Browse Topic: Carbon dioxide

Items (2,441)

Assessing the Water Resource Impacts of Carbon Conversion Technologies

8/1/2026

In the race to combat climate change, scientists are developing technologies to turn carbon dioxide (CO2) into valuable fuels and chemicals. These innovations help curb greenhouse gases while providing a low-carbon fuel to power our future. As the U.S. shifts to a low-carbon economy, we need environmentally friendly fuels to power vehicles that are hard to electrify, like planes, ships and trains. Scientists are developing the technology to convert CO2 to fuel. However, this conversion requires a lot of energy and water.

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

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.

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

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

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

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

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

Prediction of CO ₂ Emissions from Light-Duty Vehicles Based on Highway Alignment

2026-99-1713

5/22/2026

In order to allow for the precise prediction of the CO2 emissions of light-duty vehicles during the road design phase and to methodically examine the effect of road alignment on CO2 emissions, this paper classifies the operating conditions of light-duty vehicles according to Vehicle Specific Power (VSP) and the design speed of different road levels. The test vehicle’s environmental data and operational parameters under various road conditions were gathered using a Portable Emission Measurement System (PEMS). The CO2 emissions of the test vehicle under different operating conditions were statistically analyzed. Based on the road’s horizontal and vertical alignment, the road was separated into analytical units, including straight sections, longitudinal slope sections, horizontal curve sections, and curve-slope combination sections. The indicators of each analysis unit were used to anticipate the speed and acceleration of light-duty vehicles in each unit, and a model for forecasting light-duty vehicle CO2 emissions based on road alignment was developed. The results show that the predicted CO2 emissions based on road alignment have a relatively small error compared to actual emissions, indicating high model accuracy. This model enables relatively accurate predictions of CO2 emissions for light-duty vehicles on target road sections during the road design phase. Among the various road alignment indicators, slope has a greater effect on the test vehicle’s CO2 emissions.

Liang, Yao, Wang, Yixuan, Zhao, Xiaoyan, Cheng, Shenzhen, Wu, Bing, Zeng, Weiyi

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

The Impact of Zero-Carbon Fuels on CO ₂ Emissions Reduction from the Long-Haul Heavy-Duty Truck Fleet in Mainland China

13-07-01-0003

5/22/2026

The decarbonization of heavy-duty trucks (HDTs) is a crucial path for China to achieve its “dual-carbon” goals and transition to decarbonized freight transport. Zero-carbon fuels are key alternatives to fossil fuels for these high-emission vehicles. This study develops an integrated scenario analysis framework to quantify the theoretical CO₂e emission trajectories of China’s long-haul HDT fleet from 2020 to 2060. Functioning as a macro-level stress test, the model derives theoretical equivalent stock from anticipated logistics turnover demand, integrating them with well-to-wheel (WTW) emission factors under six distinct policy stringencies (Projects 1 through 6), representing varying paces of fossil fuel vehicle phase-out. The results demonstrate that policy stringency primarily governs the timing and depth of emission reductions, while fuel technology defines the minimum achievable emission level. Three-dimensional visualization analysis reveals a nonlinear “emission cliff” under aggressive policies, marked by accelerated HDT fleet renewal and exponentially growing mitigation benefits. This cliff is more pronounced for the green hydrogen pathway and demonstrates its superior potential for deep decarbonization. In Project 1, CO₂e emissions reach a mid-term peak in 2035. Compared to the diesel baseline, the green hydrogen and green ammonia transition pathways reduce peak CO₂e emissions by 158 and 137 million tons, corresponding to reductions of 10.0% and 8.6%, respectively, under the modeled theoretical boundaries. In contrast, the aggressive Project 6 policy suppresses this peak, triggers the “cliff” effect much earlier, and achieves an extremely low stabilization level by 2040—15 years ahead of Project 1. This study provides a macro-theoretical quantitative decision-support tool for policymakers. It demonstrates that transparent and aggressive phase-out policies are essential to accelerate fleet turnover, trigger the “emission cliff,” and firmly cap total cumulative emissions.

Wu, Yunmei, Huang, Hua, Li, Rui, He, Guijia, Liu, Bo, Liu, Ruowei, Xie, Yongliang

Beyond PFAS: Unlocking the Potential of R290 and R744 for EV Efficiency

2026-01-0127

4/7/2026

The anticipated PFAS ban in the US by 2029 has created a need to evaluate alternative refrigerant solutions for automotive thermal management systems. This work compares three candidates—Propane (R290), Carbon Dioxide (R744), and R1234yf—through system-level testing and demonstration projects. R1234yf remains the current industry baseline. Test results show that Propane (R290) delivers comparable efficiency while offering a significantly lower global warming potential. However, its flammability presents integration challenges, not present with R1234yf or R744. CO₂ (R744) demonstrated promising performance as well. To address safety concerns with Propane, AVL developed mitigation measures including rapid leak detection, robust containment strategies, and optimized circuit layouts designed to reduce ignition risks. These countermeasures were validated in practice through the European Commission’s QUIET project. Within this program, a Honda B-segment electric vehicle was equipped with a Propane-based heat pump, thermal storage, infrared cabin heating, and lightweight materials. Testing under real-world conditions showed a 25% increase in driving range in cold conditions while maintaining passenger comfort [25,25]. An AI-based control strategy further improved system efficiency by coordinating thermal and energy management. The findings demonstrate that Propane can be a feasible replacement refrigerant for electric vehicle applications if appropriate safety measures are implemented. CO₂ also remains a strong candidate, offering a cost-effective and PFAS-compliant solution. Together, these results contribute to the evaluation of sustainable refrigerants and provide guidance for future thermal system development in the automotive sector.

bires, Michael, Possegger, Jonathan

Sensorless Estimation of In-Cabin CO ₂ Concentration for Model-Based Air Recirculation Control

2026-01-0130

4/7/2026

This paper introduces a sensorless approach for data-driven modeling of in-cabin CO2 concentration to optimize air recirculation flap control without the need for a dedicated CO2 sensor. Elevated CO2 concentrations, resulting from passenger exhalation, can impair occupants’ cognitive function and comfort. Current state-of-the-art solutions rely either on time-based control strategies, which lack responsiveness to actual cabin conditions, or on direct CO2 measurements via sensors, which increase system complexity and costs. In contrast, the proposed approach aims to replicate the benefits of sensor-based control without requiring physical sensors. In this study, a model-based methodology is presented, utilizing empirical CO2 measurement data collected from real-world test drives at varying occupancies, fan stages, vehicle speeds, and flap positions. Data acquisition involves a multi-gas analyzer positioned within the passengers’ breathing zone under controlled operation of the vehicle’s climate control unit. Based on these measurements, time-dependent CO2 concentration profiles are represented using exponential functions. These regression curves capture CO2 accumulation, depletion, and balancing behaviors, considering factors such as cabin leakage, pressure differentials at varying speeds, and ventilation conditions. These influences are inherently included in the calibration curves due to their empirical basis. The derived regression curves are implemented into a control model to simulate CO2 concentration throughout the drive, including situations where outside pollution is high and prolonged air recirculation is necessary – such as when driving through tunnels or behind trucks. On the baseline of this simulation, the sensorless control strategy adjusts flap positions accordingly, thereby minimizing both excessive CO2 buildup and unnecessary energy losses due to overventilation. By omitting CO2 sensors and relying solely on existing in-vehicle databus signals, this approach offers a cost-effective solution for cabin air quality management. Future work will focus on real-world validation of the control model and integration of exterior air quality monitoring as a complementary input.

Stürmer, Michael, Geier, Bertram, Hofstetter, Martin, Hirz, Mario

BEV Incremental CO ₂ Emissions in a Ranked Order Electric Grid

2026-01-0424

4/7/2026

Battery Electric Vehicles (BEV) have been sold as ‘Zero Emissions Vehicles’ (ZEV) by governments to reduce transportation CO2. While they are not ZEV because they run on grid electricity, they could be ‘effectively ZEV’ if the incremental CO2 is ‘very small’. At the national level, this is estimated using following metrics: (1) Internal Combustion Engine Vehicle (ICEV) fuel consumption, from the total US gasoline consumption divided by the total fleet miles driven, 25 mpg or 350 g CO2/mi, (2) Strong Hybrid Electric Vehicles (HEV) about one third less, 240 g CO2/mi. (3) BEV energy consumption, using data from systematic on-road testing of a wide range of vehicles, estimated at 40 kWh/100 mi for a US sales mix. (4) Electricity marginal CO2: in a ranked order grid, zero-CO2 sources are prioritized and supplemented by fossil sources. IEA hourly data show that the US 48 contiguous states are self-contained, with zero-CO2 sources providing a third of total demand. The response to hourly demand changes comes largely from natural gas and coal power stations, with EPA data showing a combined marginal CO2 of 600 g CO2/kWh. On replacing an ICEV by a BEV, the reduction in gasoline use, - 350 g CO2/mi, is offset to two thirds by higher electricity consumption, 40 x 600 / 100 = + 240 g CO2/mi. BEV marginal CO2 is therefore similar to HEV, and not ‘much smaller’ than ICEV. This is because HEV engines and fossil power stations have similar efficiency and similar fuel CO2 intensity.

