Browse Topic: Emissions

Items (24,386)

Research on Urban Bus Timetable Optimization Based on Deep Reinforcement Learning

2026-99-0538

7/10/2026

Public transportation serves as a crucial component of urban mobility, contributing to the alleviation of urban congestion, reduction of travel expenses, and mitigation of air pollution. Nonetheless, the dynamic passenger demand and the complex traffic conditions render traditional bus timetables inadequate, leading to ineffective allocation of public transportation resources. Consequently, it is essential to create bus timetables that are responsive to actual traffic scenarios and fluctuating passenger demand. This study regards the bus timetable planning problem as a Markov decision-making process within a discrete time framework, proposing a deep reinforcement learning-based optimization model for bus timetables. In particular, the model is designed to account for both bus companies and passengers, incorporating a state space and reward calculation method that emphasizes passenger comfort. Then Deep Q-Network (DQN) methodology is employed to issue instructions on whether a bus departure at each time, and bus timetable is generated gradually over time. Experimental results indicate that the proposed approach significantly reduces bus travel costs and enhances the overall travel experience for passengers in comparison to traditional methods.

Xu, Jie, Xia, Dong, Yang, Jianxi, Wang, Bing

Sustainable Airport Emissions Reduction through Optimized End-Around Taxiway Operations: A Simulation Approach

2026-99-0582

7/10/2026

To mitigate the risks of runway incursions during aircraft transitions between closely spaced parallel runways, major hub airports globally have implemented End-Around Taxiway (EAT) as an effective safety solution. Operational data from leading international airports confirms that EAT installations have successfully enhanced surface safety while maintaining operational efficiency. However, the EAT involves a longer taxiing route, resulting in higher fuel consumption and pollutant emissions. This study takes the example of a set of closely spaced parallel runways at a domestic airport to analyze the ground taxiing process of arrival and departure flights, proposing a dynamic allocation strategy for EAT operations that can achieve energy conservation and emission reduction during the taxiing process. Through simulation, its effective operational performance is studied.

Wang, Zinan, Ye, Bojia

Study on Diesel-Methanol Non-Premixed Combustion Characteristics of a Marine Dual-Fuel Engine at Different Methanol Substitution Rate

2026-99-0517

7/10/2026

Methanol use in marine engines has the potential to reduce nitrogen oxide emissions, particulates, and greenhouse gas emissions. A turbocharged four-stroke marine diesel powerplant was converted to run as a double-DI (direct injection) diesel-methanol hybrid engine. Experimental studies using a non-premixed combustion scheme showed that higher methanol substitution ratios (MSR) led to increased peak heat release rates. The combustion process displayed distinctive two-phase behaviors. Increasing MSR caused retarded ignition timing, shortened combustion duration, and improved thermal efficiency. Combustion stability was significantly improved at higher MSR. Emissions results showed NOX and HC were increased in proportion to MSR, whilst particulate emissions and CO concentrations were inversely reduced. Methanol enrichment was found to enhance NOX and HC formation processes but also accelerate soot particulate decomposition and CO oxidation mechanisms.

Li, Xiao, Jiang, Yuqi, Yan, Ping, Zheng, Liang, Li, Hongmei, Zhang, Wenzheng, Chen, Chao, Man, Zhongguo

Experimental Study of Warm-Up And Startability Operations in a Spark Ignition Engine Fueled with Ethanol Gasoline Blends

2026-01-0738

7/1/2026

The mitigation of Greenhouse Gas (GHG) emissions poses a major challenge for the transportation sector, driving the need for renewable fuels. Bioethanol represents a promising fuel for Spark-Ignition (SI) engines, combining a reduced life-cycle CO₂ impact with advantageous combustion properties. However, despite its proven performance under steady-state conditions, the widespread of fuels with high ethanol content is still constrained by significant difficulties during engine cold-start operation. This study aims to experimentally assess the effect of ethanol concentration on cold-start performance and warm-up transient behavior of a Naturally Aspirated (NA), Port Fuel Injected (PFI) SI engine. Warm-up tests were conducted at an operating condition of 2000 rpm engine speed and 20 Nm torque using three fuels with increasing ethanol content: commercial gasoline (E5), E30 and E60. In addition, dedicated startability tests were carried out for E60 and neat ethanol (E100) at different initial engine wall temperatures to evaluate fuel sensitivity to thermal conditions during engine start. The experimental results indicate that increasing ethanol concentration has a negligible effect on the overall duration of the warm-up process, while leading to a modest reduction in both engine wall and exhaust gas temperatures. At the same time, E100 displays severe startability limitations at low initial wall temperatures, requiring repeated cranking attempts before stable operation can be achieved. The same startability issues have been observed for E60 but with limited intensity. Two minimum engine wall temperature ranges were identified for reliable cold-start operation at 20-25 °C for E60 and 25-30°C for E100. Overall, these findings experimentally confirm the dominant influence of engine thermal conditions on the reliable startability of ethanol-fueled spark-ignition engines.

Falbo, Luigi, Falbo, Biagio, Perrone, Diego, Castiglione, Teresa

NO _x Formation Characteristics of Lean Hydrogen Combustion: From 0D Analysis to Comprehensive 3D-CFD Engine Investigations

2026-01-0732

7/1/2026

The transition toward climate-neutral transportation requires powertrain concepts that combine high efficiency with low pollutant emissions. In this context, hydrogen-fueled internal combustion engines represent a promising solution when hydrogen is produced from renewable energy sources. Owing to its specific molecular properties, hydrogen offers new possibilities for influencing and optimizing the combustion process and reducing the emission formation. This paper presents a numerical approach for characterizing the NOx formation in a single-cylinder research engine equipped with port fuel injection and a passive pre-chamber ignition system. The single-cylinder is operated over a wide range of engine loads and speeds, covering air-to-fuel ratios from λ=1.5 to 2.5 and achieving up to 23 bar indicated mean effective pressure. The study focuses on the influence of engine load and mixture composition on NOx emissions. A dedicated look-up table approach in combination with several reaction parameters based on the extended Zeldovich mechanism are evaluated through comparison with experimental data. Furthermore, multiple sampling positions within the CFD mesh are examined. The simulations reproduce measured trends across variations in load and air-to-fuel ratio with good accuracy. At high load and λ=1.5, NOx emissions of up to 6000 ppm are produced, decreasing exponentially with increasing excess air. Finally, potential NOx reduction strategies for the single-cylinder are examined. While influencing the mixture homogenization shows limited effectiveness, temperature-based actions prove to be more effective. Among the investigated approaches, a Miller intake valve strategy yields the largest benefit, achieving approximately 10% NOx reduction by lowering end-of-compression temperatures and increasing residual gas dilution under otherwise identical operating conditions.

Gal, Thomas, Vacca, Antonino, Chiodi, Marco, Schmelcher, Robin, Kulzer, Andre Casal

Numerical Analysis of Directly Injected Hydrogen into a High-Pressure Chamber

2026-01-0745

7/1/2026

Hydrogen Internal Combustion Engines have emerged as an option for decarbonizing heavy-duty transportation. However, injecting high-pressure hydrogen gas into pressurized combustion chambers induces complex compressible flow phenomena, including choked flow and under-expanded supersonic jet structures, which challenge conventional modeling approaches for optimizing engine performance and emissions. This study conducts a numerical investigation of transient hydrogen injection into a high-pressure argon environment, benchmarking a 2D axisymmetric Computational Fluid Dynamics (CFD) model against high-fidelity experimental optical measurements. Utilizing Ansys Fluent with a density-based solver, coupled with the k-ω SST turbulence model and species transport equations, simulations were performed at injection pressures of 6 MPa and 10 MPa into a 1 MPa ambient chamber. The simulation successfully captured fundamental compressible physics, including Mach disk formation and significant expansion cooling near the nozzle exit. Validation results revealed a strong dependency on the nozzle pressure ratio (nPR). At 6 MPa (nPR=6), the model achieved good agreement with experimental data, predicting tip penetration depth within 10% . However, at 10 MPa (nPR=10), while axial penetration depth predictions remained within the 10% error margin, they were consistently underestimated, and radial dispersion was significantly under-predicted. These discrepancies at high energy levels highlight the challenges of predicting turbulent entrainment within the current modeling framework. The results suggests that the observed deviations are likely to be caused by combined limitations related to the RANS turbulence model, the potential shortcomings of the 2D axisymmetric assumption in resolving highly transient mixing phenomena, the meshing strategy used, the constant assumption made about the coefficient of discharge, and the crucial role of the Turbulent Schmidt number (SCt).

Castilla Batun, Uriel Isaac, Alzahrani, Fahad

Biofuel Effect on Regeneration Capability and Soot Reactivity in SCRoF Systems

2026-01-0750

7/1/2026

Biodiesel blends (B7, B20, B100) were evaluated in a Stage V-compliant SCR on Filter (SCRoF) system for heavy-duty applications to quantify soot reactivity and filter regeneration capability. Compared to conventional diesel (B7), B20 showed slightly faster regeneration performance under real-driving conditions, while B100 resulted in reduced particulate formation and higher soot reactivity, with more intense exothermic events requiring careful management. These differences are attributed to the distinct physical-chemical properties of the fuels (oxygen content, lower heating value) and their interaction with Diesel Oxidation Catalyst (DOC)/SCRoF. All tests were conducted on an engine dynamometer with a Cursor 9 FPT (Fiat Powertrain). Findings are discussed in the context of EU Stage V limits and practical control strategies for heavy-duty applications.

