Combustion Efficiency Research Articles

Optimizing combustion efficiency and environmental impact: the influence of SUPERTHERM K2R coal catalyst

ABSTRACT In the contemporary energy landscape, coal remains a dominant choice due to its widespread availability and cost efficiency. However, addressing the pressing need to mitigate fuel expenses and emissions demands enhanced operational efficiency. Enter SUPERTHERM K2R, a versatile combustion catalyst meticulously crafted to optimize the combustion process of Coal/Petcoke, the primary fuels across various industries. This innovative solution aims to curtail direct fuel consumption by 10–15%, offering efficacy across diverse coal variants including Indian, Indonesian, Australian, South African, US Coal, and Petcoke. The key advantages of this coal additive encompass reduced coal usage, diminished pollutant emissions, decreased trace metal presence, and mitigated land degradation resulting from mining activities. There are some auxiliary advantages with this product like – reduction in coal crusher power consumption, reduce forced draft (FD) fan power consumption, reduce coal handling cost because of less coal consumption as compare to normal operation of industry. In case of power plant increased consumption of demineralized (DM) water has been observed.

Numerical Study on the Mechanism of Gas Explosion Suppression by Different Arrangement Forms of Staggered Cylinders

ABSTRACT In order to study the suppression mechanism of porous media on gas explosion, the gas explosion behavior in a pipeline with one end closed and the other end temporarily closed by a thin film was numerically simulated in this paper, in which the porous media structure was characterized by “pseudo-porous media” composed of staggered cylinders. The RANS method is used to simulate turbulence in numerical calculation, and the coupling effect between turbulence and combustion is described by the reaction progress variable equation. The calculation results show that, compared with porosity, hole spacing is a more critical parameter affecting gas explosion. The function of pores is mainly reflected in the initial stage of explosion flame development, and the function of pore spacing is reflected after the flame reaches the maximum instantaneous displacement velocity. When the Pe number calculated based on local aperture and laminar flame velocity is less than 72, the flame cannot pass through porous media, and the influence of porous media on gas explosion can be shown. When the Pe number is greater than this value, the influence of porous media on gas explosion is not obvious; The hole spacing has a significant effect on the flame shape, bifurcation number, and flame thickness. When the hole spacing is larger, the flame front is more slender and bifurcated, while when the hole spacing is smaller, the flame presents a more blunt shape, and its expansion is delayed to a greater extent. This law provides a strong basis for the optimization of porous media in burner design, especially in adjusting the flame shape and improving combustion efficiency.

Numerical Simulation and Structural Optimization of Combustion Processes in a 750 t/d Waste Incinerator

This paper presents a numerical simulation and structural optimization study of the combustion process within the grate and boiler furnace of a 750 t/d waste incineration. The study focuses on adjusting the secondary air velocity, secondary air inclination angle, and the arrangement of secondary air nozzles. These adjustments aim to optimize parameters such as the temperature field, pollutant emission, flow field, particle residence time, and filling degree. The findings demonstrate that high-temperature zones, which lead to slagging problems, are likely to form beneath the front arch. The combustibles inside the furnace are thoroughly burnt, reflecting efficient combustion. The concentration of NOx in the flue gas at the furnace outlet generally ranges between 170 and 200 ppm. Optimal operating conditions are identified as a secondary air inclination angle of 20° with an air velocity of 55 m/s, and an angle of 30° with an air velocity of 55 m/s and 65 m/s, in conjunction with a relative arrangement of the nozzles. Under these conditions, the incineration furnace achieves its best operational state.

Optimization of Hydrogen Supercritical Oxy-Combustion in Gas Turbines

This study investigates the combustion of hydrogen in supercritical gas turbines, emphasizing the optimization of combustor design through computational fluid dynamics (CFD) simulations. Key parameters analysed include the number of oxygen inlets, operating pressure, excess working fluid in oxygen inlets, power output, and the use of different working fluids: supercritical argon (sAr) and supercritical xenon (sXe). The results highlight how these parameters influence temperature distribution, flame stability, and overall combustion efficiency. Findings suggest that increasing the number of oxygen inlets can significantly affect temperature profiles, while higher operating pressures lead to shorter flames. The dilution of oxygen by argon reduces the peak temperatures, and the choice of working fluid impacts cooling efficiency and flame dynamics. This study provides valuable information on optimizing the design of supercritical combustion chambers for hydrogen combustion in novel supercritical gas turbine systems.

