Heat Of Combustion Research Articles

Catalytic production of fused tetracyclic high-energy-density fuel with biomass-derived cyclopentanone and benzoquinone

High-energy-density (HED) fuels (e.g. JP-10) are of great importance in safeguarding territorial air security, since they can increase the flight range and payload of military aircrafts. To reduce the reliance on limited petroleum source, the production of HED fuel with renewable biomass feedstocks is highly appealing. But currently, most of the synthetic biofuels, due to their intrinsic ring structure, are incapable of competing with JP-10 in terms of energy density and freezing point. By emulating the structural characteristic of JP-10, we herein design and prepare a special C16 fused tetracyclic biofuel using renewable cyclopentanone and benzoquinone as feedstocks. Key to success depends on selective dehydration of vicinal diol (dimer of cyclopentanone) over Amberlyst-15 in [Hmim]Cl. The Amberlyst-15/[Hmim]Cl system effectively suppresses the dominant pinacol-type rearrangement pathway and also exhibits good reusability for the dehydration. The hydrogen-bonding interaction between vicinal diol and imidazolium ring, as well as electrostatic force between carbocation intermediate and chloride anion contribute to the high diene selectivity. The compact ring framework gives rise to a density of 0.966 g/mL, combustion heat of 43.1 MJ/L, freezing point of ‒67 °C, and kinematic viscosity of 12.4 cSt, which are comparable to the properties of JP-10. It is expected that this as-prepared HED biofuel may potentially serve as a renewable alternative to petroleum fuel JP-10.

Preparation of modified epoxy resin with high hydrophobicity, low dielectric constant, toughness, and flame retardant by epoxy-functionalized siloxanes

A series of α, ω-dimethylglycidoxypropyl-terminated PDMS oligomer (PDMS-GE) oligomers with different polymerization degrees were synthesized and used to modify the bisphenol-A diglycidyl ether E51 (DGEBA) / 4,4-diaminodiphenylmethane (DDM) epoxy resin, resulting in epoxy resins with high hydrophobicity, low dielectric constant, good impact toughness, low combustion heat release rate, and low total heat release. The combustion heat release rate and total heat release of the material decreased with the increase in the loadings of PDMS-GE. Relative to pure epoxy resin, the composite E51/D30–10, which using DGEBA as the matrix, PDMS-GE with a degree of polymerization of 30 as the modifier in an amount of 10 phr relative to the mass sum of DGEBA, PDMS-GE and DDM, exhibited the best comprehensive performance with a water contact angle of 102.42°, a dielectric strength of 6.49 kV/mm, a dielectric constant of 2.93 at 14.2 GHz, the peak rate of heat release (PRHR) and total heat release (THR) are of 378.3 kW/m2 and 134.4 MJ/m2, respectively. These comprehensive performances underscore the potential of PDMS-GE oligomers in significantly improving epoxy resin properties. When the loadings of PDMS-GE oligomers are less than 5 wt%, PDMS-GE with a lower degree of polymerization can improve the toughness of epoxy resins. The impact strength of the composite E51/D24–5, which uses DGEBA as the matrix, PDMS-GE with a degree of polymerization of 24 as the modifier in an amount of 5 phr relative to the mass sum of DGEBA, PDMS-GE, and DDM, reaches 98.1 kJ/m2, which is about 28.9 % higher than that of pure epoxy resin. The results also indicated that the degree of polymerization of PDMS-GE oligomers has less influence on the dielectric properties and mechanical properties of composite materials.

The Effect of Harvest Time and Plantation Age on the Yield, Chemical Composition, and Calorific Value of Reed Canary Grass (Phalaris arundinacea L.) Intended for Energy Purposes