Phlips, Patrick

Model-Based Development of a Heavy-Duty H ₂ -ICE and Integrated, Turbogeneration, Electrification, and Supercharging (ITES) System

2026-01-0426

4/7/2026

Changing global economic conditions and efforts to reduce greenhouse gas emissions are driving the need to develop efficient, near-term, alternative propulsion system technologies for heavy-duty vehicles. This study combines a hydrogen internal combustion engine (H2-ICE) with electrically assisted turbocharging, exhaust energy recovery, and mild hybridization to maximize propulsion system efficiency and reduce NOx emissions. To reduce cost and packaging impact of integration of these technologies on an engine, the study presents a model-based development and optimization of an Integrated Turbogeneration, Electrification, and Supercharging (ITES) system that combines the enabling components into a single compact unit. In the first phase of this study, a H2-ICE and aftertreatment concept for a MY2027 7.7L medium heavy-duty on-road engine was developed and evaluated through 1D simulation. The concept was to convert a diesel engine by changing the cylinder head to implement a port fuel injection (PFI) lean H2 SI combustion system with two-stage turbocharging and no external EGR. The concept was optimized for compression ratio, valve lift profiles, turbocharging, aftertreatment size/specification, and calibration using 1D system simulation in GT-SUITE. In the second phase of this study, the H2-ICE concept performance was further improved by integrating the ITES system and evaluated through 1D simulation. The ITES system replaces the conventional low-pressure stage of the boosting system and adds the capability of electrically assisted turbocharging, turbogeneration from exhaust energy, and P1 mild-hybridization. Applying a model-based approach, the H2-ICE & ITES component sizes were optimized for the best performance and emissions benefit. Using 1D simulation of validated models, the efficiency benefit of the ITES system on engine and vehicle level system was predicted. Finally, a vehicle level simulation was conducted comparing the fuel consumption between a conventional advanced boosting system H2-ICE concept and H2-ICE+ITES concept for Class 6-7 medium heavy duty truck application.

Bustamante, Oscar, Correia Garcia, Bruno, Joshi, Satyum, Franke, Michael

Real-Time Observations of the Effect of Fuel Dilution in an Engine Transient Friction Rig. Along with Real-Time Observations of Fuel Entering and Leaving Internal Combustion Engine Oil, over Both Standard Engine, ICE and Plug-In Hybrid, PHEV Dynamic Drive Cycles

2026-01-0351

4/7/2026

Hybrid electric vehicles (HEVs) with an increasing level of electrification, are becoming a major part of the global energy transition. To achieve lower engine tailpipe exhaust emissions and improve total fuel consumption, typically the HEV control system expertly and frequently switches between the internal combustion engine and electric motor drive, with multiple stops and restarts of the internal combustion engine (ICE). As a consequential result of this switching, are typically slower or even incomplete engine warm-up times, depending on the engine speed, load pattern and run time of the vehicle drive cycle. Along with the speed and load transient control, the engine stop and start processes are also challenging to control, with respect to cold start fuel and combustion by-products entering the oil. Consequently, contamination enters the engine oil but may not completely leave. These effects are highly transient over the drive cycle. Contaminants and in particular, fuel dilution, will affect the engine oil viscosity. To demonstrate this whilst yielding insights, a precisely controlled engine test cell, running the cold start Worldwide Harmonized Light Duty Transient Cycle (WLTC) for both, a non-hybridized ICE only vehicle and a HEV in charge sustaining mode operation is described. This also has on-line viscosity sensing and oil sampling. Typical data is shared along with engine oil comparisons. For complimentary insights, the impact of the fuel dilution on engine friction was investigated using a novel, precise, fully transient engine friction test rig, which measures gasoline direct injection high pressure fuel-pump friction and engine oil viscosity accurately. The cycle is based on measured data from vehicles tested on a chassis dynamometer. On-line friction data, with oil comparisons is used to show real-time data of the effect of fuel dilution on the frictional energy required, thus CO2 over the full WLTC.

Butcher, Richard, Bradley, Nathan, Thedering, Dennis

Study of Deposit Control Additive Efficacy in Gasoline Direct Injection Engines

2026-01-0349

4/7/2026

There is an increasing adoption of Direct-Injection Spark-Ignition (DISI) engines in the market, which per 2024 US Environmental Protection Agency (EPA) Automotive Trends Report represents 73% of new vehicles sold in the US. And while it is well accepted that DISI offers advantages over Port Fuel Injection (PFI) technology in meeting stringent CO2 emissions and fuel economy requirements set by the EPA, DISI engines are also associated with increased formation of injector deposits. These deposits may foul injectors and accumulate on the injector tip causing distorted spray patterns and diffusive combustion. Ultimately, this leads to engine performance deterioration and increased harmful emissions. To control deposit formation, detergent-type chemistries are added to the fuel in small amounts. Deposit Control Additives (DCAs) function by preventing the formation of deleterious injector deposits as well as removing existing ones. This study used standardized protocols describing the assessment of DCA in controlling injector deposits that have been developed by industry in both the US and Europe. When used at standard concentrations, DCA showed some engine performance and emission benefits over untreated base fuel. This investigation also demonstrated that engine performance can be recovered, in an engine with fouled injectors, with the use of higher DCA concentrations, accompanied by improved fuel economy and reduced particulate and total hydrocarbon emissions. This further confirms previous findings that, although DCA increases gum levels in the fuel, higher concentrations of DCAs improve injector cleanliness enough to outweigh any negative impacts from the increased gum content.

Soriano, Nestor, Williams, Rod, Cracknell, Roger, Lang, Wendy, Chahal, Jasprit

A New Approach for SI Combustion Modeling to Address the Upcoming Fuel Diversity Scenario

2026-01-0276

4/7/2026

Climate change concerns demand a drastic reduction in CO2 emissions, tending to what is called carbon neutrality. Even if political guidelines promote electrification, considering the transportation sector, not all applications have the same requirements and boundary conditions, and hence, their optimal solution is not necessarily the same. In this context, in parallel with pure electric powertrains, the internal combustion engine (ICE) still has a relevant role to play, mainly in hybrid powertrains, working together with an electrical motor. In this hybridization context, the spark-ignition (SI) engine uses to be the most adopted solution because of its lower cost and complexity. Consequently, it can be concluded that the SI engine will still play a significant role in the near future. However, when ICEs are considered, the search for carbon neutrality requires the use of fuels other than fossil fuels. At this point, many alternatives arise, from biofuels to synthetic e-fuels, or even H2. This extreme variety of fuels introduces complexity from the combustion modeling point of view. This study proposes a methodology for developing a 0D combustion predictive model that characterizes the engine flame front effective area (FFEA) of the engine based on a reference fuel (gasoline) and extrapolates it to other engine conditions and/or to other fuels (e.g., H2), predicting the in-cylinder pressure evolution. To allow the prediction for any other fuel, the only requirement is to know the laminar flame speed of that fuel at different operating conditions. The results show that, for different engine conditions, the proposed methodology could predict the in-cylinder pressure with an average error of ~2.1% for the reference fuel and an average error of ~2.6% for Hydrogen (H2). These findings indicate that the proposed methodology has good performance and could be used for analyses requiring a limited number of experiments and a short computational time.

