Browse Topic: Hybrid engines

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Study on Diesel-Methanol Non-Premixed Combustion Characteristics of a Marine Dual-Fuel Engine at Different Methanol Substitution Rate2026-99-05177/10/2026
Methanol use in marine engines has the potential to reduce nitrogen oxide emissions, particulates, and greenhouse gas emissions. A turbocharged four-stroke marine diesel powerplant was converted to run as a double-DI (direct injection) diesel-methanol hybrid engine. Experimental studies using a non-premixed combustion scheme showed that higher methanol substitution ratios (MSR) led to increased peak heat release rates. The combustion process displayed distinctive two-phase behaviors. Increasing MSR caused retarded ignition timing, shortened combustion duration, and improved thermal efficiency. Combustion stability was significantly improved at higher MSR. Emissions results showed NOX and HC were increased in proportion to MSR, whilst particulate emissions and CO concentrations were inversely reduced. Methanol enrichment was found to enhance NOX and HC formation processes but also accelerate soot particulate decomposition and CO oxidation mechanisms.
Li, Xiao, Jiang, Yuqi, Yan, Ping, Zheng, Liang, Li, Hongmei, Zhang, Wenzheng, Chen, Chao, Man, Zhongguo
Synergistic Integration of Advanced Combustion and Air-Path Technologies to Maximize Internal Combustion Engines Efficiency in Hybrid Applications2026-01-07337/1/2026
This paper assesses the efficiency limits of light-duty vehicle propulsion systems based on reciprocating internal combustion engines (ICE) in the current state of the art and in the next five-year horizon, considering their combination with technologies such as electric turbocharging and hybridization, while excluding plug-in hybrid configurations so that fuel remains the primary onboard energy source. A systematic methodology is applied to evaluate the influence of key variables—heat transfer, air–fuel ratio, and compression ratio—on engine performance, integrating these variations into a simulation model to capture their interactions and effects. The resulting parametric study enables the generation of new engine maps that exploit synergies between parameters and enhance the prediction of engine behaviour across different operating conditions, forming the basis for assessing potential advancements in hybrid powertrain architectures. These maps are then used to define performance expectations for hybrid vehicles, identifying optimal parameter combinations to guide future technology development and improve efficiency in hybrid powertrain design. The proposed powertrain architectures are integrated into a representative vehicle model, considering two vehicle typologies: a compact passenger car and a sport utility vehicle (SUV). To quantify the potential fuel-consumption benefits, an intelligent energy-management algorithm is implemented to supervise and optimize system operation over a WLTC driving cycle. The results indicate that the proposed configurations can achieve fuel-consumption reductions exceeding 20%, demonstrating the effectiveness of both the powertrain designs and the control strategies. Overall, the findings highlight the significant efficiency potential of advanced ICE-based propulsion systems when combined with near-term technologies such as electric boosting and hybridization, confirming the viability of these improvements and providing a robust basis for future hybrid vehicle development focused on maximizing energy efficiency in transportation.
Pla, Benjamin, Dolz, Vicente, Serrano, Jose R., Gómez-Vilanova, Alejandro, Oliva, Fermin, Cardenas, Maria, Ariztegui, Javier
NVH Design and Refinement of Dedicated Hybrid Engine on Range-Extended Electric Vehicle2026-01-06886/20/2026
Simplicity and electrification of the propulsion system are one of the most important trends in vehicle development and integration process. The complexity of NVH (Noise, Vibration and Harshness) design and refinement is the core challenge to this process. Customers’ expectations of an unnoticeable engine during driving make this challenge more critical [1]. Apart from the overall sound pressure level, the sound quality is even more important due to the lack of noise masking effects [2]. Therefore, the development team has reached an internal consensus that NVH attributes are the top priority in engine development. This paper describes the NVH development process of a dedicated hybrid engine for the range extender electric vehicle (REEV) application, beginning with an introduction to REEV system as well as the operating condition data of long-distance road tests. Based on the road test data, the engine technical specification is defined accordingly and broken down into design targets for all individual components. Subsequently the design target is finally achieved through the definition of engine architecture, hardware selection, and individual component simulation and optimization. With regard to the NVH refinement, the NVH issues such as global crankshaft vibration, start impacts, high-pressure fuel system ticking, and acoustic encapsulations studies are discussed. Finally, the appropriate optimization proposals are summarized and the bench test results are presented.