Based on our own research conducted on a purpose-built plantation, the production capacity of reed canary grass (Phalaris arundinacea L.) was assessed depending on the age of the plantation and the date of the biomass harvest. The aim of this study was to assess the influence of the harvest date and plantation age on the yield, chemical composition, and calorific value of reed canary grass intended for energy purposes. The biomass on the plantation was cut twice during the growing season (summer/winter). The obtained biomass was analyzed for its ash content and selected elements, i.e., nitrogen, phosphorus, potassium, calcium, magnesium, sodium, sulfur, and chlorine. The total moisture, calorific value in working condition, and combustion heat were also assessed. The two-cut harvest system allowed us to obtain 3.85 t∙ha−1 of biomass from reed canary grass in the first year of cultivation. The highest biomass yields were obtained in the third and sixth years of cultivation and amounted to 8.50 and 8.75 t∙ha−1, respectively. Regardless of the age of the plantation, the biomass yield harvested in the summer period was always higher than the yield obtained from the winter harvest. The contents of some elements in the biomass also depended on the age of the plantation and the harvest date. The biomass of reed canary grass obtained from the summer harvest of the annual plantation was characterized by a high content of nitrogen (1.97% d.m.), potassium (2.35% d.m.), and phosphorus (0.31% d.m.) compared to the content of these elements in the biomass obtained from the three- and six-year plantations. In the case of sodium, the highest content (0.072% d.m.) was found in the biomass obtained from the summer harvest of the three-year plantation, and the lowest was obtained from the winter harvest of the six-year plantation (0.037% d.m.). The average sulfur content was the highest in the biomass obtained from the annual plantation, regardless of the harvest date (0.20% d.m.—summer harvest and 0.21% d.m.—winter harvest). On the other hand, the lowest amount of sulfur was contained in the biomass obtained from the winter harvest of the six-year plantation (0.12% d.m.). Only the magnesium content (from 0.09% d.m. to 0.14% d.m.) in the biomass remained at a similar level, regardless of the age of the plantation or the harvest date. The calcium content was the highest in the biomass obtained from the winter harvest of the annual plantation (0.35% d.m.), and the lowest was obtained from the six-year-old plantation, also from the winter harvest. In addition, the moisture and ash content of the obtained biomass depended on the age of the plantation and the harvest date. The highest moisture content (12.50%) was characteristic of the biomass harvested in the summer period from the one-year plantation. On the other hand, the lowest moisture content was found for the biomass harvested in the winter period from the six-year plantation. The highest ash content was obtained from biomass harvested in the summer period from the one-year plantation (75 g∙kg−1 d.m.) and the three-year plantation (69 g∙kg−1 d.m.). The lowest ash content was obtained from the winter harvest from the six-year plantation (45 g∙kg−1 d.m.). The highest calorific value of 16.0–16.2 MJ∙kg−1 d.m. was obtained for biomass harvested in the sixth year of the study (irrespective of the harvest date). The value of the combustion heat was also dependent on the age of the plantation and the date of the biomass harvest. The highest value for the combustion heat of 17.5 MJ∙kg−1 d.m. was obtained for biomass harvested in the winter period from the six-year plantation

Comprehensive accurate prediction of critical jet fuel properties with multiple machine learning models

Quantitative structure–property relationship (QSPR) model development driven by emerging machine learning (ML) shows promise for accelerating design and preparation of jet fuels with complex hydrocarbon compositions. In this work, we collected 104 jet fuels from different refineries, determined the detailed components of the fuel composition, and tested the fuel properties (density, viscosity, net heat of combustion, freezing point and flash point) using standard methods to form a database of molecule structure/composition and properties. Subsequently, six mainstream ML algorithms were adopted to establish the QSPR models, in which the prediction accuracy of the best ML models for each property is improved to above 0.93. Finally, the best ML property models are applied to predict unseen RP-3 fuels, and all prediction errors are within acceptable limits. This effort not only provides valuable data for the construction of the jet fuel database, but also provides tools for predicting its critical properties.

Combustion characteristics of regenerative heating furnace for oil shale retorting based on top air supply

To comply with stricter air pollution standards, a new top air supply technology was proposed. Through numerical simulation, the effects of the number of air nozzles (A), air inclination (B) and fuel gas nozzle position (C) on the average temperature in the furnace, incomplete combustion heat loss and NO emission were analyzed. The research results show that the number of air nozzles has an important impact on the vortex in the pre-combustion chamber, the installation position of the fuel gas nozzles has a certain impact on the vortex formed in the combustion chamber, while the inclination of the air nozzles has no obvious effect on the vortex formation; the mean furnace temperature is most significantly affected by the interaction of factors A and B(A × B), and other factors have relatively little influence; the incomplete combustion heat loss at the exit of the combustion chamber is mainly dominated by factor A, followed by factors A × B and C. For the NO emission value at the exit of the combustion chamber, factors A and A × C have a significant impact, factors A × B also have a certain impact, and other factors can be ignored.

