Gaseous Combustion Products Research Articles

Study on the Characteristics of Combustible Mixed Gas Production during Lignite Oxidation Process

CO, H2, and other combustible gases will be produced during coal oxidation in coal mines, which will increase the risk of explosion when mixed with methane. Therefore, it is very important to understand the production characteristics of combustible gas during coal oxidation. In this paper, a programmed temperature gas test system is built to study the impact of lignite on the production of gases at different particle sizes and temperatures, and the release characteristics of gases are also analyzed. The result shows that the production of combustible gas is influenced by the coal particle size significantly when the temperature is above 200 °C, and it decreases as the particle size increases. CO is the main gas during the early stage of coal spontaneous combustion, and the release of CH4 and H2 increases after 300 °C. The fitted equations of gas generation and temperature are consistent with the experimental results. The research results are helpful in understanding the hazards of coal spontaneous combustion and have a certain guiding significance for coal mine monitoring and prevention of coal spontaneous combustion.

Assessment of the impact of smoke from thermal destruction of materials of different origins on soil health.

The results of the study of the influence of smoke from the thermal destruction of materials of vegetable and synthetic origin on the enzymatic activity of ordinary chernozem are presented. The decrease of activity of investigated indicators (catalase, peroxidase, polyphenol oxidase, invertase) from thermal destruction of pine sawdust, straw, coniferous and leaf fall, peat, and materials based on polystyrene, rubber, and polyvinyl chloride was revealed. A significant decrease in the activity of soil enzymes after exposure to gaseous products of combustion during 15-60min of soil fumigation was found. Oxidoreductases turned out to be the most sensitive to smoke. Smoke from peat burning has minimal inhibitory effect, activity of catalase after 30min of fumigation decreased only by 15%, and peroxidase and polyphenol oxidase - by 8 and 12%. While the activity of the same enzymes when exposed to smoke from thermal degradation of rubber-based materials decreased by 16-42%, and polyvinyl chloride - by 29-73%, to a lesser extent from polystyrene (decrease by 7-29%). All obtained data on changes in the enzymatic activity of soils are reliable with the level of statistical significance p < 0.05.

ВЛИЯНИЕ ТЕПЛОФИЗИЧЕСКИХ СВОЙСТВ ПРОДУКТОВ СГОРАНИЯ БИОГАЗА НА ТЕПЛОВЫЕ ПАРАМЕТРЫ ВОДОГРЕЙНЫХ КОТЛОВ

The combustion products of biogas and natural gas differ in the content of components, which affects their heat content and heat exchange in boilers. To determine the possibility of using biogas in boilers designed for burning natural gas, the work compares the thermophysical properties of the combustion products of natural gas and biogas and their influence on the results of boiler calculations. Methods were obtained for calculating the thermal conductivity and viscosity of a mixture of gases depending on their composition and temperature. The comparison showed that the calorimetric and thermophysical properties of biogas combustion products differ from the properties of natural gas combustion products by up to 4 %, and the difference from the reference properties of combustion products given in the standard method for calculating boiler units is on average 6 %. A comparison has been made of the results of verification thermal calculations of low-power hot water boilers KVMG-1.0 and KSV-1.0 using the properties of combustion products given in the standard method for calculating boiler units, and when calculating them using the proposed equations. Calculations have shown that the results of calculations based on reference data of the standard method lead to higher values of exhaust gas temperatures and fuel consumption. It can be concluded that natural gas in boilers can be replaced by biogas without the need to reconstruct the boiler, but for thermal calculations it is necessary to take into account changes in the composition and properties of fuel combustion products.

