Combustion Of Ethanol Research Articles

Improvement of High Temperature Oxidation of Low Carbon Steel Exposed to Ethanol Combustion Product at 700 °C By Hot-Dip Aluminizing Coating

Low carbon steel (AISI 1005) was coated by hot-dipping into a molten Al-10% Si bath at 700 °C for 18s. After hotdipping treatment, the coating layers consisted of Al, Si, FeAl3, τ5-Fe2Al8Si, and Fe2Al5. The bare steel and the aluminized steel were isothermally oxidized at 700 °C in ethanol combustion product at atmospheric pressure for 49 h. The aluminized steel shows good performance in high temperature oxidation because the formation of Al2O3 layer on the coating surface. The growth of iron oxide nodules on the surface coating was accelerated by rapid outward diffusion of Fe-ions due to the presence of H2O-vapour generated by ethanol combustion. Thus, the oxidation rate of aluminized steel increased, resulting in a substantial mass-gain as the oxidation time increased. After longer exposure, the τ1(Al,Si)5Fe3 phase was completely transformed to the FeAl in the outer layer. The FeAl formed near the steel substrate was due to Fe-atoms diffusing into the Fe2Al5 layer when the time and temperature increased.

Experimental and Modeling Study of Premixed Laminar Flames of Ethanol and Methane

To better understand the chemistry of the combustion of ethanol, the structure of five low pressure laminar premixed flames has been investigated: a pure methane flame (φ=1), three pure ethanol flames (φ=0.7, 1.0, and 1.3), and an ethanol/methane mixture flames (φ=1). The flames have been stabilized on a burner at a pressure of 6.7 kPa using argon as dilutant, with a gas velocity at the burner of 64.3 cm/s at 333 K. The results consist of mole fraction profiles of 20 species measured as a function of the height above the burner by probe sampling followed by online gas chromatography analyses. A mechanism for the oxidation of ethanol was proposed. The reactions of ethanol and acetaldehyde were updated and include recent theoretical calculations while that of ethenol, dimethyl ether, acetone, and propanal were added in the mechanism. This mechanism was also tested against experimental results available in the literature for laminar burning velocities and laminar premixed flame where ethenol was detected. The main reaction pathways of consumption of ethanol are analyzed. The effect of the branching ratios of reaction C2H5OH+OH→Products+H2O is also discussed.

Emission Characteristics of Ethanol Blending Fuels from a Laboratory Gasoline Engine

In Taiwan, 3% ethanol (E3) blending fuel was introduced to the market to lessen the pressure of energy deficit and carbon reduction from global warming. This study is aimed at discovering the environmental impacts of exhaust emissions imposed by ethanol blending fuels. The tested fuels are 0%, 5%, 10%, 15% and 20% of ethanol blending, and engine testing set rotation speeds at 1500, 2500 and 3500 rpm to simulate slow, normal and fast speeds of vehicle driving. Gaseous emissions from engine exhaust were collected to determine the concentrations of CO, NOx, HC, BTEX, formaldehyde and acetaldehyde. Ethanol blending fuels were found able to reduce the emission of regulated air pollutants (CO, NOx and HC) and containing toxic compounds (BTEX) more or less. However, formaldehyde and acetaldehyde emissions were greatly enhanced due to ethanol combustion in the engine. With the use of ethanol blending fuels, the environmental impact on the release of formaldehyde should be aware and carefully controlled.

Oxy-fuel Combustion of Ethanol in Premixed Flames

First measurements of the adiabatic laminar burning velocities of lean ethanol + oxygen + carbon dioxide flames, at 1 atm and initial gas mixture temperatures of 298, 318, and 338 K, are presented. The oxygen content O2/(O2 + CO2) in the artificial air was 35%. The laminar burning velocities were determined using the heat flux method, where a non-stretched flame is stabilized under adiabatic conditions. The measurements were found in qualitative agreement with modeling performed using the Marinov model, the San Diego model, and the model by Leplat et al. In comparison to experimental data, the Marinov model gave the best quantitative agreement. Notable quantitative differences between the models were analyzed using sensitivity analysis and reaction path diagrams. Reaction path analysis showed that the Marinov and the San Diego models have the same 12 most important species. Among the 12 most important species in the model of Leplat et al., 10 species are in common with the other two models. According to predictions of the Marinov model, combustion of ethanol in air and at oxy-fuel conditions proceeds via the same reaction path; however, the sensitivities of the key reactions are different.

