Combustion Behavior Research Articles

Coke breeze combustion and emission behaviors of CO and NO during iron ore sintering

CO emission reduction, especially the coordinated emission reduction of CO and NO in sintering flue gas, has attracted widespread attention in the world. The effects of different sintering raw materials, temperature and atmosphere on coke breeze combustion and CO and NO emission behaviors were studied. The results show that, sintering raw materials significantly improved the combustion performance of coke breeze, and promoted the simultaneous reduction of CO and NO emissions. Among them, Dolomite had the strongest catalytic effect, which reduced the apparent activation energy of coke breeze combustion reaction from 99.35 kJ/mol to 56.11 kJ/mol, and the emission reductions of CO and NO were as high as 47.84 % and 73.25 %, respectively. The catalytic ability of the raw materials components was CaO ＞ MgO ＞ Fe2O3. However, during the combustion process of coke breeze without raw materials, the reduction of NO by CO was affected by the atmosphere of the boundary layer, the conversion of N element was negatively correlated with the content of CO. When the temperature increased from 600 ℃ to 1 050 ℃, the combustion performance was improved, the thickness of the combustion zone was reduced by 47.92 %, the total emission of CO was decreased by 65.39 %, and the total emission of NO was increased by 23.05 %. The O2 concentration decreased from 21 % to 10 %, the combustion rate decreased, the combustion zone thickened by 90 %, incomplete combustion was promoted, the total emission of CO increased by 101.15 %, and NO decreased by 21.09 %. The CO2 concentration increased from 5 % to 15 %, the gasification reaction was enhanced, the combustion time was extended, the combustion zone thickened by 45.9 %, the total emission of CO increased by 87.12 %, and the reducing atmosphere was enhanced, which was conductive to the reduction of NO by CO, and the total emission of NO decreased by 50.59 %.

Role of volatile secondary char on the combustion behavior of cellulose-based hydrochars

Hydrothermal carbonization (HTC) can transform a wide range of biomass into renewable biofuels. Hydrochar, the solid fuel resulting from HTC, has a similar energy density to low-rank coals. Despite an extensive body of literature detailing the thermogravimetric analysis (TGA) of hydrochar under slow pyrolysis and oxidation, there remains a limited understanding of hydrochar's behavior in realistic combustion settings. In this work, we integrate combustion experiments and TGA to understand the combustion characteristics of a model hydrochar fuel. Cellulose-based hydrochars produced at different temperatures along with solvent-extracted chars are tested in a Hencken burner across varying temperatures and oxygen concentrations in the oxidizer gas. Simultaneous CH* chemiluminescence, particle image velocimetry, and two-color pyrometry are used to measure ignition delay time and identify homogeneous/heterogeneous ignition mechanisms and combustion phases. Incorporating TGA with combustion results shows that the ignition mode and combustion processes are strong functions of surrounding gas temperature and oxygen mole fraction. The level of carbonization of the hydrochar dictates the ignition delay time and combustion modes. Further, the presence of a tar-like secondary char on the as-carbonized hydrochars leads to more rapid ignition due to high volatility.

Effect of stratification on the combustion behavior and dynamic response of a bluff-body stabilized ammonia–hydrogen flames with radial staging

The present study deals with the flames of ammonia–hydrogen blends that form a prospective fuel for power generation in practical devices. In particular, the spatial flame dynamics of the bluff body stabilized laminar and stratified ammonia–air/hydrogen–air mixtures with acoustic excitation are considered. For this, we consider a radially staged burner consisting of two concentric tubes namely, the inner and outer tubes with the bluff body housed by the former. Two annulus passages are formed between (i) the inner and outer tube, and (ii) the inner tube and bluff body in which premixed hydrogen–air and ammonia–air mixtures are supplied, respectively. The stratification is controlled by varying the upstream location of the inner tube about the burner exit, termed mixing length taking the values namely, 20 mm (stratified), 60 mm, and 100 mm (unstratified). Time-resolved images of the flames are obtained using OH* (320 ± 10 nm) and NH2* (632 nm ± 10 nm) filters. For the unforced stratified flames, the flames are narrower and the spatial separation between OH* and NH2* region increases towards rich NH3/air mixtures ( ϕNH3–air) compared to the unstratified flames. In addition, the mean spatial OH* is relatively localized for the unforced stratified flames. For any operating condition of the flames, the forced flame response is significant for frequencies < 120 Hz. The rich stratified flame exhibits a higher response at a frequency of ∼ 40 Hz compared to the unstratified flame having a flatter response. The forced flames accompany lobed spatial patterns in OH* and NH2* for richer ϕNH3–air. The flame oscillation registers a non-sinusoidal oscillation for the rich stratified flame compared to flames of any other condition. The main effect of stratification is the alteration of flame shape resulting in a low-frequency response for which regions of significant flame flapping coincide with regions of peak flame OH*.