Microwave plasma conversion of food waste using carbon foam: Production of heteroatom-doped graphene and combustible gas

The mass production of food waste (FW) has a terrible impact on the environment, but with proper treatment, FW can be transformed into a new resource. Currently, thermal conversion (especially incineration) has been the most common and efficient means of handling FW, but it also entails negative impacts, such as high carbon emissions and lower added value. In this study, a new high-efficiency thermal conversion process is proposed that uses carbon foams to induce the formation of microwave plasma (MP), which generates very high final temperatures to enable the direct conversion of FW into combustible gases and high-value-added heteroatom-doped microwave plasma graphene (HMPG) in 5–20 s. This work investigated the optimal carbonization temperature of the melamine sponge (carbon foam precursor) and the effect of microwave plasma reaction duration on the distribution of the gas products and the properties of HMPG, and HMPG was characterized in detail by Raman spectroscopy, X-ray diffraction, scanning electron microscope, etc. Ultimately, HMPG was tested in potassium ion battery anodes for evaluation of its energy storage potential, and the results showed that the capacities were able to reach ∼270 mAh g−1 at 50 mA g−1 after 60 cycles.

Chronic and Periodic Effects of Smoke from Crop Residue Combustion on Soil Enzymatic Activity

Wildfires lead to the emission of large volumes of toxic smoke, which is transported hundreds of kilometres away from the fires and can have a negative impact on soil, biota and humans. A series of modelling experiments on pyrogenic fumigation of soil were carried out to assess the effects of gaseous products from wildfires on soil biochemical parameters. The effects of chronic exposure to gaseous substances and periodic, repetitive effects of smoke exposure on soil were determined. The results were compared with a single intensive smoke exposure. It was found that pyrogenic impact significantly affected the change of enzymatic activity of ordinary chernozem. The degree of influence depended on the duration and periodicity of smoke exposure. In all experiments enzymes of oxidoreductase class (catalase, peroxidase, polyphenol oxidase) were more sensitive to fumigation than invertase from hydrolase class. The reason of suppression of enzymatic activity of soils is high concentrations of toxic gases. The following concentrations exceeded the maximum permissible concentrations for atmospheric air: CO 714 times, phenol (hydroxybenzene) 441 times, acetaldehyde 24100 times, formaldehyde 190 times. Accumulation of polycyclic aromatic hydrocarbons (PAHs) in soil after fumigation was revealed, the total content of PAHs was 377 ng/g. The highest values were recorded for naphthalene, where the concentration was 4.4 times higher than the maximum permissible and phenanthrene 2.8 times higher than the maximum permissible. It was found that 60-minute intensive smoke affects the soil to a lesser extent than chronic and periodic. Indicators of enzymatic activity of chernozem after such fumigation decreased by 15-33% depending on the enzyme, in chronic and periodic by 41-84 and 31-78%, respectively. The obtained data indicate a significant effect of smoke on enzymatic activity of soils under chronic and periodic exposure to gaseous products of combustion.

Production of high calorific value hydrogen-rich combustible gas by supercritical water gasification of straw assisted by machine learning

This article reveals the basic laws of straw supercritical water gasification (SCWG) and provides basic experimental data for the effective utilization of straw. The paper studied the impact of three operational conditions on the production of high-calorific value hydrogen-rich combustible gases through SCWG of straw within a quartz tube reactor. The findings reveal that elevated reaction temperatures, extended residence times, and reduced feedstock concentrations favor the SCWG of straw. When combustible gas contains carbon dioxide, the maximum low heating value (LHV) of the gas is 21 MJ/Nm3. Upon removing carbon dioxide, the LHV of the gas reached 38 MJ/Nm3. Subsequently, a machine learning (ML) model was developed to forecast gas yield and LHV during the SCWG process. The results demonstrate that the model exhibits robust generalization capabilities. ML can be extensively applied to forecast biomass SCWG processes across various operational conditions.