Robayo-Rueda, Daniel, Lopez, J. Javier, Martin, Jaime, Novella, Ricardo

Analysis of In-Cylinder Flow for Hybrid Gasoline Engine using High-Speed Particle Image Velocimetry

2026-01-0298

4/7/2026

To increase the thermal efficiency of a hybrid inline 4-cylinder direct injection engine, combustion promotion was carried out by enhancing the in-cylinder flow. The intake port and piston top shape were optimized using CFD. In-cylinder flow analysis in steady flow showed that the mean steady flow tumble ratio with the in-cylinder flow enhancement specification increased to 1.7 compared to 1.0 with the previous model and 1.4 with the early development specification. The limit engine speed, which is the engine speed at when the mean flow coefficient decreases due to the choke, and the mean steady flow tumble ratio with the in-cylinder flow enhancement specification were positioned on the trade-off line between the NA and the TC engine. In-cylinder flow analysis on the single-cylinder optical engine showed that the in-cylinder flow entering the cylinder smoothly flowed to the exhaust side, and the in-cylinder flow descending on the exhaust side was smoothly converted to the upward flow by the piston top. Thus, the tumble ratio with the in-cylinder flow enhancement specification in the latter half of the compression stroke increased from 1.0 to 1.7 compared to the early development specification. Turbulent analysis was performed by applying the time filter method, a turbulence decomposition method proposed by the authors, to the in-cylinder flow field. The turbulent kinetic energy with the in-cylinder flow enhancement specification in the latter half of the compression stroke increased by 21.9%. The flame structure was located in the corrugated flamelets region on the turbulent premixed diagram, and the combustion promotion effect by in-cylinder flow enhancement was expected. Evaluation of combustion characteristics on the metal engine showed that the initial combustion duration with the in-cylinder flow enhancement specification decreased by 2.3 deg., the main combustion duration decreased by 4.4 deg., and the time loss decreased by approximately 2%. Therefore, the indicated thermal efficiency increased from 41.9% to 42.2%, proving the concept of combustion promotion by in-cylinder flow enhancement.

Okura, Yasuhiro, Urata, Yasuhiro

Effect of Renewable Fuel Blends on Particulate Emissions under Medium Engine Load and Injector Coking Conditions in a GDI Engine

2026-01-0301

4/7/2026

Renewable gasoline is blended with fossil gasoline as part of the effort to achieve zero net carbon emissions. This study examined how five gasoline fuels with different hydrocarbon compositions affect engine-out gaseous and particle number (PN) emissions. Gasolines F3 and F4 reduce GHG emissions by 54% and 35%, compared with fossil gasoline. The other three gasolines reduce GHG emissions by 4-9%. Tests were conducted on a single-cylinder GDI engine at 10-14 bar indicated mean effective pressure (IMEP) and 2000 rpm. The injector-tip coking behavior of the test fuels and the resulting PN emissions were also investigated at 10 bar IMEP. Spray plume targets and start-of-injection (SOI) timing were adjusted to examine how the test fuels affected PN emissions. An endoscope was used to identify the sources of soot during fuel combustion. The experimental results show that PN varies with gasoline composition and engine operating conditions. Aromatics and olefins contribute more to injector coking. Coked injector conditions showed 95% higher PN than clean injector conditions. Reducing the injector umbrella angle reduces coking. At 10-14 bar IMEP, PN emissions increased with higher aromatics content in the gasoline. Additionally, olefins and naphthene contributed to PN at higher IMEPs. 10-200 nm size particles accounted for 70-95% of total particles. Gasoline with higher C9+ aromatics and T50 to FBP values showed higher 10-200 nm particles. Replacing 10% of paraffins with olefins and naphthene in gasoline changed >10 nm particles by 25%. Increasing 4% paraffins and decreasing 4.5% aromatics in gasoline reduced PN emissions by 125%. Increasing the aromatics content of gasoline by 8% increased fuel consumption by 2% and hydrocarbon emissions by 30%. Retarding the SOI timing by 20 CAD reduced PN emissions by 60%.

Muniappan, Krishnamoorthi, Dahlander, Petter, Helmantel, Ayolt, Alemahdi, Nika, Lehto, Kalle

Achieving Euro 7 WHSC NOx Emission Targets from a Spark Ignited Engine Using Methanol-Hydrogen Co-Fuelling

2026-01-0321

4/7/2026

E-methanol is increasingly seen as a promising clean fuel because its chemical makeup is close to fossil fuels, making it easier to use in existing engines. It offers a carbon-neutral option to help reduce greenhouse gases in sectors where cutting emissions is especially difficult, such as transportation. However, while e-methanol avoids adding new carbon dioxide, burning it in internal combustion engines still releases harmful gases like oxides of nitrogen (NOx) and other toxic by-products like formaldehyde and formic acid that damage both health and the environment. This report explores a new strategy that combines methanol with hydrogen to run engines under “ultra-lean” conditions and its impact on emissions, performance and efficiency. Experiments were carried out on a single-cylinder spark ignition engine, with directly injected methanol and port fuelled injection of hydrogen. The findings show that adding about 10% hydrogen (energy basis) at low engine loads can extend the lean limit from air-fuel equivalence ratio (λ) of 1.7 to 2. This change cut NOx emissions by 99% and reduced formaldehyde emissions by 18% compared to pure methanol operation at stoichiometric. Furthermore, the NOx emissions were reduced sufficiently that engine could operate within Euro 7 World Harmonic Stationary Cycle (WHSC) limits.

Ambalakatte, Ajith, Geng, Sikai, Cairns, Alasdair, Varaei, Amirata, Harrington, Anthony, Hall, Jonathan, Bassett, Mike, Cracknell, Roger

The Influence of Split Injection Ratio on Efficiency and NO _x Emissions in a Pilot Diesel-Ignited Hydrogen Direct Injection Engine

2026-01-0329

4/7/2026

This study investigates the impact of the hydrogen split injection ratio on the combustion of pilot diesel-ignited hydrogen direct-injection engines, which is expected to affect hydrogen-air mixture conditions and thus flame propagation and diffusion flame developments. Experiments were conducted on a 1-litre single-cylinder diesel engine equipped with an additional hydrogen injector operating at 35 MPa. Hydrogen accounting for 95% of total input energy was injected at 150 and 60 °CA bTDC for the first and second pulses, which were selected as high-efficiency injection timings from previous equal-split injection tests. The 5% diesel energy was injected near TDC to control CA50 at 10 °CA aTDC. While varying the split ratio between the two hydrogen injections, in-cylinder pressure/aHRR profiles, engine efficiency/power output and engine-out emissions of NOx and CO2 were evaluated. Results showed that the hydrogen split ratio does not significantly affect IMEP/efficiency, which consistently achieved a 17.2% increase over the diesel baseline. While CO2 emissions remained at a very low level due to high substitution of hydrogen energy, they showed no dependency on the split ratio. By contrast, NOx emissions were highly sensitive to the hydrogen injection split ratio. Increasing the first hydrogen injection fraction to 30% reduced NOx, attributed to decreased locally rich mixtures formed by late second hydrogen injection and increased lean mixture homogeneity from early first hydrogen injection, leading to a slower burning effect. However, further increasing the first injection fraction led to higher NOₓ emissions due to increased hydrogen compression, which raised TDC and combustion pressure.

Zhao, Yifan, Chan, Qing Nian, Kook, Sanghoon

Predicting of Transport Carbon Dioxide Emission of Light-Duty Gasoline Vehicles Based on Driving Behavior with Machine Learning Algorithm

2026-01-5012

2/20/2026

Driving behavior is a significant factor influencing vehicle emissions, and it must be carefully considered when modeling emissions for real road transportation vehicles. This study aims to contribute to this field by improving the intelligence and accuracy of distinguishing driving behavior volatility through the use of clustering algorithm. The research begins by processing raw emissions data collected from light-duty gasoline vehicle during real-driving emissions (RDE) test, which are used as input features for the clustering algorithm. Subsequently, a driving behavior classification method based on the gaussian mixture model (GMM) clustering algorithm is proposed. The results show that aggressive driving has a significantly higher CO2 emission rate compared to normal and calm driving. Specifically, the average CO2 emission rate for aggressive driving is 5.61 g/s, which is substantially higher than that of calm driving (2.40 g/s) and normal driving (2.91 g/s). Following this, the study employs Pearson correlation coefficients and an intelligent machine learning modeling approach, incorporating driving behavior–related parameters as part of the input features for the virtual CO2 emission prediction model for light-duty gasoline vehicles. This further highlights the effectiveness of using a clustering algorithm for driving behavior classification, and it demonstrates the significant impact of driving behavior–related parameters on CO2 emission rates, providing an accurate emission model for virtual calibration of vehicles.

Yu, Hao, Ma, Yi, Tan, Jianxun, Wang, Jing, Zhang, Honghao, Hu, Wei, Chen, Hao, Yu, Wenbin

Enhancing Combustion, Performance and Emission Profiles Using Kapok Methyl Ester Blends with Hydrogen

2026-28-0058

2/12/2026

This study investigates the potential of using a dual green alternative fuel combination, the one is hydrogen fuel and another one is biodiesel for enhancing the Performance, combustion and emission profile of a compression ignition engine. The kapok oil biodiesel was blended with Diesel in proportions of 20% (K20) and 40% (K40) by volume. The hydrogen gas was supplied at a constant flow of 4 liter per minute (LPM). The experimental fuels are neat diesel D100, K20 (80% Diesel and 20 % kapok methyl ester), K40 (60% Diesel + 40 % Kapok methyl ester), K20 + H4L (K20 with 4 LPM hydrogen) and K40+H4L (K40 with 4 LPM hydrogen). These test blends are investigated in a single cylinder direct injection CI engine under 0% to 100% load conditions at a fixed speed of 1500 rpm combustion, and emissions characteristic were evaluated and compared with base fuel. The outcomes indicated that the use of B20 and B40 blends without hydrogen led to reduced BTE because of their lower cetane number and calorific value. Additionally, higher viscosity of the blends resulted in increased BFSC. However, the introduction of hydrogen and the K20H fuel blend demonstrated notable emission improvements compared to conventional diesel, achieving reductions of 9–11% in unburned hydrocarbons, 5.3% in carbon monoxide, and approximately 8% in nitrogen oxides (NOₓ). These findings highlight the potential of K20H as a cleaner alternative fuel.