Systematic review of mitigation approaches in Ethiopia's energy sector: Strategies for sustainable development and climate resilience

Abstract The global energy sector is a primary contributor to greenhouse gas (GHG) emissions, predominantly through fossil fuel combustion for electricity, heating, and transportation (IEA, 2021). This study systematically reviews Ethiopia’s energy sector mitigation approaches, focusing on renewable energy strategies and energy efficiency initiatives. While Ethiopia has made significant progress in hydropower, accounting for over 90% of its electricity generation, challenges remain in diversifying its energy mix to include geothermal and wind energy (Ethiopian Ministry of Water, Irrigation, and Energy (2019) and African Development Bank, 2020). The Climate Resilient Green Economy (CRGE) strategy sets ambitious targets for achieving carbon neutrality by 2030, challenges remain in diversifying its energy mix to include geothermal and wind energy (Benti, Woldegiyorgis, et al., 2023 and Federal Democratic Republic of Ethiopia, 2011), yet its implementation faces barriers, including financial constraints, technological gaps, and weak institutional capacity (Silitonga et al., 2020). The study highlights the potential of Ethiopia’s vast renewable energy resources, such as geothermal and wind, to enhance energy security and foster economic growth through job creation. Despite the hurdles, opportunities exist for scaling up mitigation efforts, particularly through public-private partnerships and improved policy frameworks. This review underscores the importance of addressing barriers to achieve a sustainable energy transition in Ethiopia, contributing to local and global climate mitigation goals. Thus, the policymakers should boost investments in solar, wind, and geothermal energy, reduce reliance on hydropower through incentives, and establish an inter-agency task force for policy alignment. And also, exploring green bonds and fostering human capital development through training and partnerships are essential. A strong monitoring and evaluation framework is crucial for tracking progress towards energy sustainability goals.

Investigating the impacts of charge composition and temperature on ammonia/hydrogen combustion in a heavy-duty spark-ignition engine

Ammonia, as a hydrogen carrier with mature production technology and convenient storage, has become one of the most promising zero carbon fuels in recent years. The use of ammonia/hydrogen mixture fuel in spark ignition (SI) engines has drawn significant attentions since it solves the problems of low flame speed, high ignition energy requirement and narrow flammable range of pure ammonia. In this study, the combustion and emission processes of an ammonia/hydrogen port fuel injection (PFI) engine at high load operation are numerically analyzed to investigate the effects of intake hydrogen energy ratio (HER), equivalence ratio (φ), intake temperature and combustion chamber wall temperature on energy distribution and pollutants. The results indicate that under the same HER of 25%, the lean-burned mode provides favorable thermal efficiency compared to stoichiometric mode due to reduced combustion and wall heat loss. However, lower cylinder temperature at lean condition inhibits the participation of NH3 in the reduction reactions and the consumption of N2O, increasing the residuals of both pollutants. The NOx emission is promoted by excessive O radicals at lean conditions, and the pathways of fuel NOx and thermal NOx are also discussed using an isotope labeling method. At stoichiometric mode, increasing fuel HER (10%–25%) only has minor impacts on improving thermal efficiency, but can promote the consumption of NH3 and N2O by increasing H radicals and cylinder temperature. The study also shows that optimizing the intake and wall temperatures can effectively reduce NH3 and N2O emissions by 87.5% and 71.7%, respectively, while slightly reducing NOx.

Experimental investigation of Gyroid recuperator performance integrated with internal combustion engine

The recuperator has the potential to enhance engine performance, reduce fuel consumption, and lower pollutant emissions, making it a promising technology for promoting environmental sustainability. This study investigates the impact of a Gyroid recuperator on the performance of a four-stroke internal combustion engine. Experimental analyses compared engine performance at various set points of rotational speeds before and after recuperator installation. The results validate the effectiveness of the Gyroid recuperator in recovering waste heat, thereby leading to improvements in fuel efficiency. The optimal performance, characterized by an 832.31 J/s increase in recovered combustion heat energy, was observed at 7000 RPM. Additionally, the Gyroid recuperator achieved a maximum overall heat transfer coefficient of 7.9215 W/m2 K at 8000 RPM. The performance of the Gyroid recuperator was further analyzed using the log mean temperature difference method, which yielded a peak value of 114.4 °C at 7000 RPM. The effectiveness-number of transfer units’ method was also employed to assess its effectiveness. These results show that the recuperator can efficiently transmit and recover heat under certain working circumstances. The analysis suggests higher heat energy losses at lower speeds than high speeds, indicating a more efficient energy conversion process at higher engine speeds. The possibilities of the Gyroid recuperator to improve engine performance and its suitability for internal combustion engines are highlighted in this study. This technology offers a promising solution for improving vehicle efficiency and promoting environmental sustainability.