Aspects of Reduced Performance of Proton-Exchange-Membrane Water Electrolysis Via Continuum Modeling

Proton-exchange-membrane water electrolysis (PEMWE) is a technology, where hydrogen is electrochemically produced from water. Efficient industrial-scale production of hydrogen via PEMWE is contingent upon developing systems that are sufficiently resilient to operate under non-ideal operating conditions. Mathematical models can provide insight into the underlying physical mechanisms and inform the development of mitigating strategies. In the current work, a cell-level non-isothermal continuum model that is based on concentrated-solution theory that accounts for multiple ionic mobile species in the membrane and ionomer, energy transport, and fluid flow through porous media, was used to investigate two challenges to PEMWE becoming a viable technology, specifically contamination and hydrogen crossover. In cationic contamination, dissolved salts in the reactant water supplant protons in the membrane and ionomer and significantly increase the applied potentials required for operation. Hydrogen crossover is a concern especially in low-current operational modes, which can arise due to PEMWE powered by variable and cyclical renewable energy sources and can result in the production of combustible gas mixtures.For cation-contaminated cells, simulation results suggest that the uptake of the contaminant cation increased as a function of current density until local conditions in the cathode catalyst layer (cCL) allowed the contaminant desorption to occur. The model suggests that the increased cell potential is primarily due to proton activity losses in the hydrogen evolution reaction within the cCL and that ionic conductivity losses are insufficient to cause the performance losses observed experimentally. Agreement with experimental data lends the model as a possible method or predictive models for PEMWE cell recovery methods. Observations of hydrogen crossover simulations suggest several aspects of hydrogen crossover, which include that localized pressures within the catalyst layers can enhance crossover, bubble-nucleation kinetics limit the exhaust of product gases, and convective fluxes due to electroomostic drag are negligible. An improved understanding of the crossover mechanisms can inform the development of low-crossover designs and mitigation strategies. Figure 1

Study on radiation heat transfer characteristics of aeroengine combustion chamber

The thermal radiation of gaseous combustion products in an aero-engine combustion chamber has obvious non-ash-body characteristics. In this paper, based on the OpenFOAM platform, a numerical study on multi-field coupled turbulence-combustion-radiation radiative heat transfer was carried out for a certain type of aero-engine combustion chamber using the mean weighted sum of grey gas (WSGG) gas radiation model, which can accurately describe the non-ash characteristics of the gas. The results show that the radiation heat transfer characteristics are influenced by several factors such as equivalent ratio, combustion pressure and wall emissivity, among which the equivalent ratio is dominant. Increasing the equivalence ratio from 0.11 to 0.4 resulted in a 189% increase in average incident radiation at the combustion chamber wall and a 233% increase in average incident radiation at the exit. Increasing the equivalent ratio, combustion pressure or wall emissivity will increase the average radiation intensity in the combustion chamber and the inhomogeneity of radiation distribution at the exit of the combustion chamber. The radial radiation distribution factor (RRDF) also increases with the increase of equivalent ratio, combustion pressure and wall emissivity.

Computer simulation of heat and mass transfer processes during water vapor condensation from natural gas combustion products on smooth cylindrical tubes

Computer simulation of heat and mass transfer processes during water vapor condensation from natural gas combustion products on smooth cylindrical tubes

Interconnected pyrolysis and activation with in-situ H3PO4 activation of biochar from pear wood chips in a pilot scale dual fluidized bed

Interconnected pyrolysis and activation is a novel technology for combustible gas and biochar production in dual fluidized bed (DFB). The study proposed one-step and two-step methods for pyrolysis and activation of biomass in a pilot scale DFB with capacity of 100 kg/h. Physical and chemical activation occurred simultaneously in DFB system by phosphoric acid (H3PO4) impregnation pretreatment of pear wood chips, and flowing hot flue gas and steam. Stable operating parameters were observed for both methods. The one-step method was superior to the two-step method in terms of the pyrolysis gas quality, biochar pore distribution, micro- and meso-pores structures of biochar, while one-step method reduced the biochar yields. As an activation agent, H3PO4 increased the yields of biochar and pyrolysis gas, promoted formation of micropores and enriched the surface functional groups of biochar with increasing ratio of H3PO4. H3PO4 to biomass ratio of 1:5 reached the maximum biochar yield of 42.3 wt% and highest iodine adsorption value of 648.5 mg/g, increasing by 70.6 % and 90.3 % compared to the biochar without H3PO4 pretreatment, respectively. This DFB system facilitated the diversified use of fluidized beds and the co-production of biochar and product gas with energy saving and CO2 emission reduction.

