Analysis Of Combustion Process Research Articles

Study of the Combustion Characteristics of a Compression Ignition Engine Fueled with a Biogas–Hydrogen Mixture and Biodiesel

Increasing the use of renewable energy sources is essential to reduce the use of fossil fuels in internal combustion engines and to reduce greenhouse gas emissions. An experimental and numerical simulation study of the combustion process of a compression ignition engine was carried out by replacing fossil diesel with a dual fuel produced from renewable energy sources. In conventional dual-fuel applications, fossil diesel is used to initiate the combustion of natural gas or petroleum gas. In the present study, fossil diesel was replaced with advanced biodiesel – hydrotreated vegetable oil, and natural gas was replaced with biogas. In the experimental study, a gas mixture of 60% natural gas (by volume) and 40% carbon dioxide (by volume) was used to replicate the biogas while maintaining a 40%, 60%, and 80% gas energy share in the fuel. It was observed that using fossil diesel and biogas in the dual-fuel engine significantly slowed down the combustion process, which normally resulted in poorer energy performance. One way to compensate for the lack of energy (due to the presence of carbon dioxide) in the cylinder is to use a gas such as hydrogen, which has a high energy content. To analyze the effect of hydrogen on the dual-fuel combustion process, hydrogen gas was added to the replicated biogas at 10%, 20%, and 30% of the natural gas volume, maintaining the biogas at a (natural gas + hydrogen)-to-carbon dioxide volume ratio of 60%/40% and the expected gas energy share. The combustion process analysis, which was conducted using the AVL BOOST software (Austria), determined the heat release rate, temperature, and cylinder pressure rise in the dual-fuel operation with different renewable fuels and compared the results with those of fossil diesel. It was found that when the engine was operated at medium load and with the flammability of the biogas approaching the limit, the addition of hydrogen significantly improved the combustion characteristics of the dual-fuel engine.

Methods and equipment for analysis and diagnosis of marine engines during navigation

ABSTRACT Expert diagnostic systems are required for the development of intelligent marine engines and other ship systems. Measurement and analysis of marine engine parameters are fundamental in ensuring the efficient operation of these key propulsion systems. This paper introduces a novel measurement device and method capable of real-time monitoring of cylinder pressure and emissions in marine engines. The experimental procedure involved measuring critical engine parameters and emissions, such as NOx, CO2, and particulate matter, under various operating conditions. The device provided accurate real-time data acquisition, enabling detailed analysis of combustion processes and emission profiles under various operating conditions. Furthermore, a numerical model was developed, like digital twins, which utilized the measured data to simulate engine performance, predict potential failures, and optimize operational parameters to enhance efficiency and reduce environmental impact. The two most important parameters: the indicated cylinder pressure and NOx emissions were simulated and validated. Measured NOx was measured 889 ppm at 90% and simulated results was 985 ppm, which is 10% difference. Specific fuel consumption has less than 1% difference between measured and simulated data. Novelty of this work is the methodology used in the testing and calibration processes. Current actual parameters of engine operation are monitored, based on which a comparative analysis is made in real time. Previous diagnostic control systems did not provide diagnostics, comparative analysis and optimization in real time. The integration with digital twin allowed potential wear and tear predictions, fuel consumption optimization, and emission reduction strategies, showcasing the potential of this technology to improve marine engine diagnostics and maintenance. The device and its virtual counterpart worked well together to provide a complete understanding of the engine’s response. This facilitates proactive maintenance strategies and contributes to eco-efficiency in the maritime sector.

Post-Extractivism and Bioeconomy: An Experimental Analysis of Combustion and Pyrolysis Processes as Alternatives to Add Value to Agro-Residues (Coffee Husks) Generated in Farmer Cooperatives of the Ecuadorian Amazon

