Combustion Temperature Research Articles

The Conversion of Ethanol to Syngas by Partial Oxidation in a Non-Premixed Moving Bed Reactor

An experimental investigation into the conversion of ethanol to syngas by partial oxidation in a non-premixed counterflow moving bed filtration combustion reactor was carried out. Regimes of conversion depending on the mass flow rates of fuel and air (separate feeding), as well as a granular solid heat carrier, were studied. Depending on the mass flow rate of the heat carrier, two combustion modes were realized—reaction trailing and intermediate—with different temperature patterns in the gas preheating, combustion, and cooling zones along the reactor. The product gas composition is far from the predictions of the equilibrium model; it contains substation fractions of methane and ethylene. Combustion temperature and conversion are limited by the relatively high level of heat loss from the laboratory-scale reactor. The effect of the heat loss can be reduced by enhancing the absolute flow rate of the reactants.

Strategic optimization of dual-fuel diesel/gas engines by numerical approach for environmental and economic benefits

The study introduces a framework for optimizing eco-friendly dual-fuel engines, combining CFD and ANN, to reduce carbon emissions and improve sustainable transportation.We achieved optimal performance with a 52–65 % NG substitution ratio. SOI timing had a big effect on NOx emissions; later injection decreased NOx formation because it made the mixture more homogeneous. We developed a radial basis function neural network model to predict engine performance and emissions with 99 % accuracy. The study examines the effect of fuel droplet spraying on cylinder walls on engine performance and emissions, utilizing response surface methodology to create engine maps. Numerical experiments revealed that a lowered natural gas replacement ratio of less than 50 % resulted in decreased flame propagation and the attainment of a burn mixture mode. The decrease in flame propagation speed during CA10 led to a fivefold increase in CO emissions. As the NG substitution ratio exceeded 50 %, the air/fuel ratio neared equilibrium, resulting in a reduction in NOx emissions and in-cylinder combustion temperature. Nevertheless, the highest RoHR level decreased by 25 %. The downward trend proceeded until the natural gas substitution ratio reached to 90 %. The TOPSIS method was utilized to identify optimal operating conditions for DFDI engines, offering valuable insights for efficiency and emissions reduction.

Strategic optimization of engine performance and emissions with bio-hydrogenated diesel and biodiesel: A RVEA-GRNNs framework

This study investigates the effects of blending bio-hydrogenated diesel and biodiesel on engine performance and emissions across various engine speeds (2000-3000 rpm) and loads (25-90%), addressing the growing demand for sustainable transportation fuels. Using a single-cylinder diesel engine from POLAWAT ENGINE Company Limited, we evaluated different bio-hydrogenated diesel and biodiesel blends, optimizing their composition through the Reference Vector Guided Evolutionary Algorithm with a surrogate objective function via Generalized Regression Neural Networks. Results indicate that engine performance is closely linked to combustion temperature, which significantly affects fuel consumption and thermal efficiency. Bio-hydrogenated diesel demonstrated superior performance compared to conventional diesel, with lower fuel consumption and higher thermal efficiency, attributed to its higher cetane index (78 vs. 56) and heating value (47.02 MJ/kg vs. 43.48 MJ/kg). However, increasing biodiesel content in blends tended to increase fuel consumption and decrease efficiency due to biodiesel's lower heating value (39.62 MJ/kg) and higher viscosity (5.16 cSt vs. 2.58 cSt for bio-hydrogenated diesel). Emission analysis revealed that bio-hydrogenated diesel generally produced lower hydrocarbon, carbon monoxide, and smoke emissions than conventional diesel, though nitrogen oxide emissions were slightly higher. Biodiesel blends often showed increased emissions, particularly at higher blend ratios, due to poor fuel atomization. The Generalized Regression Neural Networks model demonstrated high accuracy in predicting engine performance and emissions, with coefficient of determination (R2) values exceeding 0.98 and mean absolute percentage errors below 5%. Optimization results indicated that bio-hydrogenated diesel ratios centered around 90% provided the best balance of performance and emissions. This research bridges critical gaps in combined bio-hydrogenated diesel and biodiesel usage and artificial intelligence-driven biofuel optimization, providing valuable insights for practical implementation in Thailand's agricultural sector.