Study of improving the quality of charcoal briquettes mixed to sago barks and sago dregs as an alternative energy source

Abstract The sago processing industry generates waste in the form of sago barks and dregs, which often polluting the environment, To address this issue, one promising solution is the conversion of these waste into renewable energy such as briquettes. This study aims to improve the quality of sago dreg briquettes by incorporating sago barks, aiming for compliance with charcoal briquette standards and indoor air quality regulations concerning to briquette combustion emissions. Various mixing ratios were examined, to determine the optimal composition. The manufacturing process followed the standard guidelines outlined in SNI 01-6235-2000. Testing procedures encompassed proximate analysis, calorific value determination via bomb calorimetry, and assessment of CO gas emissions using an Environmental Combustion Analysis (ECA) tool. Results indicated a significant influence of the Barks-dreg ratio on physical characteristics, combustion behavior, and CO emissions. The KBA2 mixture, comprising 90% barks and 10% dregs, exhibited the most good attributes, including moisture (2%), ash (10.32%), fly matter (20.66%), bound carbon content (69.02%), and calorific value (5806.4 cal/g). Emission testing with the ECA tool confirmed CO emissions of 357 mg/Nm3, well within acceptable limits. In conclusion, this study shows that mixing sago barks and sago dregs in certain proportions can produces briquettes that meet quality standars, which have the potential for sustainable energy production in the sago industry.

Experimental study on the transitional behavior of the room fire under sub-atmospheric pressures

Fuel diffusion combustion and flame behavior within a confined space is a fundamental scientific problem in the energy and combustion field, it involves complicated chemical reaction, fire behavior, thermal dynamics, heat transfer, room-opening flowing and sub-processes of over-ventilated and under-ventilated room fire. However, previous classical knowledges and models about it are usually at standard atmospheric pressure (100 kPa), no work considers the fire evolution and flame behavior within the room for various sub-atmospheric pressures. In this paper, the experiment is carried by utilizing a 0.3 m × 0.3 m × 0.3 m reduced-scale cubic room with an opening of various dimensions, and using propane as fuel to simulate fuel combustion inside, which was placed at the Low Pressure Chamber creating various atmospheric pressures. The flame behavior and temperature evolution within the room was recorded and measured with 693 experimental conditions. The experimental results show that, (1) the air inflowing rate through opening into room and heat release rate within the room increase with atmospheric pressure; (2) the flame extinction or reaching well-mixed condition are more easily occurred for lower atmospheric pressure and opening dimension. These characteristic parameters and fire behaviors could be well described by new corrected opening ventilation factor involving effect of atmospheric pressure and the opening dimension. The research work fills the gap in basic scientific research of building fire at sub-atmospheric pressures, which also has important practical applicability of urban building fire protection design code (such as the materials in wall) in different altitudes, room fire suppression, and protecting urban safety.

