Browse Topic: Exhaust gas recirculation (EGR)

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Development and Experimental Validation of a 1D Model for Performance and Emissions Analysis of Oxygenated Fuel Blends in a CI Engine2026-37-00286/9/2026
Emissions reduction remains a major concern for internal combustion engines in view of increasingly stringent environmental regulations. To address these challenges while maintaining acceptable engine performance, a wide range of alternative fuels and fuel blends have been investigated to ensure the continued viability of CI engines. This study reports the effects of blending the oxygenated fuel diethylene glycol diethyl ether (DGDE) with hydrotreated vegetable oil biodiesel (HVO) on engine performance and emissions. The investigation is conducted on a 2.3-liter, four-cylinder, common-rail diesel engine, equipped with a variable geometry turbocharger and a high-pressure exhaust gas recirculation system. The objectives of this study are achieved by developing a one-dimensional predictive engine model using the commercial GT-SUITE software. The engine model is developed and experimentally validated, at various operating conditions and HVO–DGDE fuel blends, to predict their effects on combustion characteristics and emissions formation. The validation is performed against measurements collected at the engine test bed. The results indicate that increasing the blending ratio of oxygenated fuel leads to improvements in indicated mean effective pressure and a more favorable Soot–NOx emissions trade-off compared with neat HVO operation. The findings highlight the potential of oxygenated fuel blends to enhance CI engine performance while reducing emissions. This study demonstrates the effectiveness of combining experimental and numerical approaches to evaluate biodiesel–oxygenated fuel blends and provides insights for future research aimed at minimizing CI engine emissions.
Arain, M Wajahat Rasool, Foglia, Antonio, Frasci, Emmanuele, Vitek, Oldrich, Pianese, Cesare, Arsie, Ivan
Combined EGR-Air Dilution Effects on Performance, Combustion and Emissions of a Single-Cylinder Spark-Ignition Direct-Injection Hydrogen Engine2026-37-00096/9/2026
Hydrogen internal combustion engines (H2ICE) have emerged as a promising solution for decarbonisation of the transport sector, due to low cost and potential for rapid deployment. However, abnormal combustion and high nitrogen oxide (NOx) emissions limit stoichiometric operation, making dilution strategies essential. While lean combustion has been widely studied, combined dilution strategies of air and exhaust gas recirculation (EGR) require further investigation. This work presents experimental results from a boosted 0.5-litre spark-ignition direct-injection single-cylinder research engine equipped with high-tumble ports and cooled high-pressure EGR. Relative air–fuel ratios (lambda) of 1 to 3 and EGR rates of 0 to 40% are evaluated at 5, 10, and 15 bar of indicated mean effective pressure (IMEP) at 2000 rpm to assess effects on net indicated thermal efficiency (nITE), combustion, and emissions. A peak nITE of 43.5% is achieved at 10 bar IMEP, λ = 2.5, and 30% EGR, which can be primarily attributed to low heat losses while maintaining lower combustion losses than at higher dilution levels. NOx emissions are effectively mitigated with increasing EGR and are largely independent of lambda at 5 bar IMEP under EGR dilution. At high load, EGR is shown to be beneficial to achieve high efficiency and lower NOx at lower dilution rates, thereby reducing boosting requirements. Equivalent dilution parameters are used to investigate combined effects of EGR and air dilution, from a mass dilution perspective with the mass dilution rate (MDR) and equivalent thermal reduction with the thermal dilution parameter (TDP). Indicated efficiency and unburned hydrogen emissions correlated strongly with MDR, while temperature-dependent parameters showed a high correlation with TDP. At constant engine speed, burn durations are shown to depend mainly on degree of thermal dilution, with no effect of load observed. At high dilution rates, combustion became increasingly insensitive to further dilution, indicating the presence of thermodiffusive instabilities under high levels of both EGR and air dilution.
King, Aidan, Islam, Reza, Pickering, Simon, Yuan, Hao, Mudge, Henry, Giles, Karl, Goyal, Harsh, Jones, Peter, Akehurst, Sam, Esposito, Stefania
Predictive Modelling of NO x and Unburned Hydrogen Emissions in a Direct-Injection Hydrogen Spark-Ignition Engine2026-37-00076/9/2026
Hydrogen is emerging as a compelling energy carrier for future transportation due to its potential to enable fully decarbonised operation and near-zero tailpipe pollutant emissions. Realising this potential in reciprocating internal combustion engines requires a detailed understanding of the complex interactions governing hydrogen combustion and emissions formation. In this context, physics-based reduced-order emission predictive modelling offers a powerful means to accelerate the development and optimisation of hydrogen-fuelled engines by enabling rapid evaluation of operating strategies without the need for extensive experimental campaigns. This study investigates the simulation of nitrogen oxides (NOx) and unburned hydrogen (uH2) emissions from a 0.5L spark-ignition direct injection single-cylinder research engine within a 1D-0D simulation approach. For NOx prediction, a simplified kinetic mechanism is coupled with both a 0D two-zone combustion model and a thermal multi-zone in-cylinder representation, enabling assessment of the need to account for temperature stratification for accurate prediction. For uH₂ emissions, phenomenological sub-models describing flame wall quenching and top-land crevice mechanisms are implemented and calibrated to capture the dominant sources of hydrogen escape during combustion. The models are validated against an experimental dataset spanning a wide range of engine conditions, including variations in engine load, relative air–fuel ratio from stoichiometric to ultra-lean combustion, dilution via exhaust gas recirculation, and spark timing. The comparison highlights the models' ability to reproduce observed physical trends across different engine operating conditions for both NOx and uH2. Regarding NOx emissions, the accounting of temperature stratification with the multi-zone model enables more accurate predictions of trends and absolute values. The uH2 model provides fundamental insights into hydrogen engine flame propagation by highlighting the need for flame propagation in the top-land crevice at richer λ to reproduce observed trends. Overall, the study provides insights into both hydrogen-specific emission mechanisms and key modelling requirements for accurate pollutant simulation in hydrogen engines.
Malfi, Enrica, De Felice, Massimiliano, Esposito, Stefania, Ribnishki, Aleksandar, King, Aidan, Akehurst, Sam, Jones, Peter, Goyal, Harsh
Numerical Modeling Techniques for Jet Engine Test Cell AerodynamicsAIR6355 (Current)6/5/2026
This SAE Aerospace Information Report (AIR) has been written for individuals associated with ground level testing of turbofan and turbojet engines, and particularly for those who might be interested in investigating steady-state performance characteristics of a new test cell design or of proposed modifications to an existing test cell by means of numerical modeling and simulation. It is not the intent of this standard to provide specific test cell design recommendations, which are covered in the reference documentation.
EG-1E Gas Turbine Test Facilities and Equipment
Effect of EGR Rate on Cyclohexanol-Diesel Dual-fuel Engines2026-99-17095/22/2026
To reduce high NOx emissions from diesel-cyclohexanol blends, this study employed a marine medium-speed diesel engine as the experimental platform. An in-cylinder combustion model was developed and meshed using AVL - FIRE software, with model validity validated against experimental data. Tests were conducted at four load conditions (25%, 50%, 75%, and 100% load) with a 30% cyclohexanol blend (C30) and four EGR rates (0%, 7.5%, 10%, and 12.5%) to analyze combustion characteristics, emissions, and fuel economy. The results showed that the introduction of EGR had a striking inhibitory effect on NOx emissions. At 100% load with 12.5% EGR rate, NOx emissions were substantially reduced compared to baseline operation without EGR. However, EGR implementation led to delayed ignition timing, reduced in-cylinder pressure, and worsened fuel economy. Therefore, an appropriately calibrated EGR strategy can effectively reduce NOx emissions, though it requires optimization to mitigate adverse effects on combustion performance and efficiency.
Liu, Yuchen, Yang, Chenxi, Fan, Jinyu, Chen, Ke, Ye, Zixiao, Huang, Jialiang
Fuel Effects on EGR Tolerance of Synthetic Gasoline Fuels in a DISI Engine2026-01-03054/7/2026
Drop-in synthetic gasoline fuels are an attractive alternative to traditional fossil fuels for transportation due to their high energy density, compatibility with the existing fleet and potential to decrease carbon intensity. Despite of meeting gasoline standards, the composition of these fuels can vary depending on the feedstock used for production and the production process, which has been shown to affect engine performance and emissions. This study investigated the effects of synthetic fuel composition on combustion in a direct-injection spark-ignition engine. Spark timing sweeps from the stability limit to the knock limit were performed with three different bio-fuels, methanol-to-gasoline, ethanol-to-gasoline and hydrotreated-biomass gasoline, at different exhaust gas recirculation (EGR) rates, and results were compared against a research-grade E10 (10%vol ethanol) regular gasoline representative of petroleum gasoline available in the US. Octane index analyses showed that knock resistance differences between fuels cannot be explained by their octane rating when EGR is added. Results demonstrated that adding EGR at medium loads is a very effective approach to increase efficiency despite of increasing burn duration because higher EGR rates led to lower pumping loses and lower heat transfer, while keeping combustion efficiency constant. The impact of EGR on combustion has shown to be very sensitive to fuel composition, and the knock resistance of fuels with strong low-temperature chemistry increased more with EGR addition that that of fuels with mild low-temperature chemistry. Similarly, the early flame propagation of fuels with strong low-temperature chemistry is more affected by EGR, limiting retardability and EGR tolerance. Results from this study indicated that, despite being considered drop-in, composition variability of synthetic fuels can be leveraged to improve engine performance.