Selection Criteria and Performance of Energycane Clones (Saccharum spp. × S. spontaneum) for Biomass Production Under Tropical and Sub-tropical Conditions

The urgent need to reduce our reliance on oil and at the same time reduce carbon emissions, has triggered the search for alternative energy sources such as biofuels. New technologies have made possible the conversion of cellulose and hemicellulose into sugars that can be fermented to produce ethanol. This opened the possibility that any plant species can be used for ethanol production. Species that produce large amounts of biomass in a short time are desirable. For this reason, one of the most critical steps in the development of biofuel production is to identify appropriate species that will provide the necessary biomass for cellulosic ethanol or direct combustion. Energycanes are wide crosses of commercial sugarcane (a complex hybrid of Saccharum spp.) with S. spontaneum clones which produce high-biomass plants with high fiber content and good cold and disease tolerance as well as excellent ratooning ability. A large scale study has been established to evaluate biomass production, growth characteristics and invasive potential of energycane clones under tropical (Limón, Costa Rica) and subtropical (South Florida) conditions since 2008. In Florida in a low fertility sandy soil, energycane clones and the grass species Pennisetum purpureum var. Merkeron showed the highest yields ranging from 50 to 78 ton ha-1 of fresh weight. These clones were not susceptible to smut (Sporisorium scitaminea) unlike the energycane L79-1002 which is currently the most widely grown clone of energycane. Most clones showed lateral vegetative growth, but no pollen or seed viability. In Costa Rica, the evaluation of 15 energycane clones is still in progress, however preliminary results indicated that the energycane clones had faster and more vigorous growth than the commercial sugarcane varieties, only exceeded by P. purpureum. In comparison with commercial sugarcane varieties, the energycane clones recorded 37% higher leaf area index (LAI) and height, and 65% more stalks per unit area. No evident disease susceptibility was observed in the energycane clones in the tropics, although lateral vegetative growth was observed in all clones. Additionally, all clones flowered and produced viable pollen which suggests that these clones have a higher invasive potential in the tropics. The information available until now suggests that the behavior of energycane germplasm varies importantly between tropical and sub-tropical conditions. Therefore, selection and breeding programs must be carefully developed accounting for the unique responses that this germplasm could show under these two different climatic conditions.

The effect of the addition of individual methyl esters on the combustion and emissions of ethanol and butanol -diesel blends

Biodiesel fuel is known to improve the properties of alcohol-diesel blends for use in compression ignition engines. In this work the effects on combustion characteristics and emissions of preselected methyl esters (i.e. biodiesel components) have been assessed. The most representative individual fatty acid methyl esters (FAMEs) were added to alcohol blends in order to understand the effect of carbon chain length and degree of unsaturation on combustion and emissions. The effects of alcohol addition on the properties of fuel blends were also investigated using ethanol and butanol. Relating to the physical properties, emphasis was given to both stability and lubricity of alcohol-diesel blends. The results showed that 15% of all methyl esters was enough to avoid phase separation of alcohol-diesel blends and keep the wear scar diameter of the blends below the limitation required by the lubricity standard. For combustion, the use of alcohol blends shows a clear benefit in terms of CO and soot emissions with respect to biodiesel blends with the same oxygen content. Short carbon chain length and saturated methyl esters are recommended to improve alcohol blends. Comparisons between the alcohols, show that butanol rather than ethanol produces lower CO, THC and soot emissions.

Baseline measurements of ethene in 2002: Implications for increased ethanol use and biomass burning on air quality and ecosystems

While it is well known that combustion of ethanol as a biofuel will lead to enhanced emissions of methane, ethene (ethylene), acetaldehyde, formaldehyde, and oxides of nitrogen (primarily NO) when compared to gasoline alone, especially during cold starts or if catalytic converters are not operating properly, the impacts of increases in atmospheric ethene levels from combustion of fuels with higher ethanol content has not received much attention. Ethene is a well known and potent plant growth hormone and exposure to agricultural crops and natural vegetation results in yield reductions especially when combined with higher levels of PAN and ozone also expected from the increased use of ethanol/gasoline blends. We report here some baseline measurements of ethene obtained in 2002 in the southwestern and south central United States. These data indicate that current ethene background levels are less than 1 ppb. Anticipated increases in fuel ethanol content of E30 or greater is expected to lead to higher atmospheric levels of ethene on regional scales due to its atmospheric lifetime of 1.5–3 days. These background measurements are discussed in light of the potential enhancement of ethene levels expected from the anticipated increases in ethanol use as a renewable biofuel.