Costa, Simone

Improved Thermal Management for Operating a Battery Electric City Bus under Real Driving Conditions

2026-01-0758

7/1/2026

The goal of reducing global CO2 emissions requires actions especially for the transportation sector. To achieve the goal, electric traction motors are frequently implemented in passenger vehicles, as well as in commercial vehicles like heavy-duty trucks or buses. Particularly electric city buses have the potential to reduce the local emissions in urban areas and provide local exhaust-emission-free mobility. While their number of registrations rises, research focusses on the improvement of the overall system in order to increase energy efficiency. High importance is gained by the thermal management of the whole system. This research investigates a simulative approach to improve the thermal management and therefore the energy efficiency of an electric city bus. The different thermal components of an electric city bus like drive system, battery system and heating, ventilation and air conditioning system (HVAC system) are modelled. Their thermal behavior has been validated in previous research. Based on the validated model, this study proposes an improved thermal management that, state-dependent, combines the thermal circuits of the single components to reduce the overall energy demand. Cooling or heating is provided by the HVAC system. Furthermore, the simulation utilizes real driving cycles of a city bus in the Hamburg area. Measurement data from an entire year are examined by a cluster analysis that results in typical application profiles for urban bus traffic. These profiles are used as basis for further research. An operating strategy for the thermal management of an electric city bus under real driving conditions is developed using the simulation model. Results are presented, which show that the overall energy demand decreases due to an improved, application profile-dependent thermal management system.

Schäfer, Henrik, Hellberg, Tobias, Meywerk, Martin

Experimental Investigation of Fuel Cutout Strategies in a Heavy-Duty Gasoline Compression Ignition Engine

03-19-03-0015

6/26/2026

This study investigates Gasoline Compression Ignition (GCI), a family of advanced combustion strategies that can be used to achieve low engine-out criteria pollutant emissions in the heavy-duty transportation sector. In particular, high fuel stratification GCI (HFS-GCI) has been shown to have high thermal efficiencies while maintaining a highly controllable and responsive mixing-controlled combustion event. However, stable combustion at low loads has been shown to be the principal challenge to the implementation of HFS-GCI in production applications. It has also been observed that several strategies that achieve stable combustion at low loads result either in increased emissions or efficiency penalties. While the achievement and maintenance of high enough exhaust temperatures for efficient aftertreatment operation is a significant challenge at low loads even for traditional diesel engine operation, this challenge is exacerbated by the low reactivity and colder flame temperature of gasoline. In recent single-cylinder and 1D simulation studies, fuel cutout strategies have been proposed as an enabling strategy to simultaneously improve combustion stability at low loads and increase exhaust temperatures. In this study, fuel cutout strategies are studied in a prototype multicylinder heavy-duty GCI engine based on a Cummins ISX15 diesel engine. Steady-state engine studies are conducted at warm and cold idle conditions to identify combinations of cylinders that provide the most benefit. NOx and soot limits are set and the performance of cutout strategies are compared to a pre-optimized baseline. The most optimal strategies from steady-state testing are then implemented under transient test cycle conditions similar to those required under United States regulatory testing. The strategies were found to offer simultaneous improvements in stability, fuel consumption, criteria pollutants, and turbine outlet temperature. The choice of cylinders whose fuel supply was cut was seen to be important in realizing the observed benefits. The use of fuel cutout strategies offered optimal performance at all the conditions considered, offering an additional lever to improve the performance of HFS-GCI and highlighting a promising pathway to the use of gasoline-like fuels as alternatives to diesel in heavy-duty engines.

Viswanathan, Aravindh Babu, Zhang, Yu, Merritt, Brock

Spray–Wall Interaction at Thermal Swing Coatings in SI Engines

03-19-03-0014

6/25/2026

As a contribution to the reduction of greenhouse gas emissions in the transportation sector, the indicated efficiency of SI engines can be increased via thermal swing coatings. Thereby, a decrease in greenhouse gas emissions can be achieved, although not at all operating conditions. Here, the often-observed increased hydrocarbon emission partially overcompensates the reduced wall heat losses. The main root cause is always attributed to the increased surface roughness and porosity, leading to an increased crevice volume. Further investigations were performed at a single-cylinder engine equipped with a FTIR for species analysis of hydrocarbon emissions. A comparison of direct injection and port fuel injection were performed for RON95 E10 and methanol to assess the influence of mixture preparation. 3D CFD was used to additionally investigate the in-cylinder processes. The comparison of port fuel injection and direct injection showed a significant influence on the fuel hydrocarbon emissions for the direct injection when the thermal swing coating was applied. The effect is more pronounced for methanol. For port fuel injection nearly the same or reduced fuel hydrocarbon emissions can be observed. This is mainly attributed to an increased wall film agglomeration at the piston for the thermal swing coating in case of direct injection, which can be observed in 3D CFD. Due to the low thermal effusivity of the coating, the droplet impingement leads to a notable decrease in the surface temperature. This results in lower evaporation of the fuel and a longer droplet lifetime. Consequently, a fuel wall film is still present at top dead center after ignition leading to additional hydrocarbon emissions.

Fischer, Marcus, Pischinger, Stefan

Holistic Sound Package Design for Optimal NVH and Carbon Footprint of a BEV

2026-01-0708

6/20/2026

Vehicle sound packages are usually designed to provide a given level of vehicle Noise, Vibration, and Harshness (NVH) comfort, within weight and cost constraints. Optimal comfort results can be obtained by considering the interaction of all the parts as a full physical system. So far, extensive research has already been performed and published on optimizing vehicle sound packages to achieve effective noise reduction at lowest cost and weight. Nowadays, due to the urgency of the transition to carbon neutrality, sound packages must also address the reduction of the full vehicle life cycle carbon emissions. Sound package components should use materials that have a low emission impact during production and that are suitable for recycling at the end of the vehicle’s life. This entails reconsidering the material solutions chosen for the sound package as a whole, rather than for each individual component. This article describes possible differentiations in the design of a sound package involving NVH, sustainability, and weight/cost requirements. The study examines how interior and exterior trim components were combined to achieve both optimal NVH and polymer rationalization, through the introduction of mono-material parts and focusing in particular on the use of a new polyester fiber-based floor decoupler, which achieves comparable NVH performance to polyurethane foam without affecting static compression. The article summarizes the vehicle-level performance related to NVH, sustainability, and weight for three sound packages prioritizing either NVH, sustainability or material cost, including a breakdown to analyze the contributions of various components to the overall outcome. A simple metric is introduced to evaluate sustainability, including material, production, use-phase and end-of-life related Greenhouse Gas (GHG) emissions [7–10]. The NVH evaluation involves measuring airborne transfer functions (ATF), complemented by indoor road noise tests. NVH improvements were achieved without an increase in weight, and weight reduction was also possible without negatively impacting NVH performance, both results enhancing the carbon footprint.

Courtois, Theophane, Cardillo, Marco, Criscione, Mattia, Gerges, Youssef, Massocco, Andrea

A Modeling and Experimental Study of the Argon Power Cycle Using Mixing-Controlled Combustion

2026-01-5043

6/19/2026

The closed-cycle hydrogen-fueled argon power cycle is a zero emissions concept that combines a carbon-free fuel with argon as a diluent replacement for nitrogen. The lack of nitrogen in the argon power cycle results in zero NOx emissions on an internal combustion engine platform. There is also massive efficiency improvement because argon is monatomic and has a very high ratio of specific heats. However, this will also result in combustion temperatures and pressures exceeding those normally achieved on an air-standard engine platform. The literature shows conflict between modeling, which promises incredibly high efficiency gains, and experiment, which show more modest efficiency gains. This work combined thermodynamic modeling, literature analysis, and experiments to understand this discrepancy and ultimately understand what level of efficiency gain can be expected for the argon power cycle. It was found that while low compression ratio engines stand to see the largest relative efficiency improvement, high compression ratio engines are the ones that can ultimately achieve ~60%+ efficiency, corresponding to a 15–20% relative improvement in efficiency over an air-standard engine platform operating at or above 50% efficiency. The elevated temperatures and pressures of the cycle result in knock in spark ignition, so either a high compression ratio knock mitigation strategy or mixing-controlled operation is required. Experiments conducted using a diesel-fueled compression ignition engine showed that a 30% argon replacement resulted in ~6% and full nitrogen replacement with argon resulted in ~14% relative efficiency improvement at 8 bar gross indicated mean effective pressure (IMEPg) without intake boosting on a heavy-duty engine with a compression ratio of 20.0 and late intake valve closing, agreeing with modeling results. The key takeaway to match modeling and experimental trends is to accurately model heat transfer, which increases significantly for the argon power cycle.

Gainey, Brian, Ahrling, Christoffer, Tunestal, Per, Tuner, Martin

Accelerated Computational Fluid Dynamics (CFD)-Based Quantitative Prediction of Urea Deposition in Selective Catalytic Reduction (SCR) Systems

2026-01-5041

6/12/2026

Mitigation of harmful emissions from oil-based engines is essential to avoid environmental pollution and comply with various NOx regulations across the globe. This can be partially achieved by injecting urea to produce ammonia (NH3), which reacts with NOx in a catalyst to produce harmless nitrogen (N2) and water vapor (H2O). However, urea deposition in a selective catalytic reduction (SCR) system poses a significant threat to the NOx removal process by not only reducing the urea conversion rate but also blocking the incoming flow and causing an additional pressure drop. Numerical modeling of this urea deposit formation involves multiphase flow physics coupled with accurate heat transfer calculations. Additionally, since urea decomposes into various by-products like biuret, cyanuric acid (CYA), and ammelide, detailed chemical kinetics modeling is equally important. Accurate and fast computational fluid dynamics (CFD) simulations can help accelerate SCR system design cycles, leading to a reduction in experimental cost. In this study, we employ CONVERGE CFD to model the whole process from urea–water solution (UWS) injection to droplet evaporation and decomposition (using 12-step detailed-chemistry), film formation, and final deposition as a solid. A new spray-wall interaction model is introduced based on published experimental observations. The efficacy of the numerical model is demonstrated using an S-bend tube, where the UWS is injected just at the end of the S-bend. The predicted deposit mass and patterns are compared with the experiments, and good agreement is observed for three different operating conditions. A novel boundary morphing feature is activated to model the deformation of the tube walls because of urea deposition. Finally, to accelerate the simulations, a spray database approach is introduced. Coupled with the fixed-flow feature, this results in around 58% reduction in computational time without compromising accuracy. The present work thus provides a numerical framework to accurately capture urea deposition with a fast turnaround time.