Wang, Hao, Zhang, Guiqiang
AI Based Energy Sustained Series Hybrid Aircraft2026-26-07766/1/2026
This paper investigates the energy consumption characteristics of series hybrid aircraft with a focus on comparing conventional energy management approaches against an AI-powered optimization framework. The study comprehensively models the energy demands of a series hybrid aircraft across all major flight phases, including Idle & Ground Operations, Taxi, Takeoff, Climb, Cruise, Descent, Approach, Landing, and Rollout & Taxi. For each phase, detailed mathematical formulations are developed to capture power requirements and energy flow, incorporating real-time operational parameters to enhance the accuracy of the energy consumption estimations measured in kilowatt-hours (kWh). The AI-based optimization leverages advanced control strategies, specifically Model Predictive Control (MPC) and Reinforcement Learning (RL) algorithms, to dynamically manage the aircraft’s energy systems. MPC is employed to predict and optimize future energy usage by solving constrained optimization problems over a moving time horizon, ensuring efficient energy distribution while satisfying operational constraints. Concurrently, RL algorithms enable adaptive learning from operational data to improve decision-making in energy management, optimizing performance under varying flight conditions and uncertainties. Comparative analysis demonstrates that the AI-driven series hybrid aircraft achieves significant energy savings compared to conventional methods, quantified in both absolute kWh reductions and percentage improvements. These savings are particularly pronounced during overall phases such as Takeoff, Climb, and Cruise, etc. where optimal control of energy flows directly translates to improved efficiency and extended operational endurance. The findings underscore the potential of AI-integrated control systems in advancing sustainable aviation technologies by enabling smarter, energy-efficient hybrid propulsion. This paper provides a foundation for future development of intelligent energy management systems that can be deployed in next-generation hybrid series aircraft, contributing to reduced environmental impact and enhanced operational performance.
Kanchagar, Amogha
Multi-Physics Modeling of Aircraft Hybrid Propulsion Systems Integrating Batteries, SOFC, and Jet Engine2026-99-17035/22/2026
This paper presents a multi-physics modeling approach for a hybrid propulsion system designed for High-Altitude Long-Endurance Unmanned Aerial Vehicles (HALE UAVs), integrating solid oxide fuel cells (SOFCs), lithium-ion batteries, and a jet engine. A dynamic model was developed to analyze the coupled characteristics of pressure, temperature, and power under steady-state conditions. Simulation results demonstrate that the internally integrated system achieves efficient fuel and waste heat recovery, delivering a net power output of 300–700 kW, sufficient to meet the operational demands of HALE UAVs. Key innovations include a heat exchanger maintaining SOFC stack inlet temperatures above 850 K for optimal performance and a compressor-fan subsystem enhancing gas compression efficiency. Experimental validation confirmed the accuracy of the SOFC model, with simulated electrical characteristics aligning closely with empirical data. The proposed hybrid system addresses limitations in specific power and transient response while improving energy density, offering a viable solution for long-endurance flight missions. This study provides a foundational platform for advancing hybrid propulsion technologies in aviation.
Zhang, Lin, Zhang, Di, Zhao, Lulu, Li, Xi
Conceptual Design of Hybrid-Electric Propulsion System for a Light UAVF-0082-2026-01645/5/2026
The present work focuses on the sizing and analysis of a parallel hybrid propulsion architecture for a conventional rotary light Unmanned Aerial Vehicle (UAV) in the 200kg class. First, the design methodology is outlined, with an emphasis on the optimization of the battery pack, which is one of the most crucial component of the whole powertrain. The sizing approach is applied to a wide range of thermal and electric power ratios, as well as two distinct hybridization strategies, to investigate the broad design space and discover possible sweet spots. For this aim, the various design points are then evaluated in terms of impact on aircraft capabilities, considering both extensive and intensive performance. Hence, the results provide the main advantages and disadvantages, performance wise, of the hybrid propulsion in comparison to a conventional full thermal solution.