Bifurcation analysis of the effect of hydrogen addition on the dynamic behavior of lean premixed pre-vaporized ethanol combustion

In this work, a mathematical model of fuel conversion and energy balance has been developed to study the dynamic behavior of a lean premixed pre-vaporized combustor fed with ethanol/air and ethanol–hydrogen/air mixtures. The combustor was modeled as a well stirred reactor (WSR). Results show that, for a simplified model reaction, Hopf bifurcations occur. Spontaneous oscillations have been found, suggesting that the combustion reaction plays an important role in the development of dynamic regimes. Hydrogen addition stabilizes ethanol combustion, damping the oscillations.

Effect of undiluted bioethanol on combustion and emissions reduction in a SI engine at various charge air conditions

This paper investigates the effects of neat bioethanol combustion on the performance and emission reduction characteristics of a spark ignition (SI) engine at various air temperature conditions. The experiments were carried out for different intake air temperatures and various operating conditions, and the results were compared to those for conventional gasoline fuel. The investigated results show that as intake ambient air temperatures is decreased, the intake flow rates is increased by the increased density of the intake air. The ethanol fuel has a higher volumetric efficiency than gasoline for all engine speeds and ambient temperature conditions. The cylinder pressures are increased with the improvement of volumetric efficiency due to the decrease of intake temperature. In addition, ethanol combustion creates higher combustion pressures than that of gasoline due to the high latent heat evaporation rate and low boiling point. The coefficients of variation of maximum pressure show slightly decreasing trends as the ambient air temperature increases. The concentration of NOx emissions tends to increase proportionally with the increase of ambient air temperature and engine speed for all test conditions. However, the HC, and CO emissions from ethanol combustion are improved than those of gasoline combustion.

Investigation of aqueous ethanol combustion in the reciprocating internal combustion engine

The results of an experimental research, conducted to study a possibility of reducing nitrogen oxide emission in the reciprocating internal combustion engine (ICE) at the combustion mode close to stoichiometric one by increasing the water content in the aqueous ethanol solution are presented. It has been established that as the water quantity in aqueous ethanol grows, a 30-fold reduction in the nitrogen oxides emission level is achieved without a drop in the engine power-to-weight ratio.

Kinetic study of the combustion of ethanol and ethyl acetate mixtures over a MnCu catalyst

A kinetic study of ethanol and ethyl acetate combustion on an efficient catalyst identified as Mn9Cu1 is reported in this contribution. Ethanol and ethyl acetate are typical VOCs which can be found in effluents of printing industries. Ethanol oxidation produces an intermediate product, acetaldehyde. On the other hand, ethyl acetate oxidation produces directly CO2 and H2O. Acetaldehyde reacts more slowly than ethanol, while ethyl acetate is slightly more difficult to oxidize than acetaldehyde.Strong inhibition effects among the species involved (ethanol, ethyl acetate and acetaldehyde) should be explicitly considered to propose reaction rate expressions. Thus, experimental data were satisfactorily fitted employing LHHW type expressions. The estimated activation energy of ethyl acetate and ethanol oxidation lies in the range of values reported in the literature for similar catalysts.

Cooperative effect of Ce and Pr in the catalytic combustion of ethanol in mixed Cu/CoMgAl oxides obtained from hydrotalcites

The cooperative effect of Ce and Pr in the modification of mixed copper and cobalt oxide catalysts which were synthesized starting from the co-precipitation method of a hydrotalcite structure was evaluated in the catalytic combustion of ethanol. The solids were characterized by XRD, XRF, H 2–TPR, O 2–TPD and N 2 adsorption. The greatest catalytic performance was associated with the increase in the oxygen storage capacity and reducibility in the solids that contain rare earth elements (Ce–Pr) and with the improvement in the specific surface area. Additionally, the high selectivity towards CO 2, which is the principal product in total oxidation, demonstrates that the solids modified with Cu and/or Co and promoted with rare earth elements, are excellent catalysts in the total oxidation of ethanol, evidencing a cooperative effect among the metals.

Development of reduced and optimized reaction mechanisms based on genetic algorithms and element flux analysis

The present paper introduces an approach for the automatic development of reduced reaction mechanisms for hydrocarbon combustion. An iterative reduction procedure is adopted with the aim of gradually reducing the number of species involved in the mechanism, while still maintaining its predictiveness in terms of not only ignition delay times, but also the time evolution of important species. In particular, a global error function is defined taking into account a set of 18 ignition delay calculations at different, engine-relevant, initial mixture compositions, temperatures and pressures. The choice of the species to be deleted is performed exploiting the element flux analysis method, first introduced by Revel et al.; when a global error function of the reduced mechanism exceeds the required accuracy, the collision frequencies and activation energies of selected reactions are corrected by means of a GA-based code. The procedure is repeated until the lowest number of species at the required global error tolerance is achieved. The methodology is applied to a detailed mechanism of ethanol combustion consisting of 58 species and 383 reactions to produce an optimal reduced mechanism of 33 species and 155 reactions.

