Combustion Temperature Research Articles

Kinetic Study of Pure Oxygen Combustion of Coke Blended with Calcium Oxide

ABSTRACT In order to elucidate the mechanism of CaO on pure oxygen combustion of coke, non-isothermal TGA technique was use to test coke blended CaO samples of varying C/Ca molar ratios (CMCa-2, CMCa-3, and CMCa-4). The characteristic combustion temperatures at varying β were measured. The representative CMCa-2 and CMCa-4 were tested by TG-MS to determine the effect of CaO on coke combustion. Kinetics parameters for the blended samples across various reaction phases were determined using the improved Coats-Redfern method. The results showed that in the pure oxygen atmosphere, the combustion characteristic temperature rise with the increase of β. The material transformations during different reaction stages proceeded as follows: coke combustion generated CO2, CO2 combined with CaO to generate CaCO3, and finally CaCO3 decomposed to release CO2. The E values of three reaction stages were as follows: the highest E was observed in stage 3, ranging from 128.05–151.18 kJ·mol−1, the lowest E in stage 2 was below 46 kJ·mol−1, and the E in stage 1 laid between 99.35–128.71 kJ·mol−1. The C/Ca molar ratio was proportional to the kinetic parameters of the blended sample.

Theoretical model and control-parameter classification analysis for solid oxide fuel cell systems with cooling air bypass into burner

The burner is central to the thermal management of solid oxide fuel cell (SOFC) system. Using cooling air bypass (CA) into burner is simple and effective to control the excessive temperature. A novel theoretical model for SOFC systems equipped with CA into burner is developed and verified with multiple experimental data. A comprehensive control-parameter classification analysis is carried out with the model, revealing quantitatively the impacts of the fuel utilization (Uf), air flow rate (Vair), and maximum burner temperature (TBM), on the system performance. The results confirm CA can minimize thermal shock to the stack. Favorable combinations of (Uf, Vair, TBM) satisfying the thermal constrains of maximum cell temperature and temperature difference are identified, and capable of achieving a system alternating current efficiency of 55 % or more. The theoretical model can help the system design optimization targeting the specifics of the stack.

Red mud in high-strength ceramics production

The work is devoted to the creation of high-strength ceramic materials with technogenic waste fillers.Purpose: Investigation of the ceramic and composite production based on chemical and metallurgical wastes to create new types of high quality constructional ceramics.Methodology/approach: The use of refractory clay with the addition of high-iron bauxite sludge as the main raw material. Bauxite sludge functions in compositions with aluminosilicate raw materials at burning at 1100 to 1200 °С, reduce to sintering due to its melting at 1150 °С.Research findings: Refractory clay compositions with red mud in the amount of 20 to 50 % at the burning temperature of 1050 °С, provide the ceramic formation possessing the compressive strength 1.3 to 1.5 times higher than that of clay samples without additives, i.e., 91 and 122–132 MPa, respectively.Value: The obtained ceramic compositions based on red mud determine a production of high-strength anorthite and anorthite-helenite ceramics using dry pressing.

Numerical studies of a water-cooled premixed burner for low NOx combustion of natural gas

Natural gas, known for its high combustion efficiency and low CO2 emissions, is experiencing a significant increase in both market share and application range. Despite these advantages, there are also challenges emerged during the combustion process, including occurrence of high flame temperature, difficulty in controlling nitrogen oxide emissions, combustion instability, and a tendency to backfire. To address these issues and achieve clean and stable burning, a novel 14 MW water-cooled pre-mixed burner has been developed. In-depth simulations are conducted to assess the impact of various structural and operating parameters on combustion and pollutant emission characteristics. Results indicate that the combustion temperature follows a “W" shape with height of the low cooling component while its width governs combustion stability. Gas inlet spacing influences the flame center position and anti-backfire performance. The flare angle of gas channels determines the minimum ignition energy of the mixed gas fuel which affects ignition point and flame center position. Although large height of high cooling component contributes to low NOx emissions at the gas outlet, the resultant low temperature is undesirable for combustion stability. Further examinations of operating parameters through simulations reveal that combustion temperature initially decreases and then increases with excess air coefficient, while a significant decrease is noted with lower operating load. The premixed water-cooled technology could achieve low-NOx emissions to 2.89 mg·Nm−3 with the combustion temperature controlled at 1642K. This study provides valuable data for the design of low-NOx gas burners, serving as a reference for achieving clean and stable combustion of gas fuel.