MacDonald, James, Narayanan, Abhinandhan, Lopez Pintor, Dario, Matsubara, Naoyoshi, Kitano, Koji, Yamada, Ryota, Sugata, Kenji
1D System Evaluations for Efficiency Trade-Offs for a Heavy-Duty H2ICE Concept2026-01-02744/7/2026
Lean H2 combustion strategies have shown promising gross thermal efficiency and ultra-low engine-out NOx emissions for H2-fuel based internal combustion engines (H2ICE) in heavy-duty (HD) transport. Implementing lean combustion strategies require excessive air flow demand that further increases with the engine load increase. To meet such air flow demands efficiently across a wide engine operating region, a detailed system optimization is warranted including next generation turbocharging systems. In this 1D system analysis campaign, a detailed study of various air-system configurations was conducted for a modified HD, direct-injection (DI), H2ICE concept based-off a Cummins heavy-duty 15L engine. The concept engine configuration had a geometric compression ratio of 10.4 and no external exhaust gas recirculation (EGR) was implemented. First, a calibrated 1D engine model representing the H2ICE concept was developed. Using the 1D model, a detailed system-level analysis was conducted at five operating conditions from the heavy-duty SET cycle: A75, A100, B75, B100, and C100. A wide range of lambda levels, valve phasing, miller strategies were characterized by the gross engine performance improvements. Subsequently, different air-system configurations were evaluated for closed-cycle efficiency vs pumping losses trade-offs, while meeting the air flow targets. For next-generation turbocharging, both single stage (1S) and two-stage (2S) boost systems were simulated. Air versus external EGR dilution strategies were also studied at boost-limited engine operating conditions. From the results, high lambda levels reflected the benefits of lean combustion operation. Implementing millerization and cam phasing further elevated these benefits, at the expense of high boost pressure demands. The 1S boost system, with advantages of low-complexity and post-turbine thermal performance, incurred rapidly deteriorating turbocharger performance from the choke and the surge limits for lambda levels beyond 2.2. A 2S boost system achieved higher lambda levels without risking compressors choke or surge limits. Irrespective of turbocharging, the required intake charge cooling was noted ~2-3x times of the conventional diesel engine levels, depending on the targeted lambda levels. A detailed fuel-energy balance analysis was conducted to highlight system trade-offs between the 1S and the 2S based H2ICE configurations.
Kumar, Praveen, Sari, Rafael, Merritt, Brock, Popuri, Sriram
Simultaneous Reduction of NOx and Fuel Consumption for Off-Road Powertrains2026-01-02964/7/2026
Simultaneously reducing criteria pollutants and fuel consumption is important for clean air and improving vehicle total cost of ownership. The goal of this effort was focused on a 90% NOx reduction and 10% fuel savings for an off-road 407 kW diesel engine. The baseline was a production Fiat Powertrain 13L engine and aftertreatment system meeting 0.4 g/kW-hr NOx. The baseline system was quantified over the NRTC, RMC, new low load cycle and five field cycles. A next generation engine was built incorporating several fuel-efficient design features, including a higher compression ratio, increased fuel-rail pressure, low-friction piston rings, and a high-efficiency variable-geometry turbocharger. Cylinder deactivation and EGR pump technologies were added to this engine as well. The combination was optimized prior to adding advanced aftertreatment systems, showing the trade-off of engine out NOx and exhaust temperature. Two next-generation catalyst technologies were employed into a LO-SCR plus main SCR system, both with and without an electric heater upstream of the LO-SCR. These catalysts were hydrothermally aged to simulate significant field use. Dual SCR dosing with newly developed controls played a critical role in achieving the proper split between the upstream LO-SCR and the downstream main SCR. Adding a next generation mixer for the downstream SCR proved essential in obtaining the final results. The optimal configuration required adding an electric heater to elevate the exhaust temperature at the LO-SCR for early cycle NOx reduction. The final results showed a 94.8% NOx reduction and 15.7% fuel savings on the composite NRTC.
McCarthy, Jr.,, James, Wine, Jonathan, Bradley, Ryan, Hasseman, Andy, Prikhodko, Vitaly, Howell, Thomas
Ultra-Low NOx Technologies for Heavy-Duty Applications with Reduced Total Cost of Ownership2026-01-02944/7/2026
The utilization of gasoline engines in heavy-duty vehicles for the purpose of continental transportation is in direct competition with conventional diesel engines. It’s imperative that the operating performance of the gasoline engine is equivalent to the diesel engine, and that the gasoline engine shows efficiency benefit to both cost segments, the product manufacturing costs and total cost of ownership (TCO). The 11.6-liter gasoline engine developed has been designed and applicated in such a way that it operates at a stoichiometric combustion air ratio (λ = 1) across the entire engine map range without exception. In combination with external exhaust gas recirculation (EGR) this strategy does not result in a substantial decrease in the absolute NOx concentration in raw emissions compared to the diesel engine with 15.0-liter displacement, but it facilitates the cost-efficient utilization of the three-way catalyzer as the main exhaust aftertreatment system, thereby reducing NOx emissions to the detection limit. This reduction is necessary for adherence to the stringent future emission standards for heavy trucks that are being established by the U.S. regulatory authorities (EPA; CARB) for model years commencing in 2027. In addition to the stoichiometric operating strategy, the engine features an innovative combustion chamber geometry, including a high compression ratio, high EGR compatibility within the real engine operating range, and an optimized crankshaft drive. This already tested technology package is now being applied to heavy-duty engines, proving its scalability and effectiveness. Its application to heavy-duty engines not only promises significant production cost savings but also ensures compliance with future emission regulations. By integrating high EGR rates and high compression ratio, the engine achieves optimal combustion efficiency, thereby minimizing emissions without compromising performance. The engine efficiency is demonstrated by its brake thermal efficiency of 43.1% and an extended map range with a specific consumption of less than 200 g/kWh. In a real heavy-duty driving cycle, the average consumption is 228 g/kWh (vs. 217.5 g/kWh), resulting in a significant reduction in total operating costs on the American market using gasoline as fuel.
Medicke, Mario, Arnold, Thomas, Bohme, Jan, Krause, Matthias, Leesch, Mirko
Combustion and Emission Characteristics of Biodiesel and Renewable Diesel in a 4-Stroke Locomotive Engine2026-01-03154/7/2026
Rail transportation in North America consumes over 4 billion gallons of diesel fuel [1]. This is raising energy security and supply chain resilience concerns. Adopting renewable or alternative fuels is a practical approach to reduce petroleum dependence and improve supply security. The objective of this paper is to investigate the combustion and emission characteristics of biodiesel and renewable diesel as drop-in fuels without engine modification. In this study, a single-cylinder, four-stroke locomotive engine was employed to investigate the combustion and emissions characteristics of four fuels: conventional diesel No. 2, plant-based biodiesel, animal-based biodiesel, and renewable diesel. The experimental campaign was carried out under both part-load and full-load operating conditions, with injection duration adjusted to achieve the targeted engine load and speed. Results indicate that both biodiesel fuels and renewable diesel deliver comparable peak in-cylinder pressure and brake thermal. efficiency relative to No. 2 diesel, demonstrating their possible use as drop-in fuels. Reductions in smoke emissions were observed for both biodiesels and renewable diesel fuels. However, plant-based and animal-based biodiesels both showed increases in NOx emissions under part-load conditions. At full load, elevated exhaust gas recirculation (EGR) ratios suppressed NOx formation across fuels, limiting assessment of biodiesel-specific NOx effects. Among the fuels tested, renewable diesel provided an additional advantage: reduced CO₂ emissions compared to both biodiesels. This study suggests that renewable diesel is a promising option for rail applications, combining operational performance comparable to petroleum diesel with reduced smoke and CO₂ emissions. Biodiesel, while effective at reducing smoke, may require further strategies to control NOx emissions.
Ewphun, Pop-Paul, Biruduganti, Munidhar, El-Hannouny, Essam, Longman, Douglas, Fu, Xiao, Subramanya, Raghavendra
Total Cost of Ownership Reduction Using Passive Pre-Chamber Ignition in Natural Gas Engines2026-01-03094/7/2026
Spark plug durability is a factor affecting the total cost of ownership (TCO) of spark-ignited natural gas engines, with some heavy-duty platforms requiring plug replacement after only 750 hours of operation. The high ignition energy demand under lean or diluted conditions accelerates electrode wear, shortening plug life and increasing maintenance frequency. This work evaluates passive pre-chamber (PC) ignition operating at lowered spark energies as a strategy to reduce spark energy requirements and extend plug durability, thereby lowering TCO. Experiments were conducted on a medium-duty Cummins 6.7L ISB engine at 1600 RPM and 50% load under varying exhaust gas recirculation (EGR) dilution levels (0–40%). Two passive pre-chambers with 1.1 mm and 1.6 mm nozzle diameters were compared with conventional spark ignition (SI). SI was operated with a fixed coil dwell of 4 ms (~90 mJ), while the PC configuration was tested across 2–4 ms dwell times (~30–90 mJ). Cylinder pressure analysis revealed that PC ignition sustained stable combustion at significantly lower spark energies than SI, with improved combustion stability at ~30 mJ compared with SI at ~90 mJ. The PC system also extended the dilution tolerance beyond that achievable with SI, while delivering up to ~2% higher indicated thermal efficiency and reducing the COV by nearly 90% at 30% EGR. A TCO analysis was conducted to assess the economic benefit of adopting a passive PC system operating at reduced spark energies compared to SI. It was found that adopting a passive PC system could reduce TCO by approximately $11,000 per engine over a five-year operational period, primarily due to fuel savings, extended spark plug life, and reduced maintenance frequency. These projections were weighed against the additional hardware cost of the pre-chamber, yielding a rapid estimated return on investment of ~300 operating hours. Therefore, this work motivates continued research and development of passive PC technology and its commercial adoption in natural gas engines used in transportation applications.
Dhotre, Akash, Voris, Alex, Okey, Nathan, Kane, Seamus, Rajasegar, Rajavasanth, Northrop, William
Emission and Combustion Characteristics of a Hydrogen Direct-Injection Spark Ignition Engine Using EGR2026-01-03254/7/2026
This study experimentally investigates the combined effects of exhaust gas recirculation (EGR) and injection timing on the combustion and emission characteristics of a hydrogen direct injection engine. A single-cylinder 395 cc research engine was used, with injection timing varied from 60° to 180° BTDC and EGR rates from 0% to 30%. In-cylinder pressure, apparent heat release rate (AHRR), NOx, and unburned hydrogen concentrations were measured to analyze the influence of mixture formation and dilution on engine performance. Under non-EGR conditions, retarding the injection timing promoted mixture stratification, resulting in faster flame propagation and shorter combustion duration. However, localized high-temperature regions increased NOx formation, while incomplete combustion in lean or rich zones elevated unburned hydrogen emissions. When EGR was introduced, both ignition delay and combustion duration increased due to reduced oxygen concentration and thermal dilution. Nevertheless, the net indicated mean effective pressure (nIMEP) and indicated thermal efficiency (ITE) decreased by less than 1.6% and 1%, respectively, demonstrating that hydrogen’s fast combustion characteristics compensated for the reactivity loss. As the EGR rate increased, the formation of NOx and the emission of unburned hydrogen showed noticeable changes. At 30% EGR, NOx emissions decreased by up to 76% compared to the non-EGR baseline while maintaining stable combustion. However, excessive EGR resulted in increased unburned hydrogen emissions. These findings confirm that, with a properly optimized EGR rate, EGR is a more effective strategy than injection timing control for NOx reduction, achieving significant reduction with minimal efficiency penalty, and providing design insights for practical hydrogen-fueled engines.