Morab, Sumant R., Khalate, Suraj, Ansari, Shoaib, Yang, Pengze

SAE Truck & Off-Highway Engineering: June 2026

26TOFHP066/11/2026

Hitting the road in the all-new VNR Volvo Trucks' revised VNR brings updated safety tech, improved fuel economy and driver comfort features to the regional haul segment. In fuel control How to ensure off-highway combustion systems operate with sufficient control to meet tightening emissions standards and evolving fuel landscapes without sacrificing reliability. Keeping industrial vehicles secure in a digital landscape OEMs, integrators and suppliers must continuously process, assess and identify platform vulnerabilities to prioritize and implement updates that protect systems from cyberattacks and data breaches. Editorial Diversification key for sustainable fleets ACT 2026: Uncertainty still exists over EPA 2027 NOx limit ZF bets big on hybrid transmissions Moog simplifies off-highway electrification Bosch shows off its first U.S. electrolyzer Microvision fast-tracks adoption of Luminar tech; eyes defense, industrial sectors Future-ready, customizable connectivity powers precision agriculture Kenworth's new C580 clocks in for work Harbinger extends its range of medium-duty EVs Kubota's SVL110-3 brings new tech and service features to CTL segment Product Briefs SPOTLIGHTS: Diesel Engines & Subsystems; Manufacturing Tools & Materials; Motors, Inverters & Gearboxes Q&A Volvo turns attention to vocational trucks

Development and Experimental Validation of a 1D Model for Performance and Emissions Analysis of Oxygenated Fuel Blends in a CI Engine

2026-37-0028

6/9/2026

Emissions reduction remains a major concern for internal combustion engines in view of increasingly stringent environmental regulations. To address these challenges while maintaining acceptable engine performance, a wide range of alternative fuels and fuel blends have been investigated to ensure the continued viability of CI engines. This study reports the effects of blending the oxygenated fuel diethylene glycol diethyl ether (DGDE) with hydrotreated vegetable oil biodiesel (HVO) on engine performance and emissions. The investigation is conducted on a 2.3-liter, four-cylinder, common-rail diesel engine, equipped with a variable geometry turbocharger and a high-pressure exhaust gas recirculation system. The objectives of this study are achieved by developing a one-dimensional predictive engine model using the commercial GT-SUITE software. The engine model is developed and experimentally validated, at various operating conditions and HVO–DGDE fuel blends, to predict their effects on combustion characteristics and emissions formation. The validation is performed against measurements collected at the engine test bed. The results indicate that increasing the blending ratio of oxygenated fuel leads to improvements in indicated mean effective pressure and a more favorable Soot–NOx emissions trade-off compared with neat HVO operation. The findings highlight the potential of oxygenated fuel blends to enhance CI engine performance while reducing emissions. This study demonstrates the effectiveness of combining experimental and numerical approaches to evaluate biodiesel–oxygenated fuel blends and provides insights for future research aimed at minimizing CI engine emissions.

Arain, M Wajahat Rasool, Foglia, Antonio, Frasci, Emmanuele, Vitek, Oldrich, Pianese, Cesare, Arsie, Ivan

Forecasting Electric Vehicle Fleet Growth and Energy Requirements in the UK

2026-37-0043

6/9/2026

With the United Kingdom’s goal to achieve a fully decarbonised energy sector by 2035 and achieve net zero greenhouse gas emissions by 2050, the transition of the UK’s passenger car fleet to battery electric vehicles (BEVs) plays a crucial role in reaching this goal. This study evaluates the environmental and energy impact of large-scale BEV adoption by modelling future uptake scenarios using historical fleet data combined with assumed impact of future policy such as the 2030 ban on the sale of new petrol and diesel vehicles. Three predictive models have been developed: fast uptake, in which approximately 100% of the passenger car fleet is replaced by BEVs; moderate uptake, where a large majority of passenger cars are BEVs; and slow uptake, in which BEV adoption does not reach a majority. The results have shown that, if a medium- or large-scale adoption is possible by 2040 predicting nearly 37 million BEVs on the road, the associated electricity demand is predicted to rise close to 110 TWh annually, signifying the need for rapid development in renewable energy generation. Although BEVs significantly reduce transport sector emissions, the overall climate impact is dependent on a continued effort of grid decarbonisation.

Burke, Bradley, Kateregga, Sunny, Sodre, Jose Ricardo

Methane Emission Mitigation in Large-Bore Dual-Fuel Engines via Negative Valve Overlap Diesel Injection: Thermochemical Pathways and Reactivity Control

2026-37-0045

6/9/2026

Low-load natural gas–diesel reactivity controlled compression ignition (RCCI) in medium-speed marine engines is constrained by an insufficient charge thermal state. This limitation leads to partial fuel oxidation, producing high methane emissions. This work evaluates the use of negative valve overlap (NVO) combined with NVO diesel injection as an in-cylinder reactivity enhancement strategy. The simulation study was performed using the University of Vaasa’s advanced thermo-kinetic multi-zone model (UVATZ), extended for reactive simulations during NVO. The extended framework was validated against test-bench data from a prototype Wärtsilä 6L20 dual-fuel engine operating in RCCI mode. The baseline low-load operating point for reforming simulations was defined by reducing the intake manifold temperature to replicate conditions close to partial misfire with 52% combustion efficiency. The parametric sweeps of NVO injection timing and ratio showed that the strategy can be used for in-cycle fast thermal management, effectively restoring complete combustion on an individual cycle basis. In simulated conditions, the best performance was obtained with an NVO injection ratio of 0.3, with the injection scheduled before top dead center. In contrast, increasing the NVO fraction beyond ~0.3 provided no benefit and led to complete misfire due to excessive reduction of main-event high-reactivity fuel. The simulations revealed a coupled thermal–chemical control mechanism. Early NVO injections stabilize combustion through recompression heat release and an increased next-cycle intake valve closing temperature. Sufficiently late injections stabilize combustion by carrying unreacted diesel into the subsequent cycle. Injections near NVO TDC primarily undergo fuel conversion to CO, H2O, and unsaturated light/mid-range hydrocarbons with negligible thermal boost, yielding an overall reactivity deficit.

Soleimani, Amir, Nurmi, Mikael, Hunicz, Jacek, Kim, Jeyoung, Hyvonen, Jari, Mikulski, Maciej

Combined EGR-Air Dilution Effects on Performance, Combustion and Emissions of a Single-Cylinder Spark-Ignition Direct-Injection Hydrogen Engine

2026-37-0009

6/9/2026

Hydrogen internal combustion engines (H2ICE) have emerged as a promising solution for decarbonisation of the transport sector, due to low cost and potential for rapid deployment. However, abnormal combustion and high nitrogen oxide (NOx) emissions limit stoichiometric operation, making dilution strategies essential. While lean combustion has been widely studied, combined dilution strategies of air and exhaust gas recirculation (EGR) require further investigation. This work presents experimental results from a boosted 0.5-litre spark-ignition direct-injection single-cylinder research engine equipped with high-tumble ports and cooled high-pressure EGR. Relative air–fuel ratios (lambda) of 1 to 3 and EGR rates of 0 to 40% are evaluated at 5, 10, and 15 bar of indicated mean effective pressure (IMEP) at 2000 rpm to assess effects on net indicated thermal efficiency (nITE), combustion, and emissions. A peak nITE of 43.5% is achieved at 10 bar IMEP, λ = 2.5, and 30% EGR, which can be primarily attributed to low heat losses while maintaining lower combustion losses than at higher dilution levels. NOx emissions are effectively mitigated with increasing EGR and are largely independent of lambda at 5 bar IMEP under EGR dilution. At high load, EGR is shown to be beneficial to achieve high efficiency and lower NOx at lower dilution rates, thereby reducing boosting requirements. Equivalent dilution parameters are used to investigate combined effects of EGR and air dilution, from a mass dilution perspective with the mass dilution rate (MDR) and equivalent thermal reduction with the thermal dilution parameter (TDP). Indicated efficiency and unburned hydrogen emissions correlated strongly with MDR, while temperature-dependent parameters showed a high correlation with TDP. At constant engine speed, burn durations are shown to depend mainly on degree of thermal dilution, with no effect of load observed. At high dilution rates, combustion became increasingly insensitive to further dilution, indicating the presence of thermodiffusive instabilities under high levels of both EGR and air dilution.

King, Aidan, Islam, Reza, Pickering, Simon, Yuan, Hao, Mudge, Henry, Giles, Karl, Goyal, Harsh, Jones, Peter, Akehurst, Sam, Esposito, Stefania

An Open-Source Framework to Automate Virtual Optimization of Internal Combustion Engine Calibration Maps through Shape-Based Strategy

2026-37-0001

6/9/2026

The automotive industry is facing increasingly stringent regulatory constraints, driving the need for faster and more efficient powertrain development. This results in higher systems complexity, making internal combustion engine calibration progressively more challenging to meet performance and emissions targets. This, combined with the manual nature of traditional calibration workflows, leads to a time-consuming process that heavily relies on human expertise. Although virtualization can reduce development time and costs, the overall workflow remains largely dependent on manual decision-making and iterative refinement. In this context, this work presents a virtual calibration framework based on a genetic algorithm, aimed at the automated optimization of engine calibration maps to satisfy performance and emissions constraints, while reducing manual effort. Each calibration map is represented through a polynomial parameterization. Specifically, a generic three-dimensional polynomial with map-specific order encodes the shape of each map, ensuring smoothness which directly impact on drivability. Accordingly, the calibration problem is reformulated as the optimization of a compact set of polynomial parameters that uniquely define the full set of calibration maps, rather than individual set-point. Each candidate solution is assessed by generating the corresponding calibration maps and simulating the engine behavior through a neural-network-based digital twin, providing predictions of operating conditions, hardware limits, performance metrics, and emissions. The proposed framework was validated on a passenger-car diesel engine, considering a reduced yet representative set of calibration maps, including main injection start of injection, air mass, boost pressure, and injection rail pressure. The objective of optimization was the minimization of brake mean fuel consumption, subject to an upper bound constraint on nitrogen oxides emissions. The global optimization process explored approximately 106 different calibration candidates within about 36 hours, leveraging parallel computation on a standard laptop. The results indicate that the procedure can deliver multiple near-optimal preliminary calibration solutions, providing an effective starting point for subsequent manual finetuning.