Ignition and combustion of Al–Mg–Li alloy particles at elevated pressures

Al–Mg–Li ternary alloy particles can be a promising metal additive to replace aluminum in solid propellants to improve combustion efficiency by reducing agglomeration during combustion. In this paper, Al–Mg–Li ternary alloy was prepared and its basic physical and chemical characterization parameters were obtained by SEM-EDS, ICP-AES, and XRD analysis. The ignition and combustion characteristics of single Al–Mg–Li particles under different pressures were investigated by using a self-developed experimental setup. The ignition process and combustion flame structure of Al–Mg–Li particles were significantly affected by the increasing pressure, and the ignition delay and combustion time decreased. The ignition mode was clearly identified: surface ignition (0.1–0.2 MPa) and gas phase ignition (0.4–1.2 MPa). Al–Mg–Li particles showed white-pink flame during combustion, and the characteristic peaks of AlO, MgO, and Li were identified, confirming that the particles performed a gas-phase combustion at pressures above 0.4 MPa. The combustion temperature of Al–Mg–Li particles could exceed 3000 °C when the pressure surpassed 0.6 MPa. The composition of different regions in the condensed combustion products were analyzed. Reaction mechanism was proposed to reveal the addition of elemental Mg and Li could improve the ignition and combustion characteristics of Al, especially at higher ambient pressures.

Morphological and Elemental Classification of Freshly‐Emitted Individual Particles From Field and Laboratory Residential Biomass Burning

AbstractResidential biomass burning significantly contributes to air pollution in developing countries. However, the microscopic properties of individual particles in their emissions have not been well understood. In this study, individual primary particles from 14 kinds of biomass fuels (including firewood, crop residue, and animal dung) were collected in laboratory and field measurements, and their morphology, composition and mixing state were acquired using transmission electron microscope. These results constitute a source profile database of individual primary particles from residential biomass burning. The database reveals that different types of biomass fuels exhibit different emission characteristics, that is, residential firewood burning mainly emits pure carbonaceous particles (including organic matter (OM) and soot particles), crop residue burning mainly emits K‐containing particles (including OM‐K, soot(‐OM)‐K, and K‐rich particles), and animal dung burning mainly emits pure carbonaceous particles and K‐containing particles. Moreover, our results indicate that the emission characteristics obtained from laboratory and field measurements are different. Field measurements conducted in two selected villages in North China Plain exhibit a higher presence of soot particles compared to laboratory measurements, owing to their higher combustion temperatures. In contrast, field measurements conducted in one selected village in Qinghai‐Tibet Plateau contain less soot particles than those from laboratory measurements in plain areas, due to the deficient oxygen supply during combustion process in the high‐altitude regions. These results warn us that the emission estimation from residential biomass burning should notice the large emission differences among different biomass types and between field and laboratory measurements.

Comprehensive experimental investigations on Co-combustion dynamics and multi-pollutant formation characteristics of coal gangue and biomass in oxy-fuel atmosphere

Based on the co-combustion principle of coal gangue and biomass, the combustion characteristics, kinetic mechanisms, and pollutant emission characteristics of mixed coal gangue and wheat straw in oxy-fuel atmosphere were investigated by conducting experiments with a thermogravimetric analyzer and a tube furnace in this paper. The results indicated that the comprehensive combustion characteristics, reaction rate and burnout rate of the samples can be improved with the increase of O2 concentration in oxy-fuel atmosphere. When O2 concentration is 50 %, the emission peaks of pollutants SO2 and NOx are the highest. The increase of biomass content can accelerate the combustion reaction rate, increase the total weight loss rate, enhance the comprehensive combustion characteristics of the samples significantly, and reduce the release of SO2. A faster heating rate corresponds to higher ignition temperature, burnout temperature, and the maximum weight loss rate temperature, leading to the improvement of comprehensive combustion characteristics and flammability. The combustion temperature has a significant effect on pollutant release, and the release of CO and SO2 is relatively low under the condition of 900∼1000 °C. Therefore, the use of oxy-fuel co-combustion technology holds the potential to significantly improve the combustion performance of coal gangue, reduce pollutant emissions, and provide a theoretical guidance for the resource utilization of coal gangue and biomass.