A post-extractivist development model for communities in the Amazon that is not based on non-renewable resource extraction demands the study and demonstration, in the field, of alternative economic activities that add value to currently generated residual biomass. Following the principles of bioeconomy, this study presents an experimental analysis of a retort burner and a pilot-scale auger-type pyrolysis reactor used to convert coffee husks generated in a collection and post-harvesting center of a farmer’s cooperative into thermal energy and biochar, respectively. This study shows that coffee husks, whether used as feedstock for combustion or pyrolysis processes, can supply the thermal energy required by the post-harvesting processes. The combustion or pyrolysis of coffee husks avoids its accumulation and decomposition while replacing fossil fuels used in post-harvesting operations, reducing costs and making farmers independent of fossil fuel subsidies. Unlike combustion (11,029.4 mg/Nm3), the CO concentration in the flue gas during the pyrolysis process was 458.3 mg/Nm3, which is below the eco-design standard of 500 mg/Nm3. According to the European Biochar Certificate, carbon content (67.4 wt%) and H/Corg, O/Corg (0.6 and 0.1, respectively) are within the typical values of biochars used for soil amendment and carbon sequestration. Nonetheless, the concentration of polycyclic aromatic hydrocarbons must be assessed to fully regard this material as biochar. Finally, further studies are required to assess the ability of cooperatives to generate and trade carbon credits linked with the application of biochar in their cropping systems.

Thermodynamic modeling and optimal short-term scheduling of a green H2-fueled combined heat and power generation system for industrial zones

This paper presents a novel green combined heat and power generation system for industrial applications. It composes of a hydrogen-fueled combined cycle power plant and a battery energy storage. Firstly, the hydrogen-air rich mixture enters the combustion chamber of the gas turbine cycle for generating electricity, while recovering the heating energy from the exhausted flue gases for driving a steam turbine cycle. The heating energy extracted from the condenser heat exchanger is also used to supply the heating demand of the end-user. Moreover, a comprehensive thermodynamic model and analysis of H2 combustion process is provided to estimate the adiabatic flame temperature based on enthalpies of reactants and products. The optimum operating point of the cogeneration system is found by solving a mixed-integer nonlinear problem using MATLAB and GAMS over a 24-h study horizon aiming to minimize its daily operation cost considering all technical constraints of system components and load-generation balance criterion. It is found that the energy efficiency of the hydrogen-fueled combined cycle changes from 46 to 58 % while generating 11.331–12.982 MW electricity and 4.436–4.984 MW heat. Two cases are studied without and with participation of battery in energy procurement strategy. It is demonstrated that the objective function of the optimization problem improves from 18 $ cost in case 1 to 29 $ revenue in case 2.

Analysis of pulse combustion processes and thermodynamic cycles in pulse combustors

This study explores the dynamic behavior of pulsating combustors during stable operation, examining pressure characteristics, flame dynamics, and thermodynamic cycles. Through analysis of pressure signal derivatives and high-speed photography, it unveils a distinctive counterclockwise thermodynamic cycle in these combustors, diverging from prior research. Crucial points in the combustion process, including zero-pressure points, valve timings, and flame ignition dynamics, were successfully identified. The research introduces a novel clockwise thermal cycle diagram based on ignition events and valve operations, providing real-time insights into combustion processes. Key findings include the identification of critical combustion process points, immediate flame ignition upon valve opening, and the introduction of an innovative thermal cycle diagram. The study's comprehensive approach, integrating pressure analysis, flame dynamics, and derivative curves, offers profound insights into the dynamics of pulsating combustors, furthering our understanding and providing avenues for optimization. Our comprehensive approach enhances the understanding of pulsating combustor dynamics and provides valuable insights for system improvement. The unconventional thermodynamic cycle underscores the novelty of our work. These findings are pivotal for enhancing combustion efficiency and reducing emissions, emphasizing the significance of further research and development in this field.

The effect of ignition diesel injection conditions on the combustion process of natural gas engine

As transportation is a major contributor to carbon emissions, the significance of researching dual-fuel engines lies in their potential to substantially reduce such emissions. Based on the experimental engine of diesel micro-ignition and air intake channel injection natural gas engine, the effects of pilot diesel quality, diesel injection timing and excess air coefficient on combustion process were studied. The test was performed on a single-cylinder engine modified with the WP12 natural gas engine at 1000 rpm under medium load condition. The results revealed that there is a critical pilot energy proportion that affects the combustion stability and that increasing the pilot diesel mass below the critical value improves the combustion stability. The critical diesel energy share increases as the diesel injection moment is delayed and the λ is increased. From the combustion process analysis early ignition diesel injection time is beneficial to improve the thermal efficiency, reduce THC and CO emissions, but sometimes worsen the NOx emissions. Reasonably improving the quality of pilot diesel can accelerate the combustion process and improve thermal efficiency by up to 47.7%.

