Search Results (2,254)

Heavy-duty vehicles dominate global freight movement and primarily rely on fossil-derived diesel fuel. However, fluctuations in crude oil prices and evolving emissions regulations have prompted interest in alternative powertrains to enhance fleet energy resiliency. This study paired real-world operational data from a large commercial fleet with high-fidelity vehicle models to evaluate the potential for replacing diesel internal combustion engine (ICE) trucks with alternative powertrain architectures. The baseline vehicle for this analysis is a diesel-powered ICE truck. Alternatives include ICE trucks fueled by bio- and renewable diesel, compressed natural gas (CNG) or hydrogen (H₂), as well as plug-in hybrid (PHEV), fuel cell electric (FCEV), and battery electric vehicles (BEV). While most alternative powertrains resulted in some payload capacity loss, the overall fleetwide impact was negligible due to underutilized payload capacity for the specific fleet considered in this study. For sleeper cab trucks, CNG-powered trucks achieved the highest replacement potential, covering 85% of the fleet. In contrast, H₂ and BEV architectures could replace fewer than 10% and 1% of trucks, respectively. Day cab trucks, with shorter daily routes, showed higher replacement potential: 98% for CNG, 78% for H₂, and 34% for BEVs. However, achieving full fleet replacement would still require significant operational changes such as route reassignment and enroute refueling, along with considerable improvements to onboard energy storage capacity. Additionally, the higher total cost of ownership (TCO) for alternative powertrains remains a key challenge. This study also evaluated lifecycle impacts across various fuel sources, both fossil and bio-derived. Bio-derived synthetic diesel fuels emerged as a practical option for diesel displacement without disrupting operations. Conversely, H₂ and electrified powertrains provide limited lifecycle impacts under the current energy scenario. This analysis highlights the complexity of replacing diesel ICE trucks with admissible alternatives while balancing fleet resiliency, operational demands, and emissions goals. These results reflect a US-based fleet’s duty cycles, payloads, GVWR allowances, and an assumption of depot-only refueling/recharging. Applicability to other fleets and regions may differ based on differing routing practices or technical features such as battery swapping. Full article

Passenger transport companies have often been affected by fires in their vehicles, causing considerable damage. As a result, it is important to study the causes and effects of these fires, as well as to define the maintenance policies and strategies to be implemented to minimize the probability of this type of accident occurring. The support for this paper was based on the study of an accident that occurred in Portugal involving a passenger bus that suffered a fire in the engine compartment, which spread to the passenger compartment and caused the destruction of the vehicle, with no personal injuries. This study used infrared image analysis technology, oil ignition temperature analysis, maintenance history, accident history and operator interviews to determine the possible cause of the ignition. It was found that the cause was due to oil leaks from the engine compartment cooling system. The present communication will share a set of explanatory elements of the circumstances in which the accident occurred. In addition to identifying the causes of the accident, the study warns of the importance of more effective and efficient maintenance, particularly when using Condition Based Maintenance (CBM), including periodic visual inspections of the various mechanical and electrical components that make up the vehicles. The conclusions presented in the study also show that these events are not unrelated to the poor or even non-existent maintenance policy for the entire fleet, including the applicable standards. Full article

Based on high-performance engine technologies, this study investigated the performance enhancement of marine diesel engines through a numerical analysis based on computational fluid dynamics simulations. Three key injector parameters—spray angle, insertion depth, and nozzle hole diameter—were selected for the analysis. A total of 27 simulation cases were generated to examine their combined effect on engine output and efficiency. The simulation model was validated using engine commissioning data, and the error margin was within ±5%, thus confirming the reliability and accuracy of the computational approach. The nozzle hole diameter had the greatest influence on performance, followed by spray angle and insertion depth. Notably, Case 21 (150° spray angle and 0.27 mm diameter) and Case 27 (150° spray angle, 0.27 mm diameter, and 2.7 mm depth) achieved the highest efficiency. In both cases, engine output was maintained while fuel injection was reduced by approximately 10.3% compared with the reference condition (from 0.155 to 0.139 g). Unlike previous studies that were limited to single- or dual-parameter analysis, this study simultaneously varied three injector parameters, yielding a comprehensive set of performance outcomes. The results provide valuable baseline data for the future design and development of high-efficiency marine diesel engines. Full article