Yang, Heetae, Ki, Youngmin, Kim, Jungho Justin, Kim, Jinsu, Bae, Choongsik, Hwang, Joonsik
Optimization of Combustion Stability and Fuel Economy for Dedicated Hybrid Engines with High Exhaust Gas Recirculation Rate03-19-02-00082/26/2026
In recent years, the rapid growth of hybrid vehicles has driven the development of dedicated hybrid engines (DHEs) as a key powertrain technology for achieving high thermal efficiency and low emissions. Driven by stringent emissions regulations and demand for improved fuel economy, enhancing thermal efficiency in gasoline engines remains a critical industry challenge. Exhaust gas recirculation (EGR) technology dilutes oxygen in the intake charge, suppresses knock, and optimizes combustion phasing. However, excessive EGR rates compromise combustion stability by inducing elevated cyclic variability and potential misfire, posing challenges in maintaining stable combustion and improving fuel efficiency at high EGR levels. Thus, combustion stability and fuel efficiency optimization in Geely’s DHEs under high EGR conditions was investigated in this article. In this study, a high tumble combustion system was designed to enhance charge motion and promote stable flame propagation. Furthermore, exhaust gases were drawn from the upstream side of the three-way catalyst to realize high EGR rate. Additionally, high-energy ignition system was applied to ensure stable combustion under high EGR dilution conditions. Compared with the 1.5T engine with a similar technical route, the optimized DHE achieved a 5.4% increase in EGR rate and a 7.2 g/kWh reduction in brake specific fuel consumption (BSFC). These results demonstrate the feasibility of high EGR operation in gasoline engines through synergistic combustion system design and ignition enhancement, offering a scalable solution for meeting future fuel efficiency and emissions targets.
Li, Qiang, Deng, Xiaorong, Ren, Siming, Zhang, Peiyi, Zhu, Yunfeng, Li, Hongzhou, Yan, Pingtao, Gu, Xiangsheng
Development of High BMEP Natural Gas Engine with Knock Mitigation2026-26-01211/16/2026
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
Optimizing Hydrogen Engine Performance a Comparative Study of Lean & Stoichiometric Calibration Approach2026-26-02611/16/2026
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
Leveraging AI/ML Algorithms for Analyzing Fleet Vehicles In-Use Performance Ratio Monitoring Data2026-26-06371/16/2026
In recent times, the governments are pushing for stringent emission regulations. These regulations call for reduction of pollutants as well as monitoring of engine components which are critical for emission control. Monitoring these emission critical engine components are to be done in real world driving conditions. The In-Use Performance Ratio Monitoring (IUPRm) framework quantifies how often onboard diagnostic systems check these components within defined boundaries for each vehicle. IUPRm is divided into several monitoring groups like catalyst monitoring, oxygen sensor monitoring, exhaust gas recirculation (EGR) monitoring, gasoline particulate filter monitoring and others. These groups are differentiated based on fuel type, engine technologies and exhaust treatment system configurations. For an Automotive manufacturer analyzing these parameters across large vehicle fleets is a complex and data intensive task. To address this, a user-friendly application was developed in-house, which includes the new method based on Artificial Intelligence and Machine Learning algorithms for automating complex IUPRm Data analysis. This method contains techniques, such as structured decision tree based classification and rule based logic algorithms for automating classification of vehicles into a particular OBD family from a large and mixed fleet data and filtering all anomalies in the data. The K-Means clustering along with the elbow logic, groups the vehicles with similar IUPRm ratios and checks if selected vehicles meets the compliance requirement. This application enables to automate and speed up large scale IUPRm data analysis by reducing manual effort and enhancing overall efficiency. The newly developed method also provides automated reports. This paper explains selection and working principles of different algorithms and techniques used in development of this application for efficient IUPRm monitoring.
Ghadge, Ganesh Narayan, Jadhav, Marisha, Hosur, Viswanatha
Development of a Passive Regeneration Diesel Particulate Filter System for an Agricultural Tractor Engine2026-26-02171/16/2026
This paper presents the development and evaluation of a passive regeneration Diesel Particulate Filter (DPF) system for a 4-cylinder, 3.18-liter naturally aspirated agricultural tractor engine based on the mDI engine family. The primary objective is to significantly reduce particulate matter (PM) emissions while maintaining optimal engine performance and fuel economy. The passive regeneration DPF system leverages the engine's operating conditions to generate sufficient heat for the oxidation of trapped particulate matter, eliminating the need for active regeneration techniques. The paper details the design process, including the selection of DPF material, filter geometry, and integration into the exhaust system. Rigorous experimental testing was conducted to assess the performance of the DPF system under various engine load and speed conditions. Results demonstrate substantial reductions in PM emissions without compromising engine power, torque, or specific fuel consumption. This novelty of this work lies in developing a new engine capacity from a legacy engine architecture and then develop the engine from an inline pump fuel injection system to make it compatible for Common rail technology and at the same time integrate a DOC+DPF after treatment system. The development also enhanced the maximum torque capability and improved the noise characteristics of the engine. The work also included developing the engine with two different after treatment system suppliers, two different EGR system suppliers, two different Fuel injection system suppliers and yet meet the engine performance and efficiency requirements. Thus, a legacy Mahindra Engine Platform was successfully made ready for future emission norms without compromising on fuel efficiency and performance requirements of the application.
Maddali, Varun Suman, Jidigonti, Shashank, Kannan, S, Ramesh, Natrajan
Multi-Objective Optimization of Oxyfuel Gas Engine Using Stochastic Engine Model and Detailed Chemistry2025-01-052911/25/2025
The energy transition initiatives in Germany’s renown coal mining region Lusatia have driven research into Power-to-X-to-Power technologies, where synthetic fuel is produced from renewably sourced hydrogen and captured CO2, and converted to electricity and heat through oxyfuel combustion. This work investigates the multi-objective optimization of oxyfuel gas engine using a stochastic engine model and detailed chemistry. Exhaust gas recirculation (EGR) rate, initial cylinder temperature and pressure, spark timing, piston bowl radius and depth are selected as design parameters to minimize the exhaust temperature at exhaust valve opening and indicated specific fuel consumption (ISFC) corresponding to oxyfuel operation with different dry and wet EGR rates. The optimization problem is solved for a dry EGR and four wet EGR cases with various CO2/H2O fractions, aiming to achieve comparable performance as in conventional natural gas / air operation, and energy-efficient carbon capture. The case with the lowest humidity (T10deg) had the lowest temperature of 1537 K, while the one with the highest vapor fraction (T70deg) attained the minimum 260 g/kWh ISFC. The superiority of the T10deg case is offset by much higher cooling demand (3.06 kW) for CO2 separation than that for T70deg case (0.81 kW). The constraint for combustion efficiency (>65%) limited the solution space towards high ISFC values, while the constraint for low indicated mean effective pressure (IMEP) (>7 bar) and the constraint for high IMEP (<8 bar) limited the solution space in between the two distinct clusters of feasible designs, and towards high exhaust temperature, respectively. The optimized designs from all the cases could outperform the reference case in terms of IMEP, nevertheless they fell below 31% indicated efficiency, which is associated with stoichiometric combustion.
Asgarzade, Rufat, Franken, Tim, Mauss, Fabian
Experimental Analysis of Hydrocarbon Injection Strategies and In-Cylinder Injection Impact on Oil Properties in Diesel Engines2025-28-023811/6/2025
The engine has played a pivotal role in controlling regulated pollutants at the in-cylinder combustion level through strategies such as Direct Injection, Common Rail Systems, and Exhaust Gas Recirculation up to Bharat (CEV/Trem) Stage-III. With the advent of more stringent emission norms, specifically Bharat (CEV/Trem) Stage-IV and V, the importance of Exhaust After-Treatment Systems (EATS) in managing emissions outside the engine has significantly increased. The inclusion of Particulate Number (PN) limits in Bharat (CEV/Trem) Stage-V necessitates the use of Diesel Particulate Filters (DPF), which trap soot particles that must be periodically removed through a process known as regeneration. Regeneration requires elevated exhaust temperatures, typically achieved via exothermic reactions in the Diesel Oxidation Catalyst (DOC), facilitated by diesel fuel addition through external injection or in-cylinder injection strategies. This study investigates both external and in-cylinder injection mechanisms, proposing an optimal system tailored to the intended vehicle application. During regeneration, late post-injections, especially those with retarded timing and increased fuel quantities, can lead to fuel dilution in engine oil, adversely affecting the oil properties and oil drain intervals. Experimental investigations were conducted on an engine test bench to evaluate the impact of post-injection parameters on fuel burn fraction, regeneration temperatures, and engine oil characteristics. Optimal parameter values were derived to balance regeneration efficiency and oil integrity. Additionally, real-world vehicle trials across different terrains and duty cycles were performed using the optimized post-injection parameters to assess the oil dilution effects on key oil properties such as kinematic viscosity, Total Base Number (TBN), and Total Acid Number (TAN). The results demonstrate that with optimized post-injection parameters, engine oil degradation remains within acceptable limits, supporting the target oil drain interval. Although wear element traces (e.g., Fe, Cu, Al) showed an increase, their concentrations remained within the oil specification thresholds.
Bandaru, Balaji, M, Balasubramanian, V, Shunmuga, G, Senthil Kumar, Mahesh, P
Effect of EGR and Ethanol additive on Performance and Emission Characteristics of Diesel Engine Fuelled with Rubber Seed Biodiesel Blends2025-28-022411/6/2025
Alcohol is being considered as an alternative to traditional fuels for compression ignition engines due to their oxygen content and biomass origin. Although alcohol generally has lower cetane numbers, which makes them more favorable for premixed combustion, they also offer potential for lowering emissions in internal combustion engines, particularly when combined with strategies such as exhaust gas recirculation (EGR). This research focuses on enhancing the performance of a single-cylinder, four- stroke diesel engine by introducing ethanol into the intake port during the intake phase. Diesel and rubber seed biodiesel were used as primary fuels and were directly injected into the combustion chamber. The findings indicated that adding ethanol to rubber seed biodiesel, along with 10% EGR, led to improved brake thermal efficiency and a reduction in NOX emissions. The ethanol injection timing and duration were optimized for effective dual-fuel operation. At full engine load, the highest brake thermal efficiency recorded with a 20% ethanol energy share was 34% for diesel, 31.16% for B20 with EGR, and 31.15% for B20 without EGR. Furthermore, NOX emissions were reduced by 25.44% and 26.08% for B10 with EGR and B20 with EGR, respectively, at peak thermal efficiency. On the downside, increasing ethanol contribution raised HC, CO₂, and smoke emissions across all loads for both B10 and B20 with EGR. Additionally, B10 and B20 with EGR experienced higher peak cylinder pressures and maximum rate of pressure rise, while ethanol uses also resulted in shorter combustion duration and increased heat release rates.
