Combustion Parameters Research Articles

Evaluation of Kinetic and Thermodynamic Parameters of Pyrolysis and Combustion Processes for Bamboo Using Thermogravimetric Analysis

As a typical forestry waste, bamboo has gained increasing attention for its potential applications. In order to optimize its valorization, understanding the kinetic and thermodynamic parameters of bamboo pyrolysis and combustion is crucial. In this study, thermogravimetric analysis (TGA) was employed to examine bamboo powder’s pyrolysis and combustion behaviors under different temperature ramps in nitrogen and air environments, and the kinetic and thermodynamic parameters were evaluated using the Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Starink (STR) model-free approaches. The main findings are as follows. (1) The thermogravimetry (TG) and derivative thermogravimetry (DTG) (DTG) curves reveal that bamboo pyrolysis occurs in three distinct stages: drying, devolatilization, and carbonization. Similarly, combustion also proceeds through three stages: drying, devolatilization, and char combustion. Notable differences in the temperature ranges of the key stages were observed between pyrolysis and combustion. (2) The activation energies during the oxidative devolatilization stage of combustion are notably lower compared to those during pyrolysis devolatilization. The disparity in activation energy is even more pronounced in the third stage. (3) Thermodynamic analysis shows that the pyrolysis and combustion of bamboo are endothermic and non-spontaneous. It can be stably converted into value-added energy through the pyrolysis or combustion process. This study provides essential data to aid in designing and scaling up the thermochemical conversion processes for bamboo and promote its efficient valorization of bioenergy.

Hydrogen-fueled PFI SI engine investigation for near-zero NOx emissions in de-throttled and supercharged ultra-lean burn conditions

This study investigates the efficiency and combustion characteristics of a hydrogen port fuel injection (PFI) spark ignition (SI) engine under various load levels, excess air ratios and intake pressures. Experiments were conducted on a single-cylinder research engine to evaluate the effects of throttle opening and supercharging on pumping work and combustion parameters. The key findings indicate that abnormal combustion events are more closely related to the relative air-fuel ratio (λ) than to load, further limiting load increases during de-throttled operation. Additionally, combustion variability compromised mixture enleanment in both naturally aspirated and supercharged conditions. The gross indicated efficiency was approximately 40.7% across the range of 2.2 < λ < 3.5 with minimal variation. Efficiency gains were linked to reduced heat transfer losses in lean conditions, as validated by computational heat transfer, thermodynamic and fluid dynamic models on Gamma Technologies GT-ISE software. Moreover, nitrogen oxides (NOx) emissions were nearly zero for all test conditions when λ was above 2.2. These findings provide crucial insights into optimizing hydrogen engine performance under various intake pressures, highlighting the potential for achieving high efficiency and low emissions.

Thermogravimetric Assessment of Biomass: Unravelling Kinetic, Chemical Composition and Combustion Profiles

Thermogravimetric analysis (TGA) was performed on six samples of pine wood, poplar sawdust and olive residue, and the kinetic parameters were evaluated by using isoconversional models. The hemicellulose, cellulose and lignin contents were also estimated using the Fraser–Suzuki deconvolution method. In addition, a range of thermodynamic parameters and combustion indices was calculated. Significant correlations were found between the kinetic, thermodynamic and combustion parameters. The ignition index showed an inverse relationship with the activation energy, whereas the burnout index correlated with enthalpy values for most samples. Higher heating rates during TGA increased ignition and combustion efficiencies but decreased combustion stability. Differences in behaviour were detected between the olive residues, which had a much higher lignin content (51.2–56.9%), and the woody biomass samples (24.2–29.2%). Moreover, the sample with the highest ash content also exhibited some distinctive characteristics, including the lowest high heating value and ignition index, coupled with the highest activation energy, indicating a less favourable combustion behaviour than the other samples. The particle size of the samples was also found to be critical for both combustion efficiency and safety.