Numerical analysis of combustion process and pressure oscillation phenomena in low-pressure injection natural gas/diesel dual fuel low speed marine engine

Dual fuel strategy is a promising way to achieve low-carbon emission for marine engines, but engine knock restricts the compression ratio and engine thermal efficiency by adopting premixed combustion mode. Engine knock of natural gas/diesel dual fuel low speed marine engine is not well understood under high compression ratio. The characteristics of combustion process and pressure oscillation phenomena were investigated by varying compression ratio, pre-chamber number, energy proportion of pilot diesel with a single-cylinder engine model with numerical simulation. The results show that, with increase in pre-chamber number using the same energy proportion of pilot diesel under compression ratio of 16, the maximum amplitude of pressure oscillation can be significantly reduced from 0.62 MPa to 0.23 MPa in main chamber, while both resonance modes follow (1,0) mode. With double pre-chamber, when the energy proportion of pilot diesel increases from 0.6% to 1.2%, due to the stronger intensity of jet flame, the heat release rate is accelerated as well as the accumulation of H2O2 radical become less before high speed spontaneous combustion, resulting in lower amplitude of pressure oscillation. When the energy proportion of pilot diesel increases from 1.2% to 3.0%, excessive amount of pilot diesel cannot strengthen the jet flame obviously while the amplitude of pressure oscillation increases slightly. These results suggest that about 1.0% in energy proportion of pilot diesel should be optimal by considering the thermal efficiency, pressure oscillation and NOx emission together.

Synergetic analysis between polyvinyl chloride (PVC) and coal in chemical looping combustion (CLC)

This effort is to investigate three different Cu-based oxygen carriers (OCs) with polyvinyl chloride (PVC) and coal in chemical-looping combustion (CLC). The combustion process and synergetic analysis of PVC with coal were evaluated. There were four stages in the reaction of OCs with PVC, which HCl released from PVC could react with OCs at about 200–400 °C. CuO and CuO modified by limestone showed better immobilization of chlorine while CuO modified by iron ore and chrysolite inhibited the reaction of HCl with CuO. PVC char combustion temperature started at about 500 °C which were lower than that of coal char. The combustion efficiency of PVC CLC was all above 92%, except using Cu-Fe as OC which was about 88%. The presence of ZD in PVC showed positive effect on every stage. The addition of coal inhibited the reaction of HCl with CuO. The presence of PVC in ZD reduced the temperature of coal char and the addition of ZD in PVC increased the reaction rate. The synergistic effect was obvious between the PVC and coal blends which is beneficial for the complete combustion in solid fuel CLC

Coupling effect of reaction conditions on the catalytic activity of Cu-Mn composite oxide catalysts for toluene.

Volatile organic compounds (VOCs) are one of the major components of air pollution. Catalytic combustion is a promising technology for the treatment of VOCs and at its center is the preparation of efficient and cheap catalysts. In this study, by loading copper (Cu) and manganese (Mn) on Santa Barbara Amorphous-15 (SBA-15) molecular sieve, the Cux-Mny/SBA-15 (x = 1, 2; y = 1, 2) composite metal oxide catalyst was prepared using the equal volume impregnation method. Their performance in the toluene catalytic combustion reaction was investigated by adjusting the molar ratio (x : y), and the loading of Cu and Mn. The results of the Brunner-Emmett-Teller (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) analyses show that the CuMnO spinel phase can be detected in the Cu-Mn composite metal oxide catalyst doped with a low concentration of Cu. The overall rod-like structure of the fibrous network structure provides a large specific surface area, and the particle crystallinity is low and the dispersion is good. Due to the synergistic effect of Cu and Mn, the greater the amount of Mn3+ and adsorbed oxygen species (Oads) that are available, and the higher the turnover frequency (TOF) value, the better and more superior catalytic performance and excellent stability is obtained, when compared with the single-component oxides used in toluene catalytic combustion. After a continuous catalytic reaction for 12 h, the toluene conversion rate remained above 95%. The coupling effect of the catalytic reaction temperature and concentration of oxygen on the catalytic combustion of toluene was also studied. At a low reaction temperature (<250 °C), the increase of the concentration of oxygen played a superior role in promoting the conversion of toluene. The kinetic analysis of the toluene catalytic combustion process showed that the catalytic combustion of toluene by Cu-Mn/SBA-15 followed both the Mars-Van Krevelen (MVK) and Langmuir-Hinshelwood (L-H) reaction mechanisms. With the increase of the Oads amount caused by the decrease of the Cu ratio, the proportion of the L-H reaction mechanism increases.