Anbarasan, B, M, Kumaresan, Balamurugan, S, Rajesh, Munnusamy

New Material Significantly Enhances Green Hydrogen Production Efficiency

TBMG-54561

2/1/2026

Green hydrogen, produced through water electrolysis, is a next-generation eco-friendly energy source as it does not generate pollutants like carbon dioxide during production. Catalysts play a crucial role in the water electrolysis process, splitting water into hydrogen and oxygen. The efficiency of green hydrogen production largely depends on the performance of these catalysts. Therefore, the commercialization of green hydrogen hinges on the development of cost-effective catalysts capable of maintaining high performance over extended periods.

Prediction of REESS Factor for SOC Correction in Hybrid Vehicles

2026-26-0471

1/16/2026

The regulatory mechanisms to measure emissions from automobiles have evolved drastically over the years. Certification of CO2 emissions is one of them. It is not only critical for environmental protection but can also invite heavy fines to OEMs, if not complied with. In homologation test of a Hybrid Vehicle, it is necessary to correct the measured CO2 to account for deviations in measurement from failed Start-Stop phase and difference between start and end State of Charge (SOC) of battery. The correction methodology is also applicable for vehicle simulation in Software-in-Loop environment and for analyzing vehicle test data for CO2 emissions with programmed digital tools. The focus of this paper is on the correction of CO2 derived from SOC delta in the WLTP homologation drive cycle. The battery energy delta due to difference in SOC between start and end of drive cycle should be converted to corresponding CO2 expended from Internal Combustion Engine. The resulting correction factor is known as the REESS factor. To provide a reasonable correction factor for one type of engine in a particular car/weight class, a minimum of 3 measurements are required. Digitalization of the same will provide a significant cost benefit and a faster prediction of REESS factor with wider boundary condition of SOC balance applied. The current full vehicle simulation model was adopted to have better validation with REESS correction factors from measurement. A detailed analysis of the impact of operating strategy on the REESS correction factor is reviewed in this paper. The simulations are carried out on well validated models of different powertrain types. The aim of this study was to achieve a simulation setup which can predict REESS factor in tolerance range of +-0.03 (gCO2/km)/(Wh/km) in comparison to measurement.

Gopinath, Shravanthi Poorigali, Khatod, Krishna

Study of Drive Trace Indices and Their Correlation with CO ₂ in Chassis Dynamometer

2026-26-0517

1/16/2026

With introduction of Corporate Average Fuel Efficiency norms (hereafter referred as CAFÉ norms) in India, the manufacturers of all M1 Category vehicles (not exceeding 3,500kg GVW) must ensure that they comply with Annual Corporate average CO2 target as defined in regulation. Moreover, this target will become stricter at various stages in the coming years. Hence CO2 emissions are becoming one of the major focus parameters during vehicle development. There are several factors that can impact CO2 emissions during measurement in laboratory-based test cycles such as MIDC or WLTC. One such major factor is driving variations. Although speed and time tolerances are provided during the test (as part of AIS 137/AIS 175) to limit the variation, even within these tolerances, drive-related effects make significant contribution to test results variability. Monitoring and control of such variations is important to understand the true fuel economy potential of the vehicle. Drive Trace indices are standardized metrics that can be used to evaluate the driving variations. The aim of this study is to understand the different driving behaviors on drive indices and consequently on CO2. Drive indices such as Energy Rating (ER), Distance Rating (DR), Energy Economy Rating (EER), IWR (Inertial Work Rating), RMSSE (Root Mean Square Speed Error) defined in SAE J2951 document have been referred for this study. Multiple MIDC & WLTC emission test data have been used for evaluation of driving behavior. An attempt has been made to establish a correlation between the drive trace indices and CO2 (and fuel economy) in MIDC by using mathematical techniques similar to study done by JRC for WLTC.

ER, Shivram, Rawat, Vijaypal, Khandelwal, Vineet, Kumar, Arun, Malhotra, Jitendra

Hybrid Topology Selection & Optimization of a Compact SUV to Meet Future CO ₂ Norms – an Indian Case Study

2026-26-0077

1/16/2026

Rising environmental concerns and stringent emissions norms are pushing automakers to adopt more sustainable technologies. There is no single perfect solution for any market and there are solutions ranging from biofuels, green hydrogen to electric vehicles. For Indian market, especially in the passenger car segment, hybrid vehicles are favoured when it comes to manufacturers as well as with consumer because of multiple reasons such as reliability, performance, fuel efficiency and lower long-term cost of ownership. For automakers planning to upgrade their fleets in the context of upcoming CAFE III (91.7 g CO2 / km) & CAFE IV (70 g CO2/km) norms, hybridization emerges as the next natural step for passenger cars. Lately, various state governments have also promoted hybrid vehicle sales by offering certain targeted tax breaks which were previously reserved for EVs exclusively. Current study focuses on various parallel hybrid topologies for an Indian compact SUV, which is the highest selling and fastest growing segment in India. The selected SUV with curb weight ~1255 kg has a 1.2 L turbocharged gasoline engine with peak power and peak torque of 88 kW and 170 Nm respectively. Simulations of various low voltage (LV) and high voltage (HV) hybrid topologies like P0 LV (base scenario for 2030), P0P2 LV, P0P2 HV and P0P4 HV are performed as per Worldwide Harmonized light vehicle Test Procedure (WLTP) in line with upcoming CAFE norms. Results are analysed to gauge performance (acceleration, gradeability) and fuel consumption. Regeneration and torque boosting capabilities of various hybrid topologies are also compared analytically based on simulation results. Gaussian optimization methodology is employed to systematically optimize powertrain configurations and control strategies to maximize fuel efficiency.

Warkhede, Pawan, Keizer, Ruben, Sandhu, Rouble, Emran, Ashraf

3D CFD Combustion Evaluation of Hydrotreated Vegetable Oil (HVO) as a Potential Alternate Fuel for the Future CI Engines

2026-26-0113

1/16/2026

Transportation industry is facing a growing challenge to reduce its carbon footprint and utilize the carbon neutral, more environmentally sustainable fuels to comply with the goal of carbon neutrality. Implementation of carbon free fuels such as Hydrogen, Ammonia and low carbon fuels such as Methanol, Ethanol can significantly reduce the greenhouse gas emissions, but these fuels are suitable for SI engine architecture due to their high-octane ratings. Hydrotreated Vegetable Oil (HVO) is one of the few fuel solutions available today with a high Cetane rating (70-80), that can be used as a drop-in fuel in the existing CI engines, with minimal modifications. The main constituent of HVO is pure alkane and it can be produced from feedstocks such as vegetable oils, animal fats, various wastes and by-products. A closed cycle 3-D CFD combustion simulation using a detailed chemistry-based solver has been conducted with the HVO, on a three cylinder, naturally aspirated water-cooled CI engine at its full load, rated rpm. Chemical kinetics file with 92 species and 1240 reactions has been used as a surrogate for the HVO to conduct the combustion simulation. The peak firing pressure has been observed to be lower by 3% and SoC is advanced by 2o CA for HVO as compared to the baseline diesel. HVO combustion manifests the same thermal efficiency with respect to its diesel counterpart. Soot emission has been 36% lower for HVO due to the absence of unsaturated hydrocarbons and the NOx emission is lowered by 32% for HVO, as a consequence of a lowered in-cylinder temperature. Simultaneously, a 13% reduction in CO, 77% reduction in UHC and 74% reduction in VOC have been observed for HVO as compared to diesel. A meticulous monitoring of unregulated emissions proves that the HVO exhaust is devoid of their presence. The 3D CFD combustion exploration unveils that the HVO indeed holds the potential to be a promising drop-in alternate fuel for the next generation CI engines.

