Open Combustion Research Articles

Effects of Cu(OH)F nanoparticles on the thermal oxidation and ignition characteristics of micron-sized Al powder

In this study, Cu(OH)F nanoparticles are prepared through a simple hydrothermal reaction and their effects on the thermal oxidation and ignition characteristics of micron-sized Al powder (μ-Al) are explored for the first time. Thermal analysis in air atmosphere (50∼1050 °C) shows that compared to raw μ-Al, the normalized weight gain of Al in Al-Cu(OH)F increases by about 36.9%, 64.8%, and 106.3% when the added Cu(OH)F is 1 wt%, 3 wt%, and 5 wt%, respectively. After mixed with NH4ClO4, electric ignition and open-air combustion tests show shortened ignition delay time (by 42.6%∼63.8%) and increased maximum light intensity (by 48.9%∼117.8%) for Al-Cu(OH)F. The effects of Cu(OH)F result from its decomposition products, namely, HF and CuO. HF reacts with alumina shell to form AlF3, which sublimes at high temperature and thus exposes Al core instantly, while CuO can react with Al core to release heat, further facilitating the thermal oxidation and ignition processes.

Mapping PM2.5 Sources and Emission Management Options for Bishkek, Kyrgyzstan

Harsh winters, aging infrastructure, and the demand for modern amenities are major factors contributing to the deteriorating air quality in Bishkek. The city meets its winter heating energy needs through coal combustion at the central heating plant, heat-only boilers, and in situ heating equipment, while diesel and petrol fuel its transportation. Additional pollution sources include 30 km2 of industrial area, 16 large open combustion brick kilns, a vehicle fleet with an average age of more than 10 years, 7.5 km2 of quarries, and a landfill. The annual PM2.5 emission load for the airshed is approximately 5500 tons, resulting in an annual average concentration of 48 μg/m3. Wintertime daily averages range from 200 to 300 μg/m3. The meteorological and pollution modeling was conducted using a WRF–CAMx system to evaluate PM2.5 source contributions and to support scenario analysis. Proposed emissions management policies include shifting to clean fuels like gas and electricity for heating, restricting secondhand vehicle imports while promoting newer standard vehicles, enhancing public transport with newer buses, doubling waste collection efficiency, improving landfill management, encouraging greening, and maintaining road infrastructure to control dust emissions. Implementing these measures is expected to reduce PM2.5 levels by 50–70% in the mid- to long-term. A comprehensive plan for Bishkek should expand the ambient monitoring network with reference-grade and low-cost sensors to track air quality management progress and enhance public awareness.

Ti/CuO Nanothermite Doped with Secondary Energetic Materials: A Study of Combustion Parameters.

Nanothermites have found broad applications; however, due to being systems largely reacting in condensed phases, their performance is somewhat limited by heat and mass transfer. In order to alleviate this issue, nanothermites doped with gas-generating energetic materials have been developed. In this work, we present an investigation of a model Ti/CuO nanothermite doped by four classical energetic materials and investigate their properties and combustion performance. Mechanical and laser irradiation sensitivity, as well as ignition/explosion temperatures have been determined for the studied systems to establish their safety features. In terms of combustion performance, thrust force parameters and linear combustion velocity have been determined and the structure of the evolving flame front was recorded during open-air combustion experiments. The obtained results indicate that the developed doped nanothermite formulations are extremely promising materials for future applications.

Novel NSTEX System Based on Ti/CuO/NC Nanothermite Doped with NTO

Modern energetic materials (EMs), e.g., nanothermite and NSTEX (Nanostructured Thermites and Explosive) compositions are attracting increasing research interest. In this work, we present the results of our investigation on the properties of a novel Ti/CuO nanothermite system doped with cellulose nitrate (NC) and 5-Nitro-1,2-dihydro-3H-1,2,4-triazin-3-one (NTO). In terms of safety parameters, the friction (40–>360 N), impact (40–>50 J) and laser irradiation sensitivity were determined for tested systems, which indicated tunable properties. The combustion velocity (up to 735 m/s), pressure parameters for combustion in closed vessel, thrust parameters and open-air combustion behaviour were measured. Moreover, in order to deeply study the impact of NTO on the combustion mechanism, SEM, DSC/TG and XRD analyses were conducted. The obtained results indicate that the Ti/CuO/NC/NTO system is extremely promising for future applications.