Soil smoldering in temperate forests: a neglected contributor to fire carbon emissions revealed by atmospheric mixing ratios

Abstract. Fire is regarded as an essential climate variable, emitting greenhouse gases in the combustion process. Current global assessments of fire emissions traditionally rely on coarse remotely sensed burned-area data, along with biome-specific combustion completeness and emission factors (EFs). However, large uncertainties persist regarding burned areas, biomass affected, and emission factors. Recent increases in resolution have improved previous estimates of burned areas and aboveground biomass while increasing the information content used to derive emission factors, complemented by airborne sensors deployed in the tropics. To date, temperate forests, characterized by a lower fire incidence and stricter aerial surveillance restrictions near wildfires, have received less attention. In this study, we leveraged the distinctive fire season of 2022, which impacted western European temperate forests, to investigate fire emissions monitored by the atmospheric tower network. We examined the role of soil smoldering combustion responsible for higher carbon emissions, locally reported by firefighters but not accounted for in temperate fire emission budgets. We assessed the CO/CO2 ratio released by major fires in the Mediterranean, Atlantic pine, and Atlantic temperate forests of France. Our findings revealed low modified combustion efficiency (MCE) for the two Atlantic temperate regions, supporting the assumption of heavy smoldering combustion. This type of combustion was associated with specific fire characteristics, such as long-lasting thermal fire signals, and affected ecosystems encompassing needle leaf species, peatlands, and superficial lignite deposits in the soils. Thanks to high-resolution data (approximately 10 m) on burned areas, tree biomass, peatlands, and soil organic matter (SOM), we proposed a revised combustion emission framework consistent with the observed MCEs. Our estimates revealed that 6.15 Mt CO2 (±2.65) was emitted, with belowground stock accounting for 51.75 % (±16.05). Additionally, we calculated a total emission of 1.14 Mt CO (±0.61), with 84.85 % (±3.75) originating from belowground combustion. As a result, the carbon emissions from the 2022 fires in France amounted to 7.95 MtCO2-eq (±3.62). These values exceed by 2-fold the Global Fire Assimilation System (GFAS) estimates for the country, reaching 4.18 MtCO2-eq (CO and CO2). Fires represent 1.97 % (±0.89) of the country's annual carbon footprint, corresponding to a reduction of 30 % in the forest carbon sink this year. Consequently, we conclude that current European fire emission estimates should be revised to account for soil combustion in temperate forests. We also recommend the use of atmospheric mixing ratios as an effective monitoring system of prolonged soil fires that have the potential to re-ignite in the following weeks.

Performance and emission characteristics of domestic LPG gas burners with hydrogen integration

Abstract Domestic gas burners are a significant source of indoor air pollution and contribute substantially to household energy consumption. While transitioning to carbon-free fuels, such as hydrogen, presents considerable safety challenges, blending hydrogen with conventional fuels can improve combustion efficiency and reduce emissions. However, factors like the differences in the Wobbe index, loading height, power input, and fuel blending complicate understanding the aerated burner performance. This is particularly relevant for large establishments like restaurants and canteens, where hydrogen blending can have a notable impact. This study evaluates four burner designs—commercial (A), straight holes (B), slots (C), and swirl (D)—across thermal inputs (0.8–1.6 kW), with a focus on the swirl burner using hydrogen blends (0%, 34%, and 52% by volume) and varying loading heights (5 mm, 10 mm, and 15 mm). Straight hole (B) and swirl (D) burners were 3D-printed using stainless steel metal powder, while the slot (C) burner was machined. Key performance metrics such as flame behavior, thermal efficiency, pressure drop, and CO emissions were analyzed. Improving primary aeration by reducing flow resistance and enhancing secondary aeration through swirl action resulted in better flame-load interaction and minimized heat loss. The slot burner (C) achieved a thermal efficiency of 63.5%, while the swirl burner (D) reached 65% efficiency at a 10 mm height. The swirl burner maintained high efficiency with up to 52% hydrogen by volume across a wide range of operational conditions, with some exceptions. Additionally, the use of hydrogen eliminated soot emissions. Optimal performance occurred at a 10 mm loading height, with stable efficiency and lower emissions across various power inputs and hydrogen blends. The complex interactions between primary aeration, secondary mixing, and flame-load dynamics during hydrogen blending require thorough evaluation before incorporating hydrogen into aerated LPG burners.