Flame temperature and emissivity distribution measurement of solid propellant based on clustering analysis of multispectral radiation images.

To measure the combustion parameters of a solid propellant, this Letter researches the fitting method for flame temperature and emissivity based on multispectral images and proposes the particle swarm optimization-K-means (PSO-K-means) clustering optimization algorithm of a flame multispectral image. Considering the difference in flame radiation characteristics in different regions, the flame multispectral image is clustered, and spectra in different regions are analyzed and selected in different fitting bands to inverse temperature and emissivity. On this basis, the method is applied to measure solid propellant combustion parameters with different formulations. The measurement shows that the flame temperature is between 1700 and 2100 K, and the emissivity is concentrated in 0.1-0.5. Compared with temperature measurements obtained from tungsten-rhenium thermocouples, the relative deviation of multispectral imaging thermometry is less than 5%. The distribution characteristics of solid propellant combustion parameters with different formulations were analyzed, which provided important data support for evaluating combustion conditions and optimizing solid propellant formulations.

Flame Speed Measurements of Ammonia-Hydrogen Mixtures for Gas-Turbines

Abstract Ammonia (NH3) is a promising sustainable fuel, as it has historically been shown to provide high energy potential and zero carbon emission. As a hydrogen (H2) carrier, NH3 serves as a possible solution to the U.S. Department of Energy?s Hydrogen Program Plan by providing efficient H2 storage and conservation capabilities. As a result, applied turbine-combustion research of NH3 and H2 fuel has been conducted to identify combustion performance parameters that aid in the design of sustainable turbomachinery. One of these key combustion parameters is the laminar burning speed (LBS). While abundant literature exists on the combustion of NH3 and H2 fuels, there is insufficient evidence in high pressure environments to provide a comprehensive understanding of NH3 and H2 combustion phenomena in turbine combustor settings. The effect of H2 addition to NH3 fuel was observed by comparing the LBS for various NH3-H2 mixture compositions. Experimental results revealed increased LBS values for H2 enriched NH3, with the maximum LBS occurring at stoichiometry. The experimental data were accurately predicted by the UCF NH3-H2 mechanism developed for this investigation, while NUI 1.1 simulations overestimated recorded LBS data by a significant margin. This study demonstrates and quantifies the enhancing effect of H2 addition to NH3 fuels via LBS and strengthens the literature surrounding NH3-H2 combustion reactions for future work.

Isothermal Flow Field Characterization of a Full-Scale Sector Combustor at Elevated Pressures

Abstract An experimental investigation in a sector (20 deg) of full-scale annular gas turbine combustor is performed. The sector combustor is optically accessible for the flow and flame visualization of the primary and exit zones of the combustor. The distinctive feature of the experimental setup is that it preserves the geometrical details of an annular combustor that includes the casing, dome and combustor liner. The combustor design features a series of primary and secondary dilution holes with multiple film cooling strips on the outer and inner liner. In the present study, the combustor is operated at inlet Mach numbers of 0.02–0.3 at operating absolute pressures of 1–5 bar. Static pressure measurements are performed at multiple locations in the rig to characterize the pressure drop across the combustor. Two-dimensional particle image velocimetry (PIV) is performed to measure the velocity fields of the primary and exit zones of the combustor simultaneously. The results show the presence of a central recirculation zone (CRZ), high-velocity annular jets, and a pair of dilution jets in the primary zone of the combustor. The steady-state flow structures are invariant of inlet Mach number and pressures. The relationship between the relative pressure drop across the combustor and the combustor inlet condition is obtained. Mass flowrate and momentum flux are calculated for the flow through the swirler, central recirculation zone, the primary dilution jets, and the exit zone. The paper shows how the flow structures in a realistic combustor change with variations in global combustor parameters.