137Cs in outdoor air due to Chernobyl-contaminated wood combustion for residential heating in Thessaloniki, North Greece

Wood combustion was the key heating source in Greece during the first years at the beginning of the financial crisis. Signals of 137Cs were detected in Thessaloniki during the winter of 2013–2014 on weekends and holidays when the residents were at home burning the biggest amount of wood all day. 137Cs signals were >6–21 μBq m−3 detected using high-volume air filters and γ-spectrometry. No signals have been detected since then, as gas has replaced oil for residential heating, reducing forest wood. Besides, signal <6 μBq m−3 is undetectable because this is the minimum detectable activity. 40K concentrations were also measured, revealing a constant value of 143 ± 16 μBq m−3. The Cs-to-K ratio in air was 0.04–0.14 compared to 0.05 ± 0.01 measured before and after. Higher levels were measured when the air temperature was the lowest, but no correlation was observed with wind or pressure. Simulations using the HYSLIT model were applied on the dates on which the ratio was the highest. The model confirms the experimental results observed. 137Cs signals detected and related to the Chernobyl-contaminated biomass used for central heating indicate that contaminated forest ecosystems remain a source of unwanted radioactivity in the environment.

Combustion and thermodynamics properties of erythritol tetranitrate-based energetic films composed by electrospinning nano fibers

ABSTRACT High energy composite films made from high explosives has important applications in pyrotechnics. In this study, electrostatic spraying was used to prepare energy-containing films based on 1,2,3,4-butanetetrol tetranitrate (ETN). The results show that all energy containing films are made of nanofibres. They have excellent hydrophobicity and combustion properties. In particular, monolayer films in which ETN is the main energy containing substance. Once ignited, the trace monolayer film generates a maximum pressure of 0.85 MPa and an adiabatic flame temperature of 2,855 °C. For single and double layer films, the heat of combustion can reach 9899 J/g and 11975 J/g respectively. The level of combustion heat can also be controlled by adjustment of the ETN content. The results of the thermo-properties performance evaluation show that by optimizing the nanostructure, the ETN-based energy-containing fiber membranes can meet the requirements of advanced pyrotechnic products. In particular, there is great potential in the metastable intermixed composites (MICs) field.

The Gasification and Pyrolysis of Biomass Using a Plasma System

This research paper analyzes the use of plasma technology to process biomass in the form of dried, mixed animal manure (dung containing 30% moisture). The irrational use of manure as well as huge quantities of it can negatively impact the environment. In comparison to biomass fermentation, the plasma processing of manure can greatly enhance the production of fuel gas, primarily synthesis gas (CO + H2). The organic part of dung, including the moisture, is represented by carbon, hydrogen, and oxygen with a total concentration of 95.21%, while the mineral part is only 4.79%. A numerical analysis of dung plasma gasification and pyrolysis was conducted using the thermodynamic code TERRA. For 300–3000 K and 0.1 MPa pressure, the dung gasification and pyrolysis were calculated with 100% dung + 25% air and 100% dung + 25% nitrogen, respectively. Calculations were performed to determine the specific energy consumption of the process, the composition of the products of gasification, and the extent of the carbon gasification. At 1500 K, the dung gasification and pyrolysis consumed 1.28 and 1.33 kWh/kg of specific energy, respectively. A direct-current plasma torch with a power rating of 70 kW and a plasma reactor with a dung processing capacity of 50 kg/h were used for the dung processing experiments. The plasma reactor consumed 1.5 and 1.4 kWh/kg when pyrolyzing and gasifying the dung. A maximum temperature of 1887 K was reached in the reactor. The plasma pyrolysis of dung and the plasma–air gasification of dung produced gases with specific heats of combustion of 10,500 and 10,340 kJ/kg, respectively. Calculations and experiments on dung plasma processing showed satisfactory agreement. In this research, exergy analysis was used to quantify the efficiency of the plasma gasification of biomass. One of the research tasks was to develop a methodology and establish standards for the further standardization of monitoring the toxic emissions of dioxins, furans, and Benzo[a]pyrene.