Optimizing coal mill for efficient Thar lignite utilization

ABSTRACT To achieve energy security and sustainable economic development, Pakistan is shifting focus to its abundant Thar lignite, aiming to reduce dependence on costly coal imports for powering industries and homes. This research explores coal pulverizers and mills, focusing on optimizing their design and functionality to efficiently utilize Thar lignite. The study examines Thar coal properties at various blend ratios, highlighting its value as a domestic resource. It explores lignite drying techniques using flue gas and primary air to reduce moisture content, enhancing calorific value and combustion efficiency. The core of the research proposes modifications to Beater Mills and Vertical Roller Mills (VRMs) to seamlessly accommodate Thar lignite. These adjustments ensure efficient lignite utilization and address challenges posed by its distinct properties. To highlight the economic impact of this transition, the research conducts a comprehensive cost analysis. The findings reveal the substantial foreign exchange savings that could be achieved by substituting imported coal with Thar lignite, with the potential for annual savings reaching a maximum of US$1.226 Billion. In essence, this research serves as a beacon guiding Pakistan toward a future powered by its abundant lignite, setting the stage for enhanced energy independence, economic resilience, and a more sustainable tomorrow.

Flame Retardancy and Heat Shielding in Green Polypropylene Composites Using Biohybrid Fibers and Agro-Waste Fillers.

The current work presents the flame-retardant performance of hybrid polypropylene composites, reinforced with specific short woven flax fabrics (SWFs), short basalt fibers (BFs), and rice husk powder (RHP), using polypropylene grafted maleic anhydride (MAPP) as the coupling agent. Horizontal burning test (HBT), microcalorimeter test (MCT), and cone calorimeter test (CCT) were conducted on these composites. The formulations used were 25% SWF/PP, 25% SWF/20% BF/PP, and 25% SWF/20% BF/PP with 6% RHP and 25% SWF/20% BF/PP with varying RHP contents (6, 12, and 18%) in combination with 6% MAPP. A peak heat release rate (pHRR) reduction of 14.42% was recorded in microcalorimeter test results. However, cone calorimeter test results indicated a reduction of 80.95% in pHRR and 23.84% in total heat release rate (THR). Furthermore, the emissions of CO and CO2 were reduced by 68 and 67%, respectively, in the 25SWF/20BF/PP.6MAPP-18RHP composite compared to pure PP, indicating an overall improvement in combustion efficiency. Fire performance index (FPI) also improved remarkably: FPI increased by 130% and fire growth index (FGI) improved by 81.34%. Moreover, the horizontal burning test showed an improved performance, with the burning rate further reduced by 11.10% compared to that of the 25% SWF/PP composite. These results highlight the synergy among natural fibers, agro-waste fillers, and MAPP in improving flame retardancy of polypropylene composites, and hence their potential application in automobiles and construction, where the demand for fire safety is very high.

Contrasting Summertime Trends in Vehicle Combustion Efficiency in Los Angeles, CA and Salt Lake City, UT.