Prediction Model for Aero-engine Combustor Temperature Field with Physical Constraints of High Temperature Deviation

Rapidly predicting the temperature field of the aero-engine combustion chamber can assist researchers in quickly understanding the combustion state. Although deep learning methods can solve this problem in some situation, the generalization ability of this method still faces challenges. This research proposes a deep learning prediction scheme with the loss function based on high-temperature deviations for the temperature field of an aero-engine combustion chamber. Comparative results indicate that the network models with high-temperature deviation constraints demonstrate significantly better prediction accuracy outside the learning area compared to network models without physical constraints. The results also demonstrate that the involvement of the physical constraint loss function at different stages of network training has a significant impact on the predictive performance of the network model and generalization ability. Compared to network models trained solely on mean square error, the fully-connected network model with mid-to-late stage of physical constraint training improves by 64.5%, and the optimized attention network model improves by 94.0%.

The Combustion of Lean Ethanol–Air Mixtures in a Swiss-Roll Combustor

A novel meso-scale 3-channel 5-turn Swiss-roll type combustor was designed and tested. The non-catalytic combustion of lean ethanol–air mixtures was experimentally investigated in relation to the oxygen excess ratio (α), which varied from 1.5 to 7. Depending on the control parameters used, two distinct regimes of combustion were experimentally observed: one with a combustion zone within the central chamber and another with a combustion zone in the inflow channel. The combustion temperature was virtually independent of stoichiometry. For richer mixtures and lower flow rates, the combustion zone is established in the inflow channel, thus limiting the combustion temperature. A qualitative model was proposed for the process and solved analytically; it described how the combustion regime self-adjusted, with the reaction zone moving into the inflow channel from the central chamber. This study confirmed the possibility of the sustainable combustion of ultra-lean fuel mixtures in a Swiss-roll combustor.

Experimental study on fire characteristics of urban rectangular tunnels based on different slopes

Abstract To explore the combustion pattern and temperature distribution law of urban rectangular tunnels when a fire occurs. Considering the influence of variables such as different firepower, fire source spacing, and tunnel slope, the vertical and horizontal flame combustion patterns and tunnel temperature distribution of double fire sources under different slopes were studied by the indoor model experiment method. The results show that under the same conditions of the fire source spacing ratio μ, when the slope of a rectangular tunnel is between 0% and 3%, the influence of dual flames combustion morphology on tunnel slope is relatively small; When the tunnel slope is 4% to 5%, that has a significant impact on the combustion morphology of dual flames, and the flames are more dispersed and sparse than the tunnel slope is between 0% and 3%. As the tunnel slope increases, a high-temperature zone forms at the top of the tunnel and gradually moves towards the uphill direction of the tunnel, the high-temperature area gradually decreases as the slope increases with the same μ. The research results provide a theoretical basis for the fire protection design standards and fire prevention measures of urban rectangular tunnels.

Constant temperature line identification on prototype gas turbine combustor with multi-colour change coating

Abstract This research focuses on identifying isotherms on the surface of a gas turbine combustion chamber using a colour-changing solvent known as temperature-indicating paint (TIP). The study employs a Multi Colour Change (MCC) 350-8 TIP to detect surface temperature variations. An innovative algorithm is proposed to identify these variations through irreversible colour changes, utilizing a colour-matching technique. The surface temperature data obtained from this method is compared with experimental calibration and computational analysis, showing not just agreement, but a high level of agreement, reinforcing the reliability of the method. This approach aims to enhance the accuracy of temperature detection in combustion chambers, which is crucial for optimizing performance and reducing emissions. The findings contribute to developing more efficient gas turbine systems by providing a reliable method for monitoring and controlling combustion temperatures. This study’s novelty lies in its use of colour-changing technology to achieve precise temperature mapping on complex surfaces.