Halogen-free epoxy flame retardant & promoter with diimidazole skeleton improves overall properties of epoxy resins

In order to solve the widespread problem in the field of flame retardancy epoxy(FREP), for the deterioration of the overall properties, we designed a novel structural flame retardant & promoter DOPO-CDI and synthesized it using a simple nucleophilic addition one-step method, which exhibits remarkable flame retardant and curing promotion, the flame retardant and promote mechanism of DOPO-CDI on neat EP is illustrated in Fig 0a, which obtained excellent overall properties shown in Fig 0b. Compared with neat epoxy, it has high flame retardancy, low additives results in an limiting oxygen index(LOI) of up to 37.5 % and a V-0 rating of UL-94, a lower curing exothermic peak temperature, a shorter curing time. And in terms of mechanical properties, the excellent strength of epoxy has been further enhanced, flexural strength and tensile strength are increased by 13.3 % and 21.6 % respectively. Moreover, the toughness of epoxy, which is generally lacking, has been greatly improved, in particular, compared with neat epoxy, the impact strength of epoxy with 3 wt% DOPO-CDI increased by 103.6 %. Unlike most FREP, glass transition temperature(Tg) of the epoxy with the introduction of DOPO-CDI raises to 165.6 °C, which is a significant improvement compared to that of the neat epoxy, in terms of combustion behavior, DOPO-CDI has a considerable inhibitory effect on the combustion exotherm and smoke emission. This work explores a way to balance processing, mechanical and thermal properties when preparing FREP, which has great potential for application.

Investigation of the Effect of Temperature on the Biofuel Performance of Hydrochar Obtained from Kidney Bean Shell

In this study, hydrochar products were obtained from kidney bean shell (KBS) biomass at different temperatures using the hydrothermal carbonization (HTC) method. Hydrochar products were produced at three different temperatures (200, 220 and 240 C) and a holding time of 90 minutes. Biomass/water ratio was taken as 1:10. Analysis techniques such as Thermogravimetric analysis (TG), Ultimate analysis and Fourier Transform Infrared Spectroscopy (FTIR) were used in the characterization of raw materials and hydrochar products. In addition, the fuel properties (high heating value, energy yield and energy densification ratio) of raw KBS and hydrochar products were also investigated. As the HTC temperature increases, the high heating value of hydrochar products increases. Among hydrochar products, the highest high heating value belongs to the product obtained at 240 C. The combustion behavior of raw and hydrochar a product was examined using the thermogravimetric analysis method and combustion parameters (Ti, Tb and Tm) were determined. As a result, this study has shown that the hydrochar product produced from KBS by hydrothermal carbonization method can be used as a biofuel material.

Enhancing the potential application of food-waste biochar as a sustainable bio-solid fuel: Analysis of post-treatment and combustion behavior

Food-waste biochar holds significant potential as a bio-solid fuel for achieving carbon neutrality; however, its high content of sodium (Na), potassium (K), calcium (Ca), chlorine (Cl), and nitrogen, inhibits its potential use. This study explored the effects of post-treatment with ascorbic, acetic, citric, and iminodiacetic acids on the properties of food-waste biochar and volatile ionic substances to establish a foundation for assessing both the environmental impact and practical use of food waste. Post-treatment with organic acids achieved 92% Cl-removal efficiency and induced deformation of the functional groups of food-waste biochar surfaces, leading to the re-adsorption of alkali and alkaline earth metals. This re-adsorption of alkali metal ions showed a distinct correlation with NOx mitigation. The amount of re-adsorbed Na and K varied based on the types of organic acids, resulting in different NOx emission reduction effects. Iminodiacetic acid was particularly effective in alleviating Ca and PO4 volatilization, whereas citric acid exhibited the highest Ca elution performance, and the Ca-contained leachate is a potential source of CO2 storage through indirect mineral carbonation. Acetic acid is the most feasible alternative, considering both economic and environmental aspects. The findings suggest that the post-treatment of food-waste biochar effectively mitigates air pollutants during combustion and is beneficial for sustainable biosolid fuel production and bio-waste management.