Effectiveness of empty fruit bunch ash as the catalyst for palm oil transesterification

Empty Fruit Bunch (EFB) resulted from oil palm plantations and mills can be converted into ash through open combustion. The EFB ash then treated by simple calcination and used as a heterogeneous catalyst for biodiesel production. The characteristics of EFB ash were identified based on its elemental composition, porous structure, and active site size. The effectivity of the EFB ash as a catalyst was tested in a transesterification reaction of Refined Bleached Deodorized Palm Oil (RBDPO) with excess methanol (30 %-w) in various catalyst loads (in%-wt). The lab-scale experiments were conducted in a three-neck glass reactor, which was put on the hot plate stirrer at 450 rpm. The EFB ash performed the best as a catalyst by attaining optimal conversion at 65 °C for 1 h with a 16 %-wt of catalyst load. In this condition, most of the standard quality of biodiesel were complied with total glycerol under 0.24% and ester methyl contents up to 98.9 %. The characteristics tests showed that the properties and active side of the EFB ash are excellent after calcination at 600 for 5 h. The recyclability test of EFB ash as a catalyst showed high performance in two repetition cycles, each showing an increase in the yield of biodiesel, which was 92.21 % in cycle 2 and 91.23 % in cycle 3.

Changes in the state of matter of KCIO4 to improve thermal and combustion properties of Al/MoO3 nanothermite

To improve the thermal and combustion properties of nanothermites, a design theory of changing the state of matter and structural state of the reactants during reaction was proposed. The Al/MoO3/KClO4 (Kp) nanothermite was prepared and the Al/MoO3 nanothermite was used as a control. SEM and XRD were used to characterize the nanothermites; DSC was used to test thermal properties; and constant volume and open combustion tests were performed to examine their combustion performance. Phase and morphology characterization of the combustion products were performed to reveal the mechanism of the aluminothermic reaction. The results show that the Al/MoO3/Kp nanothermite exhibited excellent thermal properties, with a total heat release of 1976 J·g− 1, increasing by approximately 33% of 1486 J·g− 1 of the Al/MoO3 nanothermite, and activation energy of 269.66 kJ·mol− 1, which demonstrated higher stability than the Al/MoO3 nanothermite (205.64 kJ·mol− 1). During the combustion test, the peak pressure of the Al/MoO3/Kp nanothermite was 0.751 MPa, and the average pressure rise rate was 25.03 MPa·s− 1, much higher than 0.188 MPa and 6.27 MPa·s− 1 of the Al/MoO3 nanothermite. The combustion products of Al/MoO3 nanothermite were Al2O3, MoO, and Mo, indicating insufficient combustion and incomplete reaction, whereas, the combustion products of Al/MoO3/Kp nanothermite were Al2O3, MoO, and KCl, indicating complete reaction. Their “coral-like” morphology was the effect of reactants solidifying after melting during the combustion process. The characterization of reactants and pressure test during combustion reveals the three stages of aluminothermic reaction in thermites. The excellent thermal and combustion performance of Al/MoO3/Kp nanothermite is attributed to the melt and decomposition of Kp into O2 in the third stage. This study provides new ideas and guidance for the design of high-performance nanothermites.

Progress towards the standardization of test parameters and protocols for evaluating densified fuel products

Densification technologies used in managing biomass and coal fines to produce fuel briquettes or pellets are gaining rapid acceptance and application due to the widespread uptake of renewable energy. This has resulted in the mushrooming of many standard and non-standard evaluation tests for densified solid fuels in this industry. These tests are sometimes inconsistently applied especially if the available options for evaluation, underlying assumptions and principles of the test methods chosen are misunderstood. A critical review of the fuel briquettes evaluation tests to understand their relevance, strengths and limitations is necessary to advance public and research knowledge. This study investigated current methods of standardization to identify best practices, inconsistencies, trends and gaps in the application of fuel briquettes testing protocols. Procedures for evaluating combustion or thermal properties include calorific value, burn rate, open air combustion test and water boiling test; ignition time; after-glow test; specific fuel combustion or thermal efficiency were discussed. Physical and chemical property evaluations involved densities and related ratios, proximate and ultimate analyses. Equally important are mechanical parameters frequently informed by tensile/compressive strength, impact resistance, friability and water resistance. As renewable densified fuels gain more global popularity, it is critical to have a uniform standard of evaluating their quality.