Romano, Gianvito, Aglietti, Filippo, Spedicato, Tonio, Cozza, Ivan Flaminio, Capra, Andrea

Hybridized Diesel Powertrains - An Important Enabler for Commercial Applications on the Long Journey towards Full Electrification

2026-37-0022

6/9/2026

The ongoing efforts for reduction of the traffic-related greenhouse gas emissions and, at the same time, the mitigation of harmful pollutant emissions from vehicle exhaust emissions are important development tasks for the entire automotive industry worldwide according to demand to provide clean and efficient products. Further tightened fleet average FE standards and ultra-low limits for exhaust emissions require the continuous development of new propulsion system types. Due to the given reluctance of the end customer and corresponding low acceptance of fully electrified vehicles, especially in the commercial vehicle segment, new and innovative topologies are needed to meet regulatory requirements and maintain the high versatility of today’s dominating solutions. For further optimization of operating conditions with enhanced fuel efficiency, the technical strategy is also determined by uplifting the attractiveness of electric driving incl. the avoidance of areas with poor ICE efficiency and as well as the coverage of emission-critical operations by electric propulsion. In this context, the support provided by an electric drive on board the vehicle in a combined drive system is becoming increasingly important. This article discusses accordingly various platform strategies for hybridized Diesel powertrains in different sectors of commercial vehicle applications and delivers a comprehensive comparative analysis of different hybrid drive concepts. Specifically, several hybrid powertrain configurations that extend an electric drive platform (hybridized BEVs), such as series and parallel-series topologies, are compared with traditional parallel hybrid powertrain topologies based on internal combustion engines (ICE). The study focuses mainly on two different cornerstone applications: a large light commercial vehicle, ranging from 3,5 to 6,5 to. and a heavy-duty long-haul truck with 40…44 to. gross vehicle weight. It evaluates the advantages in terms of CO2 emissions and Diesel fuel savings and investigates the effects on emission controls aspects. In addition to technical comparisons, the paper addresses also regulatory demands and end customer merits, assessing the integrational effort and commonalities in components with pure ICE and battery electric topologies. Furthermore, it explores the additional impact of advanced operational strategies for Hybrid Diesel powertrains, incorporating insights from innovative observations from executed hybrid technology demonstrator vehicles.

Koerfer, Thomas

A Parametric Cradle-to-Grave Life Cycle Assessment Tool for Comparative Evaluation of Passenger Car CO₂ Emissions

2026-37-0040

6/9/2026

This work presents the development of a user-oriented software tool for the cradle-to-grave Life Cycle Assessment (LCA) of passenger cars, enabling robust comparisons of greenhouse gas emissions across heterogeneous vehicle configurations. The tool supports informed decision-making by quantifying and visualizing environmental impacts associated with alternative mobility choices over the full vehicle life cycle, including production, use, maintenance, and end-of-life stages. The proposed framework allows key parameters describing both the vehicle and its usage to be explicitly defined, including powertrain type, dimensions and weight, ownership profile (new or second-hand vehicles, partial ownership periods, leasing scenarios), annual mileage, vehicle lifetime assumptions, and the carbon intensity of fuels or electricity sources. Country-specific energy mixes are incorporated, enabling the same vehicle to be assessed under different geographic contexts and highlighting the strong dependence of use-phase emissions on local energy systems. Results are reported both as total life-cycle emissions and as a phase-resolved breakdown, improving transparency and supporting a clear interpretation of trade-offs between production, operation, maintenance, and end-of-life stages. Representative scenarios demonstrate that, under a standard European context, battery electric vehicles (BEVs) achieve a reduction of approximately 32% in yearly greenhouse gas emissions compared to a baseline Euro 5 gasoline vehicle. However, this trend reverses for low-mileage users relying on second-hand vehicles, for which emissions can increase by about 15%, emphasizing the critical role of usage patterns and ownership strategies in determining environmental benefits. The tool is designed to accommodate updated datasets, emission factors, and evolving energy scenarios, ensuring long-term applicability and enabling forward-looking analyses. Its capabilities are demonstrated across scenarios covering short- and long-term usage, multiple national contexts, and different powertrain technologies. The result is a robust and transparent assessment platform that enables users and policymakers to evaluate vehicle replacement strategies, providing quantitative insights into the interplay between technology, usage, and sustainability in mobility transitions.

Gastaldi, Chiara, Cibrario, Luca

Investigating the Potential of Two Individually Controlled Injectors per Rotor for a Direct Injection Hydrogen Wankel Engine

2026-37-0008

6/9/2026

Hydrogen-fueled rotary engines offer a promising zero-emission solution for compact commercial powertrains. This study reports experimental results from the further development of a naturally aspirated, direct-injection hydrogen rotary engine by HTM. Initial applications, such as an airport baggage tractor, demonstrated technical feasibility but revealed pre-ignition that limited maximum torque. To address this, mixture formation was investigated using an experimental setup with two independently controlled injectors feeding a single rotor injection channel. The effects on operating behavior, efficiency, and NOx emissions were evaluated. The dual-injector configuration significantly shortens injection duration and improves spatial distribution of hydrogen within the combustion chamber. Enhanced mixture control suppresses pre-ignition and enables higher mean effective pressure. Systematic variation of injection timing under representative steady-state conditions also shows potential for NOx reduction through differentiated injector operation. In-cylinder pressure analysis and exhaust gas measurements provide detailed insight into combustion characteristics and abnormal events. The dual-injector setup increases torque capability and operational robustness without additional mechanical complexity, supporting the use of hydrogen rotary engines in compact hybrid systems and stationary power applications.

Endres, Jonas, Beidl, Christian, Herold, Tim, Lavall, Philipp, Schmidt, Marvin, Hofmann, Silas, Kahl, Jonas

Performance and Combustion Characteristics of Coryton SUSTAIN Classic Super 80 Carbon-Neutral Fuel versus EN 228 in a 1980s Fiat 500 Engine

2026-37-0033

6/9/2026

The energy transition requires a rapid reduction in the use of fossil fuels, whose combustion generates substantial greenhouse-gas emissions. In Europe, transport alone accounts for roughly a quarter of total greenhouse-gas emissions, with road transport being the predominant component. In this context, the use of biofuels has emerged as a potential solution for limiting further increases in CO₂ emissions. However, most studies available in the literature evaluate the performance of these fuels on modern engines, while their effects on historic carburetted engines remain largely unexplored. This is particularly significant given the large fleet of historic vehicles across Europe, supported by a long-standing tradition of vehicle preservation, associations, and classic car collectors. The main historic-vehicle federations advise caution and the use of low-ethanol formulations so as not to damage elastomers, fuel tanks, and carburettor float bowls. For this reason, a few suppliers have developed fuels specifically for classic vehicles. Among this minority, in 2023 Coryton Advanced Fuels introduced the SUSTAIN Classic line, including the Super 80 variant. In the present study, the performance, fuel consumption, and emissions of an air-cooled, four-stroke Fiat 500 engine fueled with commercial RON 95 gasoline and Coryton SUSTAIN Classic Super 80 were analyzed. A first test comprised a complete sweep from 1000 to 5000 RPM and a second test evaluated four different main jets at maximum torque speed and maximum power speed. To evaluate the performance, the engine was installed on a test bench equipped with a torque meter. Static pressure and temperature sensors were employed to characterize the engine operating conditions, while a dynamic pressure sensor installed in the combustion chamber was used to analyze the combustion characteristics. Exhaust emissions were also measured using a gas analyzer, allowing for a detailed and accurate comparison of the effects associated with the use of the two fuels.

Tarchiani, Marco, Fossati, Federico, Raspanti, Sandro, Baroni, Alberto, Ferrara, Giovanni, Romani, Luca

Comparative Toxicological Assessment of Exhaust Emissions from Modern Low-Emission Passenger Vehicles

2026-37-0005

6/9/2026

As vehicle technologies evolve toward electrification and advanced aftertreatment, understanding the biological implications of their exhaust emissions remains essential. This study presents a harmonized comparative toxicological assessment of five Euro 6 vehicles representing gasoline, hybrid, plug-in hybrid, compressed natural gas (CNG), and diesel technologies. Vehicles were tested under realistic driving conditions on a chassis dynamometer. Diluted exhaust was delivered directly to human lung epithelial cells (A549) using a controlled air–liquid interface (ALI) exposure system. Solid and total particle number emissions were measured, and deposited particle mass was estimated from size-resolved distributions and deposition efficiency. Vehicles equipped with particulate filtration showed lower solid particle emissions overall, while differences between gasoline particulate filter-equipped vehicles indicated that hybridization can further influence emission levels. Diesel operation during active diesel particulate filter (DPF) regeneration produced more than two orders of magnitude higher particle number emissions compared to normal operation. When expressed as deposited mass, vehicle ranking differed from number-based emissions, highlighting that emission metrics do not directly translate into delivered biological dose. Exposure to whole exhaust consistently induced stronger cytotoxic and inflammatory responses than to gaseous phase alone. Membrane integrity disruption and IL-1β release showed clear particle-associated amplification, with the strongest effects observed during diesel DPF regeneration. These findings demonstrate persistent technology-dependent differences in particle emissions and acute biological responses among modern low-emission vehicles.