Experimental and numerical study of laminar burning velocity for Diisobutylene+ PRF/TRF mixtures

DIB (Diisobutylene, JC8H16) strongly correlates with real gasoline and significantly impacts the combustion behavior of alternative fuels designed as gasoline substitutes. However, accuracy concerns persist in laminar burning velocity data reported in literature. In this paper, the laminar burning velocities of DIB + air, DIB + PRF + air, and DIB + TRF + air mixtures were measured by the heat flux method at 1 atm. (PRF, Primary Reference Fuel; TRF, Toluene Reference Fuel) The equivalence ratio was controlled within 0.6–1.3, and the initial temperatures were set at 298K, 318K, and 338K. Additionally, by employing the mechanism proposed by Ren et al., the simulated values align with the experimental data, thus prompting the conduction of a reaction kinetic analysis. The analysis of chemical reaction kinetics reveals the reaction pathways of DIB, with a notable observation that an increase in temperature or a decrease in equivalence ratio can both lead to an elevation in the degree of unsaturation in the bonds of intermediate species. During laminar flame combustion, PRF and TRF compete with DIB for oxygen, with PRF appearing to have a stronger ability to capture oxygen. In addition, the laminar burning velocity temperature dependence coefficient α decreases first and then increases with the increase of the equivalence ratio, where the minimum α is obtained at equivalence ratio = 1.1. Additionally, the laminar burning velocity at higher initial temperatures is estimated by the extrapolation method and compared with the experimental data reported in literature.

Construction and combustion behavior of horizontal two-dimension combustion networks of boron-metal oxides

In order to break through the top-down combustion mode brought by the traditional pillars, it is explored to explore the exploration of delay composition array construction in two-dimensional dimensions. In this study, B-CuO, B-Bi2O3, B-Fe2O3 sticks and combustion networks with good forming properties were prepared with the help of a micro-pen direct ink writing device by dispersing the above materials in DMF with boron and metal oxides as the main body of the charge and F2602 as the binder. The sticks were thermally ignited using a nichrome wire, and the flame propagation behaviors of the sticks with different formulations, spacings and heights were tracked with a high-speed camera, and a series of combustion networks were designed on the premise of not leaping into flames. Results show that the B-CuO stick has the fastest ignition speed level (19.71–29.02 mm ·s−1) at equivalence ratios of 1.0–4.0, followed by B-Bi2O3 (5.99–16.01 mm ·s−1) and B-Fe2O3 is the slowest (1.91–4.94 mm ·s−1). The sticks burned best at an equivalence ratio of 1.0–1.5. A variety of combustion networks were constructed on 50 × 50 mm glass slides by selecting B-CuO, B-Bi2O3, and B-Fe2O3 at the equivalence ratios of 1.0, 1.5, and 1.5, respectively, among which B-CuO had the shortest combustion time (5.17 s), the shortest total combustion network length (252 mm), and 400 mm network could be realized for B-Bi2O3. Construction and 19.85 s, and B-Fe2O3 can realize 608 mm network length and 130.7 s combustion time. Through these studies, the two-dimensional combustion network construction of boron-metal oxides was realized, which provides a new idea for the delay action in small size.

Combustion and co-combustion of biochar: Combustion performance and pollutant emissions

Biomass is a renewable and clean energy source, offering the potential to reduce fossil fuel consumption and greenhouse gas emissions when it is used as a biofuel. However, the disadvantages of raw biomass such as poor grindability, high moisture content, and low calorific value hinder its widespread industrial combustion. Thermochemical conversion techniques are widely used to convert biomass to biochar, which serves not only as an adsorbent and soil amendment but also as solid fuels alternative to fossil energy. The upgraded biochar exhibits better physicochemical properties and improved combustion performance. This paper focuses on the properties and combustion behavior of biochar as a solid fuel, reviewing common production techniques of biochar and their effects on yields and properties of biochar. It also examines the combustion characteristics and kinetics of biochar in single- and co-combustion scenarios with other fuels, such as coal, sludge, and petroleum coke, analyzing the influencing factors of combustion behavior and kinetic parameters. This study further investigates the emission characteristics during the combustion of biochar, including gaseous pollutants (such as CO, NOx, SOx, and HCl), ash-related issues, and particulate matter (PM) emissions. Additionally, a new fuel type named “bioslurry”, which is developed with biochar as a main material, is introduced. Furthermore, this paper discusses the techno-economic and environmental aspects of biochar application, exploring the feasibility of its industrial production and utilization.

