for a compressed pressure of 20bar, with the temperatures at the end of compression ranging from 613K to 979K. The effect of n-butanol addition on the development of the two-stage ignition characteristics for the two primary reference fuels is also examined. The experimental results are compared to predictions obtained using a detailed chemical kinetic mechanism, which has been obtained by a systematic merger of previously reported base models for the combustion of the individual fuel constituents. A sensitivity analysis on the base, and the merged models, is also performed to understand the dependence of autoignition delay times on the model parameters.

Effect of the n-butanol addition on cyclopentadienyl radical formation during benzene combustion

The PREMIX code in conjunction with Chemkin II and models resulting from the merging of validated kinetic schemes describing the oxidation of the components of the n-butanol-benzene mixtures were used to investigate the effect of n-butanol addition on the formation-depletion of cyclopehtadienyl radical (C5H5), a soot precursor in the flames of mixtures of n-butanol-benzene formed under fuel-rich conditions. The first part of this study deals with the validation of the proposed combined model on benzene and n-butanol flames. The second part describes the dependence of the amount of cyclopentadienyl radical on the percentage of benzene replacement by oxygenate additive. The third part deals with the causes of the variation of mole fractions of this species with n-butanol. The principal objective of this work was to obtain fundamental understanding of the mechanisms through which an oxygenate affects amounts of C5H5. It was found that the cyclopentadienyl radical concentration was lower in the flame of the n-butanol-benzene fuel mixture than in the pure benzene flame.