Energy analysis and optimization of iso-octane and n-heptane combustion process

The energy analysis and optimization were conducted under different boundary conditions for iso-octane and n-heptane constant volume self-ignition process from the view of energy (HR: Heat Release) and exergy (EL: Exergy Loss) of chemical reactions, which were classified into five series: LTO (Low Temperature Oxidation), H2O2 Loop, Fuel Fragment，H–O and CO–CO2. The results indicate that the HRR (Heat Release Rate) and ELR (Exergy Loss Rate) increase with initial temperature as well as the equivalence ratio increasing before a certain turning point of themselves, however, the decrease of HR and EL are mainly attributed to the shortening of the ignition process. From the view of temperature correspond to the HR/EL of reaction series, the T10 (the combustion temperature of 10% HR/EL released) and T50 of EL of each reaction series are always advanced those of HR, which means there is a conflict between enhancing HR and reducing EL. Considering the cost-effective reaction series, the α, a ratio of the quantity of EL under per unit HR of H2O2 Loop，H–O and CO–CO2 is smaller than that of Fuel Fragment or LTO. Hence, a RSC (Reaction path Segmentation Control) method is proposed for HR and EL control in terms of shifting equivalence ratio between 1500 and 2000K and leading the reactions to take along the optimal α from Fuel Fragment turning to H2O2 Loop，H–O and CO–CO2. The result of RSC method proves the small α by enhancing the high-temperature reactions of H2O2 Loop and CO–CO2 series to make up the reduction of Fuel Fragment series reactions, which results in a lower exergy loss of chemical reaction and turns the reduced part into thermomechanical exergy. In terms of RSC in engine, the process of spray combustion in engine involves the phenomenon that the equivalence ratio varies with the combustion. According to RSC, reducing the global equivalence ratio in the cylinder to strength the RSC transition of the mixture from rich to lean promotes the HRR of equivalence ratio 0.5–1.5 and extends its area, which improves the indicated thermal efficiency.

Numerical investigation and experimental analysis of nanoparticles modified unique waste cooking oil biodiesel fueled C. I. Engine using single zone thermodynamic model for sustainable development

This study investigates the experimental and theoretical impact of biodiesel obtained from hydrodynamic cavitation based waste cooking oil on the performance parameters while testing compression ignition engines. Due to the alarming energy security concerns and inadequacy of fossil fuels, biodiesel is seeking importance globally. Many countries have put forth different subsidies, incentives, and mechanisms, urging the usage of biodiesel. In the current research, nanotechnology is effectively used for enhancement of the blend properties of biodiesel, making them more suitable for compression ignition diesel engines. This investigation includes a comparative analysis of diesel to biodiesel blends with and without the addition of nanoparticles CuO and ZnO. To understand the performance characteristics of a four-stroke diesel engine, a single zone thermodynamic model is developed in it. Comparative readings are taken for the test blends with varying compression ratios of 16, 17, and 18. For each ratio, a variation in the cylinder volume is noted with reference to the rotation in the crank angle. The investigated parameters include net heat release, the rate of pressure rise, brake thermal efficiency, and the heat transfer coefficient. This study concluded that the theoretical results are in close consonance with the experimental results of the comparative analysis of diesel and biodiesel blends. Results obtained from this research paper can contribute to predict combustion process analysis and recommend the effectiveness of nano-additives in biodiesel enhancement.