Shock Tube Study on the Thermal Decomposition of Ethanol

The thermal decomposition of C(2)H(5)OH highly diluted in Ar (1 and 3 ppm) has been studied by monitoring H atoms using the atomic resonance absorption spectrometry (ARAS) technique behind reflected shock waves over the temperature range 1450-1760 K at fixed pressure: 1, 1.45, and 2 atm. The rate constant and the product branching fractions have been determined by analyzing temporal profiles of H atoms; the effect of the secondary reactions on the results has been examined by using a detailed reaction mechanism composed of 103 elementary reactions. The apparent rate constant of ethanol decomposition can be expressed as k(1)/s(-1) = (5.28 ± 0.14) × 10(10) exp[-(23,530 ± 980)/T] (T = 1450-1670 K, P = 1-2 atm) without a detectable pressure dependence within the tested pressure range of this study. Branching fractions for producing CH(3) + CH(2)OH (1a) and H(2)O + C(2)H(4) (1b) have been examined by a quantitative measurement of H atoms produced in the successive decompositions of the products CH(2)OH (1a): the pressure dependence of the branching fraction for channel 1a is obtained by a linear least-squares analysis of the experimental data and can be expressed as φ(1a) = (0.71 ± 0.07) - (826 ± 116)/T, (0.92 ± 0.04) - (1108 ± 70)/T, and (1.02 ± 0.10) - (1229 ± 168)/T for T = 1450-1760 K, at P = 0.99, 1.45, and 2.0 atm, respectively. The rate constant obtained in this study is found to be consistent with previous theoretical and experimental results; however, the pressure dependence of the branching fraction obtained in this study is smaller than those of previous theoretical works. Modification of the parameters for the decomposition rate in the falloff region is suggested to be important to improve the practical modeling of the pyrolysis and combustion of ethanol.

Cálculo del beneficio ambiental de la caña de azúcar para la producción de etanol combustible

Este artículo presenta de manera detallada el cálculo del beneficio ambiental asociado al uso de la caña de azúcar para la producción de etanol combustible en una destilería de etanol diversificada que está concebida para operar como una agro-industria. Al considerar las diversas etapas del proceso de producción tales como la formación de biomasa, el transporte de la caña desde el campo hasta la fábrica, la producción de etanol, la combustión de bagazo, la digestión anaeróbica de las vinazas y la combustión del metano generado, y la combustión del etanol en los vehículos automotores, se demuestra que el uso de la caña es beneficioso para el medio ambiente porque involucra una sustracción de CO2 del ambiente de 22,639 ton / año y una incorporación al ambiente de 15,244 ton / año de O2, , para una destilería con capacidad de producción de 40,000 L / día de etanol combustible. Además, se presenta el cálculo de la cantidad de CO2 que se incorporaría al medio ambiente si en esa destilería se utilizara gas natural para la generación de electricidad mediante un ciclo de potencia combinado.

Effects of Synthesis Parameters on the Preparation of Carbon Nanofibers by Ethanol Catalytic Combustion

In this paper, the effects of position of substrates in flames, preparation time and stability of flames on carbon nanofibers are investigated in ethanol catalytic combustion. For the position of substrates, our results indicate that the temperature at the lower height (h<1cm) is too low (less that 500°C) to grow carbon nanofibers; the temperature at higher height (h>2.5cm) is suitable for the growth of carbon nanofibers, but the carbon source is insufficient because of sufficient combustion of ethanol; the optimal position of substrates in flames is more than 1cm and less than 2.5cm for massive yield because the temperature of flames is suitable for the growth of carbon nanofibers and the carbon source is also sufficient. For the preparation time, our results indicate that the optimal preparation time is more than 5min and less than 30min for massive yield. If the preparation time is excessive long (more that 30min), the deposits partly become burning in flames due to excessive products on substrates. The stability of flames has effects on the morphology and graphitization of products. Our experimental results indicate that stable flames prefer to produce noncoiled carbon nanofibers with relatively good uniformity and higher graphitization because the relatively stable flames could provide a relative stable synthesis environment.