Policy interventions and technological advances are mitigating emissions of air pollutants from motor vehicles. As a result, vehicle fleets are expected to progressively combust fuel more efficiently, with a declining ratio of carbon monoxide to carbon dioxide (CO/CO2) in their emissions. We assess trends in traffic combustion efficiency in Los Angeles (LA) and Salt Lake City (SLC) by measuring changes in summertime on-road CO/CO2 between 2013 and 2021 using mobile observations. Our data show a reduction in CO/CO2 in LA, indicating an improvement in combustion efficiency that likely resulted from stringent regulation of CO emissions. In contrast, we observed an increase in CO/CO2 values in SLC. While slower progress in SLC compared to LA may be partially due to a later adoption of vehicle emission regulations in Utah compared to California, differing driving conditions and fleet composition may also be playing a role. This is evidenced by increased CO/CO2 in LA during the COVID-19 pandemic, which led to faster driving speeds and changes to the fleet composition. Our results demonstrate the success of California's CO-reducing policy interventions and illustrate the impacts of traffic characteristics on vehicle combustion efficiency and air pollutant emissions.

Effect of rear blunt body structure and inlet conditions on the flow and combustion characteristics of an advanced vortex combustor for a gas turbine

The rear blunt body plays a crucial role in the total performance of an advanced vortex combustor. This paper presents a numerical simulation study on the flow and combustion characteristics of an advanced vortex combustor fueled by liquid aviation kerosene under atmospheric pressure conditions, with inlet velocities of 0–100 m/s and inlet temperatures of 300–800 K. Different structural and aerodynamic parameters, including cavity length, rear blunt body height, rear blunt body width and inlet conditions are studied to determine the variation trends of the velocity field, total pressure recovery coefficient, fuel concentration field, combustion efficiency, outlet temperature distribution and pollutant emissions. The results indicate that the presence of the rear blunt body facilitates the formation of a dual vortex structure within the cavity, leading to an increased total pressure recovery coefficient, an improved fuel concentration distribution, an enhanced combustion efficiency, and a more uniform outlet temperature distribution. At an inlet velocity of 100 m/s, the total pressure recovery coefficient increases from 97.01 % to 97.29 %. However, as the cavity length, the rear blunt body height and width increase, the total pressure recovery coefficient and the CO emission increases, and the combustion efficiency, outlet temperature distribution and NO emission decrease to different degrees. In addition, an increase in inlet temperature enhances the fuel concentration distribution, leading to improved combustion efficiency, better outlet temperature distribution, and an increase in NO emission. Additionally, it results in a reduction in CO emission. As the inlet temperature increases from 500 K to 800 K, the combustion efficiency increases from 86.57 % to 92.81 %, representing a growth rate of 7.21 %. In summary, when the cavity length is 24 mm, the rear blunt body height is 24 mm, the rear blunt body width is 5 mm, and the inlet temperature is 800 K, the overall combustion performance of the advanced vortex combustor is optimal, which is conducive to providing an important theoretical basis for the design and optimization of advanced vortex combustors.

A review of chemical kinetic mechanisms and after-treatment of amino fuel combustion.

Ammonia is a highly promising carbon-neutral fuel. The use of ammonia as a fuel for internal combustion engines can reduce fossil energy consumption and greenhouse gas emissions. However, the high ignition energy required for ammonia and the slow flame propagation rate result in low combustion efficiency when ammonia is used directly in internal combustion engines. The combination of ammonia with highly reactive fuels improves combustion quality and increases efficiency. However, the combustion of these combined fuels generates particulate matter, CO, hydrocarbon, and significant amounts of NOx. Therefore, pollutant emissions must be reduced through after-treatment technologies. In this paper, a series of combustion and post-treatment challenges faced by amino fuel combustion in internal combustion engines are extensively discussed and the combustion reaction mechanisms of different amino fuels are also analyzed. The paper then reviews five key technologies applicable to the reprocessing of amino fuels, including selective catalytic reduction, selective catalytic reduction filter technology, electrochemical methods for NOx removal, direct catalytic decomposition of N2O, and ammonia sliding catalysts. An in-depth discussion of the catalytic materials and reaction mechanisms involved in these technologies is also provided in this paper. Finally, the paper summarizes the main technical challenges that must be addressed for the future application of amino fuels in internal combustion engines. These discussions can serve as an essential reference for developing and applying critical technologies for combustion control and pollutant treatment of amino fuels.