Acoustic Design Parameter Change of a Pressurized Combustor Leading to Limit Cycle Oscillations

When aiming to cut down on the emission of nitric oxides by gas turbine engines, it is advantageous to have them operate at low combustion temperatures. This is achieved by lean premixed combustion. Although lean premixed combustion is a proven and promising technology, it is also very sensitive to thermoacoustic instabilities. These instabilities occur due to a coupling between the unsteady heat release rate of the flame and the acoustic field inside the combustion chamber. In this paper, this coupling is investigated in detail. Two acoustic design parameters of a swirl-stabilized pressurized preheated air (300 °C)/natural gas combustor are varied, and the occurrence of thermoacoustic limit cycle oscillations is explored. The sensitivity of the acoustic field as a function of combustion chamber length (0.9 m to 1.8 m) and reflection coefficient (0.7 and 0.9) at the exit of the combustor is investigated first using a hybrid numerical and analytical approach. ANSYS CFX is used for Unsteady Reynolds Averaged Navier-Stokes (URANS) numerical simulations, and a one-dimensional acoustic network model is used for the analytical investigation. Subsequently, the effects of a change in the reflection coefficient are validated on a pressurized combustor test rig at 125 kW and 1.5 bar. With the change in reflection coefficient, the combustor switched to limit cycle oscillation as predicted, and reached a sound pressure level of 150 dB.

Investigation of maximum temperatures in lithium-ion batteries by CFD and machine learning

Alternative fuels are becoming more popular as awareness of fossil fuel depletion, pollution, and climate change grows. Numerous industrial companies are producing electric automobiles for use worldwide. Electric vehicles’ battery packs’ cooling causes firing due to high temperatures. In this study, the surface temperatures of a single electric battery with dimensions of 160 mm × 210 mm within a battery pack were investigated using computational fluid dynamics and, subsequently, Levenberg-Marquardt machine learning as a function of ambient temperature, convective heat transfer coefficient, nominal capacity of the electric battery, and discharge rate. The transport coefficient has been calculated for a rechargeable electric battery with a nominal capacity ranging from 14.6 to 20 Ah and a discharge rate varying between 1 and 15, taking into account conditions of stagnant air at temperatures ranging from 20°C to 35°C and values between 5 and 20 W/m2.K. Insufficient or absent cooling of battery temperatures can lead to them reaching combustion temperatures of electric vehicle batteries, typically from 50°C to 80°C, depending on the operational circumstances. An artificial neural network was utilized in machine learning to forecast maximum temperatures based on operating conditions without requiring simulation. The neural network achieved an estimated mean squared error of 0.00552 and a calculated coefficient of determination of 0.99. The neural network model can predict outputs with mean and standard deviation rates below 0.237. The anticipated artificial neural network model can accurately forecast the maximum surface temperature of an electric vehicle battery.

Emission Spectroscopy-Based Sensor System to Correlate the In-Cylinder Combustion Temperature of a Diesel Engine to NOx Emissions.

Due to a rising importance of the reduction of pollutant, produced by conventional energy technologies, the knowledge of pollutant forming processes during a combustion is of great interest. In this study the in-cylinder temperature, of a near series diesel engine, is examined with a minimal invasive emission spectroscopy sensor. The soot, nearly a black body radiator, emits light, which is spectrally detected and evaluated with a modified function of Planck's law. The results show a good correlation between the determined temperatures and the NOx concentration, measured in the exhaust gas of the engine, during a variety of engine operating points. A standard deviation between 25 K and 49 K was obtained for the in-cylinder temperature measurements.

Numerical Analysis of the Co-firing Combustion of Coal and Palm Shell Kernel In Stoker Boiler

The United Nations Framework Convention on Climate Change (UNFCCC) states that Indonesia is committed to contributing to global climate change solutions. The government will also continue to encourage the development of a number of renewable energy (EBT)-based power generation projects. This is based on the use of renewable energy which is still low, namely around (1.9%) 8215.5 MW. Meanwhile, the potential for EBT to become energy can be around 443,208 MW. One source of EBT in Indonesia that can be utilized is Biomass. Co-firing of biomass is a relatively cheaper option and does not require investment in new power plants. However, Co-firing combustion has several aspects that need to be studied, such as temperature combustion and the generation of gas emissions. Therefore, this study aims to determine the temperature and the emissions resulting from co-firing of palm kernel shell biomass. This research was conducted using the Computational Fluid Dynamics method on stoker boiler model. The test parameters of the research was the maximum and average temperatures in the furnace, and the average and maximum fractions of CO2, SO2 in the stoker boiler furnace. From the research conducted, it was found that the resulting combustion temperature decreased as the co-firing fraction of the biomass increased. However, CO2 gas emissions increased and SO2 decreased with increasing fraction of co-firing biomass which showed a decrease in harmful gas emissions and complete combustion that occurred in the furnace.