The utilization of low- and zero-carbon fuels in internal combustion engines is gaining increasing interest. In marine engine applications, the co-combustion of methane and ammonia has emerged as a promising strategy for reducing carbon emissions. In this work, a chemical kinetic mechanism for n-heptane/methane/ammonia blended fuel was developed and validated. Using this mechanism, sensitivity and chemical kinetic analyses were performed to explore the ignition characteristics of the fuel mixture. The results indicate that at an initial temperature of 1000 K, reaction R152 (C₇H_15-2 = CH₃ + C₆H₁₂) exerts the strongest inhibiting effect on ignition. C₇H_15-2 is a major low-reactivity intermediate generated during n-heptane decomposition, and the accumulation of such intermediates contributes to the negative temperature coefficient (NTC) behavior. A cross-reaction between CH₄ and NH₃, R111 (CH₄ + NH₂ = CH₃ + NH₃), was identified, which impedes the smooth progression of oxidation. Elevated temperatures, oxygen-rich conditions, and higher ammonia blending ratios promote the formation of NO. The production of N₂O is primarily governed by reaction R105 (NH + NO = N₂O + H), whose rate increases with the NH₃ molar fraction. Consumption of N₂O occurs mainly via reactions R92 (N₂O + H = N₂ + OH) and R94 (N₂O (+M) = N₂ + O (+M)), both of which occur later than its formation through R105, indicating that N₂O consumption is more sensitive to temperature. Full article

This study presents a first-of-its-kind investigation into retrofitting domestic vessels with a novel hybrid system integrating a Solid Oxide Fuel Cell (SOFC) and an Internal Combustion Engine (ICE). Using a Lake Ferry and an Island Ferry as case studies, three power-sharing scenarios (10–20% SOFC contribution) were examined for cruise and port operations. The results show that increasing the SOFC power share enhances overall system efficiency, reducing daily fuel energy consumption by up to 9% while achieving SOFC efficiencies of 58–60% in port. The design analysis confirms the physical retrofit feasibility for both vessels, with all scenarios occupying 72–92% of available machinery space. However, increasing the SOFC share from 10% to 15–20% raised total system weight by 10–20% and volume by 12–27%. Economically, the system demonstrates strong viability for high-utilization vessels, with Levelized Cost of Energy (LCOE) values of 236–248 EUR/MWh, while the sensitivity analysis highlights the SOFC capital cost as the dominant economic driver. Environmentally, the hybrid system achieves annual CO₂ reductions of 46–51% and NOx reductions of 51–62% compared to conventional diesel systems, with zero NOx emissions in port. The SOFC-ICE hybrid system proves to be a robust transitional pathway for maritime decarbonization, particularly for vessels with significant port-side operating hours. Full article

Methanol is a promising alternative marine fuel due to its favorable combustion characteristics and potential to reduce exhaust emissions under increasingly stringent International Maritime Organization (IMO) regulations. This study presents a three-dimensional computational fluid dynamics (CFD) analysis of a four-stroke, medium-speed marine engine operating in methanol–diesel dual-fuel (DF) mode. Simulations were performed using AVL FIRE for a MAN B&W 6H35DF engine, covering the in-cylinder process from intake valve closing to exhaust valve opening. Nine operating cases were investigated, including seven methanol–diesel DF cases with equivalence ratios (Φ) from 0.18 to 0.30, one methane–diesel DF case (Φ = 0.22), and one pure diesel baseline. A power-matched condition (IMEP ≈ 20 bar) enabled consistent comparison among fueling strategies. The results show that methanol–diesel DF operation reduces peak in-cylinder pressure, heat-release rate, turbulent kinetic energy, and wall heat losses compared with diesel operation. At low to moderate Φ, methanol DF combustion significantly suppresses nitric oxide (NO), soot, and carbon monoxide (CO emissions), while carbon dioxide (CO₂) emissions increase with Φ and approach diesel levels under power-matched conditions. These results highlight methanol’s potential as a viable low-carbon fuel for marine engines. Full article

The utilization of thermoelectric systems within internal combustion engines has emerged as a promising approach to recuperate a portion of the energy dissipated through exhaust gases. The objective of this study is twofold: firstly, to assess the heat recovery potential of a thermoelectric generator integrated into a diesel engine, and secondly, to elucidate the impact of varying operating conditions on the efficiency of heat recovery. For this purpose, the thermoelectric generator was mounted onto the exhaust pipe of a single-cylinder diesel engine featuring a common-rail fuel injection system with pilot injection and a displacement volume of 1.12 L. The calculations were conducted under 100% engine load at 1500 RPM engine speed and three different injection timing settings (−2, STD, and +2 °CA). The optimum heat recovery efficiency was determined to be 5.02%, which was achieved under the following conditions: B50 fuel, −2 °CA injection timing, 1500 RPM engine speed, and 100% engine load. Full article