Tsakonas, Georgios, Stamatiou, Rodopi, Lazou, Antigone, Samaras, Zissis, Elihn, Karine

Alcohol-Based Energy Carriers in Transportation: Status, Standards, and Outlook

2026-37-0042

6/9/2026

The global transport sector accounts for approximately 30 % of total final energy consumption and 15.9 % of worldwide greenhouse gas (GHG) emissions, with road transport alone accounting for the largest share at 11.8 %. Decarbonizing this sector requires energy sources that combine scalable generation from renewable sources with compatibility with various modes of transportation and existing infrastructure. Methanol and ethanol emerge as promising alternative energy carriers that can leverage existing logistics infrastructure while reducing dependence on fossil fuels. Global methanol production reached 112 million metric tons, and global ethanol production totaled approximately 93.5 million metric tons in 2024, compared to more than 2 billion metric tons of gasoline and diesel produced annually. The review assesses production pathways and cost trajectories for both alcohols, evaluates fuel requirements across multiple transport modes, including passenger vehicles, light- and heavy-duty vehicles, maritime shipping, aviation, and rail, and provides regulatory frameworks governing fuel standards in six major markets, the European Union, the USA, Brazil, China, Japan, and India. From a technical perspective, the internal combustion engine is examined in greater detail as the energy conversion system, synthesizing current combustion research on engine performance, emissions characteristics, and cold-start behavior. Current standards predominantly accommodate ethanol blending for spark-ignition (SI) engines in passenger vehicle applications, with permitted concentration limits ranging from 3 % in Japan to nearly pure ethanol in Brazil. Methanol applications remain more limited in road applications. In the maritime sector, recent ISO 8217:2024 specifications and International Maritime Organization (IMO) interim guidelines have established frameworks for the use of methanol and ethanol as marine fuels. Aviation remains the most restrictive sector, with alcohol fuels explicitly prohibited in certified aviation fuels due to material compatibility and safety concerns. To unlock the decarbonization potential of methanol and ethanol in the transport sector, coordinated policy support and continued technological innovation will be essential. As production scales and regulatory frameworks mature, both alcohol fuels may play an increasingly central role in the transition toward sustainable mobility.

Fitz, Patrick, Fellner, Felix, Rößlhuemer, Raphael, Härtl, Martin, Jaensch, Malte

Engine Thermal Management Strategies for Emissions Reduction during Real Driving Tests

2026-37-0036

6/9/2026

Thermal management in internal combustion engines (ICEs) strongly affects fuel consumption and pollutant emissions, especially during engine warm-up. Particularly, the oil temperature is strictly related to the organic efficiency of the vehicle: in the early phase of a driving cycle, the low temperature produces a high-viscous oil, which increases friction losses and increases fuel consumption, with respect to full thermal regimated oil. Usually, the oil and coolant thermal behaviours are interconnected, thanks to a coolant/oil heat exchanger in the engine. In this study, a prototyped electrical coolant pump has been applied and integrated in a small SUV vehicle, replacing the original mechanical unit. An off-board experimental campaign allowed a complete hydraulic characterization of the cooling system, including thermostat operation, and led to a physically based correlation between flow rates and pressure drops in each branch. Based on these results, the pump was designed and prototyped, enabling advanced flow management strategies on board. On-road Real Driving Emissions (RDE) tests were carried out using different pump control logics. Four different control strategies have been proposed in order to reduce the warm up time of the engine and the oil. Results show that the warm-up time reduction produces also a decrease in CO, NO, THC, CH₄, and PN emissions by 15–65%, particularly during cold-start conditions. The innovation proposed can be also combined to other technological options, to further improve the thermal behaviour of the engine and increase the temperature of the oil in the early phase of a common driving cycle. Electrification also reduces parasitic losses and facilitates integration with hybrid powertrains, confirming thermal management as an effective transitional technology for improving ICE efficiency and environmental performance under real driving conditions.

Di Battista, Davide, Di Bartolomeo, Marco, Cipollone, Roberto

Potential of ORC-Based Waste Heat Recovery in Conventional and Hybrid Heavy-Duty Powertrains

2026-37-0018

6/9/2026

Heavy-duty vehicles significantly contribute to greenhouse gas emissions and urban air pollution, especially during cold-starts and transients when engine and aftertreatment efficiencies drop. Waste heat recovery (WHR) via Organic Rankine Cycle (ORC) systems offers a practical solution to improve fuel efficiency and cut CO₂ in real-world heavy-duty operations. This study examines ORC-based WHR integration into conventional and hybrid powertrains of an Isuzu FTR850 truck, analyzing four configurations: Shell-and-Tube or Plate heat exchangers with simple or regenerative ORC layouts. For hybrids, it compares two engine sizes and energy management strategies: an optimized fuzzy logic approach versus constant-power operation to enhance exhaust heat recovery. A validated quasi-static simulation framework is used to predict fuel consumption and exhaust properties over representative duty cycles. 2D performance maps using exhaust temperature and mass flow as inputs are used to model the WHR under off-design conditions. Results show that the recovery of waste heat WHR depends on the hybridization level and strategy. Conventional powertrains benefit most from Shell-and-Tube exchangers, recovering ~2 kWh of electrical energy per 8-hour cycle and reducing fuel consumption by 0.5%. Hybrid setups recover up to 3.9 kWh from exhaust gases with a simple layout coupled with a Shell-and-Tube heat exchanger under constant-power control. Electricity is used to support onboard auxiliaries and battery charging, further lowering fuel demand (-44%) and emissions. Finally, a multi-objective optimization was performed to exploit the synergy between hybridization and WHR while maintaining acceptable payload and battery operating conditions.

Donateo, Teresa, Morrone, Pietropaolo

CFD Modelling of an Asymmetric Hydrogen Injector Cap for Direct Injection Applications: Design Impact on Jets Structure and Momentum Flux

2026-37-0011

6/9/2026

The adoption of hydrogen as a carbon-neutral sustainable fuel for internal combustion is regarded as a promising solution to reduce greenhouse gases and pollutant emissions. In this framework, the injection system plays a crucial role, being responsible for delivering a large amount of fuel to the combustion chamber. Currently, low-pressure direct injection is considered one of the best solutions to ensure the appropriate fuel delivery. The use of caps has proven particularly effective, as they enable a potentially unlimited range of geometries while minimizing modifications to the injector hardware. Experimental campaigns and computational fluid dynamics (CFD) simulations can be used together as complementary tools to speed up the development process and explore multiple combinations of parameters, thereby optimizing the overall design of both the engine and the caps. In the present paper, a single-hole GDI-derived hydrogen prototype injector equipped with a two-hole asymmetric cap and fed with hydrogen is analyzed through both experiments and CFD simulations under two different operating conditions in terms of rail pressure. Cap pressure, overall fuel instantaneous mass flow rate and hole-specific jet momentum have been measured during the experimental campaign. The resulting data were used as boundary conditions and as targets for the validation of steady-state CFD computations, where the same equipment has been simulated. In particular, the momentum flux produced by the two jets emerging from the forming cap was used to validate the numerical methodology against experimental outcomes. Moreover, the exact dimensions of cap holes have been taken by means of optical microscope and applied to the simulation to compare the real geometry against the nominal one. Therefore, the impact of the effective cap geometry is explored, evidencing a noticeable dependence specifically of the cap backpressure and therefore of the injection system performance on the details of the cap design.

Pavan, Nicolo, Breda, Sebastiano, Duni, Andrea, Martino, Manuel, Fontanesi, Stefano, Postrioti, Lucio

Nitrogen-Based Emissions from Ammonia Combustion in a Heavy-Duty Spark Ignition Engine

2026-37-0032

6/9/2026

Ammonia (NH3) is a carbon-free fuel with strong potential for spark-ignition (SI) engine applications. However, the engine can produce complex nitrogen-based emissions not adequately captured by conventional engine models. This study consolidated the results of experimental and numerical studies on the use of neat NH3 combustion in a heavy-duty compression-ignition engine converted to spark-ignition operation, first for a sweep of equivalence ratios (ϕ) from 0.7 to 1.0, and another from varying the energy substitution ratio of methane (CH4)– NH3 blends from neat CH4 to neat NH3 at constant ϕ = 0.8. Two 0-D two-zone SI engine models with detailed chemistry (called “original” and “extended”) predicted engine thermodynamics and emissions. While the original model reproduced in-cylinder pressure and combustion phasing, it failed to capture the effect of fuel composition or operating condition on NO trends, both under- and over-predicting them for neat NH3 and CH4-rich operations. An extension of the model incorporating a burned-zone batch reactor and two more reactors simulating the post-combustion oxidation of the mixture exiting crevices and the DeNOx processes during exhaust blowdown were implemented to address these limitations. Analysis of NO formation pathways highlighted the differences between modeling approaches. The equilibrium assumptions in the original model restricted NO formation primarily to thermal (Zeldovich) mechanisms. In contrast, the kinetics-driven model showed that non-thermal pathways dominate NO formation for all NH3-containing cases, which shows the limitations of conventional SI models developed for hydrocarbons when applied to nitrogen-containing fuels. Post-combustion homogeneous reactors for crevice-based oxidation and exhaust blowdown revealed significant NO and N2O formation after the end of combustion at moderate temperatures (850–1200 K), suggesting that N2O formation was dominated by secondary thermal processes. Therefore, the inclusion of post-combustion chemistry and more consistent models are essential for accurate emission prediction in NH3-fueled SI engines.