Identification of combustion characteristics of high ash Indian coal, rice straw, rice straw char and their blends

The present investigation evaluates the co-combustion performance of rice straw (RS), rice straw char (RSC), high ash coal (HAC) to determine their suitability as blended fuels for power generation. Both the individual and blended fuels were characterized through proximate analysis, ash analysis, and the determination of gross calorific value (GCV). Experimental results indicate that RS and RSC possess higher GCV than HAC, improving overall GCV and combustion rate of the blends. Thermogravimetric analysis (TGA) reveals significant variations in the thermal properties of disproportionate mixtures (blends of HAC with RS or RSC). HAC has the highest ignition (Ti = 417°C), peak (Tp = 498°C), and burnout temperatures (Tf = 565°C), indicating weak thermal stability. In contrast, RS and RSC exhibit much lower Ti (226°C and 256°C, respectively) and Tf (420°C and 448°C), suggesting they ignite more easily and have moderate thermal stability. Blends with higher RS or RSC content progressively decrease Ti and Tf, but with a sharper DTGmax (maximum derivative thermogravimetry) and Pi (ignition index), highlighting more intense and quicker combustion. Increasing the RS content from 10% to 90% lowers the ignition temperature (Ti) from 416ºC to 222ºC and burnout temperature (Tf) from 564ºC to 417ºC. Performance index (Qf) increases, and rate of heat intensity (Sf) decreases as RS/RSC content increases, with RS9HAC1 and RSC9HAC1 having moderate stability and highest combustion intensity. This trend illustrates that increasing RS/RSC proportions enhance reactivity with moderate thermal stability. Thermodynamic analysis shows that blending RS and RSC with HAC decreases the enthalpy (ΔH) from 41.42kJ/mol to 37.77kJ/mol and from 42.02kJ/mol to 31.74kJ/mol as the RS and RSC content rises from 10% to 90% implying that individual combustion of coal is difficult while blending RS and RSC makes the combustion favorable. Adding 10% RS and 20% RSC can significantly improve combustion efficiency at various temperatures without major boiler modifications. The numerical study demonstrates the prospective for enhancing coal-biomass/biochar co-combustion by altering O2/CO2 gas levels, emphasizing the benefits of adding biomass and biochar, as well as substituting CO2 for N2 under specific conditions.

SCRAMJET: Future High Speed Aircraft

In the current era of technological advancement, the scramjet has become one of the most conventional engines for achieving supersonic speeds in aircraft. The scramjet comprises three basic components: the inlet, combustor, and nozzle. Various fuels, such as Kerosene, JP-7, JP-8, hydrocarbon-based fuels, and hydrogen, have been used in scramjets, demonstrating distinct performance characteristics. Tests have shown that hydrocarbon-fueled scramjet engines can achieve a Mach number range of 3.5 to 7, while solid-fueled scramjets have the potential to achieve combustion efficiencies of 0.7–0.9. Fuel injection and mixing techniques were applied in the combustor to enhance thrust and pressure ratios. Advanced injection methods were incorporated into the strut or walls of the combustor to improve combustion efficiency. The air intake capability of the scramjet depends on the inlet design, which should aim to minimize spillage drag and ensure adequate shock train formation. The flamelet approach has demonstrated improved combustion performance and maximized fuel efficiency through the effective placement of the flamelet. Additionally, the flamelet approach optimizes fuel mixing and injection processes within the supersonic flow. By employing a dual-mode scramjet isolator, an equivalence ratio range of 0.06–0.32 was achieved during the transition from supersonic to subsonic combustion. Combustion analysis revealed the behavior of the combustor when using jet fuels and additives. CFD data indicated that incomplete combustion releases harmful gases, such as carbon monoxide and nitrogen oxides, while complete combustion produces stable by-products like water and carbon dioxide. These issues are often attributed to inadequate air-fuel mixing or insufficient air supply. Simulations highlighted the need for improvements in combustor design to prevent thermal choking under specific conditions.