Synthesis of HHTPB by partial hydrogenation of HTPB using copper chromite as a catalyst

AbstractHTPB (hydroxyl‐terminated polybutadiene) is a well‐established binder in the composite solid propellant owing to its excellent compatibility with ammonium perchlorate (AP) and aluminium (Al) particles in giving rise to optimal ballistic and mechanical properties. Efforts are being made to improve the ballistic properties further, such as specific impulse. One way of increasing the specific impulse is to hydrogenate HTPB, which decreases the molecular mass of the combustion product gases. This paper is a summary of efforts in synthesizing hydrogenated HTPB (HHTPB) using copper chromite (CC) as a catalyst. A novel synthesis methodology is developed for HHTPB using a temperature‐programmed batch reactor with a variable speed stirrer and an instrumentation system to maintain the desired liquid reactant temperature. A process cycle is developed that includes addition sequence and reaction time. The product is analyzed using 1H‐NMR and FTIR to estimate the degree of hydrogenation and the geometrical isomers respectively. The estimated apparent equilibrium rate constants from the degree of hydrogenation values are respectively 74 and 2034 L/(mol MPa) for non‐catalyzed and catalyzed systems, indicating the effectiveness of the catalyst. This is also substantiated by the reduction in Gibbs free energy (ΔG), to an extent of 4.48 kJ/mol. Thermogravimetry examination indicates that the decomposition temperature of HHTPB produced by the catalytic method is marginally higher compared to HTPB. DSC curves indicate that the decomposition enthalpy of HHTPB is higher than that of HTPB. In summary, this paper proposed and validated a novel method in the preparation of HHTPB using copper chromite.

Atmosphere-dependent combustion of Ganoderma lucidum biomass toward its enhanced transformability into green energy.

Globally, the circular efficiency of biomass resources has become a priority due to the depletion and negative environmental impacts of fossil fuels. This study aimed to quantify the atmosphere-dependent combustion of Ganoderma lucidum (GL) biomass and its thermodynamic and kinetic parameters toward enhancing its circularity and transformability characteristics. The GL combustion occurred in the three stages of moisture removal, volatile release, and coke combustion. Combustion performance characteristics were more favorable in the N2/O2 atmosphere than in the CO2/O2 atmosphere under the same heating rates. The rising heating rate facilitated the release of volatiles. According to the model-free methods of Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose, the activation energies essential for the primary reaction were 283.09 kJ/mol and 288.28 kJ/mol in the N2/O2 atmosphere and 233.09 kJ/mol and 235.64 kJ/mol in the CO2/O2 atmosphere. The gaseous products of the GL combustion included CH4, H2O, C = O, CO, CO2, NH3, C = C, and C-O(H). Ash prepared in both atmospheres exhibited a tendency for slag formation, with oxy-fuel combustion lowering its risk. This study thus provides a theoretical and practical basis for transforming GL residues into a sustainable energy source.

Product regulation of potassium catalyzed pyrolysis of Chinese Baijiu grains: Towards the production of combustible gases and the reduction of tar formation

Engineering-scale conversion and utilization of Chinese baijiu grains (BG) is imperative for the sustainable development of Chinese Baijiu industry. In this study, we developed a facile catalytic pyrolysis of BG using potassium acetate and investigated the proportions of the solid, liquid, and gaseous products at different temperatures and catalyst loadings. Both parameters affected the product proportions, and the highest combustible gas content (83.3 % of total gaseous products) was observed with 1.0 mol/L potassium acetate at 800 °C. The catalyst also affected the proportion of liquid products. In particular, the bio-oil quality improved and the tar content decreased owing to a decrease in long-chain aliphatic acid and ester contents (<10 % of the total liquid products with 1.0 mol/L potassium acetate at 800 °C) and an increase in hydrocarbon content. In addition, the oxygenated groups in the biochar obtained after pyrolysis were bonded to K via K–O bonds, thus making K@biochar a good controlled-release potassium fertilizer. We believe that our catalytic strategy, which has the abovementioned multiple favorable outcomes, could promote commercial-scale valorization of BG.