Rovera, Eugenio, Corno, Matteo, Trivella, Andrea, Bonini, Valerio, Nesci, Andrea
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
TOC99-08-01-0TOC2/11/2026
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Tobolski, Sue
Equivalent Power Consumption Minimization Strategy Based Controller for a Novel Dedicated Hybrid Engine Powertrain for a Light-Duty Application2025-01-041610/7/2025
Due to strengthened CO2 regulations, the automotive industry is facing the challenge of reducing greenhouse gas emissions. In response, the industry has focused on developing various technologies that enhance fuel economy and reduce greenhouse gas emissions. Hybrid electric powertrains have demonstrated significant potential to improve fuel economy and reduce greenhouse gas emissions. The improvements resulting from hybrid electric powertrains depend on the degree of electrification, which is closely related to the sizing of the motor and battery. However, hybridization increases the complexity of the powertrain. As multiple power sources are involved, complex control algorithms must be developed to allocate power usage among various driving scenarios while fulfilling driver requests. One way to simplify hybrid power management control is to implement optimization strategies that determine the operating states for each component during different driving scenarios, aiming to minimize overall power consumption within defined constraints. In this case, an optimizer based on the Equivalent Power Consumption Minimization Strategy (EPCMS) was developed for a novel dedicated hybrid engine powertrain to reduce power consumption while fulfilling the driver's power request. The traditional ECMS approach focuses on minimizing equivalent fuel consumption, whereas this new approach follows the principle of minimizing power consumption. Total power consumption is calculated by accounting for the efficiency and operational losses of each component. The power management controller is implemented and developed within a Model-in-the-Loop (MiL) framework, utilizing a 0D/1D vehicle model as the plant. For the FTP-75 drive cycle, the hybrid optimizer chose to fulfill approximately 22% of the tractive power requirement through ICE power, with the electric components providing the remaining power usage. Additionally, the developed optimizer improved fuel economy across various driving cycles compared to the conventional internal combustion engine (ICE) powertrain.
Echeverri Marquez, Manuel, Bhoge, Mahesh, Lago, Rafael, Engineer, Nayan, Bhadra, Kaustav, Whitney, Christopher, Baur, Andrew
Data-Driven Modeling of H2-SCR Catalysts for Real-Time Estimation of NOx Reduction Efficiency2025-24-00849/7/2025
Achieving zero emissions across transportation is a tremendous challenge. The upcoming Euro 7/VII standards, set to be enforced in 2025, will mandate further reduction in ICEs exhaust emissions. Thus, additional improvements and potential new technologies and fuels are needed to design ultra-low emissions vehicles. Hydrogen seems to be a very attractive fuel, thanks to its high lower heating value, clean combustion, and extremely low pollutant emissions, due to the zero-carbon content. Nevertheless, NOx emissions are still an issue in hydrogen fueled engines and optimized lean-burn combustion and suitable after-treatment NOx reduction are mandatory to reach high specific power and efficiency and near zero NOx emissions, thus enabling H2-ICE powered vehicles to be zero-impact emitting technology solution. Selective Catalytic Reduction by using NH3 as the reducing agent is the most effective control technology for NOx abatement. Nevertheless, ongoing research and innovation are critical in developing new strategies for reducing NOx emissions, to overcome the NH3-SCR system main critical issues (extra equipment for urea storage and dosing, ammonia-slip, deactivation and fouling, low efficiency at low temperature). The SCR of NOx by hydrogen is considered a promising alternative to traditional ammonia-based deNOx technology. The H2-SCR catalysts are suitable for engine exhaust after-treatment during cold-start and urban-driving operations, exhibiting higher catalytic activity for low-temperature NOx emissions conversion (180 – 200 °C). Furthermore, in H2-ICE powered vehicles, the additional tank to store the reducing agent is not needed with a significant simplification of the engine exhaust lay-out. Experimental investigations on different H2-SCR catalysts have demonstrated that the conversion activity is greatly affected by the catalytic system configuration, the adsorption properties of the support material, the H2 spillover, that in turn are affected by H2/NO ratio and exhaust gas composition, temperature and flow rate. In the present paper, a feed-forward neural network model of H2-SCR is presented, with the aim of performing real-time estimation of reduction efficiency and supporting the design of suitable H2 management to achieve maximum NOx reduction and minimum hydrogen consumption. Model training and identification are carried out against a large set of experimental data measured on a H2-SCR small scale prototype at the Synthetic Gas Bench. The experimental tests were designed to reproduce the real conditions expected at the exhaust of a H2-fueled engine.