Enhancement of Aeroengine Combustion Chamber Air Cooling Holes Design for Emission Reduction and Pattern Factor Control

The results of a comprehensive numerical analysis of temperature uniformity and NOx and CO emission predictions in an aeroengine annular combustor liner, conducted by geometrical modifications through design changes in primary cooling air, including effusion cooling holes, are shown in the paper. A total of five geometric configurations were studied using computational fluid dynamics (CFD) simulations in ANSYS CFX. The adopted combustion model was sort of a combination of the finite-rate (i.e., chemistry, chemical processes) and eddy dissipation model (FRC/EDM). Further, the combustion of liquid kerosene (C10H22) with air, subsequent to the evaporation of fuel droplets, was simulated, and the Rosin-Rammler droplet size distribution was used in spray modeling for accurate depiction of fuel atomization. Both thermal and prompt formation mechanisms of NOx were considered, while k-ε model for turbulence was adapted to capture the nature of emission. An annular combustion chamber of realistic dimensions with a double radial air swirler was modelled in 3D CAD to undertake this study for good, tangible results. Built contour plots allowed to analyze the temperature distribution and NOx concentration along the axis from the center of the injector. Charts on the pattern factor, temperature, and NOx and CO concentrations at the outlet of the combustor served as performance metrics. The simulation was implemented with a two-step chemical kinetics scheme for kerosene combustion with the P1 radiation model, which would give an accurate thermal radiation prediction. One of the major objectives of this research is to compare the CFD results at the combustor outlet with gas dynamic and thermodynamic calculations that have been carried out using AxStream software at the Department of Aeroengine Design, Kharkiv Aviation Institute. It is important to emphasize that the mean deviation of gas dynamic results obtained from AxStream and CFD simulation results was found to be insignificant, hence the CFD approach has been validated. The results testify that redesigning the combustor liner, especially in the design related to primary and effusion cooling holes, drastically reduced NOx and CO emissions. Also, these design modifications have helped in reducing or improving temperature uniformity at the combustor outlet, either way enhancing combustion efficiency and performance.

Evaluation of Material Selection for Automotive Piston Component using Weighted Sum (WSM) Method

When choosing a material for automobile piston components, be sure to choose one that satisfies all necessary specifications, like durability, resistance to temperature, and wear resistance. To achieve maximum efficiency and effectiveness, factors including cost, weight, and production procedures are also taken into account. Aluminium alloys that are forged iron, and steel are common material for piston components; each has certain benefits and compromises in terms of expense and efficiency. Introduction: Material selection for auto piston components is critical to ensuring top performance and long-term durability. The piston, as a vital engine component subjected to high temperatures, hardship, and wear and tear, necessitates a material that promotes efficient combustion, lowers friction, and maintains its structural integrity. When selecting materials for automobile pistons such as aluminium alloys, wrought iron, or steel, aspects such as heat conductivity, resistance to wear, size, expense, and manufacturing capability are carefully considered to satisfy the specific needs of the application. Research Significance: Aluminum, steel, along with iron are the better frequently used goods for pistons. The effort from the expanding gas at great heat matters about the inside. Cylinder and many other important factors determine proper piston selection Material necessity are balanced more demanding, just as no single material meets all the properties required for a distinct application. Method: The weighted sum method is a decision-making approach that involves assigning weights to different criteria or objectives and combining them to make an overall assessment. It allows decision-makers to prioritize and balance various factors based on their relative importance. By utilizing this method, complex decision problems can be simplified and converted into a single weighted score, facilitating a clearer understanding of trade-offs and aiding in the decision-making process. Alternate Parameters: “LM-26 alloy + 0% Porcelain, LM-26 alloy + 2% Porcelain, LM-26 alloy +4% in weight Porcelain, LM-26 alloy +6 percent by weight porcelain, and LM-26 alloy +8 percentage of weight Porcelain”. Evaluation Parameters: Hardness, Compressive strength ,Tensile strength ,Specific wear rate , and Friction coefficient Result: “LM-26 alloy +6 wt.% Porcelain” is in the 1st Rank, “LM-26 alloy +4 wt.% Porcelain” in the 2nd Rank, “LM-26 alloy +2 wt.% Porcelain” in the 3rd Rank, “LM-26 alloy +8 wt.% Porcelain” in the 4rth Rank, and “LM-26 alloy +0 wt.% Porcelain in the 5th Rank”. Conclusion: For the Material Selection for Automotive Piston Component : “LM-26 alloy +6 wt.% Porcelain” is in the 1st Rank, “LM-26 alloy +4 wt.% Porcelain” in the 2nd Rank, “LM-26 alloy +2 wt.% Porcelain” in the 3rd Rank, “LM-26 alloy +8 wt.% Porcelain” in the 4rth Rank, and “LM-26 alloy +0 wt.% Porcelain in the 5th Rank”.