Enhanced open biomass burning detection: The BranTNet approach using UAV aerial imagery and deep learning for environmental protection and health preservation

Open biomass burning (OBB) in agriculture presents a significant and well-documented challenge, posing severe consequences for both environmental and human health. OBB releases air pollutants that degrade air quality and contribute to climate change, leading to premature deaths in regions with high concentrations of open crop straw burning (OCSB) emissions. Although policies aimed at prohibiting OBB are in place, the efficacy of these regulations in mitigating OCSB emissions remains ambiguous. Consequently, early prevention and monitoring of open biomass combustion are imperative for environmental preservation. Traditional monitoring techniques, reliant on fixed-position cameras, are constrained by their location and monitoring intensity, making concealed fire recognition a complex problem. To address this limitation and monitor the human living environment more flexibly and accurately, we propose a new method to identify straw fires in UAV Aerial Image Using CNN Branch Reinforce Transformer which named BranTNet, enabling early detection and rapid response to crop straw fires. By integrating computer vision technology and deep learning algorithms, straw fires in UAV-acquired aerial survey images can be detected and categorized. In the realm of artificial intelligence algorithms, we skillfully merge convolution and attention mechanisms, harnessing the full potential of both methodologies. Moreover, we seamlessly incorporate transfer learning, skillfully unifying self-training convolution modules with pre-trained transformer modules. This strategic amalgamation not only minimizes time costs but also ensures optimal experimental outcomes. Regarding data, we meticulously collected a substantial number of authentic samples, ensuring the sufficiency of our experimental dataset. The experimental results demonstrate that our proposed method exhibits exceptional accuracy and robustness in detecting and identifying straw fires in UAV aerial survey images. Our approach outperforms the use of convolution or attention mechanisms alone. By integrating this approach with drone technology, we unlock the potential for developing more versatile and precise monitoring solutions, expanding the application of drones to diverse domains. This progress contributes significantly to the early detection and prevention of crop straw fires, fundamentally reducing environmental pollution, curbing carbon emissions, and advancing the cause of carbon neutrality. This innovative technique for monitoring and preventing OBB holds substantial promise in mitigating the adverse effects of OBB on the environment and human health.

Mini-review on remediation of plastic pollution through photoreforming: progress, possibilities, and challenges.

The increasing plastic pollution has raised significant concerns about the environment and the destruction of its precious resources. Making value-added products out of plastic waste is an effective way to reduce plastic pollution and use it as a valuable resource. Plastic reforming driven by sunlight offers a quick and low-energy way to produce hydrogen from waste. Photoreforming of plastic waste is an emerging technology that cannot only break down plastic polymer waste into value-added chemicals but also produce solar fuel cell quality H2. Technologies, such as pyrolysis, combustion, and advanced oxidation, are right now being studied for converting plastic pollution into energy. A thorough summary and comparison of different technologies have not yet been published. Open dumping and combustion are two main steps to deal with waste plastics, but these processes experience inefficiencies and cannot adequately address the challenges. In this mini-review, we aimed to provide a short overview of the recently reported conventional and novel plastic waste treatment methods. The current research on the photoreforming of plastics conducted by various groups and some advantages and disadvantages of this practice has been discussed thoroughly. Also, some notes were made on the prospective future scope present in this particular research area to achieve a carbon-free fuel system. The purpose of this review is to encourage the utilisation of plastic garbage as an alternative source of energy.

Energy source impact on the economic and environmental effects of retrofitting a heritage building with a heat pump system

In terms of energy efficiency and the quality of the indoor and outdoor environment, heritage buildings are facing sustainability challenges. This study assessed the feasibility of using renewable energy sources based on air-to-water heat pumps with regard to preserving the historic values of the buildings and their ability to coexist with current energy efficiency and decarbonization requirements, and to prevent their neglect and degradation. A new approach is the use of Building Information Modelling to accurately determine energy demand and select a heating system based on renewable energy sources in such an unusual case as a heritage building. The analysis covers a selection of feasible scenario of the modernization of the over 300 years old building. A particular focus of the study is to compare the use different heat pumps systems. One is a reversible gas absorption air-to-water heat pump and the other is an electricity-powered compressor air-to-water heat pump. The building is currently supplied with a fixed-temperature boiler up to 550 kW with an open combustion chamber fed with coal. It was proven that the proposed retrofit scenario reduces final energy demand by 72.9%, while improving thermal comfort, cutting annual emissions by 121.1 Mg CO2 and 1.0 Mg PM10.