Estimated electric conductivities of thermal plasma for air-fuel combustion and oxy-fuel combustion with potassium or cesium seeding

A complete model for estimating the electric conductivity of combustion product gases, with added cesium (Cs) or potassium (K) vapor for ionization, is presented. Neutral carrier gases serve as the bulk fluid that carries the seed material, as well as the electrons generated by the partial thermal (equilibrium) ionization of the seed alkali metal. The model accounts for electron-neutral scattering, as well as electron-ion and electron-electron scattering. The model is tested through comparison with published data. The model is aimed at being utilized for the plasma within magnetohydrodynamic (MHD) channels, where direct power extraction from passing electrically conducting plasma gas enables electric power generation.The thermal ionization model is then used to estimate the electric conductivity of seeded combustion gases under complete combustion of three selected fuels, namely: hydrogen (H2), methane (CH4), and carbon (C). For each of these three fuels, two options for the oxidizer were applied, namely: air (21 % molecular oxygen, 79 % molecular nitrogen by mole), and pure oxygen (oxy-combustion). Two types of seeds (with 1 % mole fraction, based on the composition before ionization) were also applied for each of the six combinations of (fuel-oxidizer), leading to a total of 12 different MHD plasma cases. For each of these cases, the electric conductivity was computed for a range of temperatures from 2000 K to 3000 K.The smallest estimated electric conductivity was 0.35 S/m for oxy-hydrogen combustion at 2000 K, with potassium seeding. The largest estimated electric conductivity was 180.30 S/m for oxy-carbon combustion at 3000 K, with cesium seeding. At 2000 K, replacing potassium with cesium causes a gain in the electric conductivity by a multiplicative gain factor of about 3.6 regardless of the fuel and oxidizer. This gain factor declines to between 1.77 and 2.07 at 3000 K.Based on the findings of this research study, the four analyzed factors to increase the electric conductivity of MHD plasma can be listed by their significance (descending order) as (1) type of additive seed type (cesium is better than potassium), (2) temperature (the higher the better), (3) carbon-to-hydrogen ratio of the fuel (the higher the better), and finally (4) the oxidizer type (air is generally better than pure oxygen).The relative size of the two electric conductivity components (due to neutrals scattering and Coulomb scattering) at various plasma conditions are discussed, and a threshold of 10−5 (0.001 %) electrons mole fraction is suggested to safely neglect Coulomb scattering.

Experimental investigation on detonation characteristics of boron-rich gelled propellant in static premixed combustible gases

A detonation in multiphase air-kerosene-boron mixtures is studied experimentally and the initiation and propagation characteristics of multiphase pulse detonation are emphasized. The boron-rich kerosene gelled propellants are taken as the fuel to analyze its detonation characteristics in static premixed combustible gases. The factors affecting detonation initiation including component, atomization, and ignition method of propellant are elucidated respectively. Considering atomization, evaporation and combustion, a small molecular organic compound is employed to fabricate metallized gelled propellants enriched with substantial boron particles. The dynamic atomization of gelled propellant with varying boron content is imaged by means of visual observation devices, and the ejecting parameters are optimized properly from actual initiation conditions. A flame jet by hot turbulent jet is applied to amplify the ignition energy of deflagration to detonation transition in boron-rich gelled propellant, which has not been seen ever. Results show that the ignition energy is positively correlated with initial pressure formed by combustible gas products. The multiphase detonation wave of boron-rich gelled propellant is successfully induced by premixed H2/O2 mixtures, and its detonation propagation characteristic is closely associated with the increase of initial pressure of premixed gas and mass mixing ratio of working medium. The pressure peak and propagation velocity of detonation wave show a considerable improvement with increasing initial pressure of premixed combustible gas and mass mixing ratio, and the highest values can reach up to 8.65 MPa and 2750 m/s respectively.