Assessing the influence of EGR on diesel pilot ignition combustion with methane/hydrogen blends in a single-cylinder compression ignition engine

This paper experimentally investigates the impact of EGR on the combustion performance and emissions of methane/hydrogen blends for the diesel pilot ignition (DPI) combustion strategy. Different speed/load cases were evaluated on a single-cylinder compression ignition engine for hydrogen energy shares ranging from 0% to 20%. As hydrogen was added to the premixed mixture, the combustion phasing (CA50) was held constant by either adjusting the pilot start of injection (SOI) timing or using EGR at constant intake pressure (varying premixed equivalence ratio). The experimental results show that the use of EGR at constant intake pressure with methane/hydrogen blends leads to lower unburned hydrocarbon (UHC), carbon-monoxide (CO), and nitric oxide (NO) emissions when compared to the methane-only baseline. Adiabatic flame temperature calculations were used to help explain the observed engine out nitric oxides (NOx) emissions trends. The UHC emissions, however, were significantly higher than the baseline split-injection diesel case due to incomplete combustion and crevice effects. Combustion efficiency improved without a thermal efficiency reduction with hydrogen addition, suggesting that substitution with hydrogen can be beneficial for dual-fuel compression ignition strategies that utilize natural gas. The decay rate for CH4 and H2 was more than linear, which is attributed to the chemical effects of hydrogen addition and EGR.

Optimization Strategy to Reduce Unplanned Low Power Engine Breakdowns on PC-2000 Units at PT Antareja Mahada Makmur

Low-power machine breakdowns that occur unplanned (unscheduled) on the PC-2000 unit are one of the main obstacles in maintaining operational efficiency in the workshop area of PT Antareja Mahada Makmur Jobsite Mifa Bersaudara. This study aims to identify the main causes and design optimization strategies to reduce the frequency of these events. The research methodology included analysis of historical damage data, technical inspection of the affected machine components, and evaluation of the quality of the fuel used. Based on the analysis, it was found that the use of B35 fuel (35% biodiesel) is one of the significant factors affecting engine performance, especially in the combustion system and fuel injection components. The implementation of preventive maintenance-based strategies, including increased frequency of fuel injection system inspections, replacement of vulnerable components, and use of fuel additives to improve combustion efficiency, reduced the frequency of breakdowns by 40% within three months of implementation. The results of this study emphasize the importance of mitigating the impact of B35 fuel use on engine performance through a planned maintenance approach. Recommendations include developing technical guidelines specific to biodiesel fuel use and training technicians to support more reliable operational sustainability.

THE EFFECT OF PARAFFIN WAX CANDLE WITH DIFFERENT PERCENTAGE OF ADDITIVE USED ON BURNING EFFICIENCY OF THE CANDLE

Paraffin wax burned cleanly, burn brighter and was less expensive to produce than other candle fuels, it represented a significant advancement in the candle-making industry. However, since paraffin wax melts easily, most candles manufactured with it are fragile. Many experiments and techniques have shown that stearic acid and paraffin wax could work well together to produce long-lasting candles. This study examines how the proportion of stearic acid added to paraffin wax candles affects the candles' ability to burn efficiently. Few paraffin waxes candles that are, 5%, 10%, and 15% were made in accordance with the various stearic acid percentages. Result shows that, the largest percentage of stearic acid results in the lowest burning rate of 0.00135 cm s−1. It was found that the added additive affected the candles' efficiency of burning after monitoring the burning rate. The findings of this study may be very useful in the production of low-cost, long-lasting candles.