Local Burning Behavior of Wind-Driven Flames under the Influence of Mixed-Convective Turbulent Flow Conditions

ABSTRACT Experiments were conducted to investigate the burning behavior of wind-driven turbulent flames stabilized over a condensed fuel surface. A controlled turbulent crossflow environment was established to examine the impact of external flow velocity and turbulence intensity on the flame profile parameters and mass burning rates. To address the complexities of practical fire scenarios, a mixed-convection parameter ξ x in the form of G r x 1 / ψ x 2 n was defined, encapsulating the combined effects of momentum, buoyancy, and freestream turbulence. Furthermore, the property of fuel (in terms of mass transfer number B) was integrated into the mixed-convection parameter ( ξ x ) to establish a fuel-dependency factor within the formulation . The interdependence of flame characteristics and the mass burning process was observed using ξ x , that yielded several meaningful correlations. In this regard, a power-law trend was obtained between flame standoff distance and the dimensionless parameter ξ x . Finally, the local mass burning rates were estimated and plotted against mixed-convective parameter ( ξ x ), resulting in a unified local mass burning rate correlation. This correlation incorporates the fuel-dependency aspect in its formulation and is applicable in both laminar and turbulent crossflow environments.

Oxygen-rich combustion behaviors and mechanisms of a new Ni-Cr-based superalloy fabricated by selective laser melting

The mechanical and combustion behavior of a new Ni-Cr-based superalloy, fabricated by selective laser melting in an atmosphere with an oxygen concentration greater than 99.5 %, was investigated through the analysis of microstructural morphology, elements distribution and combustion kinetics. The results show that heat treatment eliminated the anisotropy of the as-built microstructures and improved the tensile strength. The studied superalloy can be ignited with a combustion threshold of about 2.5 MPa–3 MPa. The burning length and burning rate increase with the increase of pressure. The selective combustion of Al, Ti, Nb, Cr, Fe, Mo, and Cu elements occurred, resulting in the dissolution of γ′, γ", and δ precipitates and formation of holes at the grain boundaries in the heat-affected zone. The microstructures exhibit large elongated grains in the melting zone and column grains in the heat-affected zone along the heat dissipation direction. The combustion products are a mixture of oxides exhibiting dendritic structures in terms of selective combustion, density, and melting point. The findings from this study enhance our comprehension of the combustion process in nickel-based superalloys, offering valuable data and guidance for the advancement of new oxygen-rich combustion-resistant superalloys.

Combustion and heat release characteristics of micron aluminum with extremely large specific surface area obtained by L-malic acid surface corrosion

Aluminum (Al) particles are widely used in propellants, thermite and pyrotechnics. However, commonly used micro Al has drawbacks such as agglomeration, high ignition temperature and slow burning rate, making its energy potential not fully exploited in applications. Therefore, exploring pathways to enhance the combustion of Al particles has become the focus at present. Herein, L-malic acid (LMA) was used to corrode the surface of Al particles to obtain a sample (named LMAl) with an average specific surface area of 11.456 m2/g (corresponding to Al particles with a diameter of 194 nm). The particle size distribution of LMAl did not change significantly compared to pristine Al. The XPS results showed that a small amount of LMA and corrosion products remained on the surface of the LMAl particles. Thermal analysis tests showed that the thermal oxidation rate and efficiency of LMAl was dramatically higher than that of pristine Al. Compared with the pristine Al, the combustion characterization parameters of LMAl such as combustion intensity, ignition delay time, maximum combustion temperature, mass burning rate and combustion efficiency were all improved. This trend was maintained after blending the ammonium perchlorate (AP). The condensed combustion products (CCPs) of Al revealed a large number of agglomerates and unburned Al particles. While many broken particles and tentacle-like structures were found in the CCPs of LMAl. Overall, compared to Al, the combustion of LMAl is significantly enhanced. The thermal reaction and combustion behaviors of the two are quite different. This study provides new insights into improving the ignition and combustion of Al.