THE IMPROVEMENT OF THE ECONOMIC AND ENVIRONMENTAL CHARACTERISTICS OF COGENERATION PLANTS BASED ON HEAT ENGINES WITH THE THERMOCHEMICAL METHOD OF CLEANING THEIR EXHAUST GASES

The article presents the results of research aimed at improving the economic and environmental characteristics of cogeneration plants based on heat engines (ICE, GPE, GTU), with a thermochemical device for the neutralization of harmful components of its waste gases, and a boiler-utilizer (BU). The neutralization process takes place in a layer of red-hot carbon material and a gaseous medium, which includes: methane, hydrogen and carbon monoxide. The effectiveness of the proposed process was investigated both analytically, using specialized computer programs for energy management, and experimentally, by a special laboratory device, which made it possible to simulate in a wide range of temperatures (500...1000°C) how the products of natural gas combustion (the base fuel for the GPA and GTU), with a defined coefficient of excess air (oxygen), as well as the concentration of CO and NOx in their composition. The primary task of the experimental study was to determine the effect of temperature on the neutralization of nitrogen oxides and carbon monoxide in natural gas combustion products. The results of the studies (in the considered temperature range of 750...950℃) showed the possibility of reducing the concentration of nitrogen oxides by 2.5...3 times, and the concentration of carbon monoxide by almost 5 times. At the same time, it was established that the efficiency of NOx neutralization at the considered temperature range does not change significantly (within 10%), which makes it possible to carry out the neutralization process at a temperature of 750...780℃ and reduce the energy cost. The final neutralization of the exhaust gases of the engine and the utilization of their thermal potential is carried out in the boiler-utilizer. The placement of the thermochemical device in front of the boiler-utilizer, on the one hand, changes the thermal characteristics of the cogeneration plant to direction of increasing its heat loads, and on the other hand, increases the maneuverability of the plant, providing possibility of independent change of electrical and thermal load. In addition, the use of solid fuel with its gasification in the device allows not only to neutralize the harmful components of the engine's exhaust gases, but also to provide a partial replacement of natural gas in the engine and the boiler - utilizer with a corresponding reduction of thermal and harmful emissions in to the environment.

Numerical investigation of premixed combustion of producer gas with hydrogen injection in a cyclonical chamber

ABSTRACT This paper employs computational fluid dynamics (CFD) simulations with an eddy dissipation concept model (EDC) and a skeletal reaction mechanism (SK17) to analyze the impact of hydrogen addition on the premixed combustion mode of producer gas (PG) fuel in a cyclonic flow combustion chamber. The results, validated against measured wall temperature data, demonstrate a minor discrepancy between simulation and experiment. The studied result showed that injection of hydrogen into PG fuel combustion elevates the temperature of the combustion process, which can be indicated by the average temperature across the combustion chamber, outlet temperature of exhaust gas, and reactive radical species. However, increasing H2 injection over 20% results in strongly increasing CO formations. Compared to a fixed thermal input case, hydrogen injection with a variable input power resulted in a higher combustion temperature and increased emissions of both CO and NO. The maximum CO emission reached approximately 1246 ppm, while NO peaked at around 75 ppm, both observed at a 30% hydrogen injection rate. The key finding of this study revealed that direct injection of hydrogen to the combustion under the condition of a given equivalence ratio is unfavorable due to insufficient oxygen for the reaction, leading to an increase in CO emissions. The optimal condition would be a hydrogen injection below 20%, which produces low CO and NO emissions.

