Search Results (1,722)

Methanol/diesel hybrid−powered vessels represent a significant advancement in green and low−carbon innovation in the maritime transportation sector and have been widely adopted across various shipping markets. However, the dual−fuel power system modifies the fire load within the engine room compared to traditional vessels, thereby significantly influencing the fire safety of methanol/diesel−powered ships. In this study, anhydrous methanol and light−duty diesel (with 0 °C pour point) were used as fuels to investigate the mixed combustion characteristics of these immiscible fuels in circular pools with diameters of 6, 10, 14, and 20 cm at various mixing ratios. By analyzing the fuel mass loss rate, flame morphology, and heat transfer characteristics, it was determined that methanol and diesel exhibited distinct stratification during combustion, with the process comprising three phases: pure methanol combustion phase, transitional combustion phase, and pure diesel combustion phase. Slopover occurred during the transitional combustion phase, and its intensity decreased as the pool diameter or methanol fuel quantity increased. Based on this conclusion, a quantitative relationship was established between slopover intensity, pool diameter, and the methanol/diesel volume ratio. Additionally, during the transitional combustion phase, the average flame height exhibited an exponential coupling relationship with the pool diameter and the methanol/diesel volume ratio. Therefore, a modification was made to the classical flame height model to account for these effects. Moreover, a prediction model for the burning rate of methanol/diesel pool fires was established based on transient temperature variations within the fuel layer. This model incorporated a correction factor related to pool diameter and fuel mixture ratio. Additionally, the causes of slopover were analyzed from the perspectives of heat transfer and fire dynamics, further refining the physical interpretation of the correction factor. Full article

Agrophotovoltaic (APV) systems represent innovative agricultural farms and solar power plants, capable of producing electricity and crops simultaneously. Since the solar radiation required to optimize harvests varies by crop type, traditional PV panels face challenges in efficiently adjusting the shading ratio of APV systems. This study evaluates the economic viability of APV systems integrated with building-integrated photovoltaic (BIPV) systems for biofuel production. Specifically, it assesses the production forecast for corn-based biofuel—demand for which is rising due to the mixed-fuel use policy of the Korean government—and the economic feasibility of production in the APV system enhanced by BIPV integration (i.e., the APV–BIPV system). To this end, LCOE (levelized cost of energy) and NPV (net present value) are employed as performance indicators. Additionally, yield data from corn and corn stover harvested in actual APV facilities are utilized to predict bioenergy production. Consequently, the study will analyze the impact of renewable energy production from the proposed APV–BIPV system on achieving the Korean government’s renewable energy production goals and will provide guidelines on the potential benefits for farmers involved in renewable energy production and energy crop harvesting. Full article

This study examines the impact of alcohol blends on the performance and emissions of aviation micro-turbojet engines. Thus, propanol, butanol, pentanol, hexanol, heptanol, and octanol were tested at 10%, 20%, and 30% concentrations and mixed with Jet A, as well as with an additional 5% heptanol blend to preserve base fuel properties, to fuel a JetCat P80 micro-turbojet. Physicochemical properties such as density, viscosity, and elemental composition were analyzed before engine testing. Carbon dioxide (CO₂) emissions from 1 kg of fuel combustion varied, with propanol yielding the lowest at 3.02 kg CO₂ per kg of fuel and octanol yielding the highest at 3.22 kg CO₂ per kg of fuel. The following results were obtained: alcohol blends lowered exhaust gas temperature by up to 7.5% at idle and intermediate thrust but slightly increased it at maximum power; fuel mass flow increased with alcohol concentration, peaking at 20.4% above Jet A for 30% propanol; and thrust varied from −4.92% to +7.4%. While specific fuel consumption increased by up to 12.8% for propanol, thermal efficiency declined by 1.8–5.6% and combustion efficiency remained within ±2% of Jet A. Butanol and octanol emerged as viable alternatives, balancing emissions reduction and efficiency. The results emphasize the need for an optimal trade-off between environmental impact and engine performance. Full article