Saminathan, Sathiskumar, G, Manikandan, Bungag, Joel Quendangan, T, Karthi
Impact of Water Injection on Emission Formation in an HVO-Fuelled NRMM Engine2025-32-006711/3/2025
Water injection in diesel engines is a well-known method of lowering combustion temperatures and thus reducing nitrogen oxide (NOx) emissions. In this study, the influence of water injection in hydrogenated vegetable oil (HVO) operation on NOx formation, particulate emissions and ignition delay is analyzed in comparison to diesel operation on a John Deere JD4045 tractor engine. Both the fuel (HVO) and the water injection system were designed as ‘drop-in’ solutions that enable rapid implementation to reduce emissions, even in existing vehicle fleets. The standard engine control unit of the JD4045 engine was therefore used for the tests. A single water nozzle was installed downstream the charge air cooler to integrate a water injection system. The three operating points of interest were: (1) low speed and high load without exhaust gas recirculation (EGR), (2) high EGR rates at low speed and medium load and (3) the engine's ‘sweet spot’ regarding the emission-tradeoff at high speed and high load. The focus of the study is on the formation of nitrogen oxides (NOₓ) and particulate matter (PM), analyzing the particle mass and particle size distribution as well as ignition and combustion behavior. The effects of varying the mass flow of the injected water and the charge air temperature were investigated at all operating points. A comparative analysis between diesel and HVO operation shows the differences in emission behavior and the effects of water injection. The results provide insight into the potential of retrofit water injection to reduce NOₓ emissions by up to 40 %, especially in combination with the renewable fuel HVO. However, a slight increase in particulate emissions was observed, which requires further analysis of particulate mass and size distribution to analyze possible trade-offs. These findings might contribute to the promotion of sustainable and low-emission solutions for NRMM applications in the existing and upcoming fleet.
Fuhrmeister, Jonas, Mayer, Sebastian, Günthner, Michael
Effect of Plasma-Assisted Ignition on Combustion and Emission Characteristics of Two Stroke Engines with Different Fuels2025-32-003011/3/2025
This study explores the effect of plasma-assisted ignition (PAI) on combustion stability and emissions in two-stroke spark-ignition engines. Two engine platforms were evaluated: a conventional single-cylinder two-stroke engine and a thermodynamically advanced opposed-piston two-stroke (OP2S) engine. The OP2S engine configuration offers reduced heat loss and higher power density due to its uniflow scavenging and favorable geometry, but suffers from high residual gas fraction, which increases ignition difficulty and combustion instability. To address this, nanosecond-pulsed PAI was applied in various spatial arrangements and discharge voltages, using both gasoline and a low-reactivity gasoline/DMC blend fuel. Spark ignition timing was held constant at the minimum advance for best torque across all tests. Combustion stability was assessed via indicated mean effective pressure (IMEP) and its coefficient of variation, while CO and HC emissions were measured as environmental indicators. Results show that PAI significantly enhanced ignition stability, reducing COVIMEP by up to 84% and HC emissions by up to 24%, depending on fuel and engine type. The OP2S engine showed greater responsiveness to ignition configuration and plasma positioning due to its uniflow scavenging method. These findings confirm that PAI is a promising strategy for improving ignition robustness and emission performance in both conventional and advanced two-stroke engine architectures.
Liu, Jinru, Yamazaki, Yoshiaki, Otaki, Yusuke, Kato, Hayato, Kobayashi, Daichi, Umegaki, Tetsuo, Asai, Tomohiko, Iijima, Akira
Performance Analysis of a Hydrogen-blended Naturally Aspirated Gas Engine with a Dedicated Exhaust Gas Recirculation System2025-32-004611/3/2025
With the publication of the Renewable Energy Directive (RED) III in 2022, the European Union increased its renewable energy consumption target to 42.5% by 2030. Consequently, gaseous fuels derived from renewable electricity, particularly green hydrogen, are expected to play a pivotal role in the decarbonization of the energy sector. One promising application of green hydrogen is its integration into combined heat and power (CHP) plants, where it can replace natural gas to reduce CO2 emissions. Pure hydrogen as fuel or blended with natural gas has demonstrated potential for lowering both pollutant emissions and fuel consumption while maintaining or even enhancing engine performance. But it is expected, that the amount of available green hydrogen will be limited in the beginning. So new engine systems with hydrogen and natural gas for CHP plants are required, that offer more CO2-benefit and NOx reductioon than from fuel substitution only. In the LeanStoicH2 project, a novel approach was developed to optimize the operation of a four-cylinder stationary gas engine for hydrogen utilization. The project introduced a customized exhaust gas recirculation (EGR) system in which the exhaust gas from a hydrogen-fueled cylinder is fully recirculated into the intake mixture of three other cylinders operating stoichiometrically with natural gas. This configuration leverages the benefits of both lean and stoichiometric combustion strategies. After passing a lower temperature condenser, the dry recirculated exhaust gas, which is CO2- and H2O-free, dilutes the intake mixture of the three cylinders, mimicking lean operation and thus increasing engine efficiency due to the higher isentropic coefficient (κ). Simultaneously, this approach reduces combustion temperatures, thereby lowering knock tendency and engine wear. Furthermore, the stoichiometric operation of the EGR-receiving and emission relevant cylinders allows for the effective use of a three-way catalyst, significantly reducing pollutant emissions. Experimental results confirm that this innovative combustion strategy enhances indicated efficiency from 41.5% to 43.5% compared to series operation, and maintains low NOx tail pipe emissions. These findings highlight the potential of advanced hydrogen combustion strategies to improve the sustainability and performance of gas engine CHP plants, supporting the transition toward a greener energy landscape.
Salim, Naqib, Beltaifa, Youssef, Kettner, Maurice
A Physics-Guided Neural Network Approach for EGR Cooler Temperature Estimation: Addressing ECU Model Discrepancies2025-28-039310/30/2025
As the automotive industry explores alternative powertrain options to curb emissions, it is pertinent to refine existing technologies to improve efficiency. The Exhaust Gas Recirculation (EGR) system is one of the pivotal components in emission control strategies for Internal Combustion Engines (ICE). The EGR cooler is crucial in thermal management strategies, as it lowers the temperature of recirculated exhaust gases before feeding it along with fresh air, thereby reducing nitrogen oxides (NOx) emissions. Precise estimation of the EGR cooler outlet temperature is crucial for effective emission control. However, conventional Engine Control Unit (ECU) models fall short, as they often show discrepancies when compared to real-world test data. These models rely on empirical relationships that struggle to capture precisely the transient effect, and real time variation in operating conditions. To address these limitations and improve the accuracy of ECU based model, various signal processing techniques, such as noise reduction filters and bias correction within control logic were attempted. While these enhancements improve stability and consistency, they could not capture complex thermal interactions and real-time dynamic variations in EGR cooling. In this study, a Physics-Informed Neural Network (PINN) approach is used to enhance the accuracy of EGR Cooler outlet temperature estimation. Unlike conventional deep learning models, which rely solely on data, PINNs incorporate fundamental thermodynamic and fluid dynamics principles into the learning process ensuring physically consistent and interpretable outputs. The proposed framework integrates the Transient Heat-Transfer equations in addition to the primary inputs. By embedding domain-specific knowledge into the neural network architecture, significantly reduces the data dependency and improves the reliability of EGR temperature estimation, supporting fault diagnostics, and making this approach highly suitable for real-time monitoring applications.
Kumar, Amit, Kumar, Raman, Manojdharan, Arjungopal, Challa, Krishna, Kramer, Markus
Development of a Self-Adjusting Engine Out NOx Prediction Model Using Tailpipe O2 Measurements2025-01-038110/7/2025
On-Board Diagnostic (OBD) strategies utilize a predictive model to estimate engine out NOx levels for a given set of operating conditions to ensure the accuracy of the Nitrogen Oxides (NOx) sensor. Furthermore, this model is also used to determine urea dosing quantities in situations where the NOx sensor is unavailable such as cold starts or as a reaction to a NOx sensor plausibility failure. Physics-based NOx prediction models guarantee high levels of accuracy in real-time but are computationally expensive and require measurements generally not available on commercial powertrains making them difficult to implement on controllers. Consequently, manufacturers tend to adopt a mathematical approach by estimating NOx under standard operating conditions and use a variety of correction factors to account for any changes that can influence NOx production. Such correction factors tend to be outcomes of base engine calibration settings or outputs of models of other related sub systems and may not accurately capture the effect of component level drifts that directly influence NOx production such as mass air flow (MAF) sensor drifts, humidity variations, exhaust gas recirculation (EGR) rate variations, etc. Since mathematical approaches approximate physical phenomena, errors in any of the inputs tend to be compounded, thereby diminishing the accuracy of the final output. The method presented in this material focuses on using lambda values derived from tailpipe O2 measurements as the sole input to adjust the NOx model since it is a direct representation of the quality of combustion and accounts for variations in operation that can influence NOx production. This produces an easy-to-implement “self-adjusting” NOx model strategy that is consistent with the physics of NOx formation without requiring any additional hardware and ensures high levels of accuracy required to guarantee OBD robustness.
Sunder, Abinav, Suresh, Rahul, Polisetty, Srinivas
Overview of Current Developments of Pre-Chamber Spark Plugs for Passenger Car Applications2025-24-01529/7/2025
The internal combustion engine (ICE) is projected to remain the dominant technology in the transport sector over the short to medium term, and there exists significant potential for further improvements in fuel economy and emission reductions. One promising approach to enhancing the efficiency of spark ignition engines is the implementation of passive pre-chamber spark plugs. The primary advantages of pre-chamber-initiated combustion include the mitigation of knocking, an increase in in-cylinder turbulence, and a combustion process that is both faster and more stable compared to that achieved with conventional J-gap spark plugs. Additionally, the higher ignition energy provided by pre-chamber spark plugs enables operation under higher intake pressures, maintains similar exhaust gas recirculation rates, and supports leaner combustion conditions. These benefits are predominantly attributed to volumetric ignition via hot, reactive jets. However, the pre-chamber spark plug also presents several challenges. Its drawbacks include suboptimal cold-start behavior, difficulties in catalyst heating when accompanied by aggressive spark retard, and inferior low-load performance resulting from reduced charge motion, elevated residual gas concentrations within the pre-chamber, and increased wall heat transfer at low loads. Furthermore, the challenge of adequately heating the catalytic converter persists due to delayed ignition timing. In this study, various passive pre-chamber configurations were systematically investigated and evaluated based on key performance metrics. Engine operation was categorized into three specific regimes: catalyst heating on a cold engine (operated at 1200 rpm with an IMEP of 3 bar), the optimal efficiency point corresponding to a minimum brake specific fuel consumption (operated at 2000 rpm with an IMEP of 14 bar), and a high-speed load sweep conducted at 4000 rpm. The experimental campaign was executed in two phases, allowing for iterative design modifications informed by the findings of the initial phase. Ultimately, the optimized pre-chamber design successfully achieved a minimal specific exhaust heat flux (SEHF), maintained the desired combustion stability, and extended the high-load operating envelope up to an IMEP of 18.5 bar.