Numerical investigation of pre-chamber holes diameter geometry on combustion parameters in a hydrogen-powered Turbulent Jet Ignition engine

The search for substitutes for conventional fuels leads to the use of hydrocarbon-free or synthetic fuels. One of them is hydrogen. The use of hydrogen in combination with a two-stage charge creation system leads to the combustion of lean (λ &gt; 1) or very lean (λ &gt; 3) charges. The simulation tests carried out were aimed at determining the best configuration of the chamber connecting the prechamber with the main combustion chamber. Three variants of the diameter of the holes connecting the chambers were selected (d = 0.5; 1.0 and 1.5 mm) in combination with different fuel doses fed to the prechamber. A passive chamber (qo_PC = 0 mg) and an active chamber (qo_PC = 0.4 and 1.2 mg) were used, while simultaneously sending a dose of fuel to the main chamber (qo_MC = 6 mg). The research was conducted using AVL Fire 2022.1 software using the moving mesh of the LDV engine. As a result of simulation work, the most favorable conditions for carrying out the process were determined, considering the thermodynamic effects of the process and the accepted values of nitrogen oxide concentration. The resulting correlation maps of the sizes of the chamber openings and the fuel doses fed to the prechamber may determine the initial selection of possibilities for controlling hydrogen combustion in the TJI system.

Control of Liquid Hydrocarbon Combustion Parameters in Burners with Superheated Steam Supply

A numerical simulation of reacting mixture flow in a full-scale combustion chamber of a prototype burner with a fuel-sprayed jet of superheated steam and a controlled excess air ratio was performed based on a verified model. The influence of steam jets on the combustion parameters of the created prototype device was analyzed based on the results, and a comparison with data from various atmospheric burners, including evaporative and spray types, direct-flow and vortex types, and those with natural and forced (regulated) air supply, was made. Various schemes for supplying steam to burner devices were discussed. It was shown that the relative steam consumption is a parameter for controlling the emission of toxic combustion products, such as NOx and CO, for all designs. A high burner performance is achieved when superheated steam is supplied at more than 250 °C with a relative steam flow rate of &gt;0.6. The design features of the burner systems and operational parameters that ensure high thermal and environmental efficiency when burning various types of fuel and waste are identified.

Experimentally Investigating the Potential of Iso-Stoichiometric GEM Blends as a Drop-in Replacement for E50 in SI Engines

Background: Research on alternative fuels for internal combustion engines is crucial due to climate change and energy security concerns. Ethanol-blended gasoline has been a popular alternative fuel, but biomass limitations restrict its widespread use. Methanol offers a solution as it can be produced from non-food sources, extending ethanol's availability. Objective: This study explores a ternary fuel blend consisting of gasoline, ethanol, and methanol as an alternative to binary gasoline-ethanol blend. The objective is to investigate if the isostoichiometric ternary blend offers equivalent fuel properties to E50 (Ethanol 50%, Gasoline 50% (v/v)) gasohol while potentially enhancing engine performance, reducing emissions, and improving combustion characteristics. Methods: A single-cylinder, four-stroke, port fuel injection spark ignition engine was used. The engine was tested with three fuels: pure gasoline, E50 blend, and an equivalent iso-stoichiometric GEM blends. Engine tests were conducted at constant load with varying engine speeds. Performance, emission, and combustion parameters were experimentally measured and compared across all fuels. Results: E50 and its equivalent blends improved brake thermal efficiency but increased brake specific fuel consumption compared to gasoline. It significantly reduced unburned hydrocarbon and carbon monoxide emissions but slightly increased nitrogen oxide emissions. Conclusion: Formulated E50 equivalent blends have identical air to fuel ratio, lower heating values as conventional binary E50 gasoline-ethanol blends. The study suggests that iso-stoichiometric GEM blends have the potential to be a viable alternative drop-in fuel for E50 in internal combustion engines. The future advancements in GEM blends, particularly in optimizing ratios, could lead to patentable inventions.