Effective route and speed decision-making can significantly reduce vessel operating costs and emissions. However, existing optimization methods developed for conventional fuel-powered vessels are inadequate for application to methanol dual-fuel ships, which represent a new energy vessel type. To address this gap, this study investigates the operational characteristics of methanol dual-fuel liners and develops a mixed-integer nonlinear programming (MINLP) model aimed at minimizing operating costs. Furthermore, an improved genetic algorithm (GA) integrated with the Nonlinear Programming Branch-and-Bound (NLP-BB) method is proposed to solve the model. The case study results demonstrate that the proposed approach can reduce operating costs by more than 15% compared to conventional route and speed strategies while also effectively decreasing emissions of CO₂, NOx, SOx, PM, and CO. Additionally, comparative experiments reveal that the designed algorithm outperforms both the GA and the Linear Interactive and General Optimizer (LINGO) solver for identifying optimal route and speed solutions. This research provides critical insights into the operational dynamics of methanol dual-fuel vessels, demonstrating that traditional route and speed optimization strategies for conventional fuel vessels are not directly applicable. This study provides critical insights into the optimization of voyage decision-making for methanol dual-fuel vessels, demonstrating that traditional route and speed optimization strategies designed for conventional fuel vessels are not directly applicable. It further elucidates the impact of methanol fuel tank capacity on voyage planning, revealing that larger tank capacities offer greater operational flexibility and improved economic performance. These findings provide valuable guidance for shipping companies in strategically planning methanol dual-fuel operations, enhancing economic efficiency while reducing vessel emissions. Full article

A high-temperature gas plasma scheme using methane/air/K₂CO₃ mixed combustion is proposed for the application background of hypersonic aircraft. The actual combustion temperature was calculated by ANSYS Chemkin Pro software; the various components of the combustion reaction were determined; and the function between temperature and electrical conductivity was established, revealing the variation law of ionization decomposition of K₂CO₃ ionized seeds with gas temperature. At 1500 K, K₂CO₃ ionized seeds are close to complete ionization. Increasing the mass fraction of K₂CO₃ ionized seeds will enhance the endothermic effect of K₂CO₃ seed ionization decomposition. Under the same residual gas coefficient conditions, the combustion equilibrium temperature will correspondingly decrease. The increase in initial combustion temperature results in an approximately linear increase in equilibrium temperature and conductivity. With the increase in initial pressure, the equilibrium temperature of gas shows a logarithmic growth trend, while conductivity gradually decreases and the gradient of change gradually slows down. This study provides a new method for evaluating the ionization characteristics of high-temperature gas plasma formed by potassium carbonate (K₂CO₃) as ionization seed, and hydrocarbon fuel (CxHy) combined with air. Full article

Economic and legal conditions of the European power industry enforce higher participation of biomass in the thermal energy mix per power unit, due to the necessity of carbon dioxide emission reduction. One of the most important features dictating the suitability of biomass fuel for utilization in pulverized fuel-fired boilers is its grindability. The grindability of biomass is a difficult parameter to estimate due to its non-uniform morphology and inhomogeneous character. Milling and co-milling of large amounts of biomass can deteriorate the mill output and make it difficult to ensure the proper particle size distribution of the pulverized fuel fed into the combustion chamber. The main objective was to determine whether torrefaction pre-treatments could increase the grindability features of various types of biomass. Investigations of raw and torrefied biomass grindability were performed with the use of a modified Hardgrove Index for alder chips, palm kernel shells, and willow chips. Additionally, semi-industrial scale milling tests were performed, which allowed for the evaluation of torrefied biomass suitability for continuous grinding installations equipped with vertical spindle mills. According to the analysis, an increase in the biomass grindability index after the torrefaction process was shown. Additionally, it was noted that for milling low-density materials (e.g., torrefied biomass), changes in the construction of the industrial mill classifier may be necessary for the proper grinding circuit operation. Full article

The subject addressed in this article is the application of the life cycle assessment (LCA) method for studying the greenhouse gas emissions attributable to public bus transport. The article provides a discussion on the results of the authors’ in-house study on the greenhouse gas (GHG) emissions generated over the life cycle of the buses used in Poland’s public transport with the use of well-to-wheel (WTW) fuel life cycle analysis. The project started by adopting the methodology and assumptions for the research; next, the data required to perform the relevant analyses were collected and the greenhouse gas emissions attributable to the operation of buses equipped with both diesel fuel (DF) internal combustion engines and electric engines (BEVs) were assessed against real-life data using a selected Polish municipal transport company as an example in 2022. The study also included an assessment of GHG emissions from electric buses powered by renewable energy sources (RESs), using data from the chosen municipal transport company. For the RES fractions of 25%, 50%, and 75% in the energy mix, emission reductions of approx. 19%, 38%, and 57% have been achieved, respectively. For an energy mix entirely derived from RESs, the reduction in emissions comes to ca. 76% vis-à-vis Poland’s energy mix in 2022. Full article