Tripathi, Ayush, Mukherjee, Nalini, Nene, Devendra

Unveiling the Dynamics of Methanol-Diesel Dual Direct Injection Compression Ignition Combustion: A Synergistic Experimental and Numerical Study

2026-26-0110

1/16/2026

The pressing global need for de-fossilization of the transport sector, especially within the heavy-duty segment, has intensified the exploration of alternative clean fuels. In this context, methanol gained traction due to their renewable production pathways, carbon-neutrality, and are being highly promoted by the Indian government to reduce CO2 emissions. Dual direct injection compression ignition (DDICI) is an effective combustion strategy to use methanol in heavy-duty engines, which combines the advantage of high-efficiency compression ignition with the clean-burning potential of methanol. In contrast to spark-ignited premixed methanol engines, this strategy involves a diffusion combustion of the methanol flame, thereby eliminating knocking and enabling running with high compression ratios. This experimental and numerical study presents a comprehensive investigation into the DDICI strategy using methanol as primary fuel and diesel as a pilot for ignition assistance. The work benchmarks the methanol DDICI operation against baseline diesel operation, catering the required combustion chamber modifications, fuel injection strategy, system layout and capturing key metrics like thermal efficiency and emissions. The numerical study details the effect of swirl spray orientation, and positioning of the pilot injector, on the charge distribution and the ignition. The 3D-CFD models used for the simulation model are well validated against experimental results to capture in-cylinder combustion dynamics and emission trends. The experimental results demonstrate that methanol DDICI achieves a thermal efficiency improvement of up to 2.5-3.0 % at high load with NOx reduction of about 50 % at similar exhaust gas recirculation (EGR) ratio compared to the baseline diesel. Additionally, it demonstrated soot-free combustion and lower in-cylinder temperatures reducing thermal stresses. The introduction of swirl led to improved mixture formation, promoted gradual ignition and enhanced post-flame oxidation, thereby reducing CO emissions. Furthermore, the simulation results revealed that the reduced spatial separation between diesel and methanol spray plume facilitates faster ignition and smoother combustion. In this regard, the stagger angle of 12.5° with 9-hole nozzle resulted in lower maximum pressure rise rate compared to 22.5°, with similar levels of thermal efficiency and NOx emissions.

Singh, Inderpal, Dhongde, Avnish, Raut, Ankit, Güdden, Arne, Emran, Ashraf, Berry, Sushil

Development of High BMEP Natural Gas Engine with Knock Mitigation

2026-26-0121

1/16/2026

The stringent emission norms over the past few years have driven the need to use low-carbon fuels and after treatment technology. Natural gas is a suitable alternative to diesel heavy-duty engines for power generation and transportation sectors. Stoichiometric combustion offers the advantages of complete combustion and low carbon dioxide emissions. Turbocharging and cooled exhaust gas recirculation (EGR) technology enhances the power density along with reduced exhaust emissions. However, there are several constraints in the operation of natural gas spark ignition engine such as exhaust gas temperature limit of 780 °C, sufficient before turbine pressure for EGR drivability, boost pressure, peak cylinder pressure limit and knocking. These limits coulld restrict the engine BMEP (brake mean effective pressure). In the present study, tests were conducted on a V12, 24 liters, heavy duty natural gas fuelled spark ignition engine (600 HP) with different EGR and turbocharger configurations to achieve 16 bar BMEP without abnormal combustion. Considering the maximum exhaust temperature limit of 780 °C of exhaust system, minimal engine hardware changes were done to ensure less complexity, cost-effective engine development with robust design. The turbine trim was decreased from 89% to 84% to avoid excessive high before turbine backpressure, backflow of residual gases into cylinder and knock possibility. EGR system optimization with mixer enhanced EGR mixing and distribution in all cylinders that improved BSFC by 3%. During knock calibration, the offset to base ignition timing was used for individual cylinders to mitigate knock. Endurance trial of 100 hours was carried out to validate the reliability of engine design and calibration, and no issues were detected. The developed engine is the highest BMEP V12 engine in its segment in India using stoichiometric combustion with cooled EGR and three-way catalyst. The engine is certified with latest Indian CPCB IV+ emissions norms.

Khaladkar, Omkar, Marwaha, Akshey

The Aerodynamic Development of a Compact SUV for FE Improvement Compliance with CAFE Norms

2026-26-0595

1/16/2026

The Mahindra XUV 3XO is a compact SUV, the first-generation of which was introduced in 2018. This paper explores some of the challenges entailed in developing the subsequent generation of this successful product, maintaining exterior design cues while at the same time improving its aerodynamic efficiency. A development approach is outlined that made use of both CFD simulation and Coastdown testing at MSPT (Mahindra SUV proving track). Drag coefficient improvement of 40 counts (1 count = 0.001 Cd) can be obtained for the best vehicle exterior configuration by paying particular attention to: AGS development to limit the drag due to cooling airflow into the engine compartment Front wheel deflector optimization Mid underbody cover development (beside the LH & RH side skirting) Wheel Rim optimization In this paper we have analyzed the impact of these design changes on the aerodynamic flow field, Pressure plots and consequently drag development over the vehicle length is highlighted. An interaction between grill closing and underfloor design of the same nominal dimensions is explored. Customers are increasingly demanding compact hatchback-like fuel consumption and CO2 emission limits are being made more stringent with upcoming revised CAFE norms. Therefore, it is essential to increase the efficiency of the vehicle and to minimize all energy losses. Aerodynamic drag constitutes ~30% of total energy consumption on WLTC cycle (excluding extra high speed phase) which is very significant. Compared to improvements in power train and vehicle mass, reduction of aerodynamic drag can be achieved at relatively low cost. For this vehicle, we demonstrate ways to improve the aero drag coefficient, 10% lower than the first-generation of XUV 3OO, thereby delivering ~2% Fuel Economy benefit to the customers.

Vihan, Nikhil

Powertrain Optimization of Indian City Electric Bus Using Active Learning Simulation Methodology

2026-26-0657

1/16/2026

Public transport electrification is going to play a massive role in India’s COP26 pledge to achieve net zero emissions by 2070. India plans to electrify 800,000 buses in a push towards 30% EV penetration by 2030. Further encouraged by government incentives under National Electric Bus Program (NEBP), e-Bus market is expected to grow at a CAGR of ~86% annually over the next 5 years. With most OEMs going for fleet electrification for reducing CO2 emissions and to cater to growing demand in Indian cities for cleaner public transport, improving powertrain efficiency and performance of state-of-the-art e-Buses is a natural progression of e-mobility sector development in India. The first step in designing powertrain for an electric city bus is to determine the motor(s) size and transmission specifications (number of gears, gear ratios etc.). Complications arise due to a wider and non-linear operation range of eBus. This study focuses on powertrain optimization for a medium duty electric city bus for an Indian city. FEV’s in-house Vehicle Powertrain System Design & Controls (VPSC) tool is deployed for a structured approach. It uses backwards simulation approach to estimate energy consumption and performance of vehicle. An initial (reference) electric drive unit (EDU) is selected via local pre-simulation for detailed flux linked loss maps. This is followed by an iterative AI based Global Optimizer which uses Bayesian algorithm to arrive at subsequent designs until the objective is met within the stated constraints. Performance parameters considered include acceleration and gradeability. The simulation is performed on a high traffic Indian city duty cycle as well as a reference urban VECTO cycle. In both cycles, results show a significant improvement in energy consumption while at the same time improving upon performance with respect to initial pre-simulation selected design of motor and transmission.

Sandhu, Rouble, Chen, Bicheng, Emran, Ashraf, Xia, Feihong, Lin, Xiao, Berry, Sushil

Technologies and Strategies for High Brake Thermal Efficiency Gasoline Engine to Meet the Future CO ₂ Emission Targets in India

2026-26-0072

1/16/2026

The Indian automobile industry is experiencing a significant shift, propelled by environmental necessities and national climate obligations set at the CoP26 summit, aiming for a 45% decrease in CO₂ emissions by 2030 and reaching carbon neutrality by 2070 [1]. Transportation continues to be a significant source of air pollution; consequently, India is enhancing its regulatory frameworks with BS VI Stage 2 regulations, CAFE Phase III norms set for 2027, and CAFE Phase IV by 2032 [2]. Furthermore, the transition from MIDC to WLTP driving cycle is meant to increase the accuracy of the efficiency and emissions assessments [2]. To comply to these upcoming regulations, the automotive industry is moving toward producing high efficiency engines in India. A naturally aspirated (NA) 1.5L, 4-cylinder inline gasoline engine was selected from Indian market for this study. Maximum Brake Thermal Efficiency (BTE) of this engine is around 37%. Assessment of new technologies were performed by implementing them stepwise to see the impact on BTE. A well calibrated 1D GT-SUITE model was considered from FEV database to perform the simulation-based approach to increase the BTE by improving the stroke/bore (s/B) ratio, increasing the compression ratio, implementing Atkinson cycle with variable valve timing (VVT) / variable valve lift (VVL) optimization, and charge motion refinement for optimal in-cylinder combustion. Low temperature cooled EGR (TEGR < 70°C) and pre-catalyst pick-up distributed EGR strategies were simulated to improve the combustion stability and pumping loss for BTE improvement. Friction losses were further minimized by implementing the polished surfaces, electrification of auxiliary components, and other advanced surface treatments. Advanced technologies including Dual Port Fuel Injection (Dual PFI) system, high energy ignition system with thermal swing coatings, and system designed to operate with highly diluted mixture are required to achieve maximum BTE. These technologies would also be explored in this study. This paper also covers the rivals' restrictions put on engine geometry and number of cylinders concerning possible max. BTE level with which the engine can achieve. With the completed study, the efficiency step walk document indicated BTE improvement from each technology step to achieve a target max. BTE for the engine.