Korkmaz, Metin, Juressen, Sven Eric, Rößmann, Dominik, Kapus, Paul E., Pino, Sandro
Effects of Varying the Air-Fuel Equivalence Ratio at Different EGR-Rates on a Medium-Speed LNG-Diesel Dual-Fuel Engine2025-24-00419/7/2025
The dual-fuel combustion process, which is offered as a retrofit solution for conventional diesel engines by various manufacturers, represents an option for reducing emissions from internal combustion engines and is already available today. Current dual-fuel engines run on liquefied natural gas (LNG), which is usually of fossil origin. Due to the existing infrastructure and the possibility of producing LNG by means of electrolysis and methanation, LNG can already be produced in a 100% climate-neutral way and thus make a contribution to climate neutrality in the shipping industry. The adoption of exhaust gas recirculation (EGR) systems in the maritime sector became more significant in 2020 following the enforcement of the sulphur emission cap. By lowering the sulphur content in the fuel, technologies in the exhaust tract are also conceivable without the use of expensive scrubber systems. Dual-fuel LNG/diesel engines are typically operated in lean-burn mode to reduce the risk of knocking and to comply with the nitrogen oxide limits in accordance with IMO TIER III. However, one disadvantage of the lean-burn combustion process is climate-damaging methane (CH4) slip due to incomplete combustion. To address this issue, an EGR system can be employed to mitigate nitrous oxides (NOx) emissions and prevent engine knocking at richer air-fuel mixtures, as an alternative to increasing the air-fuel equivalence ratio lambda. In the context of this paper, experimental investigations are conducted on a single cylinder medium speed dual-fuel engine, where EGR rates of up to 35% are examined across various lambda values. The adjustment of lambda is achieved by varying the charge air pressure using an externally driven compressor station for charge air supply. The results of the presented investigations provide insights into the emission reduction potential of a targeted variation in EGR rates and lambda, thus making an important contribution to more environmentally friendly ship propulsion systems.
Seipel, Pascal, Glauner, Manuel, Dinwoodie, Jules, Buchholz, Bert
Comparison between Spark-Ignition and Passive Pre-Chamber Combustion in a Methanol Fuelled Heavy-Duty Engine at Different Speeds, Loads, and EGR Dilutions2025-24-00309/7/2025
Decarbonizing the transport sector requires solutions that reduce CO₂ emissions while improving the efficiency of existing engine platforms. This study explores a retrofit strategy in which a heavy-duty diesel engine is converted to Otto-cycle operation and equipped with a passive pre-chamber combustion (PPCC) system. Methanol was used as the fuel due to its high octane number, low carbon intensity, and favourable combustion properties. The performance of the PPCC system is experimentally compared to conventional spark ignition (SI) across varying engine speeds, loads, and exhaust gas recirculation (EGR) levels. A dual-dilution strategy, combining lean operation (λ = 1.6) with EGR, was applied to extend dilution tolerance and assess the feasibility of operating near stoichiometry. All tests were conducted under steady-state conditions with fixed spark timing. Results show that PPCC consistently delivers faster combustion than SI across all conditions, with greater stability and reduced sensitivity to operating variations. Increasing engine speed shortened combustion duration, while EGR extended it. At higher loads, PPCC performance improved due to increased pressure differential between the pre-chamber and main chamber. Unlike SI, which became unstable beyond an EGR-diluted λ = 1.15, PPCC maintained stable operation up to stoichiometry at 36% EGR. This enabled potential compatibility with a three-way catalyst (TWC), with less than a 1% efficiency penalty and no degradation in combustion stability. However, SI outperformed PPCC in terms of overall efficiency, largely due to higher combustion completeness. The lower combustion efficiency of PPCC, linked to increased crevice volume and surface losses, also led to significantly higher total hydrocarbon (THC) emissions. These findings highlight the trade-offs between ignition stability and efficiency demonstrating that with proper calibration, PPCC can support high-dilution operation and conventional aftertreatment in retrofitted heavy-duty engines running on low-carbon fuels such as methanol.
Fong Cisneros, Eric J., Hlaing, Ponnya, Cenker, Emre, AlRamadan, Abdullah, Turner, James WG
Experimental Investigations on the Effects of Injector Orientation in a Diesel-Gasoline-Fuelled Premixed Charge Compression Ignition Engine2025-24-00439/7/2025
Premixed Charge Compression Ignition (PCCI) presents a promising alternative to conventional diesel combustion (CDC), offering significant reductions in pollutant emissions by lowering local in-cylinder temperatures and enhancing fuel-air mixing. However, a significant challenge in implementing PCCI is controlling the start of combustion, especially given its narrow operating load range. This is primarily due to early ignition and knocking combustion at higher loads when using high-reactivity diesel fuel, which limits the practical applicability of PCCI mode in diesel engines. In the present study, experimental investigations are carried out on a light-duty diesel engine operating in PCCI mode using two fuel blends: 10% (D90G10) and 20% (D80G20) gasoline mixed with diesel on a volume basis. To facilitate combustion control and emission reduction, exhaust gas recirculation (EGR) and water vapor are used as charge diluents. A common rail direct injection (CRDi) system replaces the conventional mechanical fuel injection system, and the engine's compression ratio is reduced from 17.5 to 15 to enable PCCI operation. Initial parametric studies revealed that early direct injection combined with high injection pressure limited the PCCI operating load range to 30% of the rated load when using diesel fuel. However, incorporating EGR with diesel extended this load range to 60%, albeit with increased unburnt hydrocarbon (HC) and carbon monoxide (CO) emissions. To address these challenges, the engine's cylinder head was modified to accommodate a vertically oriented injector, and diesel was replaced with diesel–gasoline blends. Experiments were then conducted using the modified cylinder head at a constant engine speed of 1500 rpm, under varying load conditions and injection timing, to analyze the effects of injector orientation and fuel blends in combination with EGR and water vapor as charge diluent. The results indicate that the diesel–gasoline blends increase ignition delay and enhance fuel-air mixing time between the end of fuel injection and the start of combustion. Specifically, with the G20D80 blend and combined EGR and water vapor dilution, the engine's operating load range was extended to 74% of the rated load. Compared to the CDC, emissions of NOx and soot were significantly reduced. Additionally, HC and CO emissions were reduced by 11.2% and 43.2% at 60% loads, and smoke was reduced by 57.6%, compared to the baseline PCCI, using EGR and water vapor as charge diluents with D80G20 fuel blends.
Ranjan, Ashish Pratap, Krishnasamy, Anand
Characterization of Exhaust Gas Recirculation Effects in a Hydrogen-Fueled 4-Cylinder Engine with Direct Injection2025-24-00529/7/2025
The increasing importance of hydrogen as alternative energy source to reduce CO2 emissions in the transport sector makes its adoption in spark-ignited engines an attractive and cost-efficient alternative to fuel cell-powered vehicles. Lean combustion is the preferred operating strategy for H2-engines in order to achieve performance targets, enhance efficiency and at the same time avoid critical knocking and pre-ignition phenomena. Additionally, an effective approach to lower cylinder temperatures, relevant engine-out NOx emissions and boost pressure requirements at the same time, is an external exhaust gas recirculation (EGR) system. The aim of this work is to analyze and compare the effects of exhaust gas recirculation on the combustion of a lean hydrogen mixture in a turbocharged 4-cylinder H2-ICE with direct injection. For this investigation a load point at 18 bar BMEP and 4000 rpm is selected with and without the utilization of additional external EGR. In this case, a BTE of 38 % is achieved at lambda 1.8 with an 11 % EGR rate. Under these conditions, the NOx emissions are also reduced by 80 % while the efficiency rises by 0.7 %pt., compared to the case without exhaust gas recirculation. Several experiments at the test bench were carried out and used to calibrate a 3D-CFD engine model, in which the complete 4-cylinder engine is virtually reproduced, including high-pressure injection and detailed chemistry for combustion and knock modeling in a single simulation. By investigating the impact of a varying residual gas concentration and air-to-fuel ratio on the mixture formation and the combustion properties, consequences for NOx emissions and abnormal combustion events are derived. A sensitivity study regarding the EGR temperature was additionally performed by means of 3D-CFD simulation to analyze the effects of 80 °C, 160 °C and 240 °C hot external EGR on the combustion process.
Schmelcher, Robin, Kulzer, Andre Casal, Gal, Thomas, Vacca, Antonino, Chiodi, Marco, Grabner, Peter, Gschiel, Kevin
Effect of Gasoline Component on Fuel Economy of WLTC Drive with EGR and Lean Combustion2025-01-03057/2/2025
It is becoming increasingly clear that research into alternative fuels, including drop-in fuels, is essential for the continued survival of the internal combustion engine. In this study, the authors have evaluated olefinic and oxygenated fuels as drop-in fuels using a single-cylinder engine and considering fuel characteristic parameters. The authors have assessed thermal efficiency by adding EGR or excess air from zero to the maximum value that allows stable combustion. Next, we attempted to predict fuel efficiency for four types of passenger cars (Japanese small K-car N/A, K-car T/C, Series HV, and Power-split HV) by changing the fuels. We created a model to estimate fuel efficiency during WLTC driving. The results indicated that fuel economy could potentially be improved by adding an olefin fuel that burns stably even with a large amount of EGR or air and an oxygen fuel whose octane number increases. It was observed that the fuel economy improvement rate was particularly notable for Series-Hybrid Vehicle (HV) with operating under specific load and engine speed conditions.
Moriyoshi, Yasuo, Xu, Fuguo, Wang, Zhiyuan, Tanaka, Kotaro, Kuboyama, Tatsuya
Low-Temperature Coolant Circuit Nomenclature and ApplicationsJ3136_202506 (Current)6/17/2025
The document provides clarity related to multiple temperature coolant circuits used with on-highway and off-highway, gasoline, and light-duty to heavy-duty diesel engine cooling systems, or hybrid vehicle systems. These multiple temperature systems include engine jacket coolant plus at least one lower temperature system. Out of scope are the low temperature systems used in electric vehicles. This subject is covered in SAE J3073. Note that some content in SAE J3073 is likely to be of interest for hybrid vehicles. Out of scope are the terms and definitions of thermal flow control valves used in either low-temperature or high-temperature coolant circuits. This subject is covered in SAE J3142.