Treatment of Biowaste for Electrodes in Energy Storage Applications: A Brief Review

Proper and innovative waste management methods still pose a major concern in our present world. Continuous accumulation of biowaste from bio-processing industries, household, organic residues and so on makes the environment polluted and endangers the health of man and other animals. The common waste management methods which include direct dumping into water bodies, open-air combustion, and as land fillers are obsolete and are the major causes of environmental pollution. Conversion of biowastes into valuable materials aids proper waste management, and helps to attain a cleaner environment, in addition to the fact that wastes are turned into wealth. Biowastes are rich in carbon and can serve as excellent precursors for the synthesis of important carbon materials such as activated carbon, graphene, carbon nanotubes etc. Three important methods of converting biowastes into carbon materials are discussed in this review. The electrochemical, adsorption, and electrocatalytic properties of the materials and the applications in electrochemical energy storage devices are also discussed in brief. This review focuses on the synthesis of carbon materials from biowaste residues and their use in developing electrode materials for batteries and supercapacitors. Future perspectives on the need to exploit greener technology for the conversion of biowastes into important carbon materials should be considered.

Enhanced Flame Retardancy of Rigid Polyurethane Foams by Polyacrylamide/MXene Hydrogel Nanocomposite Coating.

Rigid polyurethane foam (RPUF) has been widely used in many fields, but its high flammability and frequent release of large amounts of toxic smoke during combustion limit its application. Hydrogel coatings, as a kind of environmentally friendly material, contain large amounts of water, which is beneficial to flame retardance of RPUF. MXene, as a two-dimensional inorganic nanomaterial, possesses a large specific surface area and good thermal stability, performing well in smoke suppression and as a physical barrier for flammable gas products and heat. Herein, to address the fire hazards of RPUF, MXene nanosheets were first grafted with double bonds, and then introduced into a polyacrylamide hydrogel system by radical polymerization to prepare MXene-based hydrogel coating (PAAm-MXene). The flame-retardant RPUF (coated RPUF) was prepared by painting the PAAm-MXene coating onto RPUF surface. The dispersion of modified MXene nanosheets (m-MXene) in hydrogels is improved compared with pristine MXene, and the addition of m-MXene contributes to the thermal stability enhancement of PAAm-MXene. Cone calorimetry, water retention test, and open flame combustion test were used to study the flame retardancy, smoke suppression, and water retention of flame-retardant RPUF. The coated RPUF exhibited significant flame retardancy, including reduced peak heat release rate (pHRR) at a maximum by 25.8%, and total heat release rate (THR) at a maximum by 24.6%, and total smoke production at a maximum by 38.9%. The results show that both MXene and m-MXene can improve the flame retardancy, smoke suppression, and water retention of hydrogels, but m-MXene has a better smoke suppression effect than MXene. That can be ascribed to the better dispersion of m-MXene than pristine MXene. The detailed performance improvement mechanisms are proposed. This work will not only improve the flame retardancy of RPUF, but also promotes the exploration of new flame-retardant strategies for RPUF.

Circular bioeconomy potential of rice husk as a bioplastic resource: Techno-environmental assessment

Rice is the most common cereal and staple food to about half the world's population, with high annual production. The effective utilization and exploitation of rice husk, a significant by-product of rice have been challenging. The negative environmental consequences of current practices, primarily by open-air combustion have led to several other utilization options being explored for more sustainable use. Therefore, in this study, we examine the techno-environment potential of rice husk as a resource for bioplastic production relative to open-air combustion. Specifically, we explore three technologies and their environmental implications for biodegradable bioplastics production pathways: carboxymethylcellulose, cellulose acetate, and cellulose nitrate. Using life cycle assessment (LCA), we examine the environmental impact and associated environmental cost for bioplastic transformation relative to open-air combustion. The result suggests that carboxymethylcellulose would be the most sustainable pathway, reducing the impact on human health and the cost of open-air combustion by 82 % and 74 %, respectively.