Prediction and Simulation of Biodiesel Combustion in Diesel Engines: Evaluating Physicochemical Properties, Performance, and Emissions

Environmental and energy sustainability concerns have catalyzed a global transition toward renewable biofuel alternatives. Among these, biodiesel stands out as a promising substitute for conventional diesel in compression-ignition engines, providing compatibility without requiring modifications to engine design. A comprehensive understanding of biodiesel’s physical properties is crucial for accurately modeling fuel spray, atomization, combustion, and emissions in diesel engines. This study focuses on predicting the physical properties of PODL20 and EB100, including liquid viscosity, density, vapor pressure, latent heat of vaporization, thermal conductivity, gas diffusion coefficients, and surface tension, all integrated into the CONVERGE CFD fuel library for improved combustion simulations. Subsequently, numerical simulations were conducted using the predicted properties of the biodiesels, validated by experimental in-cylinder pressure data. The prediction models demonstrated excellent alignment with the experimental results, confirming their accuracy in simulating spray dynamics, combustion processes, turbulence, ignition, and emissions. Notably, significant improvements in key combustion parameters, such as cylinder pressure and heat release rate, were recorded with the use of biodiesels. Specifically, the heat release rates for PODL20 and EB100 reached 165.74 J/CA and 140.08 J/CA, respectively, compared to 60.2 J/CA for conventional diesel fuel. Furthermore, when evaluating both soot and NOx emissions, EB100 displayed a more balanced performance, achieving a significant reduction in soot emissions of 34.21% alongside a moderate increase in NOx emissions of 45.5% compared to diesel fuel. In comparison to PODL20, reductions of 20.4% in soot emissions and 3% in NOx emissions were also noted.

An insight into the combustion analysis of low carbon alcohol infused ternary fuel blends operated by varying the compression ratios

To address the growing scarcity and rising costs of fossil fuels, researchers are exploring alternative energy sources that can mimic the conventional fuels. This study focused on ternary fuel blends made from waste fried oil (WFO) biodiesel, methanol, and diesel. To enhance their stability, 10, 20, and 30 ml of n-butanol per litre of ternary blends are added. The blends were tested in a variable compression ratio (VCR) engine under peak load conditions. The experiments are carried out by varying the compression ratio (CR) of the engine from 16:1 to 18:1. The results showed that increasing the CR improved combustion for all fuel blends. Among the ternary blends, B30M20D50 outperformed pure diesel in terms of combustion characteristics. When compared to diesel, B30M20D50 yielded 5.08 %, 5.31 %, and 4.59 % higher Pmax at CR 16:1, 17:1, and 18:1, respectively. Under the same conditions, NHRR outperformed diesel by 1.46 %, 3.12 %, and 2.44 %, respectively. While ternary blends with up to 20 % methanol exhibited stable combustion, higher methanol concentrations led to erratic rise in the coefficient of variation. The interdependency analysis revealed a strong correlation between the combustion parameters for the B20M30D50 blend across different compression ratios.

Multispectral two-dimensional temperature field reconstruction using particle swarm optimization and the Broyden–Fletcher–Goldfarb–Shanno algorithm with multiple extreme value optimization

The flame temperature is a crucial parameter in combustion, indicating heat generation and transfer. However, determining the correct temperature becomes challenging when flame emissivity is unknown. This article presents a multispectral 2D temperature field reconstruction method using particle swarm optimization and the Broyden–Fletcher–Goldfarb–Shanno algorithm, combined with multivariate extreme-value optimization. This method establishes an objective function based on the correlation between the true temperature and spectral data. The objective function was minimized by adjusting the emissivity, enabling the reconstruction of 2D temperature and emissivity images without assuming an emissivity model. Calibration with a multispectral camera yielded the spectral response coefficients, and three-time spline interpolation was used to verify the calibration data. The reconstructed 2D temperature field showed a mean absolute error (MAE) of 4.61 and structural similarity (SSIM) of 0.995. The reconstructed emissivity image had an MAE range of 0.04 to 0.053 and an SSIM range of 0.897 to 0.915. The system, tested on a butane flame, showed a temperature range of 1001 K to 1356 K, with an average temperature of 1194 K and emissivity values ranging from 0.3166 to 0.8621. The results align with the expected combustion process and radiation characteristics distribution of the butane flame.