During the diesel engine start-up phase, low rotational speed and coolant temperature result in poor fuel atomization and prolonged ignition delay. This impedes the in-cylinder combustion process and directly impacts the engine’s emission performance. As the first combustion cycle during the starting process, the initial starting cycle significantly influences subsequent combustion cycles and overall starting performance. This paper proposes a target-torque-based control strategy for fuel injection quantity during the starting process. It optimally determines the target acceleration curve for the starting process, thereby calculating the optimal fuel injection quantity for the initial starting cycle. Based on this, a combustion system simulation model of the diesel engine was established using the 3D CFD software AVL FIRE v2010. The simulation investigated the impact of first injection speed on the combustion process and performance of the first firing cycle under different ambient temperatures: normal temperature (20 °C), low temperature (5 °C), and cold start (−10 °C). The results indicate that the optimal first cycle injection quantities under normal, low, and cold start conditions are 17.3 mg, 18.5 mg, and 20.4 mg, respectively. The impact of first injection speed on the first firing cycle combustion process primarily manifests in the mixture formation rate and time, and higher speeds do not necessarily yield better results. The optimal first injection speeds at normal temperature (20 °C), low temperature (5 °C), and cold start (−10 °C) were 220 r/min, 240 r/min, and 220 r/min, respectively. Corresponding indicated thermal efficiencies were 30.74%, 28.67%, and 28.7%, with relatively low emissions of pollutants such as CO, NOx, and HC. Full article

Forestry logging is among the most hazardous economic activities, so identifying where hazards and risks concentrate supports targeted prevention. This scoping review mapped evidence on logging hazards and risks, their co-occurrence with operations, and preventive measures. PRISMA-ScR was followed. Only peer-reviewed journal articles (2015–2025) in English on occupational hazards/risks, risk-assessment methods or preventive measures in logging were included, found in Scopus, Web of Science, Inspec and Dimensions (last search 15 September 2025). Independent data screening and extraction were performed by two reviewers, with a third reviewer resolving any disagreements. No formal risk-of-bias appraisal was conducted. Forty-two studies were included. Hazards and risks concentrated in three phases—chainsaw/manual cutting, skidding/cable yarding, and loading/short-haul transport—where acute injury mechanisms (struck-by events, slips/trips/falls, rollovers, lacerations) coexisted with chronic exposures (musculoskeletal strain, noise, vibration, diesel exhaust). Preventive measures emphasised engineering and organisational controls, complemented by raining and PPE, but were inconsistently specified and evaluated. Evidence was heterogeneous and geographically concentrated in few countries, limiting generalisability. A small set of tasks consistently concentrates acute and chronic risks; prevention should integrate accident control and health protection, prioritising engineering/organisational measures supported by training and PPE. Future studies should standardise descriptors and outcome metrics to enable comparisons. Full article

The transition toward sustainable energy systems necessitates innovative solutions that reduce greenhouse gas emissions while improving fuel efficiency in existing combustion technologies. Hydrogen has emerged as a promising clean energy carrier; however, its widespread deployment is limited by challenges associated with large-scale transportation and storage. This study investigates a practical alternative in which hydrogen-rich syngas produced via steam methane reforming (SMR) is directly integrated into the diesel engine intake, thereby eliminating the need for fuel transport, storage, and separation while supporting a more sustainable fuel pathway. A validated computational fluid dynamics (CFD) model was developed to examine the effects of varying SMR gas mixture ratios (0–20%) on engine combustion, performance, and emissions. The findings reveal that increasing the SMR fraction enhances in-cylinder pressure by up to 15.7%, heat release rate by 100%, and engine power output by 102.5% compared to conventional diesel operation. Additionally, under SMR20 conditions, CO₂ emissions are reduced by approximately 12%, demonstrating the potential contribution of this approach to decarbonization and climate mitigation efforts. However, the rise in in-cylinder temperatures was found to increase NO_x formation, indicating the necessity for complementary emission control strategies. Overall, the results suggest that direct SMR syngas integration offers a promising pathway to improve the environmental and performance characteristics of conventional diesel engines while supporting cleaner energy transitions. Full article

Succinimide additives play an important role in combating engine deposits and are therefore commonly blended in fuels. As many of the methods currently used to quantify them in fuel rely on time-consuming techniques and the use of expensive laboratory equipment, a more practical approach was explored. For this purpose, an existing method for aqueous samples involving a colour reaction with Rose Bengal dye and spectrophotometric detection in the UV/Vis range was modified for usage in the nonpolar fuel matrix and tested for applicability. The result was an accessible method for determining the succinimide additive content of diesel fuel—including biodiesel—that is easy to implement in the laboratory routine. Full article