Enhancing Engine Cylinder Heat Dissipation Capacity Through Direct Optimization (DO) Techniques

Internal combustion (IC) engines are used widely as the primary power source for automobiles of all types, cars, motorcycles, and trucks. Because of the high combustion temperatures involved in the operation, the excess heat is removed by means of extended fins that increase the surface area for adequate cooling. Significant improvement in the heat dissipation characteristics of the engine cylinder can be achieved by optimizing the design of these fins. The aim of this study is to evaluate the thermal performance of engine cylinder fins using an analytical system of finite element analysis (ANSYS FEA) software, using a direct optimization (DO) approach to identify optimal fin design. Analysis shows that fin length and width play critical roles in improving cooling efficiency, lowering the maximum temperature within the cylinder to 549.46 K and enhancing total heat flux to 7225.31 W/m2, which is a 25.87% increase from the generic design, capable of heating removal of 5740.22 W/m2. The current fin design is effective but could be improved in heat dissipation, mainly at fin tips. To optimize thermal performance while minimizing material costs, a balanced fin dimension is recommended. Alternative materials, transient heating analysis, and experimental verification may be examined in the future to achieve a total understanding of fin geometry and behavior under real operating conditions. These insights lay a foundation to accelerate cooling systems development in the automotive, aerospace, and heavy equipment industries, where efficient heat transfer is key for performance and long-term durability.

Tuning the performances of smoke-light signaling agents by Zn-Mg alloys

In this study, the thermal behavior, combustion behavior, and smoke/light signal effects of smoke-light signaling agents were regulated using Zn-Mg alloys with different Mg contents (10 wt%, 20 wt%, 30 wt%, 50 wt%, 70 wt%) and particle sizes (100–200 mesh, 200–325 mesh, >325 mesh) under an oxygen balance of −20. The Zn-Mg alloy’s morphology and phase composition were characterized using SEM/EDS and XRD. The thermal performance was analyzed with TG/DSC, while the combustion process was recorded using high-speed camera and infrared thermal imaging. The visible light spectrophotometer and smoke chamber experiment tested the smoke and light effects. The results showed that increasing Mg content raised the combustion temperature to over 1400 °C, enhanced luminous intensity to over 5000 cd, reduced solid residue to under 6 %, and shortened combustion time from 7.9 s to 2.24 s. Smaller particle sizes also improved these effects. Alloys with higher Zn content produced denser smoke but had higher solid residue. This study demonstrates the potential for precise control over combustion and smoke-light effects by adjusting alloy composition and particle size, making Zn-Mg alloys promising candidates for future pyrotechnic formulations.

Comparative study on combustion and emission characteristics of methanol/gasoline blend fueled DISI engine under different stratified lean burn modes

Combining stratified lean-burn techniques with methanol offers a promising path to achieving high efficiency and low emissions in direct-injection spark-ignition (DISI) engines. This work compares the stratified and homogeneous-stratified lean-burn characteristics of methanol/gasoline fuels on a DISI engine. Combustion and emissions characteristics under two stratified lean-burn strategies were investigated. The results indicate that compared to double-injection stratified lean-burn (DISL), single-injection stratified lean-burn (SISL) leads to more timely combustion, which deteriorates more slowly as the excess air ratio increases. Using M20 fuel with SISL achieves a higher tolerance for air dilution. At the same excess air ratio, SISL results in higher maximum in-cylinder pressure and combustion temperature, but lower exhaust temperature. The economic zone for SISL occurs with M40 fuel at λ = 1.3–1.6, whereas DISL's economic zone is within λ = 1.1–1.3. When λ is below 1.5, SISL produces higher hydrocarbon (HC) emissions but lower nitrogen oxides (NOx) emissions. However, as λ exceeds 1.5, HC emissions from DISL increase sharply while NOx emissions decrease significantly. The particle concentration from SISL is at least an order of magnitude higher than that from DISL, with particle size distribution forming a unimodal curve centered around accumulation mode particles. Conversely, DISL exhibits a quasi-bimodal distribution.