Crispi, Maria Rosaria, Conde Cortabitarte, Carla, Occhicone, Alessio, Piqueras, Pedro, Arsie, Ivan, Pianese, Cesare
On a NMPC-Based Supervisory Control Logic for Energy Management Purposes in Aeronautical Hybrid Propulsion Systems2025-24-01029/7/2025
Eco-sustainability is one of the main aspects focused on motor industries, including those related to air transport, which work to realize alternative propulsion systems, such as Hybrid Electric Propulsion Systems, for reducing CO2 emissions. Despite the minor CO2 emission produced by Hybrid Electric Propulsion Systems, these categories of propulsors require a proper control architecture for managing combustion and electric energies based on driver decisions and the flight mission set. A supervisory control logic, based on a Nonlinear Model Predictive Control (NMPC), is presented in this work to guarantee a specific State of Charge level of batteries coupled with the minimization of fuel consumption of an aeronautical Hybrid Propulsion System. These two goals are achieved by the designed NMPC, which provides the best amount of torque between the propulsors belonging to the analysed aeronautical powertrain, consisting of an Internal Combustion Engine and an Electric Machine. The proposed NMPC performances are tested by a map-based model of the previously mentioned propulsors, included in a lumped parameters modelling related to the longitudinal dynamics of a Single Engine aircraft. The comparison between the same aircraft equipped with a Hybrid Propulsion System and a conventional Internal Combustion Engine demonstrates the suitability of the proposed NMPC to be adopted for improving eco-sustainability by reducing CO2 emissions.
Tordela, Ciro, Fornaro, Enrico
Methanol Cold Start Procedure for a Serial Hybrid Powertrain2025-24-00749/7/2025
Methanol obtained from regenerative sources is a renewable fuel with many advantages when used in a spark ignition combustion process. Methanol has a comparatively high enthalpy of vaporization, leading to lower combustion temperatures (compared to gasoline combustion) and, hence, lower wall heat losses as well as a reduced tendency to autoignition. Several cold start methods were examined for this paper. In a serial hybrid powertrain with one internal combustion engine, ICE, and one electric machine, the load demand of the ICE can be controlled for best efficiency. The ICE is operated on liquid renewable fuel, which provides a high volumetric and gravimetric power density, easy energy storage, delivered from a very cost effective already existing infrastructure of fuel distribution. The electric machine provides comfortable electric driving, high efficiency, locally and temporary zero emissions. The eFuel should be produced from a closed carbon cycle. Methanol is a challenging fuel, since it has a high flash point at 11 °C indicating a challenging cold start. Feasible solutions are fuel or intake air heating or blending with lightly boiling components. All of these incur expenses for additional component and processes. One of the cold start procedures presented in this paper enables the cold start of pure methanol down to –20 °C, without the necessity for additional engine components. For this the serial hybrid propulsion system is used. The electric machine was used to motor the ICE at high engine speeds and strongly throttled with minimal fuel mass, to allow for fuel evaporation in the intake and heating during the compression stroke. A 3D-CFD simulation was setup the explore the procedure. The new procedure is compared to a conventional process with air and fuel heating.