Experimental and modeling studies on char combustion under pressurized O2/H2O conditions

The desorption kinetic parameters for pressurized combustion and gasification reactions were determined based on a C++ program coupled with the Langmuir-Hinshelwood (L-H) kinetic model developed and experimental data from pressurized char combustion, and the established L-H kinetic model for pressurized char-O2/H2O combustion was refined in the current paper. The activation energy for desorption in reactions involving pressurized char-O2 and char-H2O was determined to be 250.8 kJ/mol, accompanied by a pre-exponential factor of 5.42×1010 g/(m2 s). Using this foundation, the current research conducted simulations to investigate the impacts of temperature, pressure, and H2O concentration on the oxidation adsorption rate (Rads,oxi), desorption rate (Rdes), gasification adsorption rate (Rads,gas), and the competitive influences of kinetics and diffusion processes within the pressurized char-O2/H2O combustion. The simulation results indicate a gradual increase in Rdes and Rads,gas with char conversion to reach a peak, followed by a gradual decline. Conversely, the Rads,oxi varies smoothly throughout the char conversion process. At 1673 K/1.0 MPa, the char-O2/H2O reaction rate is primarily constrained by Rads,oxi and Rads,gas, with the adsorption reaction serving as the rate-controlling step. Moreover, it was noted that a rise in pressure resulted in a linear increase in Rads,oxi, Rdes, and Rads,gas. At elevated temperatures, the impact of pressure on them becomes more noticeable. However, the introduction of H2O mitigates this effect. Elevated temperature and pressure facilitate the competition on the kinetics of char-O2 combustion for O2 diffusion, resulting in the conversion of char being more susceptible to O2 diffusion rate limitation. With the addition of 20% H2O, the competition effect was weakened. In the case of pressurized combustion involving char and O2/H2O, the char conversion is primarily constrained by the O2 diffusion rate and is scarcely influenced by the H2O diffusion rate.

Influence of swirl, tumble and squish flows on combustion characteristics and emissions in internal combustion engine- review

This study gives an overview of available literature on flow patterns such as swirl, tumble and squish in internal combustion engines and their impacts of turbulence enhancement, combustion efficiency and emission reduction. Characteristics of in-cylinder flows are summarized. Different design approaches to generate these flows such as directed ports, helical ports, valve shrouding and masking, modifying piston surface, flow blockages and vanes are described. How turbulence produced by swirl, tumble and squish flows are discussed. Effects of the organized flows on combustion parameters and exhaust emission are outlined. This review reveals that the recent investigations on the swirl, tumble and squish flows are generally related to improving in-cylinder turbulence. Thus, more experimental and numerical studies including the impacts of this organized flows on turbulence production, combustion behavior and pollutant formation inside the cylinder are needed.

Self-propagating high-temperature synthesis of AlN–TiC powder composition using sodium azide and C2F4 fluoroplastic

Producing powder compositions using conventional processing technology can lead to the formation of large agglomerates and, therefore, makes it difficult to obtain a uniform microstructure. The production of composites by self-propagating high-temperature synthesis can reduce costs and the number of technological stages, as well as lead to obtaining composites that are more homogeneous. Synthesis by the combustion of mixtures of powder reagents of sodium azide (NaN3), fluoroplastic (C2F4), aluminum and titanium with different ratios of reagents in a nitrogen gas atmosphere at a pressure of 4MPa was used for the production of a highly dispersed powder ceramic AlN–TiC composition. Thermodynamic calculations have confirmed the possibility of synthesis of AlN–TiC compositions of different formulations in combustion mode. The dependences of temperature and combustion rate on the composition of the initial mixtures of reagents were experimentally determined for all stoichiometric reaction equations. The study have shown that the experimentally found dependences of combustion parameters on the ratio of the initial components correspond to the theoretical results of thermodynamic calculations. The formulation of the synthesized composition differs from the theoretical composition by a lower content of target phases and the formation of Al2O3, Na3AlF6 and TiO2 side phases. The powder composition consists of aluminum nitride fibers with a diameter of 100–250nm and ultradisperse particles of predominantly equiaxed and lamellar shapes with a particle size of 200–600nm. As the combustion temperature increases to produce the largest amount of titanium carbide phase, the particle size increases to the micron level.