Combustion of iron particles in solid propellants at elevated pressure

Metal fuels, such as aluminum (Al) and iron (Fe), can be added to composite solid propellants to improve their performance, such as specific impulse, density, and burning rate. In comparison to aluminum, iron can theoretically provide improved density specific impulse and higher flame temperatures; reduce condensed combustion product (CCP) concentration and the associated two-phase flow losses; and eliminate hydrochloric acid (HCl) in the exhaust products. A fundamental and quantitative understanding of metal particle aggregation and agglomeration processes in solid propellants is required to understand the underlying combustion mechanisms in these systems. In the current study, composite strand and laminate AP/HTPB/AP propellant samples loaded with Fe microparticles (∼45 μm in diameter) were burned at elevated pressures in an optically accessible strand bomb. Combustion processes were monitored with transient pressure diagnostics and a high-speed camera fitted with a high-magnification lens system (3.83 μm/pixel resolution) for the laminate propellant experiments. An automated image processing algorithm was developed to measure burning rates and ejected particle/agglomerate sizes and velocities. Time-resolved statistical distributions of both particle size and velocity are presented at elevated pressure for multiple laminate propellant experiments with a high degree of repeatability and low measurement error estimated as < ±5% and < ±1.5% for particle size and velocity, respectively. The incorporation of iron microparticles into the composite strand propellants yielded over a 20% increase in the global burning rate over the range of pressures evaluated (3.45–13.8 MPa). Similarly, the addition of iron to the fuel lamina in laminate propellant samples led to an approximately 30% increase in the global burning rate at the evaluated pressure (3.45 MPa). Additive particles were observed to eject near the oxidizer/fuel interface, or to melt, aggregate, coalesce, and agglomerate on the fuel lamina surface prior to ejection. Particle velocities are controlled by a balance of gravitational forces, drag forces imparted by expanding combustion product gases, and particle inertia. The observed combustion enhancements are attributed to the combined effects of catalytic mechanisms, increased radiation heat transfer, and local energy release from reacting iron particles. In addition, discussions on the image processing methods developed in the current study, corresponding potential sources of error, and prospective areas of improvement are provided. The experimental approach developed enables high-speed and high-magnification visualization of propellant combustion at high pressures and can be utilized to better understand the fundamental combustion behavior of energetic systems.

Flammability and thermal resistance of Ceiba petandra fiber‐reinforced composite with snail powder filler

AbstractNatural fiber composites are not suitable for use in industries due to their flammability and low thermal resistance. Inorganic metal‐based fillers are known to enhance the flammability and thermal resistance of composites, while the thermal and fire‐retardant properties of organic fillers are not commonly known. This study evaluated the mechanical, thermal, and flammability properties of Ceiba petandra fiber (CPF)‐reinforced composites, which were added with snail powder (SP). To study the thermal resistance of the composite, a dynamic mechanical analyzer (DMA) and thermogravimetric analysis (TGA) were applied. SP Filler concentration increased the composite's tensile strength and thermal resistance. DMA test results showed the same trend as the composite's density value. The flame rate parameters of the composite, including the percentage of char yield and the limitation index oxygen (LOI), rose as the SP filler increased. However, the flame rate of the composite dropped because SP filler inhibited the movement of oxygen, combustible gas, and polyester degradation products. The addition of organic fillers in natural fiber composites promises better flammability and thermal resistance.

Методика определения температуры точки росы продуктов сгорания природного газа

Currently, there are various methods to determine the dew point temperature of humid air and combustion products of distinct types of fuels. It is especially important when designing deep flue gas cooling systems in boiler plants that do not consider the composition of a particular type of fuel. In this regard, the urgent issue is the development of a simple method to calculate this value when using natural gas as fuel. The authors have used the methods of thermodynamic analysis of processes in humid air and fuel combustion products, and the results of thermal calculations of fuel combustion processes. The authors have conducted the analysis of existing methods to determine the dew point temperature for natural gas combustion products, since it is necessary to prevent condensation of water vapor in chimneys and chimney flue to ensure their operation conditions, especially during deep cooling. A simple method to calculate this value is proposed, and an example of its use is presented. The authors have analyzed the influence of such factors as the moisture content of air and natural gas, the absolute pressure of combustion products and the air flow coefficient per the dew point temperature. It is shown that the final refinement of the given value can be quite significant, and therefore the use of the method that allows considering these patterns is advisable when designing deep flue gas cooling systems. It is established that the proposed method is quite universal and can be used during combustion of natural gas of various compositions and various values of factors characterizing fuel combustion.