Dobberkau, Maximilian, Werner, Ronny, Atzler, Frank
Energy-Efficient Range-Extender Study for Commercial Vehicle Electrification with Renewable Fuels02-19-01-00048/9/2025
Light-duty vehicles (LDV) are scaling up electrification technologies from battery to dedicated hybrid engines (DHEs). The success from electrification of LDVs can be a starting point to look into a similar trending development of commercial vehicles (CV), which are bigger and heavier with more demanding work cycles. “Greenhouse Gas Emissions Standards for Heavy-Duty Vehicles (HDV)—Phase 3” establishes new CO2 emission standards for MY 2032 (Model Year) and later HD vehicles with more stringent CO2 standards phasing in as early as MY 2027 for certain vehicle categories. In this article, the focus is about improving the operational efficiency of MDHD (medium-duty and heavy-duty) vehicles through a selected electrification technology in this study rather than pure BET (battery electric truck). Extended-range electric vehicle (EREVs) systems are studied here to address sustainability regarding charging infrastructure and by using the renewable fuels (hydrogen, ammonia, methanol, and ethanol). Range-extender systems with using renewable fuels are investigated to electrify CV for cost-effectiveness and carbon reduction as well as tailpipe emissions in the USA. The numeric analysis expanded from the experimental BET study shows the promising potential of EREVs for electrifying HDVs through applying renewable fuels.
Wang, Hailong, Ma, Tiancai, Shuai, Shijin, Wang, Zihui, Song, Xubin
Applied Full-Bridge Micro Strain Gauge to High Pressure Sensor for Gasoline Direct Injection/Hybrid System2025-01-02206/16/2025
High Pressure Sensors (HPS) are essential for internal combustion engines and hybrid engine systems. High pressure sensor measures the pressure in the Delivery fuel rail Pipe Module (DPM) to allow the Engine Control Unit (ECU) to control the high pressure pump to generate the required fuel pressure. Most high pressure sensors measure the displacement of the metal-diaphragm according to pressure, and are mainly composed of Half-bridge type Micro Electro Mechanical System (MEMS) elements of the piezo-resistive method. This time, we would like to introduce a high pressure sensor that uses a Full-bridge type MEMS structure. This is cheaper than the existing one and can provide higher performance with reliability. However, there are disadvantages of the full-bridge type applied to high pressure sensors. Unlike the Half-bridge method that measures displacement over a wide area, it measures displacement over a narrow area, so it has the disadvantage of weak to external noise due to increased sensitivity. This paper will introduce the methods and results to solve these disadvantages using two key solutions which are consisted of laser welding power and diameter of thread port. Through these solutions, we were able to improve performance deviation influence before and after thermal cycle and reduce the impact of external forces compared to before improvement. In conclusion, we were able to obtain improved performance and durability compared to the existing high pressure sensor.
Lim, SeungGu, Lee, DongYoung, Kim, JungTaek, Shin, MoonSung
Optimal Onboard Battery Charging Strategy for Hotel Load Management in Mild-Hybrid Heavy-Duty Truck02-18-03-00176/12/2025
Heavy-duty trucks idling during the hotel period consume millions of gallons of diesel/fuel a year, negatively impacting the economy and environment. To avoid engine idling during the hotel period, the heating, ventilation, and air-conditioning (HVAC) and auxiliary loads are supplied by a 48 V onboard battery pack. The onboard battery pack is charged during the drive phase of a composite drive cycle, which comprises both drive and hotel phases, using the transmission-mounted electric machine (EM) and battery system. This is accomplished by recapturing energy from the wheels and supplementing it with energy from the engine when wheel energy alone is insufficient to achieve the desired battery state of charge (SOC). This onboard battery pack is charged using the transmission-mounted EM and battery system during the drive phase of a composite drive cycle (i.e., drive phase and hotel phase). This is achieved by recapturing wheel energy and energy from the engine when the wheel energy is insufficient to achieve the desired SOC during the drive phase. In the authors’ previous work, a dynamic programming (DP)–based framework is developed that employs a multi-objective cost function to minimize fuel consumption and maximize the regeneration to achieve the benchmark results for the SOC trajectories. This article discusses the real-time implementable control strategies for the heavy-duty truck’s hybrid powertrain, including the mode switch and EM torque for charging. The mode switch is a rule-based control strategy that responds to the wheel torque demand, while the EM torque’s control can have several approaches, such as rule-based, optimal charging strategies that are inspired by equivalent cost minimization strategy (ECMS), or adaptive strategy that updates the equivalent factor according to the battery SOC state. This work presents and studies the different choices to control the EM torque and their impact on vehicle performance and energy consumption. The complete cycle results are compared with the benchmark results, and the energy analysis is accomplished to validate the efficacy of the proposed real-time implementable optimal control strategies (i.e., rule-based and adaptive ECMS). The adaptive optimal control strategy is the potential candidate to be implemented on a real heavy-duty vehicle for optimal management of hotel loads, as it produces the SOC trajectory closer to the benchmark results within the error of ±1.25% while costing minimal fuel consumption. The fuel saving of 2.96% is achieved when compared to conventional heavy-duty trucks for each day of a typical highway trip and hotel phase for each heavy-duty truck, which is 18.2% higher than the rule-based control strategy.