Spent tea leaves and tea bags - Promising biofuels?

The spent tea leaves used after the extraction of liquid from processed tea are insufficiently utilized waste, rich in essential amino acids, polyphenols, alkaloids, and minerals, produced in large quantities, e.g., in tea houses, hospitals, school canteens, etc. Therefore, this study is aimed at characterizing this waste, how it is processed into pellets and how it subsequently increases its energy potential by torrefaction. The influence of the method of tea packaging, i.e., loose tea leaves or tea bags, was also considered. Several types of tea waste were processed using a pilot plant pelletizing press and torrefaction stand. The prepared pellets were characterized by mechanical parameters, such as the pellet durability index, the wettability index, water resistance, hardness, or specific bulk density, and were integrated by FTIR measurements. Furthermore, pellet's energy parameters, such as higher heating value, lower heating value, and elemental analysis, were compared. The results show that non-torrefied pellets have an average combustion heat of 19 kJ kg−1, while torrefied pellets have a value of 9 kJ kg−1 higher. Overall, the study demonstrates that spent tea leaves can be converted into a sustainable source of bioenergy and presents a solution for the treatment of this waste, as well as a renewable energy option.

Fire parameters of recycled plastic pellets

AbstractDuring the recycling process, waste plastic undergoes various processes that change its geometry. The thermal properties and fire behaviour of plastic in different geometries has not been widely studied. This paper aims to determine critical thermal properties of plastic pellets made of recycled plastic. For this paper, cone calorimeter tests of various volumes of recycled plastic pellets of low‐ and high‐density polyethylene and polypropylene were conducted. During these tests, the heat release rate (HRR), mass loss rate and time‐to‐ignition were measured, thereafter the heat of combustion (HOC) was calculated. A calibration of suitable time‐to‐ignition equations is carried out. The average HRR is between 353 and 581 kW/m2 with an external heat flux of 50 kW/m2. The measured time‐to‐ignition values ranged between 27 s at 50 kW/m2 and just more than 90 s at 25 kW/m2. Values obtained analytically from the thermally thin time‐to‐ignition equations for these materials describe ignition well, which appears to be due to the particulate nature of the samples. The HOC (40–41 MJ/kg) shows good agreement with the HOC for virgin plastic found in literature. These properties can be used as a basis for material characterisation, and further testing will be done before using this as simulation inputs to determine how bulk stored plastic pellets will behave in the event of a fire.

Simulation study on combustion reaction mechanism and heat release rate of ammonia/methane fuels

ABSTRACT Ammonia/methane combustion has the potential to be a viable method for achieving low-carbon combustion. However, further research is required to enhance the combustion mechanism and to gain a deeper understanding of the heat release rate associated with ammonia/methane combustion. A one-dimensional simulation of premixed laminar ammonia/methane flame simulation was carried out based on Okafor ammonia/methane reaction mechanism. The mole fraction of radicals and heat release rate in the ammonia/methane combustion process under different conditions were calculated using CHEMKIN-PRO. The results show that the optimized reaction mechanism was in line with the experimental results in predicting the laminar flame velocity in the fuel-lean zone. The distances between the peak values of NH and heat release rates were small at XNH3 = 0.1 ~ 0.6 and fuel-rich condition. The correlation between NH and the heat release rate was significant, indicating that NH radicals are suitable as markers of the heat release rate in the ammonia/methane flames. The abilities for characterizing heat release rate of [CH][OH], [CH][NO], [NH][OH], [NH][NO], [NH2][OH], and [NH2][NO] were further evaluated. The exponent was added to the radical combination to improve the correlation with heat release rate. [NH]0.88[OH]0.01, [NH]0.92[NO]0.25, [NH2]0.92[OH]0.42, and [NH2]0.97[NO]1.27 correlate well with heat release rates from ammonia/methane flames and they can be used as good markers of heat release rates.