Bioenergy potential of millet chaff via thermogravimetric analysis and combustion process simulation using Aspen Plus

Millet chaff constitutes one of the most abundant agro-residues in the sub-Saharan Africa and its utilisation as a feedstock in developing sustainable bioenergy solutions is very sketchy. This study presents the first comprehensive physicochemical and combustion characteristics of millet chaff via thermogravimetric analysis and process simulation using Aspen Plus. The millet chaff sample was collected and assessed as received for proximate and ultimate analyses. The results showed the biomass has 71.25 wt%, 15.35 wt%, 13.40 wt% and 13.15 MJ/kg for volatile matter, fixed-carbon, ash content and higher heating value respectively. The material consists of low nitrogen and sulphur content with potassium, aluminium, magnesium, calcium, iron and sodium as the inorganic components. Kinetic study using distributed activation energy model (DAEM) revealed an average frequency factor and activation energy of 1.41 × 1018(s−1) and 149.39 kJ/mol. Ignition and burnout temperature in the range of 232-244°C and 430-489°C were recorded. The average combustion thermodynamic parameters; ΔH, ΔG and ΔS were found to be 144.75 kJ/mol, 167.12 kJ/mol and -40.08 J/mol. The combustion process analysis coupled with steam turbine cycle via process simulation revealed an excellent combustion efficiency at air-fuel ratio of 5.14. (stoichiometric air). The power generation and electric efficiency of 0.7kWh/kg and 21.07% respectively were recorded at 24% excess air with minimal environmental impacts. This suggests that millet chaff is a good biomass feedstock suitable for clean bioenergy production.

MECHANISM OF DETONATION FORMATION IN THE PROCESS OF VIBRATION COMBUSTION

Based on thermodynamic analysis of combustion processes, we build a new model of laminar combustion process of vibration combustion. If the passive component velocity for the two-component mixture is controlled at the inlet (the interior energy is pumped at the inlet of the combustion chamber), high-frequency resonance oscillations of vibration combustion are shown to develop depending on the structure of the standard chemical potential. The resonance is driven by hydrodynamic instability. Numerical experiment models the regimes of resonance with pumped internal energy, the nature of their nucleation depending on the structure of the standard chemical potential is revealed. For low temperatures, the appearance of detonation combustion with substantial pressure increase is established near resonance.

DESAIN DAN ANALISIS NUMERIK RUANG BAKAR BRIKET SAMPAH ANORGANIK UNTUK PENGAPLIKASIAN PADA MIKROTURBIN GAS

The utilization of briquettes as a source of electricity generation is still low due to the briquette characteristics that have high moisture content. This research analyzes the briquette's potential as a source of electrical energy by utilizing its syngas with microturbine gas. The high quality of syngas can be reached by the optimal combustion chamber design. Therefore, the research aim is to be able to design the optimum combustion chamber for the briquette combustion process to generate the syngas. This research method uses two steps, i.e., the design of the combustion chamber and numerical analysis of the briquette combustion process through Computational Fluid Dynamics (CFD) simulations. Numerical analysis of the combustion process using three types of briquettes with different inorganic waste compositions, i.e., K1 type, K2 type, and K3 type. The research results explain the optimum design of the combustion chamber with a total length dimension of 220 mm, an inlet fuel section, and combustion chamber-syngas pipeline diameter of 50 mm and 75 mm, respectively. In addition, the dimensions of the primary air holes are 7 mm, and the secondary air holes are 5 mm. Type K1 briquettes are capable of producing syngas (kg/s) consisting of 6.9x10-13 CO, 3.04x10-31 H2, and 1.8x10-20 CH4. That syngas composition includes in the criteria of syngas in the microturbines gas that produce electric power of 2.3-2.5 kW. The conclusions explain that the combustion chamber can be added to the microturbine gas component, and K1 type briquette can be a solid fuel.

Зависимость температуры сублимации образующихся в пламенах сажевых частиц от их размеров и структуры

In this paper, the dependence of the sublimation temperature of soot particles synthesized during the combustion of various hydrocarbons, depending on their size and structure, is obtained. The experimental approach is based on the analysis of the thermal radiation of particles heated to the sublimation temperature by a nanosecond laser pulse. The sublimation temperature of soot particles was measured using the two-color pyrometry method. In this paper, it is proposed to use the average size of primary particles to compare data in different flames. It is established, that the sublimation temperature of soot particles depends mainly on the stage of their formation, which is characterized by an increase in average size. It is shown, that with an increase in the average particle size from 12 to 23 nm, their sublimation temperature increases significantly from 2700 to 4500 K. This reflects a significant difference in the thermodynamic and optical properties of the so-called "young" and "mature" soot particles, which must be taken into account when developing methods of soot diagnostics and in the thermo-physical analysis of combustion and pyrolysis processes with the formation of soot.