La1−xCaxMnO3 perovskites as catalysts for total oxidation of volatile organic compounds

La1−xCaxMnO3 perovskites were prepared by the citrate method and characterized by means of X-ray diffraction, temperature programmed desorption of oxygen, temperature programmed reduction, and measurement of specific surface area. The characterization results indicated that pure perovskite phases were obtained and their specific surface areas are appropriate for the application in catalytic oxidation. The unsubstituted perovskite, LaMnO3, could present a certain amount of Mn4+ and cationic vacancies, which is generally called oxidative nonstoichiometry. The electronic unbalance yield by the partial substitution of lanthanum by calcium, a cation of lower oxidation state, caused an oxidation state increase of part of the manganese occupying the B sites of the structure. Concurrently, the amount of cationic vacancies decreased with the increase of calcium amount. The catalytic activity was evaluated in the combustion of ethanol and n-hexane. Both reactions would occur by means of a suprafacial reaction mechanism in which the adsorbed oxygen species are relevant.

Experimental study of combustion characteristics of nanoscale metal and metal oxide additives in biofuel (ethanol)

An experimental investigation of the combustion behavior of nano-aluminum (n-Al) and nano-aluminum oxide (n-Al2O3) particles stably suspended in biofuel (ethanol) as a secondary energy carrier was conducted. The heat of combustion (HoC) was studied using a modified static bomb calorimeter system. Combustion element composition and surface morphology were evaluated using a SEM/EDS system. N-Al and n-Al2O3 particles of 50- and 36-nm diameters, respectively, were utilized in this investigation. Combustion experiments were performed with volume fractions of 1, 3, 5, 7, and 10% for n-Al, and 0.5, 1, 3, and 5% for n-Al2O3. The results indicate that the amount of heat released from ethanol combustion increases almost linearly with n-Al concentration. N-Al volume fractions of 1 and 3% did not show enhancement in the average volumetric HoC, but higher volume fractions of 5, 7, and 10% increased the volumetric HoC by 5.82, 8.65, and 15.31%, respectively. N-Al2O3 and heavily passivated n-Al additives did not participate in combustion reactively, and there was no contribution from Al2O3 to the HoC in the tests. A combustion model that utilized Chemical Equilibrium with Applications was conducted as well and was shown to be in good agreement with the experimental results.

Combustion of volatile organic compounds on a MnCu catalyst: A kinetic study

Catalytic combustion is a well-developed process to eliminate volatile organic compounds (VOCs). Although there is a continuous effort in formulating new catalytic materials, studies devoted to estimate kinetic parameters suitable for design and optimization of catalytic combustors are scarce. A kinetic study of ethanol combustion on an efficient catalyst identified as Mn 9Cu 1 is reported in this contribution. Ethanol is a typical VOC, which is found, for example, in effluents of printing industries. The study aims to develop reaction rate expressions and estimate kinetic parameters. The presence of only one intermediate, namely acetaldehyde, has been detected in significant amounts. Acetaldehyde turns out to react more slowly than ethanol. Experimental data were satisfactorily fitted employing LHHW type kinetic expressions. The estimated activation energy of ethanol oxidation lies in the range of values reported in the literature for similar catalysts.

Kinetic modeling study of ethanol and dimethyl ether addition to premixed low-pressure propene–oxygen–argon flames

The chemical composition of flames of mixed hydrocarbon–oxygenate fuels was examined systematically for a series of laminar, premixed low-pressure propene–oxygen–argon flames blended with ethanol or dimethyl ether (DME). All flames were established at a carbon-to-oxygen ratio of C/O = 0.5 at 40 mbar. Propene was replaced incrementally by either additive, so that the entire range from pure propene to pure ethanol or pure DME was accessible. Experimental results have been reported previously (J. Wang et al., J. Chem. Phys. A 112 (2008) 9255–9265), including temperature profiles measured with laser-induced fluorescence (LIF) and quantitative mole fraction profiles for a large number of species obtained from molecular-beam mass spectrometry (MBMS), using electron ionization (EI) and vacuum-ultraviolet (VUV) photoionization (PI). The effects of oxygenate addition to the propene base flame were seen to result in interesting differences, especially regarding trends to form aldehydes. The entire flame series is now analyzed with a comprehensive kinetic model that combines the chemistries of propene, ethanol, and DME combustion. The flames of pure fuels are also compared with the predictions of different detailed mechanisms taken from the literature. Quantitative comparison of C 1- to C 6-species from this model with the measurements is provided. Major trends of propene replacement by the oxygenates are reproduced in quantitative agreement with the experiments, enabling a more detailed understanding of the combined reaction sequences in such fuel blends.