This paper presents a comprehensive SWOT (strengths, weaknesses, opportunities, and threats) analysis of utilizing hydrogen as a renewable fuel of non-biological origin (RFNBO) in Poland’s energy transition. Given Poland’s reliance on fossil fuels, its deep decarbonization poses socio-economic and infrastructural challenges. This study examines the strengths, weaknesses, opportunities, and threats associated with integrating hydrogen as an RFNBO fuel into Poland’s energy mix, focusing on economic, regulatory, technological, and social factors. The strengths identified include potential energy independence from fossil fuels, increased investment, and hydrogen’s applicability in hard-to-abate sectors. Weaknesses involve a low share of renewable hydrogen in the energy mix and the need for infrastructure development. Opportunities arise from European Union policies, technological advancements, and global trends favoring renewable hydrogen adoption. Threats encompass high production costs, regulatory uncertainties, and competition from other energy carriers. The analysis concludes that while hydrogen as an RFNBO fuel offers potential for decarbonizing Poland’s energy mix, realizing this potential requires large-scale investments, a supportive regulatory framework, and technological innovation. Full article

To reduce dependence on fossil fuels, gas turbine plants using hydrogen/methane blends provide a crucial solution for decarbonizing thermal power generation and promoting a sustainable energy transition. In this context, the development of fuel-flexible burners is fundamental. This work reports the development of a novel burner geometry for gas turbines that can operate with natural gas and hydrogen mixtures (HENG, hydrogen-enriched natural gas) over a wide range of hydrogen content while maintaining low NO_x emissions. The methodology used in this work is multidisciplinary, incorporating (i) CFD numerical simulations to determine the burner’s geometry, (ii) mechanical design for prototype construction (not discussed in the article), and (iii) experimental tests to assess its hydrogen content capacity, stabilization, and pollutant emission characteristics. The geometry was initially optimized through several RANS simulations to enhance reactant mixing and minimize flashback risks. Additionally, some LES simulations were conducted under specific conditions to achieve more accurate predictions and investigate potential combustion dynamics issues. The proposed solution was then transferred into a prototype. Through experimental testing, the burner prototype was characterized in terms of four key performance indicators: (1) the ability to operate with HENG mixtures with more than 20% ${\mathrm{H}}_2$ content, showing a technological trend exceeding 50%; (2) the ability to operate with low ${\mathrm{NO}}_{\mathrm{x}}$ (<25 ppm) and CO emissions within the 30–70% hydrogen volume range; (3) the ability to ignite HENG mixtures with ${\mathrm{H}}_2$ in the 30–70% hydrogen volume range; and (4) the ability to operate with a fluctuating hydrogen content, ±15% over time, while still complying with ${\mathrm{NO}}_{\mathrm{x}}$ and CO emission limits. Full article

In a global landscape where the launch of satellites into space is growing exponentially, there is an increasing demand for propulsion solutions to perform various types of maneuvers. In this context, the present study aims to investigate a 3D-printed ABS (Acrylonitrile Butadiene Styrene)-based fuel for use in a 10 N-scale hybrid rocket in order to promote cost-effective and environmentally friendly access to space. As this material is currently unknown in this field and lacks a thermodynamic database, characterization of its pyrolysis process was carried out through a mixed approach combining experimental data and numerical simulations. The experiments show excellent performance of the H₂O₂-3D-printed ABS pair; despite the lack of information on its thermodynamically relevant quantities, it was possible to accurately reconstruct the fuel consumption profile as well as its regression rate and the spatial and temporal average values using the numerical model and Arrhenius parameters derived in this work. The methodology and results obtained herein represent tools that can be useful for the design of small-scale rockets using 3D-printed ABS-based fuels as well as a starting point for the development and analysis of the complex geometries made possible through additive manufacturing. Full article

The transition from fossil fuels to renewable energy sources often requires shifting toward biomass fuels such as agriculture residues and waste, which tend to emit higher emission rates during combustion, and one of them is sulfur compounds. The main objective of this study is to clarify the regularities of the formation of sulfur compounds depending on the technological factors when burning sulfur-containing biomass. The experiments were conducted on two experimental stands—models of 20 kW and 25 kW capacities of industrial boilers equipped with reciprocating grates—by burning sunflower husk pellets and meat bone meal. The influence of incomplete combustion (indicator CO concentration), flue gas recirculation, and combined effects of both factors on concentrations of SO₂, SO₃, and H₂S were investigated during experiments. In addition, 20–90% of the sulfur in the fuel is converted to SO₂, contingent upon the combustion conditions. These findings have practical implications for the design and operation of biomass combustion systems. The highest SO₂ emissions were observed when primary air was mixed with flue gas recirculation and at the highest content of CO. The correlation of SO₂ and SO₃ and SO₂ and H₂S concentrations in flue gases of boilers was investigated. The conversion ratio of SO₂ to SO₃ was determined under different combustion modes and showed that this ratio can reach up to 5%. The sulfur content in ash deposits in different areas of the actual industrial boiler was analyzed. The highest percent of sulfur (S = 20%) in ash was found on the first boiler pass. Full article