Mathematical modeling and characteristics evaluation of coke replacing with commercial biochar in iron ore sintering process

For green production of iron ore sintering, the research on replacing traditional coke with clean energy such as biochar is a new hot topic. Most of the work conducted in biomass fuel utilization in sintering is done on a laboratory or pilot-scale. Little work was reported by using mathematical models to predict the influence of biomass-based fuel replacement on sintering performance quantitatively. In this paper, a more comprehensive numerical model that incorporates most of the significant reaction processes and heat transfer modes was proposed first, especially with considerations of coke/biochardual-fuelphase heat supply and their pyrolysis, volatiles release, and combustion processes. Experimental data of the sintering pot reasonably agreed with the numerical results, which validated the model. Based on the equivalent fixed carbon method, the combustion and sintering behaviors in replacing proportions, particle size, and fuel types of commercial biochar for coke in the sintering bed were compared. With the lower replacement proportions (<20 %), both two biochars (Oak and Pine) can ensure thermal state indicators (PT, RT, MQI, CR) and combustion performance indicators (FFS and combustion efficiency), and keep the yield enough high. When the replacement proportion exceeds 50 %, the sintering index is worsened significantly. The emission of NOx can be decreased by 57.62 % when a 100 % replacement proportion of biochar is used. The results also indicate that coarsening particle size (2.4 mm was recommended for use) can further improve sintering indicators, and make Oak char 50 % replacing proportion reach the level of all coke method. The performance of pine sintering is even better than Oak sintering. The multiphase multicomponent model is used to give a mechanism explanation for the behavior and performance of biochar replacing coke in the sintering process.

Thermal behavior of adhesively bonded timber‐concrete composite slabs subjected to standard fire exposure

AbstractFire tests were performed for the first time on adhesively bonded timber‐concrete composite slabs. The two medium‐scale (1.8 × 1.25 m) slabs were produced by gluing an 80‐mm thick three‐layer cross‐laminated timber (CLT) board to a 50 mm thick prefabricated reinforced concrete (RC) slab with epoxy and polyurethane (PUR) adhesives, respectively. The behavior of the composite slabs under elevated temperature was monitored by (1) observing the burning behavior of the used CLT, for example, charring and delamination and (2) measuring the temperature development at different locations of the CLT slabs, in the adhesive bond between concrete and timber boards, and in RC slabs. It was found that employing a one‐dimensional charring model for pure softwood, as prescribed by Eurocode 5‐1‐2, underestimated the charring depth of CLT due to the delamination effects. Measurements revealed that the average charring rates in the middle layer of CLT panels were approximately 0.65 mm/min, suggesting that the presence of concrete does not significantly affect the thermal behavior of the CLT panel. Delamination within the CLT was observed when its adhesive temperature was around 230°C. It was followed by the free‐fall of delaminated wood plies, which progressed slowly and lasted until the end of the test. At 90 min into the test, the temperatures of epoxy at the nine locations ranged between 55°C and 130°, while that of PUR between 60°C and 100°. The adhesive between concrete and CLT could lose stiffness significantly along the rising of temperature after surpassing of glass transition temperature (58°C for epoxy and 23°C for PUR in this study). The results indicated a high risk of weakening the composite action between the concrete slab and timber board. The measured temperatures of steel rebar were lower than 50°C. However, the concrete temperature reached about 120°C and the concrete cracked due to the distinct thermal expansions between concrete and timber and the rigid constraint of adhesive bond.