Garg, Shivam, Fischer, Marcus, Emran, Ashraf, Jagodzinski, Bartosch, Franzke, Bjoern

Replacing Diesel Engines with CNG Engines – Impact on Emissions, Based on Chassis Dynamometer Tests of Medium and Heavy-Duty Buses

2026-26-0127

1/16/2026

This paper compares carbon dioxide, carbon monoxide, methane, and oxides of nitrogen emissions from medium and heavy-duty buses using diesel, diesel-hybrid, and CNG powertrains. Comparisons are made using results from chassis dynamometer-based tests with driving cycles intended to simulate a wide range of operating conditions. Tail pipe emissions are measured by diluting the vehicle’s exhaust in a full-scale dilution tunnel by mixing with conditioned air. Samples are drawn through probes of raw exhaust, diluted exhaust and measured using laboratory grade emission analyzers. Fuel consumption of diesel is measured using a weighing scale, while a gas flow meter is used for measuring CNG consumption. Experimental data from 19 buses tested on a chassis dynamometer over the last 8 years has been analyzed and a comparison of results from similar buses with the differently fueled powertrains is presented. Based on these test results, it is shown that replacing diesel engines with CNG engines does not significantly reduce the emissions of carbon dioxide, while it increases carbon monoxide and methane emissions, reduces oxides of nitrogen emissions, and does not substantially help to reduce global warming.

Iyer, Suresh

Extreme Learning Machines for Fast Instantaneous Prediction of Emission Level of an Automobile

2026-26-0226

1/16/2026

Addressing climate issues is a key aspect of good global governance today. A key aspect of managing the threats caused to the environment around is to ensure a sustainable transportation system so that humans exist in peace with nature. According to sources, in 2020 alone, cars accounted for approximately 23% of global CO2 emissions. In addition, they also emit dangerous pollutants thus damaging the ecosystem. To keep pollutants in check there are emission level testing strategies in place in each country. However, we can do better for a sustainable future. On one hand, the huge volume of vehicles around the world makes it an excellent choice and source for a vast emission level dataset comprising of input features as well as the target variable representing the emission band of the vehicle. In addition to the big data available as mentioned above, major advancements in the machine learning algorithms are done today. The advent of algorithms such as Artificial Neural Networks (ANN) has made it possible to develop models with very high accuracy. In this paper, the authors therefore propose the application of Extreme Learning Machines (a type of feedforward neural networks) to solve the pressing challenge of classifying the emission band of a vehicle which can be used by agencies to ensure that healthy vehicles operate on road at large. Extreme Learning Machines (ELM), by definition, is an excellent choice for emission band prediction task as it offers a significant reduction in training time and thereby is scalable such as to the task confronted with in this paper. Results from the metric, namely classification accuracy, are discussed at length. The highly accurate trained model, thus developed, can be used by agencies to then predict the emission band for any given vehicle scenario thus complementing the strategies already in place today for a greener earth.

Sridhar, Sriram, Aswani, Shelendra

Evaluating the Environmental Footprint of Electric Vehicles: A Life Cycle Assessment Approach for Sustainable Mobility in India

2026-26-0235

1/16/2026

Road transport contributes 12% of India’s energy-related Carbon Dioxide (CO2) emissions. It is one of the major source of air pollution in urban area. These vehicle related emissions has increased more than three times since 2000 which is mainly driven by rapid urbanization and the growing demand for private vehicles. If there is no shift away from fossil to renewables, climate change intensity and air quality challenges will increase. Among sustainable alternatives, electric vehicles (EVs) have emerged as a promising solution. However, a comprehensive understanding of their environmental performance, particularly in the Indian context, is essential for informed decision-making. This study employs a Life Cycle Assessment (LCA) method to evaluate the environmental consequences of typical passenger vehicle with an gasoline/diesel powered vehicle compared to its EV powertrain covering Cradle-to-Grave life cycle phases. Key life cycle stages—manufacturing, transportation, distribution, maintenance, and end-of-life—are analyzed using real-world data wherever feasible. To capture the evolving energy landscape, the study incorporates India’s projected grid evolution, considering increased renewable energy adoption in 2025, 2030, and 2040 to evaluate use phase impacts for EVs. The findings reveal that EVs demonstrate 14–38% lower CO2 eq. emissions compared to ICE over 150,000 km vehicle lifetime which is subject to pace of grid decarburization and related policy implementation. The study is further extended to cover scenarios with use of 50% & 100% use of solar energy for charging the vehicle which further reduces CO2 eq. emissions up to 61% and to covers other impact categories for all the scenarios. The analysis also identifies a break-even point, after which EVs deliver superior environmental performance compared to their diesel counterparts. The study clearly emphasizes environmental benefits of EVs and highlights the crucial role of renewable energy integration and supportive policy frameworks in effective decarburization. By presenting a robust evaluation, it emphasizes the extensive potential of EVs in advancing India’s sustainable mobility goals and clearly define the significance of accelerating the transition toward greener transportation systems.

Sonawane, Nayan, Sathaye, Asmita, Gode, Abhishek, Deshpande, Ashish, Shinde, Harshavardhan, Kothe, Anjali

Migration from MIDC to WLTP in India: Challenges & Solutions for a Small Commercial Vehicle

2026-26-0215

1/16/2026

In line with global peers (EU, Japan, etc.), the Automotive Industry Standard (AIS) Committee in India has decided to adopt “World harmonized Light vehicle Test Procedure (WLTP)” for M2 and N1 category vehicles not exceeding 3500 kg and for all M1 category vehicles. As a result, “World harmonized Light-duty vehicles Test Cycle (WLTC)” is set to replace currently applicable “Modified Indian Drive Cycle (MIDC)” in the next couple of years. The draft Corporate Average Fuel Economy (CAFE) III & CAFE IV norms for CO2 emission limits, which are set to be implemented in year 2027 and 2032 respectively refer to a shift to WLTP from MIDC. The latest draft of Central Motor Vehicle Rules (CMVR) for BS-VI emissions is also being revised to use WLTC as test cycle. This migration to WLTC is in sync with the demand for test procedures to replicate real driving conditions more appropriately. Further, the move to WLTC along with stricter emission norms is a major step towards realizing India’s COP26 pledge to achieve net zero emissions by 2070. WLTC being much more dynamic with higher average speeds and acceleration compared to MIDC, has a major impact on the vehicle CO2 emission. Other gaseous pollutants like NOx also increase significantly with WLTC. This study takes into consideration the impact of change in test procedure on a conventional small commercial vehicle. Using the well validated models from FEV, simulations are performed to quantify the differences in various gaseous emissions under both MIDC and WLTC as well as under a typical Indian Real Driving Emissions (RDE) cycle with base calibration. Further, a step wise approach is detailed to have vehicles compliant with upcoming norms. The methodology lists both basic measures like calibration and hardware upgrades (e.g., change in injection pressure) as well as advanced measures including deploying additional technologies like advanced aftertreatment systems and hybridization etc. to improve fuel efficiency as well as reduce tail pipe emissions.