Cooling Systems Standards Committee
Influence of Exhaust Gas Recirculation on Knock in a Spark Ignition Engine Fueled with Ethanol–Gasoline Blends03-18-03-00194/28/2025
Exhaust gas recirculation (EGR) is widely used in spark ignition engines to reduce throttling losses, decrease exhaust gas temperatures, increase efficiency, and suppress knock. However, the effectiveness of EGR as a knock suppressor is dependent on the fuel type and operating condition. In this study, the effectiveness of EGR to suppress knock was tested with E10, E30, E50, E75, and E100 at a moderately boosted condition. It was found that EGR was effective at suppressing knock with E10, but high EGR rates were required to achieve a knock suppression effect with E30 and E50. No knock suppression effect was observed with E75 and E100 across all tested EGR rates. With E30 and E50, EGR that was passed through a three-way catalyst was more effective at suppressing knock at all EGR rates. Chemkin modeling with neat ethanol revealed that nitric oxide enhanced ignition by increasing the hydroxyl radical concentration in the end gas, resulting in earlier auto-ignition. Directly seeding nitric oxide in the intake system with neat ethanol resulted in an increase in knock intensity, which required a knock-limited CA50 retard of 3.5 crank angle degrees with 660 ppm of nitric oxide.
Gandolfo, John, Gainey, Brian, Lawler, Benjamin
Real-Time Control of Hydrogen Injection in a PFI Internal Combustion Engine based on an Online Physics-Based Model for Estimating Trapped Air and EGR2024-32-01034/18/2025
The use of hydrogen in port fuel injection (PFI) engines faces challenges related to abnormal combustions that must be addressed, especially in transient operation. The in-cylinder air-to-fuel ratio and the amount of trapped exhaust gas have a significant impact on the probability of abnormal combustion as well as NOx emissions, and should be real-time monitored in hydrogen engines. Thus, the real-time estimation of the composition and thermodynamic state of the trapped gas mixture is crucial during transient operations, although highly challenging. This study proposes an on-line real-time physics-based MIMO (Multi-Input-Multi-Output) model to accurately estimate the amount of trapped air and exhaust gas in the cylinder at the intake valve closing (IVC) event, based on the instantaneous in-cylinder pressure measurement. With proper estimation accuracy, the injector can be controlled to correctly provide the amount of fuel necessary to achieve the target air-to-fuel ratio (AFR) and reduce the probability of abnormal combustion events. Moreover, the proposed model includes an online controller that corrects the estimation delay by means of a single-cycle prediction, adjusting the injection process and preventing from over- and under- estimation of air and fuel trapped masses. This technique can be applied to a wide variety of engines, reducing calibration efforts at the test bench. The proposed model, developed in the MATLAB/Simulink framework, is modular and physics-based, meaning that it requires a few calibrations in the form of heat exchange coefficients and can be easily varied to account for different factors. The physics-based model for the estimation of the amount of air and EGR was validated against 1-D numerical results and experimental data for a hydrogen-fueled PFI engine prototype in both steady-state and transient conditions. Results show average errors below 4.24% when estimating IVC trapped air, EGR and temperature in steady operation. Moreover, the model effectiveness was validated in open (without injection control) and closed loop (with injection control) in two transient profiles, showing limited AFR over/under shoots and proper load-following when controlling the fuel injector.
Galli, Claudio, Ciampolini, Marco, Drovandi, Lorenzo, Romani, Luca, Balduzzi, Francesco, Ferrara, Giovanni, Vichi, Giovanni, Minamino, Ryota
Experimental and Numerical Investigation of Different Dilution Techniques in a High-Performance H2 - Fueled SI Engine2025-01-84244/1/2025
Nowadays, hydrogen (H2) is rising as a key solution to fuel internal combustion engines (ICE) since it allows carbon free combustion process. At the same time, ICE fueled with H2 can reach similar performance and driving experience of gasoline fueled ones. In stoichiometric conditions, hydrogen shows higher flame speed, lower ignition energy and lower quenching distance than gasoline. Mainly for these reasons, H2 combustion is characterized by a high risk of abnormal combustion (i.e. knock and pre-ignition), relevant NOx emissions and high heat losses. On the other hand, the wide flammability range and high combustion stability of H2 allow the use of different techniques to reduce combustion reactivity. This work presents a combined approach, experimental and numerical, to assess the benefits of three mixture dilution methods. The experimental campaign, in different operating conditions, was carried out on a production derived high specific power gasoline Single Cylinder Engine (SCE) retrofitted to H2 with Direct Injection (DI). Three different dilution techniques were tested: enleanment, cooled Exhaust Gas Recirculation (cEGR) and manifold Water Injection (WI). The impacts on combustion of the different strategies were analyzed in order to evaluate their effectiveness on engine thermal efficiency and NOx emissions. Enleanment has a relevant impact on the size of the turbocharger system, cEGR affects the engine total heat rejection, while WI requires dedicated injection system and tank. Therefore, each dilution strategy requires a dedicated hardware optimization. In this regard, a 1D-CFD simulation model of complete 6-cylinder engine was developed with the aim to assess the above-mentioned techniques in terms of fuel economy and heat rejection at low-medium loads.
Tonelli, Roberto, Medda, Massimo, Gullino, Fabrizio, Silvestri, Nicola, Zaffino, Francesco, Mariconti, Roberto, Rossi, Vincenzo
Nitrogen Oxides Reduction Potential Via Water Direct Injection in a Single-Cylinder Hydrogen-Fueled Direct Injection Spark Ignition Engine2025-01-84274/1/2025
In hydrogen-fueled internal combustion engine (H2ICE), there are some ways to reduce nitrogen oxides (NOx) emissions. Using the wide flammability range of hydrogen, such as conducting lean combustion to reduce nitrogen oxides and employing exhaust gas recirculation (EGR), have been adopted. However, challenges exist in terms of load expansion, and due to the absence of high heat capacity of carbon dioxides in the exhaust, EGR also struggles to exhibit significant effects. In such a scenario, there is growing interest in injecting water into the H2ICE as an alternative to augment the EGR effect. In this study, the spark ignition (SI) single-cylinder engine equipped with two direct injectors was used to evaluate the hydrogen and the water dual direct injection combustion system. This system involved the direct injection of hydrogen using a wall-guided gasoline direct injector and the direct injection of water into the combustion chamber using a diesel injector. This approach utilizes the vaporized water not only to act as EGR but also to aid in combustion chamber cooling through the latent heat of vaporization of water, thereby reducing the impact on volumetric efficiency. The main variables were injection timing and the amount of water. Engine speed was fixed at 1,500 rpm and there were two excess air ratio conditions at 2.2 and 1.5(richest limit condition). The result emphasized that the maximum NOx reduction potential was 80% when the water amount was 15.8 mg/str under the excess air ratio of 2.2 due to its latent heat and dilution effects. In addition, this value correspondence to EGR 27.4% so that water direct injection was effective to reduce NOx emissions.
Kim, Kiyeon, Lee, Seungil, Kim, Seungjae, Lee, Seunghyun, Min, Kyoungdoug, Oh, Sechul, Son, Jongyoon, Lee, Jeongwoo
Technology Package Optimization for Power, Cost, and Efficiency in a Dedicated Range Extender Engine for Electrified Vehicles2025-01-83734/1/2025
A reemergence of manufacturer interest in range-extended electric vehicles is being driven by increasing diversification of consumer interest in low carbon-intensity technologies in the passenger vehicle and other markets. A major advantage of range-extended electric vehicles is that they curtail consumer vehicle range anxiety while maintaining a lower vehicle cost when compared with battery electric vehicles (BEV). By incorporating a small liquid-fueled internal combustion engine (ICE), the range and “refueling” time of electrified vehicles can be significantly improved while overcoming issues with cost and weight faced by long-range battery packs. Compared to ICEs designed for non-hybrid and mild hybrid vehicles, the ICE in a range-extended electric vehicle has a unique set of requirements focused on compact size, low cost, and efficient operation within a limited engine map. A Range Extender (REx) 0.9L 2-cylinder engine was selected which prioritizes these attributes in a configurable design. This paper describes the optimization of the REx engine to meet various customer performance requirements. Dedicated range extender engines such as the REx have significant advantages in size, installation flexibility, and overall system weight when compared to engines of similar brake power. These design features are key enablers for one potential market trend of retrofitting vehicles with BEV powertrain architectures to incorporate an optional range extender ICE. The performance of the REx engine can be tailored for a given mission profile through the incorporation of engine technologies such as exhaust gas recirculation, water injection, Miller cam timing, and pre-chamber ignition. The impact of these various technologies on performance, supported by engine test data, and implications on system cost are discussed. Technology packages are proposed for variants of the REx engine optimized for power, efficiency, and cost.
Peters, Nathan, Marion, Joshua, Pothuraju Subramanyam, Sai, Hoth, Alexander, Bunce, Mike
Exploring the Effects of Varying Pre-Chamber Geometry in a Heavy-Duty Natural Gas Optical Engine under Dilution Conditions2025-01-84074/1/2025
Pre-chamber combustion is an advanced ignition strategy that has been shown to enhance spark ignition (SI) combustion stability in natural gas (NG) engines by providing distributed ignition sites from turbulent jets and enhancing main-chamber turbulence. Pre-chamber combustion has been proven especially advantageous compared to SI in ultra-lean and dilute operating conditions. This work involves experimental investigation of the effects of varying passive pre-chamber nozzle configuration on pre-chamber and main chamber combustion under simulated exhaust gas recirculation (EGR) dilution (0 and 20%) conditions in a heavy-duty, single-cylinder, optically accessible NG engine at stoichiometric fuel-air ratio. Pre-chamber nozzle configurations include four pre-chambers with constant nozzle area to pre-chamber volume ratio (A/V) with different nozzle sizes and orientations and one configuration with larger nozzles. The optical engine is operated in a skip-fire sequence consisting of 18 motored cycles followed by two consecutive fired cycles to elucidate the effect of combustion residuals (internal EGR) on combustion evolution. Pressure-based diagnostics are used to monitor pre-chamber and subsequent main chamber combustion, and optical diagnostics include high-speed OH* chemiluminescence to visualize the development of pre-chamber jets and the resulting ignition of the main chamber charge. Heat release analysis of the in-cylinder pressure data indicates that a faster pre-chamber pressure rise does not always translate into faster main-chamber combustion. The pre-chamber with the smallest nozzle diameter produced the highest pre-chamber pressure rise and fastest combustion under non-diluted conditions. However, dilution delays the main chamber ignition for smaller nozzles despite a comparable rise in pre-chamber pressure compared to configurations with larger nozzles. This effect is more pronounced for cycles with in-cylinder combustion residuals in addition to external dilution. Additionally, it was observed that pre-chambers with swirling nozzles have a faster pressure rise in the pre-chamber and main chamber under dilute conditions. Optical diagnostics suggest that the main reason for the delay between the pre-chamber pressure rise and main-chamber combustion lies in jet quenching and delayed re-ignition, which can even lead to misfire if jets emitted from small nozzles combined with dilution fail to re-ignite.