Experimental and numerical investigation on the combustion behavior of densified wood: Differences among wood species and impact of char oxidation

Densified wood (DW) is a novel structural material with promissing application potential in construction industry due to its excellent mechanical performance. However, it could also be a disastrous fuel contributing to the development of fires. This work experimentally and numerically investigated the combustion behavior of DW. The differences among wood species (fir, pine and oak) and their char oxidation impacts are emphasized. The experimental results indicate that DW has a 44.7 K lower pyrolysis peak temperature on average, a 32.2 % lower peak mass loss rate, and a 8 % higher residual mass ratio than natural wood (NW) in N2 due to the delignification process. The hemicellulose and cellulose pyrolysis are endothermic in N2 but exothermic in air. Wood pyrolysis has an additional char oxidation reaction in air. The higher density of DW leads to longer times for ignition and flaming combustion. DW presents a higher heat release rate and average 4.7 MJ kg−1 higher effective heat of combustion of char. Two parallel pyrolysis reaction schemes based on ambiance are proposed, which well-predict the microscale characterizations but fail to represent the combustion behavior. An optimized mode was developed by adding a continuous char oxidation reaction to the N2 reaction scheme, which best predicts the combustion behaviors.

Physical characteristics and combustion behavior of pellets from sawdust and refuse-derived fuel

Experimental research findings are reported on the ignition and combustion behavior, as well as mechanical properties of pellets from wood biomass (pine sawdust) and additives of refuse-derived fuel (cardboard, plastic and their mixture). The addition of RDF was found to increase the vibration durability and moisture resistance of pellets by 3.7–45.6% % compared to samples without additives. Cardboard and its mixture with plastic contributed to 2.7–5.8% greater density of pellets % compared to wood pellets. The impact resistance coefficient of pellets with waste decreased by 0.3– 2.3% compared to samples without additives. An increase in the proportion of cardboard and plastic led to longer delay times of the gas-phase and heterogeneous ignition. The ignition delay times decreased by a factor of 1.3–2.2 as a result of mixing cardboard with plastic compared to pellets with only cardboard or plastic. On the environmental side, the use of cardboard in pellets reduced the concentrations of carbon dioxide and carbon monoxide by 10–24 % and 5–46%, respectively, compared to samples without additives. By contrast, the addition of plastic waste increased CO2 and CO by 4–15% and 5–63%, respectively. The combustion of pellets with RDF was characterized by 22–78% lower concentrations of NOx. The results of a multi-criteria decision analysis revealed that the use of RDF in wood pellets increased the efficiency indicator by 1 to 12% compared to wood pellets.

CFD Methodology to Capture the Combustion Behavior of a Conventional Diesel Engine Retrofitted to Operate in Gasoline Compression Ignition Mode

CFD Methodology to Capture the Combustion Behavior of a Conventional Diesel Engine Retrofitted to Operate in Gasoline Compression Ignition Mode

Control of burning rate pressure sensitivity for solid propellants by changing the interfacial contact of Al/HMX/AP with precisely located graphene-based energetic catalysts

The control of burning rate pressure sensitivity is essential for stable and reliable combustion of solid propellants. It has been proved that the combustion behavior of propellants can be effectively tuned by interfacial control of Al/oxidizers. In this work, core-shell Al-based composites, using oxidizers such as ammonium perchlorate (AP) and cyclotetramethylene tetranitramine (HMX) as the shell layer, have been prepared with a well-controlled location of graphene-based carbohydrazide complexes (GO-CHZ-M, M = Co2+ or Ni2+) as the catalysts. The catalysts can be located inside HMX or embedded on the surface of AP particles. The decomposition of AP and HMX could be greatly promoted with a trace amount of catalyst. Under the synergistic effects of Al/oxidizer interfacial control and GO-CHZ-M, the ignition delay time is shortened by >48 % with increased in flame radiation. More importantly, the burning rate (r) and pressure exponent (n) of the solid propellants are effectively regulated in a wide range. In particular, the use of Al@HMX/Co results in a lowered n of 0.29 within 1∼20 MPa compared to 0.79 for the blank reference sample. The agglomeration of Al particles during combustion was also inhibited due to the micro-explosion effect of Al@HMX composites. Novelty and Significance statementThe innovative approaches of integrating Al/HMX/AP composites and precise catalysis of graphene-based energetic catalysts in solid propellants have successfully achieved, regarding the modulation of the burning rates and pressure sensitivity. Moreover, the effect of catalyst location on the ignition delay and burning rates has also been studied thoroughly and clarified. This paper provides new insight into the regulation of combustion performance of solid propellants, with improved reaction efficiency and maintained energy density.