METHODOLOGY FOR EXPERIMENTAL RESEARCH OF THE FIRE HAZARD OF POWER LITHIUM-ION BATTERIES OF ELECTRIC VEHICLES UNDER THE INFLUENCE OF A HEATING PANEL

Even though lithium-ion batteries (LIBs) are the subject of various tests and research at the production stage, there are no isolated cases of electric vehicle fires, and the development dynamics are unpredictable. The particular danger of such fires lies in the oxygen release during an irreversible exothermic reaction in LIBs, which creates new challenges for fire and rescue services when extinguishing such fires. The study aims to develop the main provisions of the methodology for experimental studies of electric vehicle power batteries in terms of fire hazards using an electric heating panel. The ultimate goal of the study is to determine the temperatures at which an irreversible exothermic reaction, the opening of ventilation holes, and the combustion (explosion) of electric vehicle power batteries begin, as well as the time parameters at which such processes occur. Taking into account the peculiarities of the occurrence and course of the irreversible exothermic reaction, we have developed a methodology, the essence of which is to determine the temperatures of the onset of the irreversible exothermic reaction of the electric vehicle power battery, the opening of ventilation holes, and the combustion (explosion) of electric vehicle power batteries, the combustion temperatures of ventilation gases, as well as the time parameters at which these processes occur, which may change during battery operation and not correspond to the declared parameters of the manufacturer. For this purpose, we exposed LIBs to thermal energy from an electric heating panel and recorded the temperature and time during which an irreversible exothermic reaction occurs from the moment of an internal short circuit to a fire or explosion. The use of the proposed methodology of experimental studies of the elements of power batteries of electric vehicles regarding the fire hazard of an electric heating panel will make it possible to determine the temperature limits of the occurrence of irreversible exothermic reactions in LIBs, as well as the time parameters under which these processes occur. Keywords: electric vehicle fire, irreversible exothermic reaction, lithium-ion battery.

Ratiometric thermometry using down-conversion luminescence and solid-state lighting application of Er3+ activated strontium tungstate phosphor

Er3+ activated Sr3WO6 double perovskite crystallized in triclinic structure was synthesized via the solid-state reaction method at 1200 °C for non-contact optical thermometry and solid-state lighting. The phosphors under study were characterized via X-ray diffraction, scanning electron microscopy, diffusion reflectance spectra, and photoluminescence techniques. When excited with 380 nm, the Sr3WO6:Er3+ phosphors exhibited intense green emission, corresponds to 2H11/2/4S3/2-4I15/2 transitions of Er3+. The fluorescence intensity ratio of thermally coupled energy levels were computed within 303–513 K and subsequent relative sensitivity (0.56% K−1 at 303 K) was determined. Moreover, the PL intensity maintained 76.28% at LED burning temperature (150 °C) compared to PL intensity observed at room-temperature, denotes good thermal stability. Additionally, the fluorescent behaviour of the phosphors was examined via PL decay lifetime study. The PL quantum efficiency of the phosphor is computed via the Auzel's model using PL decay lifetime, and was obtained to be 80.32% for Sr3WO6:2% Er3+ phosphor.

The Oxidation Performance of a Carbon Soot Catalyst Based on the Pt-Pd Synergy Effect