Dhotre, Akash, Nyrenstedt, Gustav, Rajasegar, Rajavasanth, Varma, Arun, Singh, Satbir, Northrop, William, Srna, Ales
Experimental Analysis of Soot and NOx Mitigation during Energy-Buffered Diesel Engine Transients03-18-02-00143/24/2025
Transient operation of a diesel-fueled compression ignition engine will produce significant levels of engine-out criteria pollutants such as NOx and soot emissions due to turbocharger lag. Conventional pollutant mitigation strategies during tip-ins (large increases in load) are constrained by the soot–NOx trade-off—strategies that mitigate soot/NOx emissions often result in an increase in NOx/soot emissions. Hybridization offers the ability to use an e-machine as an energy buffer during a tip-in, allowing the engine to tip-in slower to give the turbocharger time to spin up and provide the necessary amount of air for clean, high-load operation. In this work, an in-line six-cylinder 12.8 L Detroit Diesel DD13 engine was used to study the impact of slowing the torque ramp rate of a tip-in on the effectiveness of transient emission reduction strategies for turbocharged diesel engines, including exhaust gas recirculation (EGR) valve closing, start of injection retard, and the air–fuel ratio threshold with which these emissions reduction techniques are activated. The experiments showed that smoke emissions can be reduced without a corresponding increase in NOx emissions by slowing the tip-in. It was also found that the NOx penalty of reducing EGR flow was attenuated with a slowed tip-in, enabling more aggressive smoke mitigation strategies. Overall, it was shown that a combination of slowing a B25-B75 (from the 13-mode supplemental emissions test) tip-in and reducing EGR flow during the tip-in, the smoke emissions during the tip-in could be reduced by approximately 50% while reducing NOx emission by approximately 4%.
Gainey, Brian, Datar, Aditya, Bhatt, Ankur, Lawler, Benjamin
Mixing-Controlled Combustion of Ethanol Enabled by Prechamber Ignition (PC-MCC): A Preliminary Experimental Demonstration04-18-02-00123/17/2025
This experimental study presents preliminary investigations of prechamber-enabled mixing-controlled combustion (PC-MCC) at −2 bar brake mean effective pressure (BMEP) and 2200 rpm with fuel-grade ethanol (E98). Experimental results are conducted on a prechamber retrofitted single-cylinder Caterpillar C9.3B test engine. First, a series of prechamber-only experiments were conducted with a motored engine to evaluate the salient combustion trends in response to relevant prechamber operating parameters. Under firing conditions, the prechamber operating strategy was assessed with respect to the impact on ignition assistance of direct-injected E98 and overall engine performance. The preliminary results indicate the jet-induced ignition process is robust and prompts diffusion combustion of E98 at diesel-like boundary conditions. The effect of external exhaust gas recirculation (EGR) on the residual tolerance of the prechamber combustion process was also investigated and showed stable combustion in both the main chamber and prechamber up to 30% EGR. Experiments were also conducted with the stock diesel engine for baseline comparison. At matched combustion phasing, mixing-controlled combustion of ethanol enabled by prechamber ignition was able to achieve heightened gross thermal efficiency while simultaneously reducing NOx and practically eliminating smoke emissions relative to diesel combustion. In addition, the covariance of load and standard deviation of combustion phasing was diesel-like and less than 2% and 1 CAD, respectively.
Zeman, Jared, Dempsey, Adam
Exploring H 2 /O 2 Injection in an Active Pre-Chamber Ignition Engine03-18-02-00133/4/2025
Active fuel injection into a pre-chamber (PC) promotes high-temperature and highly turbulent jets, which ignite the cylinder gas with a very high exhaust gas recirculation (EGR) ratio, reducing emissions such as NOx. In the present study, two active PC injection strategies were designed to investigate the effect of injected hydrogen mass and PC mixture air-to-fuel equivalence ratio λ on PC combustion, jet formation, and main chamber (MC) combustion. Stoichiometric or rich hydrogen/oxygen mixtures are actively injected into the PC to enhance the combustion processes in the PC and the MC. A three-dimensional numerical engine model is developed using the commercial CFD code CONVERGE. The engine geometry and parameters adopt a modified GM 4-cylinder 2.0 L GDI gasoline engine. The local developments of gas temperature and velocity are resolved with the adaptive mesh refinement (AMR). The turbulence of the flow is computed with the k-epsilon model of the Reynolds-averaged Navier–Stokes (RANS) equations. The turbulent combustion process is modeled with the extended coherent flamelet model (ECFM). The obtained numerical results, which include MC pressures and heat release rates, align well with experimental data. Detailed analysis is performed to study the effect of the active PC injection with hydrogen on jet properties and turbulence–chemistry interactions. The results reveal that injecting a stoichiometric mixture of hydrogen and oxygen into the PC leads to an EGR limit of 36%, attributed to the high laminar flame speed and adiabatic flame temperature of the mixture, making it an effective method for reducing the engine’s NOx emissions.
Yu, Tianxiao, Lee, Dong Eun, Alam, Afaque, Gore, Jay P., Qiao, Li
Study on the Impact of Arrangement of Urea Injector and Mixer in Diesel Engine Selective Catalytic Reduction System on Ammonia Uniformity02-18-02-00072/12/2025
With the continuous upgrading of emission regulations for internal combustion engines, the nitrogen oxide treatment capacity of selective catalytic reduction (SCR) aftertreatment needs to be continuously improved. In this study, based on a prototype of SCR aftertreatment, the impact of the arrangement of key components in the SCR system (urea injector, mixer, and catalyst unit) on ammonia uniformity was investigated. First, parameterized designs of the urea injector, mixer, and SCR unit were conducted. Then, using computational fluid dynamics (CFD), numerical simulations of the established aftertreatment system models with different parameter factors were performed under a high-exhaust temperature and a low-exhaust temperature conditions to study the impact of each individual parameter on ammonia uniformity. Finally, an optimized solution was designed based on the observed patterns, and the optimized samples were tested on an engine performance and emission test bench to compare their ammonia uniformity. The test results showed that the ammonia uniformity of the optimized solution was improved by 2%–3% compared to the original design, reaching 0.952 and 0.967, respectively.
Jie, Wang, Jin, Jianjiao, Wu, Yifan
Fuel Efficiency Evaluation of an Off-Road Diesel Engine with an EGR Pump and High-Efficiency Turbocharger across Various Drive Cycles02-17-04-002312/10/2024
As regulations become more stringent, engine manufacturers are adopting innovative technologies to reduce emissions while maintaining durability and reliability. One approach involves optimizing air handling systems. Eaton developed a 48 V electric exhaust gas recirculation pump (EGRP) to reduce NOx and CO2 emissions while improving fuel efficiency when paired with a high-efficiency turbocharger. This study integrates an electric EGRP and a high-efficiency turbocharger onto a 13.6L John Deere off-road diesel engine to evaluate the impact on fuel efficiency and NOx emissions across various drive cycles including the nonroad transient cycle (NRTC), the low load application cycle (LLAC), the constant speed–load acceptance (CSLA) test, and the ramped modal cycle (RMC). The study highlights the benefits and limitations of the prototype EGRP on an off-road engine. Since the setup did not include aftertreatment systems, engine-out emissions were analyzed. Experiments were conducted at selected operating points to achieve optimal brake thermal efficiency while keeping BSNOx within 25% of baseline values. These results helped develop a calibration map for both transient and steady-state testing. For the CSLA tests, the time response to achieve 90% load was slower with the EGRP-equipped engine compared to the stock engine. Additionally, the NRTC, a regulatory cycle for the United States and the European Union, and the LLAC did not achieve the desired torque set points with the EGRP and high-efficiency turbocharger. The EGRP’s slower-than-desired response when it decelerates led to excess EGR flow, which affected the engine’s ability to produce torque. This was a key finding of the study. The measured engine speed and engine load with the EGRP engine configuration were utilized to develop a modified version of the NRTC and LLAC, referred to in this article as the modified NRTC and the modified LLAC. The modified NRTC and modified LLAC were run on the stock engine to accurately compare the performance of the stock hardware with the EGRP and high-efficiency turbocharger hardware for the same transient cycles, albeit cycles that are no longer specifically the regulatory NRTC and LLAC cycles. The intent of the modified LLAC and the modified NRTC is to show what the possible benefits of EGRP and high-efficiency turbocharging may likely be if the transient response shortcoming of the EGRP is addressed BSFC improved with the EGRP and high-efficiency turbocharger hardware for the modified NRTC, modified LLAC, and RMC. The modified NRTC showed a 1.3% improvement, the modified LLAC exhibited a 2.5% improvement, and the RMC demonstrated a 1.3% improvement. BSNOx increased by 12.9% for the modified NRTC, decreased by 11.1% for the modified LLAC, and increased by 2.8% for the RMC with the EGRP configuration. The BSPM increased by 34.2% for modified LLAC and improved by 33.1% for the modified NRTC.