Untangling the Efficient Boron-Initialized Hydroxyl-Terminated Polybutadiene Combustion for High Energetic Solid Propulsion Systems.

Highly energetic boron (B) particles embedded in hydroxyl-terminated polybutadiene (HTPB) thermosetting polymers represent stable solid-state fuel. Laser-heating of levitated B/HTPB and pure HTPB particles in a controlled atmosphere revealed spontaneous ignition of B/HTPB in air, allowing for examination of the exclusive roles of boron. These ignition events are probed in situ via simultaneous spectroscopic diagnostics: Raman and infrared spectroscopy, temporally resolved high-speed optical and infrared cameras, and ultraviolet-visible (UV-vis) spectroscopy. The emission spectra unravel two stages of the B/HTPB ignition─the exoergic ignition of boron followed by HTPB combustion. It was found that HTPB readily absorbs the energy from the irradiating carbon dioxide (CO2) laser but efficiently transfers that thermal energy to the densely arranged boron particles due to the lower heat capacity of the latter. This transferred energy causes a surge in temperature for the boron particles, leading to ignition (in an oxygen environment) in B/HTPB, unlike the case with HTPB alone. The accumulated energy from the second stage of boron ignition triggers the decomposition of HTPB in conjunction with hydrogen abstraction to produce radical precursors via boron oxides (BO and BO2)─the key emitting intermediates detected. Along with conventional combustion products such as carbon dioxide (CO2) and water (H2O), the formation of partially oxidized gaseous products such as methanol (CH3OH) and methyl vinyl ether have also been detected as a tracer of diverse oxidation events, suggesting a complex oxidation chemistry within HTPB and overall depict crucial insights for its use as a solid rocket fuel.

Effects of nozzle geometry, compression ratio and cerium oxide nanoparticles on algae biodiesel performance in a VCR diesel engine with hydrogen addition

This paper discusses an exploratory analysis of performance and emissions characteristics of a variable compression ratio (VCR) diesel engine using various compression ratios, nozzle hole configurations, and injection timings. Results will be employed to further elucidate interactions among those parameters as well as their influence upon the operation efficiency and environmental output. An engine was tested on the B20 biodiesel blend from the transesterification of algal oil. The sample, which contained nano-additives with cerium oxide (CeO2) at a concentration of 75 ppm, underwent extensive analysis using scanning electron microscopy and energy dispersive X-ray analysis (FTIR). The study included different compression ratios such as 16:1, 17:1, 18:1, and 19:1, utilizing nozzle designs with hole diameters of 2, 3, 4, and 5 mm. Additionally, it also examines the effects of hydrogen injection at time intervals of 3, 4, and 5 ms, aiming to comprehend the interaction between these parameters and their impact on the performance outcome. The presence of CeO2 75 ppm resulted in a significant reduction in emissions, as well as improved combustion efficiency. The configuration resulted in a 6.1% improvement in brake thermal efficiency (BTE), as well as a decrease in brake specific fuel consumption (BSFC) from 250 g/kWh to 200 g/kWh. Improving the number of holes in the nozzle revealed a drop in the temperature of the exhaust gas up to 250°C. Reduced nitrogen oxide (NOX) emissions and improved cylinder pressure accompanied these decreases, thanks to the increased heat release rates generated by hydrogen addition. The addition of CeO2 nanoparticles to the B20 blended fuel, along with modifications to the nozzle hole design and hydrogen injection, not only reduces emission values but also lowers fuel consumption, lowers exhaust gas temperature (EGT), and improves combustion efficiency.