Morphological, Thermal, and Mechanical Assessment of Polypropylene and Ammonium Phosphate Composites Enhanced with Lignosulfonate and Zirconium.

Polypropylene and ammonium phosphate (AP) composites were synthesized at a 25 wt% concentration. The changes in the morphological, thermal, and physical behavior of the composites were analyzed with the addition of lignosulfonate (LG) and zirconium phosphate (ZrP). Additionally, metallic zirconium was deposited onto lignosulfonate using the magnetron sputtering technique to develop polypropylene and zirconium-modified lignosulfonate (LGMod) composites. Thus, composites of PP/25AP, PP/25AP/8LG/5ZrP, and PP/25AP/8LGMod were synthesized. The synthesis involved mixing the materials in a Hake mixer, followed by compression molding. The composites were characterized by field emission scanning electron microscopy (SEM-EDS), a thermogravimetric analysis (TGA) with combustion parameters, a vertical burn test (UL-94), a thermal camera, and mechanical properties. All composites achieved a V2 rating according to UL-94 standards. The PP/25AP extinguishes flames more quickly compared to other materials, approximately 99.2% faster than PP and showed the lowest temperature variation and mass loss after burning. The PP/25AP/8LG/5ZrP composite exhibited a 7% higher rigidity and 84.5% better flame retardancy compared to pure PP. Additionally, substituting ZrP with LGMod led to a lower environmental impact and improved thermal properties, despite some mechanical disadvantages.

Research on combustion cycle-by-cycle variations under high load in SACI mode and application potential of i-EGR coupling air dilution when fueled with methanol and gasoline

Spark assist compression ignition (SACI) is a efficient combustion mode but roughness combustion under high load limits its application. This test analyzed the combustion parameters variation coefficient and quantified the correlation between combustion parameters with spark ignition ratio under high load SACI mode for engine fueled with methanol and gasoline, further studied the potential of i-EGR combining air dilution on improving combustion performance. Results showed that fueled with methanol can reduce in-cylinder pressure and pressure rise rate, and relieve the combustion roughness. However, compared with gasoline engine, the combustion parameters was more sensitive to ignition timing and i-EGR rate, especially for combustion phase parameters like ignition delay, combustion center and so on. Introducing small amount of high-temperature exhaust gas into cylinder will induce rougher combustion, but cylinder pressure significantly reduced and combustion phase parameters fluctuated with i-EGR rate increasing. Under high i-EGR rate, methanol as an oxygenated fuel was more beneficial to maintain stable combustion. I-EGR coupling air dilution can significantly improve the economic performance under high load SACI mode, fuel economy improvements of up to about 17.4% and 19% compared to the origin point when fueled with gasoline and methanol. EGR combining air dilution can simultaneously improve BSNOX, BSTHC, and BSCO emissions.