Morphological characteristics of low-asphalt RAP and influence of its reaction product during combustion heating on regenerated asphalt

To provide reference for regeneration of the finely separated low-asphalt reclaimed asphalt pavement (RAP), the macroscopic and microscopic laboratory testing and quantum chemical simulation were combined. The morphological characteristics of the basalt and limestone low-asphalt RAP were analyzed. The low-asphalt RAP needs to be dried before regeneration, so the reaction mechanism and product of the asphalt film on its surface during drying were clarified. The product influence on the temperature resistance and fatigue performance of the virgin asphalt was studied, so as to consider their mixing during the subsequent regeneration process. Result shows that the gradation of limestone low-asphalt RAP is coarser and particles are slenderer than basalt with the same particle size grade. The 5–10 mm low-asphalt RAP particles are slenderer than those in the 10–20 mm grade. In the drying cylinder, asphalt basically generate no new functional groups below 200℃, while the asphalt film on the low-asphalt RAP surface undergoes pyrolysis to produce carbon black with the particle size around 100μm in the combustion heating area. The most easily oxidation or pyrolysis site in asphalt molecule is the carbon atom connected to the benzene ring. The pyrolysis of asphalt molecules to generate free radicals in the local oxygen deficient environment is the prerequisite for the carbon black formation, and pyrolysis requires higher temperature than oxidation because of its higher energy barrier. As the carbon black content increases, the penetration and ductility of asphalt decrease, the softening point increases, the high-temperature performance is enhanced, the low-temperature performance is weakened, and the fatigue performance is not significantly affected. As the particle size of carbon black increases, the decrease range in penetration, ductility and low-temperature performance of asphalt declines, the increase or improvement range of softening point and high-temperature performance enhanced, while the fatigue performance still shows no significant and regular change.

Analysis of different laboratory-scale techniques for preventing coal spontaneous combustion

The focus of this study is to investigate laboratory-scale techniques aimed at preventing an increase in heat flux, which can potentially lead to spontaneous coal combustion. This research involves two pieces of equipment designed to analyze the heat flux on untreated coal and coal treated with polyvinyl alcohol (PVA). The laboratory equipment consists of a copper cell capable of holding up to 75 ml of coal samples and an aluminum cell designed to accommodate up to 3.17 ml of coal samples. The results on untreated coal showed that copper cell had a higher heat flux and took longer to reach the heat flux peak than aluminum cell. The aluminum cell provided more excellent stability, resulting in consistent heat distribution and dependable outcomes. The analysis using copper and aluminum cells on coal treated with PVA indicates that PVA can effectively reduce the heat of combustion by 35 %. This finding could have significant implications for future coal combustion studies. This study provides valuable insights for future research into coal spontaneous combustion experiments and using PVA to prevent spontaneous coal combustion.

Effect of injection distance on supersonic combustion under different combustion modes

The effect of injection distance on supersonic combustion under different modes in an ethylene-fueled scramjet combustor at Mach 2.52 is experimentally investigated. The study is based on three injectors at injection distances of 42, 21, and 7 mm. As the injection distance increases, a higher equivalence ratio is required to complete the transition from the Scram to Dual mode. The increase in injection distance will cause the reaction zone to move downstream in the Scram mode. However, the opposite is true in the Dual and Ram modes. In addition, the increase in injection distance will intensify the reaction zone oscillation under all modes. Moreover, in the Scram mode, shortening the injection distance will increase the heat release and the oscillation of heat release intensity. In the Dual mode, although shortening the injection distance cannot enhance the heat release, it will decrease the oscillation of heat release intensity. In the Ram mode, increasing the injection distance will enhance the heat release and will hardly increase the oscillation of heat release intensity. Considering the combustion heat release and oscillation, the injection distance should be shortened in the Scram and Dual modes and increased in the Ram mode.

Enhancing energy release and controlled combustion of B-based MICs by the synergistic effect between polyvinyl pyrrolidone and nitrocellulose