Pawar, Bhushan, Ehrly, Markus, Sandhu, Rouble, Emran, Ashraf, Berry, Sushil

A Thermoelectric System for Emission Control Optimization in Two-Wheeler Automotive Applications

2026-26-0218

1/16/2026

Environmental pollution is one of the growing concerns of our society. As vehicle emissions are a major contributor to air pollution, emission control is a primary goal of the Automotive industry. Vehicle emissions are higher due to improper combustion, which leads to toxic gases being generated from the exhaust system. Unburnt fuel is one of the leading causes of toxic pollutants such as Carbon Monoxide, Nitric Oxides (NOx) and Hydrocarbons. The catalytic converter converts these gases into less toxic substances such as Carbon Dioxide, Nitrogen, and water vapor. The catalytic converter performs efficiently after reaching its “Light Off” temperature, after which the catalyst becomes active. Hence, elevated temperature of the exhaust gases aids in efficient conversion. Presently, the gases from the exhaust system are approximately at a temperature of 300°C-600°C. This paper outlines the concept of a Peltier (Thermoelectric) Module - based system, which helps maintain the high temperature of the exhaust gases prior to entering the catalytic converter. Peltier Modules are thermoelectric devices well-known for their usage in heating/cooling applications. The proposed system includes a chamber in which the Peltier Module is embedded. As the gases flow through the chamber, the embedded Peltier Module, which is powered by the battery, increases the temperature inside the chamber. Therefore, with this concept, the components required to heat the catalytic converter could be potentially reduced, since the exhaust gases will be maintained at the targeted temperature required for better emission control. Moreover, the Peltier Module is also known to be used for electricity generation. Consequently, by generating electricity through heat utilization on the surface of the chamber, we provide an added benefit of this proposed concept. This can be achieved by mounting the Peltier Module on the hot surface of the chamber. The other side of the Peltier Module is exposed to ambient air and thereby a potential difference is created through the Seebeck Effect.

Venkateshwaran, Aishwarya, Soodlu, Shashikiran, M, Mathaiyan

Optimizing Hydrogen Engine Performance a Comparative Study of Lean & Stoichiometric Calibration Approach

2026-26-0261

1/16/2026

Hydrogen combustion in internal combustion engines offers numerous advantages, such as zero CO2 emissions and high flame speed, which make it a promising alternative fuel for green vehicle solutions. In order to maximize the engine performance with hydrogen, however, meticulous calibration of the air-fuel mixture must be performed, particularly when lean and stoichiometric combustion conditions are considered. Lean burning, i.e., excess air, offers better thermal efficiency and lower NOx emissions but can cause lower engine power and combustion instability. Stoichiometric combustion, however, ensures complete combustion of the fuel-air mixture, but at the cost of higher combustion temperatures and consequently, high NOx emissions. Calibration strategies for hydrogen engines are presented in this paper by comparing the lean and stoichiometric strategies and their implications on engine power output, efficiency, and emissions. Test data from several hydrogen engine configurations demonstrate that lean burn with EGR addition can be employed to minimize NOx emissions at the expense of tight engine stability and power control. On the other hand, stoichiometric operation yields more power but with the requirement for complex emission control systems. The compromises between these calibration strategies are presented in the paper and recommendations are provided on optimizing the performance of hydrogen engines for different operating conditions.

Jadhav, Ajinkya, Bandyopadhyay, Debjyoti, Sutar, Prasanna S, Sonawane, Shailesh Balkrishna, Rairikar, Sandeep D, Thipse, Sukrut S

Testing Methodology to Calculate the Fuel Economy in Km/Kg of Hydrogen Fuel Cell Electric Vehicle (FCEV) based on Current (Ampere) Method and Flow Method

2026-26-0248

1/16/2026

The globe is looking headlong to set up new benchmarks for the reduction of GHG (Green House Gases) considering short-term and long-term strategies. Efforts in the Internal Combustion Engines (ICE) domain have been accelerating to find an alternative way to reduce harmful emissions. Hydrogen is considered as a promising fuel to leapfrog this transition. Hydrogen fuel can be categorized into vast mobility areas viz. ICE and Fuel Cell Electric Vehicle (FCEV). Hydrogen fuel has attracted global attention from engine researchers due to the crude oil crisis and its rise in prices in recent years. This will serve the nation's goal towards carbon neutrality. Hydrogen has a few advantages such as less fueling time, higher heating value and more efficiency making it an eye-touching fuel for the automotive industry. In the contemporary FCEV segment, many fuel cell technologies have evolved, wherein the development of Proton Exchange Membrane (PEM) fuel cell technology has taken a new height for heavy-duty commercial vehicle applications due to its significant interest in the non-existent tailpipe CO2 emissions. Since electric vehicles are also being combined with hydrogen fuel and the opportunity persists to convert it into a hybrid system or FCEV. There is always a keen curiosity of the end user to know the mileage of a vehicle as a distinguishing measure of fuel economy. Thus, it is pertinent to determine the hydrogen fuel economy of the FCEV vehicle. This paper provides an insight into fuel cell fundamentals, the working principle of hydrogen fuel cell vehicles, vehicle operation modes and testing methodology to determine the fuel economy of FCEV based on the electric current method and pressure method. The vehicle (e-Bus) has been validated on a chassis dynamometer based on the prescribed DBDC Cycle in the AIS 049 standard to calculate the hydrogen fuel economy of the FCEV Bus. The multiple stacks of PEM fuel cells connected in series has been used along with the electric powertrain vehicle and estimation of its fuel economy are the focus of this paper.

Joshi, Ashish Rajendra, Kandalgaonkar, Siddhesh, Sontakke, Rushikesh

Calculation of Greenhouse Gas Emissions in CO ₂ Equivalent per Hectare of Sugarcane Cultivated for Brazilian Ethanol Production

2025-36-0191

12/18/2025

This study aims to quantify, through Monte Carlo simulation (100,000 iterations), the greenhouse gas (GHG) emissions associated with the complete production cycle of ethanol from sugarcane in Brazil, expressed in kg CO2eq/ha, and to project these emissions over a 20-year horizon. To achieve this, the production cycle was segmented into distinct stages - land use change, soil management and preparation, fertilization, harvesting and straw management, soil carbon sequestration, and industrial processing - and the parameters for each stage were defined based on recent. Three representative scenarios were considered: Worst-case (unsustainable practices involving conversion of native vegetation, high fertilizer dosages, and complete burning of the straw), Typical (conventional practices, with conversion of degraded pastures and sustainable management), and Ideal (best practices, characterized by reduced input dosages, the use of nitrification inhibitors, and high straw retention). The results indicate that, under sustainable practices, ethanol exhibits a significantly lower carbon footprint compared to gasoline, whose typical emissions range between 2.8 and 3.0 kg CO2eq/L. These findings reinforce the potential of Brazilian ethanol to contribute to GHG emission reductions and underscore the importance of adopting sustainable agricultural practices.

Assis, Marcelo Suman Silva, Paula Araújo, Gabriel Heleno de, Baeta, José Guilherme Coelho, Abreu, Pedro Blaso Barbosa de, Filho, Fernando Antonio Rodrigues

Effect of Ultra-High Fuel Injection Pressure on Combustion Characteristics, Engine Performance and Pollutant Emissions of a Multi-Cylinder Engine

2025-36-0212

12/18/2025

The concern about CO2 emissions from commercial vehicles powered with internal combustion engines has been motivating research and development projects to reduce the transportation sector carbon footprint. One of the promising alternatives is the use of biofuels associated with high-efficient internal combustion engines, taking advantage of the current infrastructure of car manufacturers and automotive suppliers, as well as of the potential growth in biofuel production. With the stringent emissions regulations, the use of downsized SI engines for passenger cars has driven the adoption of direct injection technology, enabling the use of different fuel injection strategies such as stratified mixtures and multiple injection events, as well as the increase of the compression ratio as a way to improve engine thermal efficiency. This path also led to a gradual increase in injection pressure, aiming to improve spray formation and reduce the formation of particulate matter. In this sense, the implementation of such technology on the Brazilian flex-fuel engine represents an important path to the transport sector decarbonization. However, the use of hydrous ethanol and gasoline-anhydrous ethanol blends on direct injection systems still demands fundamental research to fully understand the potential benefits and drawbacks of higher fuel injection pressures. Within this framework, this work aims to further understand the effect of using ultra-high fuel injection pressures (up to 1000 bar) on engine performance and pollutant emissions of a multi-cylinder prototype engine. Experimental tests with three different injection pressures confirmed the HC and soot emission reduction, as well as improvement on the engine brake thermal efficiency both when fueled with hydrous ethanol and Brazilian gasohol (blend of 27% anhydrous ethanol in gasoline). Due to the lack of dedicated hardware to pressurize and inject ethanol at ultra-high pressures, the durability of the injection components was a major concern during the experimental campaign.