Microstructural Thermal Zones in Reaction of Nanoenergetics.

Despite the potential of nanoenergetics as promising energy sources with high energy densities and fast energy release, our limited ability to predict combustion speeds restricts the utilization of nanoenergetics. Here, we provide a comprehensive analysis of thermal microstructures subject to heterogeneous reactions and propose a new scaling for combustion wave speeds. To control reaction heterogeneity, two different particle interfacial morphologies of physically mixed and core-shell Al/CuO nanoparticles were synthesized. The combustion dynamics and temperature fields were obtained at micrometer-scale resolutions using high-speed and infrared cameras. Experiments showed that the core-shell Al/CuO exhibiting less reaction heterogeneity had a faster wave speed than the physically mixed counterpart, although the measured chemical reaction rates were lower. By employing the thermal structure analysis, we found that the shortened preheat zone and the lengthened reaction zone, attributed to the lower reaction onset temperature and reaction rate, led to the increased wave speed despite the lower reaction rate in the core-shell Al/CuO. From these analyses, we developed a new scaling that describes the combustion wave speeds in nanoenergetics based on intrinsic properties and thermal structures for both morphologies.

Probing the combustion characteristics of micron-sized aluminum particles enhanced with graphene fluoride

Graphene fluoride (GF) with its two-dimensional structure and high fluorine content on the surface can be used to enhance the combustion characteristics of micron-sized Aluminum (μAl) particles. However, the enhancing mechanisms of GF in Al combustion remain not fully understood. In this work, the effects of GF on combustion temperature, flame emission spectrum, ignition delay time, and condensed combustion products (CCPs) size of μAl were studied using laser ignition and optical diagnostic experiments. The combustion characteristics of GF- or polytetrafluoroethylene (PTFE)-modified μAl composite particles were compared to elucidate the ignition and combustion mechanism of different fluorides. The results show that the thermal decomposition behavior and the energy distribution among excited Al atoms differ significantly between GF and PTFE. Compared with PTFE, GF and its decomposition products have stronger excitation ability for high energy Al atoms, which is conducive to increasing the combustion temperature of particle flame. In addition, the ignition delay time and CCPs size of Al/GF are approximately 49∼66 % and 10 % less than those of Al/PTFE, respectively. These results provide a fundamental understanding and data support for the application of functionalized graphene in metal fuels and solid propellants.

Non-adiabatic effect on NOx emissions for premixed H2-blended NH3/air combustion under rich-lean-staged conditions

The non-adiabatic effect on NOx emission for the swirl premixed NH3/H2/air combustion under fuel-rich/quick-mix/fuel-lean (RQL) conditions was experimentally studied. The wall temperature of the quartz combustor was controlled by surrounding heating. Results showed that both H2-blending and thermal insulation were in favor of enlarging the low-NOx range and lowering the valley NOx, due to the less NO and unburnt NH3, and smaller flow rate from the primary stage. In the post-flame zone of the primary stage, increasing combustion temperature significantly enhanced NO reduction, Thus, for low NOx emission, it is essential to keep enough thermal insulation there. Experimental measurements also found remarkable N2O could be formed in the secondary stage when combustion temperature was low and much unburnt NH3 was excessive. Kinetic analyses showed this phenomenon was due to the high combination rate of NH and NO, and low reduction rate of H radical.