Experimental and numerical study on the combustion characteristic of H2 and CH4 in oxygen-enriched environment

Oxygen-enriched combustion could rise the hazard of unexpected fire and explosion in industry. This study experimentally and numerically analyzed the combustion characteristic of H2 and CH4 in oxygen-enriched environment (Ω = 21%–100 %). For H2 at Φ = 1 and Ω = 100 %, the maximum explosion pressure and maximum pressure rise rate were about 3.89 MPa and 1259.2 MPa/s. For CH4, these values were about 4.77 MPa and 6279.4 MPa/s. The upper flammability limit of gases increased sharply with the increase of Ω, however, the lower flammability limit was almost unchanged. Besides, the increasing of Ω also could result in the rising of aforementioned combustion parameters. The sensitivity of burning velocity was also analyzed. For H2 flame at Φ = 0.8, R35 could slow down burning velocity when Ω = 21 %, but promote it when Ω = 30 % and 70 %. For CH4 flame at Φ = 1.4, the sensitivity coefficients of R11, R35, R43 and R84 changed from negative to positive when Ω increased from 21 % - 30 %–70 % - 100 %. It was concluded that the oxygen concentration not only affect the inert gas but also affect the reaction kinetic of flame.

RESEARCH OF THE COMBUSTION PARAMETERS OF GASOLINE WITH ADDITIONAL HYDROGEN IN A SPARK-IGNITION ENGINE IN EXTERNAL SPEED CHARACTERISTIC MODES

The directions of development and improvement of road transport around the world are inextricably linked to the desire to reduce the use of cars “on traditional fuels” due to limited oil and environmental safety of mankind. Since the modes of external speed characteristic are the most typical for the operation of cars in cities, the study of environmental performance of engines in these modes is an urgent task. Therefore, finding ways to reduce carbon dioxide emissions from automobile engines at high-speed modes is an urgent task. The rapid growth in the number of cars with internal combustion engines and the inevitable decline in world oil reserves necessitate the development and implementation of energy-saving technologies and the use of alternative fuels. Research aimed at finding ways to improve the fuel efficiency and environmental performance of automotive engines is relevant. One of the promising areas is the influence on the combustion process in gasoline engines by using additives of alternative fuels, which include hydrogen. The presented study of the parameters of combustion of gasoline with hydrogen additive in a spark ignition engine at external speed characteristics is a comprehensive analysis of the combustion process of a gasoline-hydrogen mixture and determination of its effect on the concentration of carbon dioxide in exhaust gases by developing a mathematical model that takes into account the composition of the mixture components and features of the combustion process, allows for sufficiently accurate calculation of the operating process of an engine with hydrogen additive at ψ ≤ 10%, its identification by the results of experiments. In the course of the study, dependencies were developed to determine the combustion parameters of the Wiebe model, taking into account the addition of hydrogen to gasoline in the modes of external speed characteristics, and the effect of hydrogen addition on the concentration of CO2 in exhaust gases was analyzed. It is shown that with an increase in the hydrogen additive to 10% by mass fraction to gasoline, there is a decrease in CO2 emissions to almost 30% in the external speed characteristic modes, which corresponds to modern environmental standards for gasoline internal combustion engines.

Insight into the Kinetics of Isomerization and β-Scission Reactions Following H-Abstraction in 2-Pentanone Combustion.

2-Pentanone is a significant carbon-neutral fuel. To better understand 2-pentanone combustion, the CCSD(T)/CBS method was used to calculate the potential energy surfaces (PES) for H-abstraction, isomerization, and β-scission reactions of 2-pentanone. Rate constants for the above reactions were calculated by the MESS employing conventional transition state theory (CTST) at 300-2000 K. The findings reveal adherence to the Evans-Polanyi principle in the H-abstraction reactions of 2-pentanone by H atoms. Specifically, the 2-site shows more competitive kinetics due to having the lowest energy barrier of 7.8 kcal/mol. The 4-position has the highest energy barrier, making the reaction difficult to occur. In the subsequent reactions, the breaking of C-H bonds is most competitive at low temperatures. In particular, the H transfer from INT1 to INT3 has a potential well height of 24.8 kcal/mol. The β-scission reactions become the main pathway for the depletion of pentanone radicals with increasing temperature. This study significantly extends the kinetic parameters of 2-pentanone combustion over a wide range of temperatures and pressures, which is expected to contribute to the development of 2-pentanone combustion models.