In recent years, Ammonia has emerged as a promising carbon-free fuel alternative, offering considerable potential to reduce CO₂ emissions and contribute to the decarbonization of the transportation industry. This study focuses on the economic feasibility and market price of ammonia now and in the future, highlighting the necessary infrastructure for emission-free transport operation. The project compares various production pathways for alternative fuels including hydrogen, ammonia, methanol, LNG, and diesel, considering both “green” and “gray” production methods. A key output of this research is the development of a flexible cost calculation tool, which allows users to simulate various scenarios by adjusting variables to ensure the continuity of the project. This tool enables dynamic analysis of future fuel prices and operational costs, accounting for the fluctuating electricity prices for green ammonia production and the long-term rise in CO₂ prices. Moreover, the study provides detailed cost modeling, infrastructure requirements, and refueling options for ammonia in comparison to other fuels. The findings indicate that ammonia is a promising long-term option for the maritime sector. While the adaptation to ammonia-based engines remains in the research phase, the long-term benefits of lower emissions and operating costs justify the investment in the necessary research and infrastructure, such as storage and refueling facilities. Full article

This study examines the environmental and economic impacts of transitioning RORO Pax ships from diesel to green and blue hydrogen fuel, focusing on the Jazan case study vessel. It evaluates the environmental and economic effects for both retrofitted and new vessels. Findings reveal that hydrogen-powered PEMFC engines achieve a 99.13% reduction in NOx emissions and reduce both SO_x and CO₂ emissions to minimum values. The analysis indicates that retrofitting with blue hydrogen can achieve a lifetime emission reduction of approximately 134 kton, yielding a net benefit of USD 4.46 per ton of emissions reduced. Newbuilding options present a more favorable financial profile at USD 19.31 per ton, surpassing green hydrogen’s USD 16.61 per ton. The study highlights the economic infeasibility of retrofitting existing vessels due to insufficient operational life, while hydrogen fuel becomes viable for sustainable new builds after 6 to 10 years, potentially resulting in annual cost savings of USD 2 to USD 3 million and competitive hydrogen production costs of up to USD 0.30 per kWh. Full article

Decarbonization of compression-ignition engines requires evaluation of carbon-free and low-carbon fuel alternatives. Ammonia (${NH}_3$) offers zero direct carbon emissions but faces combustion challenges including low flame speed (7 $\mathrm{c}\mathrm{m}/\mathrm{s}$) and high auto-ignition temperature (657 °$\mathrm{C}$). Methanol provides improved reactivity and bound oxygen content that can enhance ignition characteristics. This computational study investigates diesel–ammonia–methanol ternary fuel blends using validated three-dimensional CFD simulations (ANSYS Forte 2023 R2; ANSYS, Inc., Canonsburg, PA, USA) with merged chemical kinetic mechanisms (247 species, 2431 reactions). The model was validated against experimental in-cylinder pressure data with deviations below 5% on a single-cylinder diesel engine (510 cm³, 17.5:1 compression ratio, 1500 rpm). Ammonia energy ratios were systematically varied (10–50%) with methanol substitution levels (0–90%). Fuel preheating at 530 K was employed for high-alcohol compositions exhibiting ignition failure at standard temperature. Results demonstrate that peak cylinder pressures of 130–145 bar are achievable at 10–30% ammonia with M30K–M60K configurations, comparable to baseline diesel (140 bar). Indicated thermal efficiency reaches 38–42% at 30% ammonia-representing 5–8 percentage point improvements over diesel baseline (31%)-but declines to 30–32% at 50% ammonia due to fundamental combustion limitations. ${CO}_2$ reductions scale approximately linearly with ammonia content: 35–55% at 30% ammonia and 75–78% at 50% ammonia. ${NO}_X$ emissions demonstrate 30–60% reductions at efficiency-optimal configurations. Multi-objective optimization analysis identifies the A30M60K configuration (30% ammonia, 60% methanol, 530 K preheating) as optimal, achieving 42% thermal efficiency, 58% ${CO}_2$ reduction, 51% ${NO}_X$ reduction, and 11% power enhancement versus diesel. This configuration occupies the Pareto frontier “knee point” with cross-scenario robustness. Full article

This study provides a comparison between the impact of two gas fuels, compressed natural gas (CNG) and hydrogen (H₂), on the exhaust emissions of a single-cylinder diesel engine operating in dual-fuel mode. The analysis is conducted with a constant and maximum achieved gas-to-total-fuel ratio (K = 20% and K = max) under varying load conditions, specifically at an engine speed of 2000 min⁻¹ and brake mean effective pressures ranging from 0.2 to 0.43 MPa. The results reveal that H₂ significantly improves the engine’s emissions profile compared to CNG. When H₂ is used as the secondary fuel, reductions in soot, carbon monoxide (CO), carbon dioxide (CO₂), and unburned hydrocarbons (CHs) are more pronounced. However, under certain load conditions, nitrogen oxide (NO_x) emissions are higher with H₂ than with CNG and can even surpass those observed during diesel-only operation. These findings suggest that while H₂ demonstrates superior overall emissions performance, its impact on NO_x emissions under specific conditions requires further optimization to maximize environmental benefits. Full article