Pt-Pd-based noble metal catalysts are widely used in engine exhaust aftertreatment because of their better carbon soot oxidation performance. At present, the synergistic effect of Pt and Pd in CDPFs, which is the most widely used and common doping method, in catalyzing the combustion of carbon smoke has not been reported, and it is not possible to give an optimal doping ratio of Pt and Pd. This paper investigates the carbon soot oxidation performance of different Pt/Pd ratios (Pt/Pd = 1:0, 10:1, 5:1, 1:1) based on physicochemical characterization and particle combustion kinetics calculations, aiming to reveal the Pt-Pd synergistic effect and its carbon soot oxidation law. The results show that Pt-based catalysts doped with Pd can improve the catalyst dispersion, significantly increase the specific surface area, and reduce the activation energy and reaction temperature of carbon soot reactions, but excessive doping of Pd leads to the enhancement of the catalyst agglomeration effect, a decrease in the specific surface area, and an increase in the activation energy and reaction temperature of the carbon soot reaction. The specific surface area and pore capacity of the catalyst are the largest, and the activation energy of particle oxidation and the pre-exponential factor are the smallest (203.44 kJ∙mol−1 and 6.31 × 107, respectively), which are 19.29 kJ∙mol−1 and 4.95 × 108 lower than those of pure carbon soot; meanwhile, the starting and final combustion temperatures of carbon soot (T10 and T90) are the lowest at 585.8 °C and 679.4 °C, respectively, which are 22.1 °C and 20.9 °C lower than those of pure carbon soot.

Effect of Fire Exposure on the Properties of Self-Compacting Concrete reinforced by Glass Fibers

The optimal design of any structural elements requires examining all environmental risks, emergency accidents, and standard load cases. Exposure to fire is one of the most common safety threats. Nowadays wide developments are achieved in the field of concrete technology, therefore, experimental and theoretical investigations should be performed on the characteristics of such developed materials under different loading conditions. This study investigates the impact of fire exposure on the mechanical characteristics of self-compacting concrete, specifically compressive and tensile strength, modulus of elasticity, and stress-strain relation. The adopted fire exposure consisted of six steady-state temperatures (300, 400, 500, 600, 700, and 800°C) for one hour and a sudden cooling method. Four glass fiber volume fractions were adopted: 0, 0.5, 1, and 1.5%. The glass fiber volume fractions considered (0.5-1.5%) improved the mechanical properties investigated. Two states were detected for the effect of fire exposure. The effect of fire exposure was inversely proportional to fiber content in burning temperatures of 300-700°C, while the reduction in mechanical properties of 1.5% fiber content was greater than those of 0.5 and 1% when the temperature increased to 800°C. Furthermore, the addition of glass fiber changed the brittle mode stress-strain relation to semi-ductile for the non-burned and burned up to 600°C specimens, whereas a brittle behavior was detected when the temperature increased above 600°C. In general, a similar effect was noticed for all the glass fiber ratios considered regarding the slope of the stress-strain linear stage compared to the non-burned specimens, which was more salient when the burning temperature increased.

Study of the influence of different ignition times on detonation generation and shock wave propagation in high-pressure hydrogen leakage

Hydrogen is an efficient, clean, and renewable energy source. When determining a place for hydrogen energy storage and injection into vehicles, the main safety concern of hydrogen refueling stations is high-pressure hydrogen leakage. In this paper, the CFD method is used to study the effect of different ignition times on the explosion and shock wave propagation of high-pressure hydrogen gas leakage, analyze the distribution of flammable gas clouds, and evaluate the impact of combustion flames, temperature, and explosion-induced overpressure on refueling stations. The results show that the concentration of gas clouds ranges from 0 to 80% (volume concentration). Explosion and combustion phenomena occur at different ignition times during the high-pressure hydrogen gas leakage stage, with a maximum pressure of 2.6 bar and a high temperature of 1500–2400 K. After a high-pressure hydrogen leak, ignition can occur only as an explosive phenomenon. This generates a pressure of up to 3.1 bar and a short-lived high temperature. The pressure increases with the length of the leak, and the hazardous area varies depending on the time of ignition. This paper provides theoretical support for safety issues related to high-pressure hydrogen leakage in refueling stations.

Research on spontaneous combustion characteristics and high temperature point prediction method of rectangular coal pile

ABSTRACT In order to prevent and control the spontaneous combustion phenomenon of rectangular coal pile under the coal storage and transportation scenario, the spontaneous combustion process of rectangular coal pile was simulated based on the experimental platform, the spontaneous combustion temperature change characteristics of rectangular coal pile were obtained, a coal spontaneous combustion prediction model was constructed based on the proposed prediction method. The results show that the height of the coal pile of 30 cm is a demarcation line, the temperature change of the upper measurement point is more consistent, but the lower measurement point has a greater variability, and reaches the ignition point in a shorter time, the peak temperature is higher, which further exacerbates the spontaneous combustion of the coal pile; At 3 h the coal pile formed an initial high-temperature region, and at about 14 h the pile was in a state of complete spontaneous combustion; The prediction method using temperature data from surface measurement points as model inputs is more feasible; All three models have good robustness and generalization, and the specific order of merit is GA-BP > GA-RF > GA-SVR. The study has an important guide for the safe, green and economical development of coal transportation and storage.