The dependence of the sublimation temperature of the soot particles formed in the flames on their size and structure

In this paper, the dependence of the sublimation temperature of soot particles synthesized during the combustion of various hydrocarbons, depending on their size and structure, is obtained. The experimental approach is based on the analysis of the thermal radiation of particles heated to the sublimation temperature by a nanosecond laser pulse. The sublimation temperature of soot particles was measured using the two-color pyrometry method. In this paper, it is proposed to use the average size of primary particles to compare data in different flames. It is established, that the sublimation temperature of soot particles depends mainly on the stage of their formation, which is characterized by an increase in average size. It is shown, that with an increase in the average particle size from 12 to 23 nm, their sublimation temperature increases significantly from 2700 to 4500 K. This reflects a significant difference in the thermodynamic and optical properties of the so-called "young" and "mature" soot particles, which must be taken into account when developing methods of soot diagnostics and in the thermo-physical analysis of combustion and pyrolysis processes with the formation of soot. Keywords: flames, soot particles, sublimation temperature, structure of soot particles, transmission electron microscopy, laser-induced incandescence.\

Exergetic analysis of combustion processes including chemical variables

In the current paper, we illustrate a numerical simulation of the non-premixed combustion in a cylindrical combustor fueled by Methane and/or Hydrogen. The aerothemochemical parameters evolutions that characterize the reacting flow are attested for different fuel compositions in the combustor. For this, the exergy loss and its functional efficiency are applied for all considered fuels to distinguish the optimum reactive mixture composition for economic combustion. Consequently, the calculations are carried out by both computational software FLUENT code package and the Cycle-Tempo Release. Then, the results proved that the hydrogen injection has an effect on all considered physic-chemical variables.

Quantitative analysis of combustion process of marine dual fuel engine under the framework of iconology

The methane (CH4) burning interruption factor and the characteristic values characterizing the flame combustion state in the engine cylinder were defined. The logical mapping relationship between image feature values and combustion conditions in the framework of iconology was proposed. Results show that there are two periods of combustion instability and combustion stability during the combustion of dual fuel. The high temperature region with a cylinder temperature greater than 1800K is the largest at 17°CA after top dead center (TDC), accounting for 73.25% of the combustion chamber area. During the flame propagation, the radial flame velocity and the axial flame velocity are “unimodal” and “wavy,” respectively. During the combustion process, the CH4 burning interruption factor first increased and then decreased. The combustion duration in dual fuel mode is 21.25°CA, which is 15.5°CA shorter than the combustion duration in pure diesel mode.

Using the group analysis transfer operator in the method of similarity for studying the fuel combustion process in engines

In this paper, we study modelling of the process of combustion of small quantities of a pyrotechnic mixture based on potassium perchlorate and aluminium powder in impulse devices (engines). The analysis of combustion processes includes an introduced general criterion (prime criterion) of similarity composed of Wobbe numbers that are determined for the engine and its model in the course of theoretical studies or experiments. Research data show that the transfer operator in the field of group theory is mostly used for describing the process of combustion of metallized pyrotechnic mixtures.

Mixture formation and combustion process analysis of an innovative diesel piston bowl design through the synergetic application of numerical and optical techniques

The optimization of diesel engine piston bowl geometries has a crucial role in improving the near-wall flame evolution for better air/fuel mixing and soot reduction. With these aims, an innovative piston bowl for a light-duty diesel engine was designed, coupling both a sharp-stepped lip and radial bumps in the inner bowl rim. The impact of the proposed design was investigated through both 3D-CFD and single-cylinder optical engine. The numerical model, featuring a calibrated spray model and a detailed combustion mechanism, was used to analyse the non-reactive air/fuel mixing and the combustion processes. Results highlighted a reduced jet-to-jet interaction and better air/fuel mixing for the innovative bowl with respect to a conventional re-entrant design, thus enabling faster combustion process after the end of main injection. Numerical results in terms of flame’s kinematic and oxidation process were compared with the combustion image velocimetry (CIV) and OH* chemiluminescence from the optical engine, showing higher velocity near the radial bumps, and faster flame recirculation towards the piston center. Moreover, both experiments and simulations showed a more intense OH distribution in the radial-bumps region and above the step during the first stage of the combustion process, thanks to the enhanced air/fuel mixing.