РАСЧЕТНЫЕ ОЦЕНКИ ВЫБРОСОВ ЧЕРНОГО УГЛЕРОДА ОТ ПРИОРИТЕТНЫХ КАТЕГОРИЙ ИСТОЧНИКОВ В РОССИИ

Black carbon is commonly considered as a short-lived climate forcer, the relatively short lifetime of which can cause climatic effects at the regional level. The lack of mandatory reporting on black carbon emissions and a unified methodology for black carbon inventory leads to high uncertainty of existing estimates of black carbon emissions in Russia. The estimates of emissions from priority source categories are provided in the present paper. According to the estimates, averaged black carbon emissions for the period of 2010-2020 from intentional fuel combustion at anthropogenic sources in Russia, including fuel combustion at energy and industrial enterprises, small and domestic combustion, transport, hydrocarbon flaring, are 100 *103 t per year, and those from open combustion sources on non-forest lands are 10 *103 t per year. Emissions from forest fires have the greatest interannual variability and vary from 100 to 300*103 t of black carbon per year.

Antioxidant, Anti-Bacterial, and Congo Red Dye Degradation Activity of AgxO-Decorated Mustard Oil-Derived rGO Nanocomposites.

Scaling up the production of functional reduced graphene oxide (rGO) and its composites requires the use of low-cost, simple, and sustainable synthesis methods, and renewable feedstocks. In this study, silver oxide-decorated rGO (AgxO−rGO) composites were prepared by open-air combustion of mustard oil, essential oil-containing cooking oil commercially produced from the seeds of Brassica juncea. Silver oxide (AgxO) nanoparticles (NPs) were synthesized using Coleus aromaticus leaf extract as a reducing agent. Formation of mustard seed rGO and AgxO NPs was confirmed by UV-visible characteristic peaks at 258 nm and 444 nm, respectively. rGO had a flake-like morphology and a crystalline structure, with Raman spectra showing clear D and G bands with an ID/IG ratio of 0.992, confirming the fewer defects in the as-prepared mustard oil-derived rGO (M−rGO). The rGO-AgxO composite showed a degradation efficiency of 81.9% with a rate constant k−1 of 0.9506 min−1 for the sodium salt of benzidinediazo-bis-1-naphthylamine-4-sulfonic acid (known as the azo dye Congo Red) in an aqueous solution under visible light irradiation. The composite also showed some antimicrobial activity against Klebsilla pneomoniae, Escherichia coli, and Staphylococcus aureus bacterial cells, with inhibition zones of ~15, 18, and 14 mm, respectively, for a concentration of 300 µg/mL. At 600 µg/mL concentration, the composite also showed moderate scavenging activity for 2,2-diphenyl-1-picrylhydrazyl of ~30.6%, with significantly lower activities measured for AgxO (at ~18.1%) and rGO (~8%) when compared to control.

Study on the preparation and combustion performance of Al[sbnd]F composites prepared by a solvent/non-solvent method

Oxidants, such as oxygen, cannot easily approach the core Al due to the presence of dense alumina on the surface of aluminum particles, thereby resulting in high ignition temperature and long ignition duration. To overcome this challenge, we employed the solvent/non-solvent method using Viton A (a copolymer of 1,1-difluoroethylene and hexafluoropropylene) as a coating material to prepare the core-shell Al/Viton A composite particles. An orthogonal experiment was designed to identify the optimal preparation parameters by evaluating the peak pressure in a closed vessel. The sample with the largest peak pressure was compared with raw Al and Al/Viton A (prepared by the physical mixing method) using the combustion pressure and open combustion tests to evaluate the solvent/non-solvent method. The results from the orthogonal experiment revealed that the water bath temperature exhibited the greatest influence on the coating effects. The composite prepared under a water bath temperature of 55 °C and a stirring rate of 250 rpm, using 20 mL of acetone and a 5 mL/min dripping rate of the Viton A acetone solution, were uniformly coated by Viton A, and exhibited excellent combustion characteristics. In addition, the sample generated using the optimal preparation parameters burnt more vigorously and rapidly than raw Al and Al/Viton A. Finally, the reaction molecular dynamics simulation was employed to gain insight into the effect of Viton A on the combustion of Aluminum particles at the molecular level.