Antolini, Jácson, Zabeu, Clayton Barcelos, Pires, Gustavo Cassares, Polizio, Yuri

Study of the Performance, Consumption and Range of a Fuel Cell Electric Vehicle Powered by Green Hydrogen

2025-36-0007

12/18/2025

Ethanol is a hydrogen-rich liquid and has a specific energy of 8.0 kWh/kg. In a vehicle, hydrogen storage is done in high-pressure cylinders. The same fundamental technology is used at other fuel cell systems in vehicles such as Toyota Mirai and Honda Clarity. Hydrogen is also introduced into the cell to generate electricity, which will power an electric motor that drives the vehicle. Excess electricity is stored in batteries. The main characteristic of the system described here is that hydrogen can be generated through an additional process in a reformer, installed at a fixed station. The reformer transforms the ethanol stored in the fuel station tank into hydrogen, which can then fuel a vehicle equipped with high-pressure cylinders and fed into the fuel cell. The system, however, emits water vapor, heat, and CO2. This is because carbon dioxide is a byproduct resulting from the transformation of ethanol into hydrogen. According to studies, despite this the system is carbon neutral, considering the total cycle. That is, the CO2 released into the atmosphere is retained by the plantations that are cultivated to produce ethanol. Thus, the carbon is contained in a closed cycle. In addition to ethanol, the reformer can also operate with other fuels such as natural gas, biogas, etc. In view of these facts, we have the following considerations: the use of an electric traction system with a fuel cell powered by reformed hydrogen gas from ethanol can allow greater autonomy for electric vehicles, reducing the dependence on electric charging stations; it can also make a significant contribution to reducing pollutant emissions. Looking at the world situation in the medium term, it may turn out to be an alternative system to the use of internal combustion engines and reduce dependence on fossil fuels.

Fontana, Romeu

Development of a Localized Heat Treatment Route for Stamped Automotive Parts

2025-36-0089

12/18/2025

The increasing demand for sustainable and space-efficient manufacturing solutions in the automotive industry has driven the search for alternative processes to conventional hot stamping. This study proposes a novel localized heat treatment technique based on Joule heating, aiming to reduce the physical footprint of production equipment, simplify the thermal processing of structural components, and minimize the carbon footprint of the process. The method consists of cold stamping followed by localized austenitization of 22MnB5 steel using electrically powered copper electrodes, eliminating the need for large-scale gas-fired furnaces. The process is particularly advantageous in the Brazilian context, where the electric energy matrix is predominantly hydroelectric, contributing to lower CO2 emissions. Experimental trials were conducted using a Gleeble® thermomechanical simulator to optimize thermal cycle parameters (heating rate, austenitization temperature, and soaking time) ensuring the formation of a martensitic microstructure in the treated region while preserving the original ferritic-pearlitic structure elsewhere. The resulting microstructural gradient enables localized mechanical properties, with potential application in crash-relevant automotive components. The proposed route demonstrates technical feasibility and industrial relevance, offering a compact and sustainable alternative to conventional hot stamping.

Santana, Jessica, Curti, Gustavo, Lima, Tiago, Sarmento, Matheus, Callegari, Bruna, Folle, Luis

Investigation of the Performance and Emissions of a Compression Ignition Mechanical Engine Operating in a Dual-Fuel Mode with Diesel and CNG

2025-36-0127

12/18/2025

This study investigates the impact of adding compressed natural gas (CNG) to diesel on the performance of a compression ignition engine. In diesel dual-fuel systems, CNG is used to replace part of the energy originally supplied by diesel. The objective is to evaluate the performance of an Agrale BX6110 agricultural tractor engine operating in dual-fuel mode, with simple adaptations that allow it to function in its original mode as well, ensuring easy reversibility. Additionally, CNG can represent a cost-effective and environmentally advantageous alternative for farmers, significantly reducing their operational costs. Tests were conducted with four different CNG injection cases and three diesel injection cases, using an AW Dynamometer NEB 200 test bench. The maximum diesel substitution by CNG was 45.20%. In dual-fuel mode, the engine achieved maximum torque and power values of 665 N·m and 37.3 kW, respectively, representing a 20.45% loss compared to diesel-only operation. A reduction of 20.50% in carbon dioxide (CO2) emissions was observed, while unburned hydrocarbon emissions increased by approximately 4.52 times. Through economic analysis, it was concluded that, at the point of maximum torque and power operating in dual-fuel mode, a cost reduction of 14.32% per kWh produced was achieved.

Oliveira, Lucas, Alvarez, Carlos Eduardo Castilla, Cesar, Felipe

Refrigerants Selection for Automotive Air Conditioning System in Tropical Climates

2025-36-0143

12/18/2025

Automotive air conditioning systems are essential for ensuring thermal comfort for passengers. However, these systems require the elimination of refrigerants with high Global Warming Potential (GWP) and a transition toward more environmentally friendly alternatives. For many years, R134a has been the industry standard in automotive applications, following the phase-out of chlorofluorocarbons (CFCs) such as R12. This study evaluates the energy efficiency and environmental impact of several refrigerants in automotive air conditioning systems in tropical climates. A comprehensive literature review is conducted to select the refrigerants to be compared with R134a. The following is chosen: R1234yf, R744 (CO2), R290, R600a and R152a. Then a mathematical model is prepared and validated. The deviation between the results presented by the mathematical model and those in the literature varies from -1.21% to 8.33%. The simulation results suggest that the Coefficient of Performance (COP) of R152a and R600a is approximately 3% higher than that of R134a. However, these fluids are flammable, requiring additional safety investments. While R1234yf shows a slight loss in efficiency, at almost 4% lower than R134a, it offers a degree of compatibility due to its similar overall properties. The performance of R290 is slightly worse, while that of R744 is significantly lower. Finally, the environmental analysis based on TEWI indicates that R152a and R600a result in a slightly lower impact compared to R134a. In contrast, R290 and R1234yf exhibit a slightly higher environmental impact than R134a.

Oliveira Dias, Vinícius José de, Barbieri, Paulo Eduardo Lopes, Moreira, Thiago Augusto Araújo, Santos, Alex Henrique, Freitas Paulino, Tiago de

Alternative to PFAS Ban: Impact on the Systems and Implementation Challenges

2025-36-0102

12/18/2025

In early of 2023 the European Union began the process of banning the so-called Per- and polyfluoroalkyl substances, with a total elimination forecast for 2035. Currently, the refrigerant gas used by automakers is the R1234yf, a substitute for the R134a as a refrigerant with zero degree of ozone layer destruction, developed to meet the European directive 2006/40/EC that came into force in 2011. It requires all new car platforms for sale on the continent to use a refrigerant in their air-conditioning system with a Global Warming Potential below 150. The alternatives studies for the replacement of R1234yf are R744 (CO2) and R290 (Propane). The first is characterized by being a non-flammable gas and has a working pressure of 6 to 12 times higher than the current one. The second has the characteristic of having working pressure similar to R1234yf, but it is a highly flammable gas. This work focuses on the analysis of the two alternative gases to R1234yf, exploring their characteristics, detailing their impact on the systems, and discussing the challenges for the implementation of each of them.

Ariza, Valquíria Rezende, Erberelli, Diego Pivatto, Silva, Pedro Henrique Moraes da, Miyauchi, Edison Tsutomu

Research on Optimization Method for Railway Route Schemes in the Western Mountainous Area Considering the “Dual-Carbon” Strategy

2025-99-0304

12/17/2025

Building a green and ecological railway transportation system that incorporates the “Dual-Carbon” Strategy is a central focus and challenge in current industry research. In the western mountainous regions with complex engineering geological conditions and fragile ecosystems, it is particularly important to explore the optimal railway route under the framework of the “Dual-Carbon” strategy. By analyzing the characteristics of the geographic environment of the western mountainous areas and the trend of low-carbon railroad construction, and referring to the relevant principles of railroad line selection, the method of quantifying the carbon emissions during the construction phase of the railroad and the carbon sequestration capacity of the land lost as a result of the railroad project’s land occupation is proposed by selecting 23 indicators from the five aspects of engineering adaptability, low-carbon adaptability, economic adaptability, environmental adaptability, and social adaptability as the entry point. The evaluation index system for the preferred railroad line scheme in the western mountainous area, developed in the context of the “Dual-Carbon” strategy, incorporates both subjective and objective weighting of the evaluation indexes using the G1 and CRITIC methods, respectively. Additionally, symmetric cross entropy sorting method is introduced to determine the combined weights of the indexes, effectively balancing the variability and conflicts between the indexes while considering subjective experience and the authenticity of the objective data. Finally, to address issues in the traditional TOPSIS method—such as the irrationality of directly combining benefit-type and cost-type indicators and the significant difference in their magnitudes—a railroad line scheme preference model based on osculating value improvement TOPSIS approach is developed and validated through engineering case studies. The calculation results indicate that the corrected osculating values of the four line schemes in the region are 0, 1.623, 0.700, and 2.000, respectively. The scheme with the highest corrected osculating value is selected as the optimal choice. The preferred results based on the model align with the actual engineering scheme, verifying the model’s reliability. This approach holds significant value for application in the selection of low-carbon railroad lines in western mountainous areas.

Wang, Yibo

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