Trujillo Grisales, Juan, Saenz Prado, Stefany, Alvarez, Luis F., Akkerman, Vyacheslav, Dumitrescu, Cosmin E.

Predictive Modelling of NO _x and Unburned Hydrogen Emissions in a Direct-Injection Hydrogen Spark-Ignition Engine

2026-37-0007

6/9/2026

Hydrogen is emerging as a compelling energy carrier for future transportation due to its potential to enable fully decarbonised operation and near-zero tailpipe pollutant emissions. Realising this potential in reciprocating internal combustion engines requires a detailed understanding of the complex interactions governing hydrogen combustion and emissions formation. In this context, physics-based reduced-order emission predictive modelling offers a powerful means to accelerate the development and optimisation of hydrogen-fuelled engines by enabling rapid evaluation of operating strategies without the need for extensive experimental campaigns. This study investigates the simulation of nitrogen oxides (NOx) and unburned hydrogen (uH2) emissions from a 0.5L spark-ignition direct injection single-cylinder research engine within a 1D-0D simulation approach. For NOx prediction, a simplified kinetic mechanism is coupled with both a 0D two-zone combustion model and a thermal multi-zone in-cylinder representation, enabling assessment of the need to account for temperature stratification for accurate prediction. For uH₂ emissions, phenomenological sub-models describing flame wall quenching and top-land crevice mechanisms are implemented and calibrated to capture the dominant sources of hydrogen escape during combustion. The models are validated against an experimental dataset spanning a wide range of engine conditions, including variations in engine load, relative air–fuel ratio from stoichiometric to ultra-lean combustion, dilution via exhaust gas recirculation, and spark timing. The comparison highlights the models' ability to reproduce observed physical trends across different engine operating conditions for both NOx and uH2. Regarding NOx emissions, the accounting of temperature stratification with the multi-zone model enables more accurate predictions of trends and absolute values. The uH2 model provides fundamental insights into hydrogen engine flame propagation by highlighting the need for flame propagation in the top-land crevice at richer λ to reproduce observed trends. Overall, the study provides insights into both hydrogen-specific emission mechanisms and key modelling requirements for accurate pollutant simulation in hydrogen engines.

Malfi, Enrica, De Felice, Massimiliano, Esposito, Stefania, Ribnishki, Aleksandar, King, Aidan, Akehurst, Sam, Jones, Peter, Goyal, Harsh

Numerical Modeling Techniques for Jet Engine Test Cell Aerodynamics

AIR6355 (Current)

6/5/2026

This SAE Aerospace Information Report (AIR) has been written for individuals associated with ground level testing of turbofan and turbojet engines, and particularly for those who might be interested in investigating steady-state performance characteristics of a new test cell design or of proposed modifications to an existing test cell by means of numerical modeling and simulation. It is not the intent of this standard to provide specific test cell design recommendations, which are covered in the reference documentation.

EG-1E Gas Turbine Test Facilities and Equipment

Data-Driven Air Traffic Management: Forecasting Demand, Modeling Delay Propagation, and Demand Capacity Balancing

2026-26-0772

6/1/2026

Air Traffic Management (ATM) must be familiar with the exact Aircraft Take-off Weights (ATOWs) of airplanes to make the most use of runways, maintain safety margins high, and keep utilization and resources in balance. This paper aims to present a dependable ATOW forecasting methodology that can assist the air transport industry in enhancing operational decision-making. This research used datasets acquired from the EUROCONTROL Performance Review Commission (PRC) 2024 Aircraft Take-Off Weight Estimation dataset featuring 527,000 flights over Europe containing aircraft details, air trips and flight conditions. Technique comprises structured data input, inspection of missing data, timestamp aggregation to identify demand cycles over time, and domain-specific feature engineering using distance_per_minute, block_minutes, taxiout_ratio, and a strong wake turbulence metric The two supervised learning models used were Linear Regression (LR) for understanding and XGBoost for performance prediction In comparison to LR's 4,409 kg MAE (mean absolute error), 7,061 kg RMSE (root mean square error), and 0.9825 R2 value, XGBoost significantly excelled with validation results showing an R2 value of 0.9992 and an RMSE of 1,514 kg In the absence of labelled test targets, cross-validation nevertheless showed a constant degree of generalizability The residual diagnostics showed that the model was reliable for practical execution with low-variance deviations that were unbiased An accurate ATOW estimate improves the demand-capacity balance and On-Time Performance (OTP) in ATM, which in turn affects the runway schedule, wake turbulence diversion, slot allocation, and fuel planning The results highlight the need to include ATOW predictions in both tactical and strategic planning to reduce delays, increase airspace usage, and promote sustainable aviation operation and possesses significant improvements will consist of weather and runway conditions, stochastic ambiguity computation, and drift monitoring to keep up with ever-changing operating variables while maintaining accurate forecasts.

Senthilkumar, N., S, Gopalakrishnan, Gopinath, S

Adaptive HVAC Strategies for Enhanced Cabin Thermal Comfort, Air Quality and Energy Efficiency

2026-26-0791

6/1/2026

Passenger comfort within vehicles and aerospace cabins relies on finely tuned management of temperature, air quality, and energy use. This paper proposes an integrated HVAC framework that combines zonal climate control, intelligent airflow distribution, and real-time sensor data to maintain thermal balance across different cabin zones. Leveraging predictive thermal load modelling and machine learning, the system anticipates environmental changes—such as sudden shifts in external temperature or passenger load—and proactively adjusts heating and cooling outputs. Simultaneously, air quality is enhanced through a multistage filtration system, active air purification technologies, and dynamic CO₂ concentration monitoring. Comfort assessment integrates PMV (Predicted Mean Vote) and PPD (Predicted Percentage Dissatisfied) indices to adapting environmental conditions. Simulations and early-stage prototypes improve energy savings and improve occupant comfort and air quality. The proposed HVAC approach is a promising avenue for enhancing passenger experience and operational efficiency in both ground and air mobility platforms.

Mudavath, Lehitha Sai, Patil, Ashish, Saha, Sudipta

Thermo-Structural Analysis of Grid Fins for Re-Entry Modules

2026-26-0749

6/1/2026

Grid fins are non-conventional aerodynamic lifting and control surfaces which are made of a frame supporting lifting surfaces positioned in the form of a lattice structure. Grid fins are also called as lattice fins and are used as control surfaces in launch vehicles, crew escape systems, missiles etc. to achieve static stability. Each panel of the grid fin acts as fin and it produces force which increases stability of the vehicle. For a crew escape system module, grid fins are used as a passive aerodynamic control surfaces to achieve static stability. Grid fins are positioned at the end of crew escape system module to provide required static margin by increasing moment arm. In contrast to conventional fins, grid fins incorporate a distinctive waffle-like pattern or grid pattern configuration, offering superior aerodynamic performance in supersonic regimes and enabling compact storage in stowed position during launch followed by deployment at the time of exigency. In case of an emergency, crew escape system is activated and it will take crew escape module away from the launch vehicle during atmospheric regime. In this scenario, grid fins are deployed simultaneously along with firing of high-thrust, fast-acting solid rocket motors (SRMs) which provide the impulsive force needed for clean separation. Grid fins help to stabilize the crew escape system module by counteracting aerodynamic instabilities, especially when the module is moving through the atmosphere at high speeds. The primary structural loads acting on grid fins include deployment forces (hinge forces, locking), aerodynamic, and inertial forces. Additionally, the exhaust plumes from the firing of SRMs impinge directly upon the grid fins, generating intense thermal loads characterized by rapid temperature gradients and localized heating. The simultaneous presence of thermal and structural loads influences displacements, stresses, interface joints integrity and maximum buckling loads. Furthermore, elevated temperatures degrade mechanical properties such as yield strength, ultimate strength, and Young’s modulus, therefore a thermo-structural analysis is carried out to study the effects of these combined loads on grid fins. This paper presents typical grid fin configuration, thermo-structural formulation, finite element model details, and thermo-structural analysis results including stress margins, deformations, buckling load factors and preload variations for the maximum design load case.

Mali, Somanath Nandu, Sundar Raj, R, Sundaresan, MK, R, Suresh

AI-Led Sustainability Strategy: Driving Product Value from Birth to Disposal

2026-26-0781

6/1/2026

Aerospace products operate within highly complex, safety-critical environments and endure extended lifecycles, often spanning decades. Sustaining their operational value requires rigorous management of Safety, Reliability, and Availability (SRA), while global Environmental, Social, and Governance (ESG) mandates demand parallel progress toward sustainability goals. This paper introduces an AI-driven strategy that integrates these dual imperatives—Sustenance Management and Sustainability Management—within a unified Product Lifecycle (PLC) framework. The proposed approach leverages Artificial Intelligence across five PLC phases: Generative Design, Detailed Design & Verification, Manufacturing & Industrialization, Operations & Maintenance, and End-of-Life Circularity. Anchored by a certified Digital Thread, this framework ensures seamless, auditable data flow from concept to disposal. Using Life-Limiting Parts (LLPs)—such as high-stress turbine discs—as a case study, the paper demonstrates how AI interventions enhance operational efficiency while reducing embedded carbon emissions. For example, Generative AI optimizes component geometry for performance and material efficiency, Physics-Informed Machine Learning (PIML) improves Remaining Useful Life (RUL) predictions for certification readiness, and predictive analytics extend Time-on-Wing (ToW), deferring Scope 3 emissions from replacement manufacturing. At end-of-life, AI-guided valuation of Used Serviceable Material (USM) enables circularity and compliance with ISO 14067 and ISO 14040/14044 standards. The paper also discusses sustainability metrics such as Design Simulation Energy Intensity (DSEI) and the Sustainable AI Quotient (SAIQ) [25], to address the AI-energy paradox, ensuring that digital transformation remains net-positive for environmental stewardship. By positioning sustenance as the most immediate lever for sustainability, this AI-led framework delivers measurable improvements in lifecycle cost, operational resilience, and carbon footprint reduction. The discussion concludes with challenges in data governance, regulatory compliance, and model explainability, offering mitigation strategies for safe and scalable adoption.