Rice Straw: A Waste with a Remarkable Green Energy Potential

With reference to the province of Novara in northwest Italy, this study aims to raise awareness about the environmental benefits that can derive from the use of alternative rice straw management practices to those currently in use, also highlighting how the use of these straws for energy purposes can be a valid alternative to the use of non-renewable resources. Using the LCA (Life Cycle Assessment) method, the two rice straw management practices currently in place (open field combustion and straw incorporation) were compared with an alternative strategy consisting in their collection and removal. The results show that removal of straw allows reducing the emissions of pollutants significantly: about one-hundredth of the PM (Particulate Matter) formation compared to the open-field burning and about one-tenth of the ozone depletion (CFCs, HCFCs, halons, etc.) compared to both the other two practices. Moreover, the LCA results show how the use of rice straw to produce energy as an alternative to conventional fuels helps to reduce the global warming potential of rice cultivation.

Chemical Aspects of Air Pollutants Generated from Open Combustion Appliance

Chemical Aspects of Air Pollutants Generated from Open Combustion Appliance

Quality Improvement and Cost Evaluation of Pellet Fuel Produced from Pruned Fruit Tree Branches

Biomass-based pellet is an important source of renewable energy. In this study, to obtain the high-quality fuel pellet via the densification of pruned branches of fruit trees, we investigated the optimization of blending ratios for different raw materials using branches from jujube (Ziziphus jujuba Mill.), which is a widely distributed waste biomass resource in China. Through the characterization of raw materials and pellets, the effects of different raw materials on the storage, transportation, and combustion performances of the pellets can be understood. The cost evaluation analysis showed that the two optimized, co-densified pellets had great cost advantages compared with the pure jujube branch pellets. This indicates the potential industrial value of optimized pellets. The results of this study can help to improve the application value of orchard residues and generate an additional profit for fruit plantations, simultaneously avoiding the environmental damage caused by its open combustion.

Stage 3a environmental compliance of the 6-cylinder tractor engine

The development strategy of the Minsk Motor Plant, implemented within the framework of plant and state scientific and technical programs, is aimed at producing competitive products that meet modern technical requirements of international standards and quality. The mandatory requirement for the successful promotion of diesel engines on the off-road vehicle market is to ensure the required environmental performance, with low fuel consumption and low engine cost. The well-known technical solutions aimed to achieve environmental indicators of the Stage 3A level significantly increase the cost of diesel engines, therefore, the achievement of the required environmental standards without a significant increase in the cost of engines can be considered an urgent task. Purpose. Stage3A Environmental Compliance for 6 Cylinder Tractor Diesel. Methodology. Experimental studies were carried out for diesel engines equipped with: a Common Rail BOSCH accumulator fuel supply system with an injection pressure of 140 MPa, injectors with 7 nozzle holes; a direct-action fuel supply system with a MOTORPAL fuel pump providing a maximum injection pressure of 100 MPa, MOTORPAL injectors and AZPI with five nozzle holes; combustion chambers of two types with bowl diameters of 55 and 67.5 mm; cylinder heads providing swirl ratios 3–4 and 3.5–4.5; high pressure exhaust gas recirculation system. The tests were carried out at characteristic points of the NRSC cycle at three crankshaft speeds: minimum idle speed 800 min-1, maximum torque 1600 min-1, and maximum power 2100 min-1. Results. It turned out that it is possible to achieve Stage3A emissions standards on 116 kW diesel engines using direct fuel equipment and a semi-open combustion chamber, on 156 kW diesel engines using a Low Cost Common Rail fuel supply system and an open combustion chamber. Originality. The results of the combustion chamber shape choice, the parameters of the fuel-injection equipment, the swirl ratio of the inlet channels, valve timings and parameters of the exhaust gas recirculation system made it possible to organize diesel engine workflow of the Stage 3A ecological level. Practical significance. Construction elements of the six-cylinder diesel engines have been developed and introduced at the Minsk Motor Plant.