As solution combustion synthesis (SCS) becomes a universal route to metal oxide nanomaterials, it also paves the way for mixed-fuel combustion synthesis as an advanced approach to the synthesis of materials of desirable properties for diverse applications. Major significance is attached to the rates of decomposition and combustion temperatures of the fuel as determinant factors of the morphology and physicochemical properties of the materials obtained. This has promoted the use of mixed-fuel systems characterized by lower decomposition temperatures of organic fuels and higher rates of combustion. The review work presented herein provides a comprehensive analysis of the applications of mixed-fuel SCS in ceramics, fuel cells, nanocomposite materials, and the recycling of lithium battery materials while taking into consideration the effects of the mixed-fuel system on the physicochemical and morphological properties of those materials, as compared to their analogues prepared via single-fuel SCS. Full article

This study develops and validates a three-dimensional CFD model for a 12 L large-bore active-type pre-chamber spark-ignition (PCSI) engine fueled by natural gas. The model incorporates an advanced Extended Coherent Flamelet Model (ECFM-3Z) with a tuned stretch factor to capture complex turbulence–flame interactions, flame propagation, and pollutant formation under ultra-lean conditions. By systematically varying pre-chamber geometries—specifically the orifice diameter, cone angle, diverging tapered nozzle, and volume—the simulations assess their effects on combustion dynamics, heat release rates, turbulent jet penetration, and emissions (NOx and CO). Model predictions of in-cylinder and pre-chamber pressure profiles, combustion phasing, and emission trends are validated against experimental data. The results demonstrate that optimizing pre-chamber and orifice configurations enhances turbulent mixing, accelerates flame development, and reduces local high-temperature zones, thereby suppressing NOx and CO formation. Although some discrepancies in NOx predictions persist due to limitations in current turbulence–chemistry models, the findings offer valuable insights for the design of high-efficiency, low-emission PCSI engines. Full article

Climate change is a global phenomenon having wide-ranging social, economic, ecological, and environmental sustainability implications. This study assesses climate change awareness, understanding, causes, mitigation measures, and practices among residents of the Kathmandu Valley through a mixed-method approach. Quantitative surveys with 433 respondents and four Focus Group Discussions (FGDs) are conducted with diverse demographics. Descriptive statistics is used to summarize quantitative data, and the chi-square (χ²) test is used to measure the associations between awareness, understanding, causes, mitigation measures, and practices among various demographics. The analysis shows that respondents frequently link climate change to extreme weather events, particularly flooding, severe hot and cold waves, and changes in rain precipitation patterns. Furthermore, the respondents identify deforestation, industrialization, and fossil fuels as the primary causes, with mitigation strategies such as afforestation, recycling waste, and use of renewable energies for long-term environmental sustainability. Similarly, the survey analysis also revealed that greenhouse gases like carbon dioxide and methane are major drivers of climate change; individuals, industries, and governments are held accountable for climate change with industries as key polluters. Furthermore, individuals are self-aware to adopt sustainable practices, and the government can play a vital role through policies promoting renewable energy, afforestation, and waste management, alongside raising awareness. Other highlights of the analysis have been raising voices of collective action at all levels, which is crucial to mitigate the impact of climate change. The study also addresses the gaps in comprehensive climate literacy and underscores the need for targeted educational initiatives to foster informed climate actions within the community. Likewise, the study brings the findings that policymakers should prioritize inclusive engagement strategies, ensuring that climate policies and adaptation programs are accessible, particularly to those who are less represented in environmental discourse, such as older adults and unschooled individuals. Full article

Microalgal biomass contributes to the valorization of urban and agro-industrial solid waste via hydrothermal co-liquefaction (co-HTL) for the production of biocrude, a sustainable substitute for petroleum. Tropical and populous countries like Brazil generate a lot of agro-industrial waste, such as sugarcane bagasse and malt bagasse, as well as sludge from sewage treatment plants. Such residues are potential sources of biocrude production via thermochemical conversion. To increase biocrude productivity, microalgal biomass has been successfully used in mixing the co-HTL process feed with different residues. In addition to biocrude, co-HTL generates an aqueous phase that can be used to produce H₂ and/or electricity via microbial energy cells. In this sense, this paper aims to present the potential for generating energy from solid waste commonly generated in emerging countries such as Brazil based on a simplified scheme of a conceptual biorefinery employing algal biomass co-HTL together with sugarcane bagasse, malt bagasse, and sludge. The biorefinery model could be integrated into an ethanol production plant, a brewery, or a sewage treatment plant, aiming at the production of biocrude and H₂ and/or electricity by bioelectrochemical systems, such as microbial electrolysis cells and microbial fuel cells. Full article