Experimental investigation on thermal modification and burnout of residual carbon in coal gasification fine slag

Disposal of coal gasification fine slag (CGFS) has caused environmental pollution and resource waste. Its decarbonization is the bottleneck of aluminum and silicon resource utilization. A fluidization-melting combustion system is proposed in this study to realize the decarbonization. The fluidized thermal modification and burnout characters of residual carbon in CGFS were investigated experimentally on a bench-scale test rig. A two-stage decarburization path of CGFS was concluded and verified. The fluidized modification of CGFS is first conducted to decrease the particle size and improve the specific surface area and combustion reactivity. So, the modified exposed carbon in CGFS rapidly burns in the melting furnace to generate the condition above the fluid temperature of minerals. Then the mineral shell of the amorphous mineral covered carbon in CGFS is molten and damaged, and the carbon appears and burns out. The decrease in the thermal modification temperature induced deceases in melting combustion temperature and decarbonization efficiency. Efficient decarbonization of CGFS produced by three different entrained bed gasifiers was realized by the fluidization-melting combustion, the decarburization efficiencies are all above 95% and the comprehensive carbon contents of ash and slag are all below 5%.

In-situ synthesis of MEMS compatible Al/Cu2HIO6/PVDF Metastable composites film with high combustion performance

To address the challenges related to significant pressure loss and weakened combustion performance of energetic materials when ignited on Micro-Electro-Mechanical Systems (MEMS), periodate-based MICs (Metastable Intermolecular Composites) have emerged as promising candidates due to their high energy density and combustion pressure. However, the integration of periodate-based MICs onto MEMS has not been effectively achieved thus far. Herein, we propose a simple, environmentally friendly, and cost-effective approach to fabricate a MEMS-compatible Al/Cu2HIO6/PVDF (polyvinylidene difluoride) energetic composite film. Our method involves utilizing a Cu(OH)2 array as a template and employing an in-situ and spin-coating process. The resulting Al/Cu2HIO6/PVDF film was characterized using various techniques including SEM, TEM, XRD, and XPS. These analyses reveal a tightly packed nano array morphology with a porous structure. DSC-TG analysis was conducted to investigate the thermal reaction of the Al/Cu2HIO6/PVDF composite film. The results demonstrate that the thermal reaction involved a complex multi-step process, with higher heat release (1121 J g-1), a faster reaction rate, and a lower initial reaction temperature (294.5 °C) compared to the Al/CuO/PVDF composite film. the reaction process of Al/Cu2HIO6/PVDF film was also been proposed by analyzing the products at different temperatures. combustion diagnostic tests were carried out to evaluate the combustion performance of the Al/Cu2HIO6/PVDF composite film. The results indicate that as CuO transformed into Cu2HIO6, the film exhibits a reduced ignition delay (8 ms) and combustion duration (50 ms), higher combustion temperature (3710 K), and stronger flame intensity (8630 a.u.).

Dynamic evolution of terahertz permittivity of lignite during oxidation: Microstructural insights

Terahertz technology holds promise for monitoring coal fires and assessing associated risks, relying on the dielectric response of coal during the oxidation process. Besides, unraveling the response mechanism is crucial for enhancing the application's reliability. In light of these, this study focused on investigating the terahertz complex permittivity of lignite with different oxidation temperatures through microstructure analysis. Results indicated that oxidation temperature dependencies in the real and imaginary parts of lignite's permittivity, exhibiting a pattern of initial decrease followed by an increase. The decrease in permittivity during the dehydration and weight loss stage is primarily attributed to moisture content. In the oxygen absorption and weight gain stage, pore development and scattering effects contribute to the continuous decrease in real permittivity and rise in imaginary permittivity. During the oxidative decomposition stage, the hydroxyl group initiates an increased real permittivity. Upon reaching the combustion temperature, there is a sudden surge in permittivity, driven by the dominance of minerals in coal dielectric properties. The conclusions offer theoretical support for terahertz technology in monitoring coal fires, which can contribute to the sustainable development of the coal industry, mineral processing, and safety production.