Srinivasan, Karthik, G.V.V., Ravi Kumar, Vaderahobli, Devaraja Holla, Bhate, Ujwal, Veluri, Sastry

IN FUEL CONTROL

26TOFHP06_02

6/1/2026

How to ensure off-highway combustion systems operate with sufficient control to meet tightening emissions standards and evolving fuel landscapes without sacrificing reliability. Off-highway equipment is being asked to do more with less. Less margin for emissions, less tolerance for downtime and less room for inefficiency, while operating under some of the most demanding duty cycles in the transport sector. Tier 4 and Tier 5 emissions standards have reshaped engine calibration strategies. Renewable diesel and biodiesel blends are entering worksites and farms at scale. At the same time, construction, mining and agricultural machines are expected to run for 20-25 years, often at sustained high load and far from service infrastructure. In this environment, combustion systems are far from being phased out.

Anderson, Todd

ACT 2026: Uncertainty still exists over EPA 2027 NOx limit

26TOFHP06_05

6/1/2026

Though the U.S. EPA has rolled back many emissions regulations surrounding the mobility industry, its HD rules remain intact, meaning manufacturers must hit the world's most stringent NOx requirement. It was clear at a panel of industry experts that the new rule was still causing confusion among operators and fleet owners. The EPA's new limits are set at 0.035 grams per horsepower-hour during normal operation, 0.050 grams at low load and 10.0 grams at idle. A panel immediately following revealed how companies have hit the tough target, which goes into effect in January of 2027.

Clonts, Chris

Conceptual Design of Hydrogen Fuel-Cell-Based Utility Aircraft

2026-26-0783

6/1/2026

The aviation industry contributes to around 2% of global carbon dioxide emissions. As various sectors of the economy look to reduce their global carbon footprint, the aviation industry is positively acknowledging alternatives to jet fuel. Hydrogen proves to be one such alternative having a high energy density and producing zero carbon emissions on combustion. Hydrogen when used in a jet engine produces water vapour and NOx emissions. In order to reduce the effect of GHGs, the current study aims to develop aircraft concepts suitable with hydrogen propulsion through fuel cells for a short-haul commercial mission profile. Aircrafts such as Metro-23 and Dornier 228-212 were referenced for the requirements of a utility turboprop aircraft. The weight estimation was done to obtain the take-off weight of 10,863 kg following the optimization of thrust to weight ratio and wing loading to calculate the initial dimensions. OpenVSP was used to model the initial structure of the aircraft. For the propulsion system, the PEM fuel cell was sized for the aircraft to achieve a range of 2,065 km and endurance of 6 hours in two configurations. Also, various configurations of fuel tanks and their positions were analyzed. The design was able to achieve a reduction of up to 18% in the propulsion system weight through fuel stack configuration. Iterations were performed to achieve static stability and CG was estimated to be 31% of root chord. The final configuration layout with cabin seats, propellers, fuel tank and fuel cells were analysed for static stability. The flight performance of the aircraft is comparable to the reference aircrafts. The proposed design leads towards the path of sustainable aviation.

Bhattacharya, Anisha, Seetha Ramu, Sree Valli, C N, Lakshmi Manasa, Rohit, Benjamin

Polymer vs. Metal Seals: A Comparison In Critical Space Systems

26AERP06_03

6/1/2026

Sealing systems in space applications must perform reliably under demanding conditions in engineering: cryogenic temperatures, vibration, leakage control, ultra-high vacuum, ionizing radiation, abrasive particulates, and repeated thermal cycling. Each factor strains conventional sealing technologies. In combination, they can rapidly cause failure in systems where margins are unforgiving and maintenance is impossible. As spacecraft architectures evolve toward longer operational lifetimes and broader mission profiles, sealing requirements continue to tighten. Launch vehicles, satellites, and exploration platforms now operate across wider temperature ranges and in contact with more aggressive propellants and media. As a result, both metal seals and engineered polymer alternatives are evaluated-and selected-against increasingly specific, measurable performance criteria.

Advanced Silicone Materials for Harsh Aerospace Environments

26AERP06_01

6/1/2026

Aerospace and defense systems demand materials capable of maintaining performance under extreme environmental and operational stressors, including wide thermal cycling ranges, exposure to hydrocarbon fuels, vacuum conditions, and repeated mechanical strain. Silicone-based materials have become essential in these environments because they can retain elasticity, stability, and functionality where many traditional materials fail. Silicones are widely used as coatings, adhesives, sealants, and elastomers in aircraft and spacecraft applications. Their chemical structure enables resistance to both high and low temperatures, while also providing durability against solvents and fuels such as jet fuel. In contrast, many conventional elastomers degrade under prolonged thermal exposure or become brittle at cryogenic temperatures.

Experimental Investigation of Diesel, Aqueous Ammonia, and Compressed Natural Gas Mixtures on Performance and Emissions in a Compression Ignition Engine

04-19-03-0011

5/30/2026

Abstract This study investigates and evaluates systematically the combustion, performance, and emissions characteristics of heavy-duty diesel engines fueled by diesel–ammonia–compressed natural gas triple blends. While dual-fuel systems are well-documented, the interactive effects of ammonia and CNG within a single compression ignition (CI) engine remain largely unexplored. Experiments were conducted on a 300 Nm, 660 rpm diesel engine by testing pure diesel, diesel–ammonia blends (10–20 wt.% aqueous ammonia), and triple-fuel mixtures containing 10% of the total energy from compressed natural gas. Pure diesel was first tested to provide baseline data, and subsequently blends were tested for a comparative study. The primary contribution of this work is the identification of a synergistic effect of the fuel triple blends on engine performance and emissions. Results indicate that all fuel blends improve thermal efficiency and reduce fuel consumption compared to conventional diesel. The blend containing 20% aqueous ammonia, 80% diesel, and 10% of the total fuel energy supplied by compressed natural gas achieved the highest thermal efficiency of 39.7% (7% higher than diesel) and the lowest brake specific fuel consumption of 211.22 g/kWh. Furthermore, emissions analysis revealed that carbon dioxide and nitrogen oxide emissions were significantly reduced with this triple blend. The blend decreased carbon dioxide by 26.6% and nitrogen oxide emissions by 32.1%, while hydrocarbon emissions were also lowered by up to 29.2%. Carbon monoxide emissions increased slightly for the triple blends, reaching a maximum value of 3.9028 g/kWh for the A20D80CNG10 mixture, compared to diesel operation. The slight increase in carbon monoxide emissions for triple blends highlights a trade-off in emission behavior. These findings address the combined utilization of diesel–ammonia–compressed natural gas triple-fuel mixtures in heavy-duty engines, demonstrating that strategic blending can simultaneously improve efficiency while mitigating environmental impact. Graphical Abstract

Sinkala, Happy, Sarıtaş, Mehmet, Kül, Volkan Sabri, Akansu, Selahaddin Orhan, Ünalan, Sebahattin

Potential of an In-Cylinder Pressure–Based Combustion Control for Compression Ignition Aviation Engines Operated with Sustainable Aviation Fuels

2026-01-5028

5/29/2026

The aviation industry represents a significant greenhouse gas emitter and aims to reduce net CO2 emissions to zero by 2050. The deployment of sustainable aviation fuel (SAF), alongside measures such as increasing engine efficiency and enhancing ground handling processes, represents a key driver to reach this ambitious goal. SAF exhibits significantly different physical and chemical properties compared to conventional kerosene. The corresponding fuel specification (ASTM D7566 [1]) currently only defines fuel parameters relevant for the use in jet engines. To assess the suitability of SAF for the use in compression ignition (CI) aviation engines, a collaborative project was conducted at TU Wien—Institute of Powertrain and Automotive Technology, together with Austro Engine. ASTM D7566-certified fuels like Hydrotreated Vegetable Oil (HVO), Fischer–Tropsch–Kerosene (FTK), and Alcohol-to-Jet (AtJ) have been investigated on the engine test bench at TU Wien. The core contribution of this study is the experimental evaluation of a real-time capable in-cylinder pressure–based combustion control strategy that enables fuel-flexible and optimized CI engine operation across a wide range of SAF while accounting for mechanical constraints such as peak cylinder pressure and pressure rise rate. To evaluate the potential of such a control system, optimized engine operation was compared to operation with conventional ECU (Engine Control Unit) mapping. Furthermore, the influence of such a real-time combustion process optimization on critical emissions like NOx or soot has been evaluated. Through the implementation of an in-cylinder pressure–based combustion control, a considerable fuel-saving potential could be demonstrated across the entire fuel range. As combustion phasing is optimized toward early crank angle positions, a slight increase in NOx, with a corresponding decrease in soot is observed. Additionally, the use of automotive, piezoresistive pressure sensors was examined regarding a potential serial application. It has been shown that piezoresistive sensors (standard serial parts—calibrated for automotive application) are well-suited for determination of combustion phasing, while in-cylinder peak pressure and its position can only be determined with insufficient accuracy.

Kleissner, Florian, Hofmann, Peter

The Impact of Air Pollution on Clouds and Precipitation over Land and Ocean

2026-99-1701

5/22/2026

This study aims to summarize the influence of air pollution on clouds and precipitation over the ocean and land. This paper summarizes global aerosol observation networks, including GAW and AERONET, as well as aerosol observation networks from various countries. Six typical regions, including North America, North Africa, South Africa, India, China, and the Indian Ocean, demonstrate aerosols’ seasonal and compositional variation patterns. This study also summarizes the impact of aerosols on the microphysical characteristics of stratiform clouds and precipitation mechanisms. The effect of aerosols on clouds varies across regions over land and ocean, and the impact of aerosols on the cloud water path differs significantly. Air pollution significantly affects precipitation by altering the microphysical properties of clouds, and this study is of great importance for understanding and predicting weather changes.