Temperature Measurement of Ballistic Evaluation Motor Using K-Type Thermocouple

The paper presents an investigation of the burning rate of the selected solid propellant using a Ballistic Evaluation Motor (BEM) for solid-rocket propulsion study. A K-type thermocouple was used to capture the temperature of the BEM. Previous studies on BEM have been customized to specific experiments accordingly without any standardized approach for temperature measurement. Variations in the methodology have led to inconsistent and potentially unreliable results across different research efforts. The purpose of the study is to establish a more reliable and standardized method for temperature measurement in BEM by validating the temperature readings recorded by a K-type thermocouple. The scope of the study includes recording the ignition and combustion temperature of the BEM against the time. Three different propellants were used in the experiments, ammonium perchlorate with sorbitol and magnesium, potassium nitrate with sucrose, and ammonium perchlorate with sorbitol and iron (III) oxide. The results indicate that ammonium perchlorate with sorbitol gives the highest maximum temperature which is at 101℃. The other propellants, ammonium perchlorate with magnesium and potassium nitrate with sucrose, recorded maximum temperatures of 75.20 °C and 57.25 °C, respectively. The validation process confirmed the reliability of the K-type thermocouple, with an average deviation of 2.3 °C to 3.7 °C from the reference thermometer readings. A notable performance was observed for the propellant using sorbitol andammonium perchlorate with iron (III) oxide. The experiment contributes to significant findings of the solid-rocket propulsion study, hence advanced solidrocket research can be explored from here onwards.

Pulverization of municipal solid waste and utilization of pulverized product as alternative fuel for blast furnace injection

In order to utilize municipal solid waste (MSW) in blast furnace ironmaking to realize synergistic reduction of pollution and carbon emissions, a novel method for pulverization of MSW by low temperature heat treatment and crushing, and evaluation of the properties of pulverized product for blast furnace injection were performed. In the present research work, residual waste obtained from MSW classification under the conditions of most Chinese cities was used as the representative raw material. The crushing performance of MSW can be improved by heat treatment. Considering the weight loss ratio, pulverization effect and density of heated MSW at different temperatures and durations, the optimal heat treatment parameters can be set as 300 °C and 20 min. The volatile content, fixed carbon content, ash content, S content, lower heating value of the pulverized product were 61.56 wt%, 19.02 wt%, 19.42 wt%, 0.39 wt% and 25.47 kJ/g, respectively. The pulverized product had worse fluidity and similar jet flow compared to industrial injection coal. Its decomposition heat for injection was 1732 kJ/kg. The initial combustion temperature and burnout temperature of the mixed fuel gradually decreased with the increasing of added pulverized product due to its much better combustion property. About 0.163 kg CO2 can be reduced if 1 kg of raw MSW was injected into blast furnace. The experimental results demonstrates that the obtained pulverized MSW could be used for blast furnace ironmaking to some extent as an environmentally friendly, low-carbon, and economically substitute of fossil fuel.

Prediction of Efficiency, Performance, and Emissions Based on a Validated Simulation Model in Hydrogen–Gasoline Dual-Fuel Internal Combustion Engines

This study explores the performance and emissions characteristics of a dual-fuel internal combustion engine operating on a blend of hydrogen and gasoline. This research began with a baseline simulation of a conventional gasoline engine, which was subsequently validated through experimental testing on an AVL testbed. The simulation results closely matched the testbed data, confirming the accuracy of the model, with deviations within 5%. Building on this validated model, a hydrogen–gasoline dual-fuel engine simulation was developed. The predictive simulation revealed an approximately 5% increase in overall engine efficiency at the optimal operating point, primarily due to hydrogen’s combustion properties. Additionally, the injected gasoline mass and CO2 emissions were reduced by around 30% across the RPM range. However, the introduction of hydrogen also resulted in a slight reduction (~10%) in torque, attributed to the lower volumetric efficiency caused by hydrogen displacing intake air. While CO emissions were significantly reduced, NOx emissions nearly doubled due to the higher combustion temperatures associated with hydrogen. This research demonstrates the potential of hydrogen–gasoline dual-fuel systems in reducing carbon emissions, while highlighting the need for further optimization to balance performance with environmental impact.