To enhance energy release of boron-based metastable intermixed composites (MICs), a series of B-based MICs were constructed successfully by a facile one-step sol-freeze-drying (SFD) method, where copper oxide (CuO) was employed as oxidant. The structure, morphology, chemical state and specific surface area of B-based MICs were investigated by several characterization technologies, and their reactivity and combustion performance were further studied by various experimental tests. The results reveal that B and CuO nanoparticles are dispersed evenly on a nest network braided by the molecular interaction between polyvinyl pyrrolidone (PVP) and nitrocellulose (NC), and the constant volume combustion heat of B-based MICs even reaches 8956.6 ± 76.6 J·g−1 when PVP (1.25 wt%) and NC (5.0 wt%) were added into B/CuO, respectively. The heat value is about 1.7 times as big as pristine B/CuO (5345.5 ± 36.1 J·g−1) and approaches to that of raw B NPs (10335.5 ± 507.8 J·g−1). Moreover, the condensed phase residues of three composites were collected and confirmed to be Cu and Cu2O, while the smallest particle size distribution of product proves that the combustion of B/CuO/NC(NC: 5.0 wt%, PVP: 1.25 wt%) is most complete. So the unique nest network can eliminate particle aggregation, shorten the transfer distance of mass and heat and improve the “solid − solid” thermite reaction between B and CuO NPs. This work will provide a new strategy for promoting the application of boron.

Study of the Technical and Operational Parameters of Injectors Using Biogas Fuel

Using biogas fuel in a modern internal combustion engine equipped with gas equipment of the fourth and fifth generations can create several difficulties. This is due to the low heat of combustion of untreated biogas, the presence of moisture, and the specifics of the injectors. The main problem of the studies we considered is that there are no data on the operating parameters of biogas fuel injectors. Studies on the parameters of the Matrix, Barracuda, Valtek, Hana, and Keihin injectors in relation to biogas fuel were carried out according to performance indicators, the linearity of operation, the resistance of the injectors, the ability to maintain factory parameters, and service life. According to the indicators of performance and linearity of work, Valtek injectors have the highest deviation in productivity and linearity of work, with an average of 38.8%, and the lowest deviation of Barracuda injectors is 7.5%. Keihin (15.3%) and Hana injectors (19.1%) also showed good performance indicators, and therefore can be used effectively for biogas fuel systems. As a result of research on the response time of the injectors, it was established that the best indicators were found for Hana (1.75 ms) and Keihin (1.99 ms) injectors. Valtek injectors showed good response rates (2.07 ms), as did Barracuda injectors (2.19 ms), but the highest response time was found in Matrix injectors, with 2.44 ms. Keihin injectors had the lowest average resistance value of 1.25 ohms, and Valtek injectors had the highest resistance value of 3 ohms. According to the research results, Keihin, Matrix, and Barracuda injectors provide the best ability to maintain factory performance when using biogas fuel at 2 to 5%, and Valtek had the worst performance up to 20%. Keihin, Barracuda, and Hana experimental injectors had the highest service life, which is from 200 to 250 thousand km of car mileage. The lowest indicators were found for Valtek and Matrix injectors, the service life of which varies from 70 to 100 thousand km of mileage.

Combustion and Energy Parameters of Grape Pomace/Skin Waste in Wine Production—Regent Variety Grafted onto Rootstocks

The study presents the potential use of winemaking residues, specifically grape pomace, for energy purposes. The pomace was obtained from the cultivation of the Regent grape variety on three different rootstocks—125AA, 161-49, and SO4—as well as a control group grown on its own roots. The research included determining the calorific value and combustion heat, conducting a technical and elemental analysis of the potential biofuel, as well as estimating emission indicators (CO, CO2, NOx, SO2, and particulate matter) and the theoretical volume of flue gases based on stoichiometric equations. The study revealed significant differences among the combustion heat, tested properties and calorific value, ash content, and the total volume of flue gases. The highest calorific value (17.7 MJ kg−1) and combustion heat (18.9 MJ kg−1) were obtained for pomace from the SO4SO4 rootstock, while the lowest values were observed in the control group (17.0 MJ·kg−1 and 15.8 MJ·kg−1, respectively). The highest ash content was also recorded for the SO4 rootstock (9.2%), with the lowest in the control group (6.7%). The control group exhibited the lowest CO2 emissions at 1390.50 kg·Mg−1, while the highest emissions were found in the pomace from the SO4 rootstock (1478.8 kg·Mg−1). Regarding the total flue gas volume, the highest volume was estimated for the pomace from the 125AA rootstock (7.8 m3·kg−1) and the lowest for the control group (7.3 m3·kg−1). The research demonstrated that grape pomace possesses favorable energy properties and could serve as a potential biofuel, contributing to the fuel and energy balance of agricultural production enterprises. The analyzed biomass exhibits properties similar to agrobiomass.