Willoughby, Audrey, Adekanbi, Michael, Kakani, Raghav, Ahmad, Zar Nigar, Shaver, Greg, Holloway, Eric, Haaland, Eric, Evers, Matthew, Loesch, Adam, McClurg, Josiah, Bagal, Nilesh, McCarthy, James, Coates, Michael
Influence of Exhaust Gas Recirculation on Emission Metrics in a Diesel Engine Operated with Hydrogen Induction and Cassia fistula Biodiesel2024-01-522112/10/2024
The current study investigates the influence of exhaust gas recirculation technique on the hydrogen (10lpm) inducted diesel engine using Cassia fistula derived biodiesel fuel. The focus is on evaluating the emission characteristics of the engine, with a particular emphasis on reducing NOx emissions. The study also examines the impact of varying the Exhaust Gas Recirculation (EGR) flow rate 10 and 20% on the aforementioned parameters. The novelty of this investigation lies in the comprehensive evaluation of emission metrics, particularly when combining Cassia fistula biodiesel with hydrogen induction. The experiment carried in Kirloskar TV1-V4A engine with blends consists 10%, 20%, 30% and 40% by volume of CFME blends with diesel. The inducted hydrogen at 10 lpm caused increased NOx which were discussed to suppress by EGR applications. Among the tested fuels, a blend containing 40% cassia fistula methyl ester (CFME) and 60% diesel (CFME40D60) showed the lowest hydrocarbon (HC) emissions, achieving 20 ppm, 18 ppm, and 23 ppm under non-EGR, 10% EGR, and 20% EGR conditions, respectively. Additionally, the CFME40D60 blend exhibited the lowest carbon monoxide (CO) emissions, with values of 0.0141%, 0.0156%, and 0.0159% by volume under the same conditions. The blend also demonstrated superior performance in reducing smoke opacity, achieving 32%, 32%, and 31% opacity, compared with diesel. Notably, the NOx emissions were significantly low with CFME10D90 blend, showing values of 1910 ppm, 1801 ppm, and 1598 ppm, with a 312 ppm reduction at the 20% EGR rate compared to non-EGR conditions. These findings provide insights into optimizing the fuel mixture and EGR settings to achieve improved engine performance and reduced emissions, making it a viable option for sustainable transportation.
Veeraraghavan, Sakthimurugan, Madhu, S., De poures, Melvin Victor, Palani, Kumaran
Performance Evaluation of Common Rail Direct Injection Engine Run on Biodiesel of Used Temple Oil Using Response Surface Methodology03-17-08-006212/6/2024
Diesel engines produce more smoke and nitrogen oxide (NOx) emissions. Hence, one has to develop a new technique that reduces these emissions besides works satisfactorily with alternative fuels in place of diesel. In this work, used temple oil biodiesel (BTO) is a candidate to replace diesel to run diesel engine. Also, common rail direction injection (CRDi) is a technique that injects fuel at a higher pressure than conventional injectors of diesel engines that produce fine fuel droplets suitable for highly viscous biodiesel. This work also uses the design of experiments (DOE) and response surface methodology (RSM) modeling approach to evaluate the performance of CRDi engine with three operating parameters namely injection timing (IT), injection pressure (IP), and exhaust gas recirculation (EGR). From the study, it could be concluded that CRDi engine showed better performance at IT of 9°bTDC, IP of 855 bar with EGR of 20% but with little reduction in thermal efficiency. The study has reported good agreement between predicted values and experimental results.
Shaikh, Sardar Mansoor, Khandal, Sanjeevkumar V.
Effects of Fuels Properties on Combustion and Emissions Characteristics of Light Duty GCI Engine2024-01-427911/5/2024
Our research group developed Gasoline Compression Ignition (GCI) fuel matrix based on the fuel properties, specifications and fuel sources in an effort to standardize the GCI fuel. This study attempts to experimentally validate the standardized GCI fuels to comply with the operational regimes of GCI engine. Two of the formulated GCI fuels (GCI7 and GCI8) with varying physical and chemical properties, and composition were investigated in a single cylinder compression ignition (CI) engine. In addition to fuel effects, the engine variables were parametrically varied at low (3 bar IMEP) and medium (7 bar IMEP) load conditions. At low loads, the fuel chemical effects played a crucial role in governing the combustion while physical effect had a negligible impact. Due to lower cetane number of GCI8 fuel, combustion is predominantly premixed for GCI8 fuel but GCI7 fuel shows a more pronounced diffusion combustion phase. The low temperature heat release (LTHR) is evident only for GCI8 fuel due to higher octane rating (RON = 60) whereas GCI7 fuel (diesel like) showed negligible LTHR phase. Despite improvements in engine operating parameters, the combustion performance of GCI8 is lower than GCI7 fuel. However, after improving the fuel injection strategies, GCI8 fuel showed improved peak in-cylinder pressure and heat release compared to GCI7 fuel. Double injection advanced the combustion phasing, shortened the ignition delay, and improved the burn rate when compared to single injection. Fuel composition played a crucial role in emission formation in that smoke emission is increased for GCI7 due to higher fraction of aromatics in the fuel compared to GCI8. The increased premixed effect due to lower cetane number of GCI8 decreased the fuel to air equivalence ratio and in-cylinder temperature in that NOX emission is reduced.
Qahtani, Yasser Al, Raman, Vallinayagam, Viollet, Yoann, Alhajhouje, Abdullah, Cenker, Emre, AlRamadan, Abdullah
Experimental Investigation on Combustion Strategy of Light Duty GCI Fueled High Reactivity Gasoline Fuel2024-01-428211/5/2024
Diesel engines are largely used as power units with high fuel efficiency. Conversely, they have an adverse impact on the environment and human health as they emit high NOx and particulate matter emissions. As more stringent regulations for emissions are introduced, low temperature combustion strategy such as Gasoline Compression Ignition evolved and demonstrated the potential to reduce the particulate matter and NOx emissions by operating engines under a Partially Premixed Combustion mode. Therefore, a 0.55 mm single cylinder engine (Gasoline Direct Injection), was tested over range of engine loads with constant speed (1500 rpm) using RON80 without oxygenates. Different operating parameters such as injection, exhaust gas recirculation (EGR) etc. were used to control combustion phasing and mixture stratifications. At low loads, rebreathing of hot exhaust gas produced low levels of NOx and smoke emissions. It reduced NOx by 60% and smoke levels below 0.20 FSN when it is coupled with low levels of EGR. At medium to high loads, alternative injection strategies were explored to find proper combustion mode with very low NOx of 0.01 g/kwh and smoke of 0.01 FSN emissions while meeting combustion noise targets. Minimum ISFC was measured at 195 g/kwh at 13 bar IMEP.
Qahtani, Yasser Al, Sellnau, Mark, Yu, Xin
Computer-Aided Engineering Approach to Optimize Hydroformed Exhaust Gas Recirculation Tube under Thermal Load2024-01-50868/30/2024
This study emphasizes the importance of computer-aided engineering (CAE) approach in optimizing exhaust gas recirculation (EGR) tube under thermal load. With exhaust gases generating high temperatures, the EGR tube experiences increased stress and strain, posing challenges to its structural integrity. Moreover, the cyclic heating and cooling cycles of the engine imposes thermal fatigue, further compromising the tube’s performance over time. To address these concerns, the paper introduces a comprehensive CAE methodology for conducting factor of safety analysis. The nonlinear thermal analysis is performed on the assembly as due to high temperatures the stresses cross the yield limit. The strain-based approach is used to calculate the factor of safety. Moreover, a comprehensive case study is presented, illustrating how design modifications can enhance the thermal fatigue factor of safety. By adjusting parameters such as thickness and routing, engineers can mitigate thermal stresses and improve the tube’s fatigue life. This approach allows analysts to thoroughly evaluate whether the tube design can endure thermal fatigue for a specified number of cycles. By utilizing advanced simulation tools and techniques, engineers gain valuable insights into the tube’s behavior under varying thermal conditions. This enables informed decision-making regarding design modifications aimed at enhancing durability and reliability. Ultimately, the integration of CAE in the optimization process empowers automotive manufacturers to develop EGR tubes that meet stringent performance requirements while minimizing the risk of premature failure due to thermal stresses and fatigue. The tool used for simulation of the EGR tube assembly is ANSYS 2023R1.
Munde, Ganesh, Chattaraj, Sandip, Hatkar, Chandan, Godse, Rushikesh
Premixed Dual-Fuel Combustion of Camelina sativa Oil and Ethanol03-18-01-00018/6/2024
Dual-fuel (DF) engines enable efficient utilization of a low reactivity fuel (LRF), usually port-injected, and a high reactivity fuel (HRF) provided directly into the cylinder. Ethanol and Camelina sativa oil can be ecologically effective but not fully recognized alternatives for energy production using modern CI engines equipped with a common rail system and adopted for dual fueling. The high efficiency of the process depends on the organization of the combustion. The article describes the premixed dual-fuel combustion (PDFC) realized by dividing the Camelina sativa dose and adjusting its injection timing to the energetic share of ethanol in the DF mixture. The injection strategy of HRF is crucial to confine knock, which limits DF engine operation, but the influence of EGR is also important. The research AVL engine’s dual-fueling tests focused on combustion process modification by the proposed injection strategy and cooled EGR at different substitution rates. For all examined points of the engine run, the volumetric heat release rate diagrams, cylinder pressure, and temperature illustrate changes that resulted from the tested fueling options. Additionally, engine thermal efficiency and emissions are presented. Because of potential application, the tests were confined to one engine speed (n = 1500 rpm). The research confirmed the possibility of efficiently applying raw Camelina sativa oil as an HRF for DF engines and ethanol (LRF) under high-load conditions.
Pawlak, Grzegorz, Skrzek, Tomasz, Kosiuczenko, Krzysztof, Płochocki, Patryk, Simiński, Przemysław
Optimization of Hydroformed Exhaust Gas Recirculation Tube under Vibrational Load by Finite Element Analysis2024-01-50626/17/2024
This study emphasizes the importance of CAE approach in optimizing EGR tube under vibrational load. EGR tube is a weak link in the EGR system and chances of failure due to vibration and relative displacement of mating parts, i.e., overhang or improper support at exhaust manifold, intake manifold, or EGR system. Consideration of the mating parts for the EGR tube is very important to get the realistic resonance frequencies, otherwise it could have some different results in the CAE, which will deviate from the reality. So, it’s important to study the dynamic response on the EGR tube, which needs to be taken care during the design phase. This paper aims to optimize the EGR tube under vibrational load by using CAE techniques and the industry experience as a product expertise. some critical parameter such as damping is very important during the CAE, which can be generated by doing the rigorous testing and how it affects the stress and correspondingly FOS. CAE model of EGR tube is created on which modal and harmonic response analysis is made. The natural frequency and stresses in the EGR tube are assessed by using CAE Tool ANSYS Mechanical. Using the CAE result observations, the changes in design of the EGR tube is done to improve its design. The design of EGR tube is improved by changing thickness, hydroformed corrugations, materials, or using different brackets. The CAE model results is also correlated with the testing results on electrodynamic shaker. EGR tube is assembled on the shaker with engine mating components having the same orientation as on vehicle. The shaker is used to find resonance frequency and to carry durability testing of the EGR tube. The results obtained from CAE model and testing are compared and found satisfactory. All the above efforts enable analysts to make the first time right design.
Munde, Ganesh, Chattaraj, Sandip, Hatkar, Chandan, Thakur, Abhishek Kumar
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