Investigate the impact wear failure behavior of CoMoCr engine valve and valve seat pairs under harsh conditions

The wear of sealing face is one of the main reasons for the failure of engine valve and valve seat pair. Changes in engine combustion load, running time, temperature, and other operating conditions can affect the wear of valve-valve seat pair. In this work, the CoMoCr alloy cladding valves and valve seat were used as the pair, to investigate the influencing mechanism of combustion load and valve lift on wear. Three groups of tests under different combinations of combustion loads and valve lifts were completed on self-designed testing rig. The results demonstrate that the increase of combustion load and valve lift exacerbate the wear of the valve and valve seat, and valve lift has a more significant effect on wear than combustion load. The increased combustion load worsens the microslip process and intensifies the abrasive wear process. Whereas valve lift enhances the impact process, causing the dense tribofilm on the material surface to delaminate due to fatigue. Destruction of the tribofilm prevented effective protection of the underlying material, which increased wear process.

Inertinite Reflectance in Relation to Combustion Temperature

Inertinite, a product of wildfire, holds important information on global temperature change. The relationship between its reflectance and temperature has been widely used to identify wildfire events in paleo-sedimentary environments, but the currently used equations relating inertinite reflectance and combustion temperature are subject to large errors. Therefore, to clarify the relationship between inertinite reflectance and combustion temperature further, we systematically analyzed changes in inertinite reflectance under different combustion durations based on the literature’s data. Results confirmed that inertinite reflectance is related to combustion duration. Disregarding combustion duration, the combustion equation is T=267.52+110.19×RoR2=0.91, where T is the combustion temperature, Ro% is the measured inertinite reflectance, and R2 is the correlation coefficient. Under a combustion duration of 1 h, the equation is T=273.57+113.89×RoR2=0.91, and under a combustion duration longer than 5 h (including 5 h), the equation is T=232.91+110.6×RoR2=0.94. These three equations not only account for the temporal factor, but are also more precise than the commonly used formula. This study provides a scientific basis for research on paleo-wildfire.

Study on the effect pattern of moisture on the oxidized combustion of ventilation air methane

AbstractVentilation air methane (VAM) is one of the main greenhouse gas sources. Owing to the characteristics of low concentration of ventilation air methane and high moisture content, we build an experimental platform and take the oxidative combustion temperature and methane conversion rate as the research indexes, and the systematic research finds that the inhibitory effect of moisture on the oxidative combustion of ultra‐low concentration of methane (<1%) is a nonlinear polynomial law. In the meantime, we constructed OH(H2O)n+CH4 and studied its reaction potential energy surface using quantum chemical calculations, which used the most significant primitive reaction of methane combustion, OH+CH4→H2O+CH3, as the theoretical basis. We found that as moisture content increased, so did its reaction energy barrier, making the reactants more stable, strengthening the three‐body collision effect, and reducing the number of free radicals, all of which hindered the methane chain reaction. The study aimed to validate the experimental finding that moisture inhibits the oxidative combustion of ventilation air methane by examining the internal mechanism of methane oxidation. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

Combustion characteristics and NOx release of sludge combustion with coal in a 660 MW boiler

This article analyses the effects of sludge moisture content and blending ratio on combustion characteristics, furnace temperature distribution and NOx release during co-firing with coal in a 660 MW tangentially fired boiler using CFD. When the sludge water content increases from 10 % to 30 %, the water in the fuel is rapidly released during the initial combustion process and absorbs the reaction heat, resulting in a 2.8 % decrease in the temperature of the main combustion zone and a gradual decrease in the heat flux density, while the presence of water leads to the intensification of the incomplete combustion, resulting in the increase of the NOx conversion rate. With the increase of sludge blending ratio from 5 % to 25 % and the increase of water, the combustion temperature in the main combustion zone decreased by 4.0 %, and the heat flow density decreased significantly in the whole furnace and MBR area, by 6.43 % and 12.78 %, respectively. However, the nitrogen content present in the sludge is much higher than that of coal, and the fuel-based NOx produced by the combustion process increased dramatically, which led to the boiler exit NOx increasing by 35.4 %. Reasonable selection of sludge blending ratio and water content is a key issue to be considered for boiler co-combustion.