Wang, Mingxin

Research on Carbon Emission Calculation Algorithm for Trucks on Expressways in Xinjiang

2026-99-1718

5/22/2026

In the field of measuring carbon emissions from road traffic, the carbon emission factor method has remarkable advantages in terms of standardization, operational simplicity, and adaptability. Backed by the IPCC international standard framework, this method offers convenient access to a dynamic factor database and incorporates an adaptive adjustment mechanism for real-world scenarios, such as technological advancements and regional disparities. Against this backdrop, this study employs the carbon emission factor method to establish refined measurement models based on load capacity and fuel consumption, respectively. These models are then applied to quantify carbon emissions from trucks on specific sections of the G30 highway in Xinjiang. The load-based model calculates emissions by integrating truck axle weight and driving distance, while the fuel-based model analyzes fuel consumption data in conjunction with driving mileage. A comparison of the two models in terms of measurement differences is also carried out in the research. Furthermore, it provides a granular breakdown of energy consumption data for fully loaded trucks exceeding 31 tons, as specified by national standards. This introduces a novel approach to precise carbon emission measurement in heavy-duty transportation in northwestern China. It also provides a method for establishing an emission mitigation policy that is region-specific on a scientific basis.

Li, Maowen, Han, Dongchen, Gao, Yansen, Bai, Haotian, Dai, Xiaomin

Analysis on the Technical Path and Engineering Application of Ship Carbon Capture

2026-99-1730

5/22/2026

This study focuses on the engineering application and performance evaluation of shipboard carbon capture systems. A process combining amine absorption and membrane separation was constructed, and the combined process was applied to a typical 7000 TEU container ship. After sea trials, the average carbon dioxide capture efficiency achieved by the system exceeded 87%, and the power consumption was maintained within an acceptable range. The integrated system greatly improved the EEXI and CII index levels and verified its economic feasibility in the medium and high carbon price scenario. The payback period of the investment costs was reduced to five years. After port coordination tests, the operability of ship-shore carbon dioxide transfer was verified, which promoted future scalability. The engineering layout, energy recovery design, and operation data worked together to provide a practical solution for maritime decarbonization. This study provides a valuable technical reference for the implementation of the International Maritime Organization (IMO) carbon reduction strategy, and also lays a solid foundation for subsequent legislation and system standardization.

Yang, Yongjian

Overcoming the Carbon Neutrality Bottleneck: Multidimensional Innovations and Future Prospects of Carbon Capture, Utilization, and Storage (CCUS) Technology

2026-99-1736

5/22/2026

As the global pursuit of carbon neutrality accelerates, carbon capture, utilization, and storage (CCUS) technology is emerging as a critical strategic pillar for achieving significant emission reductions and facilitating the transition to green development. This review systematically summarizes the principal technological pathways and recent advances in carbon capture, resource utilization, and storage within CCUS systems, with particular attention to innovative directions including advanced adsorption and separation materials, synergistic catalytic conversion, biological carbon sequestration, and mineralization-based storage. By examining representative engineering practices and industrialization cases both domestically and internationally, this paper summarizes the major challenges currently facing CCUS, including material costs, energy consumption, environmental risks, and large-scale deployment. The positive impacts of interdisciplinary integration, process system optimization, and policy coordination on the commercialization of CCUS are also discussed. The review indicates that overcoming bottlenecks in core materials and process technologies, improving regulatory frameworks and market mechanisms, and establishing clustered industrial ecosystems are essential for CCUS to spearhead the forthcoming low-carbon energy and green industrial revolutions. This paper envisions future development trends for CCUS technology, highlights its multidimensional strategic value for global carbon governance, energy security, and the circular economy, and offers theoretical references and cutting-edge insights for scientific research, policy formulation, and industrial decision-making in related fields.

Wang, Yingfei

Research on Carbon Emission Reduction of Structural Assembly Construction Technology in Metro Station Engineering

2026-99-1731

5/22/2026

To reduce the carbon emissions during the construction period of metro stations, two structural prefabrication schemes with varying prefabrication rates, based on the top-down construction method, were proposed and analyzed for their ability to study the carbon reduction potential of structural prefabrication construction technology in metro station construction, in comparison to traditional open-cut cast-in-place methods. A BIM model of the envelope and main structure of a metro station under construction in Qingdao was established to analyses the carbon emission impact factors of the metro station in terms of the consumption of materials, personnel, machinery, and transportation of each subcomponent project. The results show that the structural assembly construction technology can greatly reduce the work of support installation and dismantling, formwork installation and dismantling, and reinforced concrete pouring in the enclosure structure. With the prefabrication rate increasing from 16% to 40%, the carbon emission of the metro station construction process can be reduced by 5.58% and 7.46%, respectively.

Gao, Guangyi, Wang, Zheyong, Dong, Silong, Gou, Jiayuan, Li, Yangqing, Zeng, Tiesen

The Spatial-Temporal Evolution of Coupling Coordination Degree Development of Carbon Emission-Passenger-Freight in Five Northwest Provinces

2026-99-1716

5/22/2026

Taking China’s five northwestern provinces as the study area, this paper investigates the spatial-temporal interactions among carbon emissions, passenger transport, and freight transport from 2010 to 2020. An entropy-weighted composite index is constructed for each system and integrated into a coupling coordination degree model to quantify interaction. It is found that (1) the average annual growth of provincial coupling coordination degree is 4.7%, but the gradient difference between regions is significant, and the extreme difference of coupling coordination degree between east and west reaches 4.5 times in 2020; (2) Spatially, it shows a unipolar leading pattern, with Shaanxi achieving a significant decrease in carbon emission intensity and Qinghai achieving a lesser coupling coordination degree of 23% in Shaanxi due to the high proportion of highway freight transport and single energy structure; (3) the driving mechanism analysis shows that the improvement of transport network density and clean energy substitution rate contributes significantly to coupling coordination degree. These findings suggest substantial room to enhance coordinated low-carbon transport development in the region. Policy efforts should prioritize interprovincial cooperation, integrated optimization of transport infrastructure and energy structure, and differentiated pathways tailored to local conditions.

Qian, Yongsheng, Li, Shaoyuan, Zeng, Junwei, He, Qingling

Effect of Burning Biomass Fuel Cyclohexanol on Diesel Engine Performance

2026-99-1708

5/22/2026

Against the backdrop of growing global demands for energy sustainability and stricter emission regulations for diesel engines, this study investigates the performance implications of incorporating cyclohexanol—a renewable oxygenated fuel—into diesel fuel blends. Using a marine medium-speed diesel engine as the experimental platform, the research systematically evaluates engine performance and emission characteristics across a range of cyclohexanol-diesel blend ratios under low, medium, and high load conditions. Experimental findings reveal multifaceted effects of cyclohexanol blending on engine operation. Combustion of the blended fuels enhances the engine’s dynamic performance, particularly under medium and high loads, where the maximum in-cylinder burst pressure exhibits a noticeable increase. This improvement is attributed to cyclohexanol’s oxygen-carrying capacity, which promotes more vigorous and sustained combustion reactions. In terms of emissions, increasing the proportion of cyclohexanol in the fuel blend leads to significant reductions in soot and carbon monoxide (CO) emissions, reflecting the cleaner-burning properties of the oxygenated component. However, this is accompanied by an uptick in nitrogen oxide (NOx) emissions, likely due to the elevated combustion temperatures generated by the more efficient fuel oxidation process. From an economic perspective, cyclohexanol blending at consistent load levels induces a postponement in the crank angle at which peak heat release occurs during combustion. This temporal shift prolongs the effective combustion duration, enabling more complete fuel utilization within the cylinder. Consequently, fuel consumption rates decrease, and overall engine efficiency improves, highlighting the potential of cyclohexanol blends to enhance operational economy in marine propulsion systems. In summary, this study underscores the complex trade-offs associated with cyclohexanol-diesel blends: while they offer tangible benefits in power output, fuel efficiency, and reduced particulate emissions, managing the increase in NOx emissions remains a critical challenge. The results provide a foundational framework for advancing biofuel applications in marine engines, emphasizing the need for integrated emission control strategies to optimize the balance between performance and environmental sustainability.

Chen, Ke, Yang, Chenxi, Wang, Yibin, Fan, Jinyu, Liu, Yuchen, Ye, Zixiao, Huang, Jialiang

Research on the Statistical Method of Real Driving Emission Data of Commercial Vehicle under Low Load

2026-99-1721

5/22/2026

Current emission regulation in China (National VI b) adopts the work-based window (WBW) method to statistically analyze PEMS experimental data. This method cannot fully account for experimental data under low load and cold start conditions. In light of this, this paper proposes a statistical method for low-load condition experimental data. Firstly, the adaptability of the WBW method to low-load condition experimental data is analyzed. Secondly, the representativeness and authenticity of statistical results from different methods are compared. The results indicate that when the power threshold of the WBW method is set at 20%, the effective window qualification rate in six experiments is less than 40%. And as the load decreases, the power threshold required to meet regulatory requirements needs to be further reduced, meaning more low-power data points are discarded. The WBW method eliminates many low output power data points with high CO and NOx emissions from test data on an urban road section with low driving speed, significantly underestimating the CO and NOx emission data under low load conditions, with NOx emissions 56.8% lower than the cumulative averaging (CA) method results. It is recommended to use the CA method for calculating CO and NOx emissions under low load conditions.

Tang, Gangzhi, Liu, Jiajun, Wang, Shuaibin, Du, Baocheng, Deng, Xuefei

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