Huang, Ying, Hanif, Athar, Ahmed, Qadeer
Infrastructure Design Criteria for Accommodating Hydrogen Electric Vertical and Takeoff Landing (H 2 eVTOL) Aircraft Technologies at VertiportsF-0081-2025-03865/20/2025
Hydrogen-electric vertical takeoff and landing (H2eVTOL) (or fuel cell-electric VTOL) aircraft technologies are poised to emerge in the next coming decades and start operating from existing heliports and new vertiports. This paper assesses how key H2eVTOL design features interact with the ground infrastructure and how facility designers can address H2eVTOL specific facility requirements–especially the supply of hydrogen to the aircraft. Vertiport design should maximize compatibility are important to facilitate the accommodation of hydrogen technologies, minimize the need for extensive capital investments, and promote safety and operational efficiency. Considerations should be given to factors such as general aircraft configuration, electric and hybrid propulsion systems, and refueling infrastructure. The definition of notional aircraft concepts representing the evolution of critical VTOL aircraft over the next coming decades can help aviation facility planners and designers understand the type of vehicles they need to account for and also evaluate the future hydrogen demand. The lack of aviation-specific standards, especially when it comes to fire prevention, might adversely impact vertiports. Strategies are proposed for mitigating the effects of hydrogen operations at space-constrained facilities.
Le Bris, Gaël, Nguyen, Loup-Giang
Optimization of HEV Vehicle’s Engine Modulated Noise2025-01-00845/5/2025
One 1.5L Miller-cycle turbocharged four cylinder gasoline hybrid engine is installed on a certain hybrid vehicle. When accelerating at low to medium speeds with a small throttle, there is a "da da" knocking noise inside the car, which seriously affects the overall sound quality of the vehicle. By analyzing the vibration and noise data of the engine, it was found that the frequency of the abnormal knocking sound is 200-2000Hz, which presents a half order characteristic in the time domain, that is, one knocking occurs when the engine crankshaft rotates twice. Through Hilbert demodulation analysis of the vibration data in the problem frequency range, it was found that the knocking noise was modulated in the frequency domain, with a modulation frequency of half of the crankshaft rotation frequency. By building a fully flexible multi-body dynamic model of a hybrid powertrain and inputting the engine's cylinder pressure excitation, the combustion excitation is coupled with mechanical vibration noise to simulate the surface vibration of the powertrain. Measures such as optimizing the cylinder pressure curve by adjusting spark angle and scavenging angle, and improving crankshaft stiffness by increasing the overlap between mainbearing diameter and connecting rod diameter, the sound quality issue of this hybrid model has been significantly improved under low speed and low throttle acceleration conditions.
Dan, Kong
Integrating for Safety – A Proposed Approach to the Integration of Propulsion Battery Systems in Hybrid Electric Aviation2025-01-01485/2/2025
The authors have witnessed a notable surge in the number of designs and in the guidance material for electric and hybrid aircraft. FAA and EASA have continued to evaluate the safety of Propulsion Battery Systems (PBS), with a focus on thermal runaway containment testing. As a result, a harmonization white paper [7] was issued to provide a certification path for Thermal Runaway (TR) Hazards, followed by an EASA certification memorandum on the acceptable approaches for the certification of Electric/Hybrid Propulsion Systems (EHPS). Recently, an FAA Advisory Circular (draft) was issued for the “powered-lift” aircraft that feature these propulsion battery systems. Despite the advances made by electric/hybrid aircraft manufacturers and the aviation authorities, there is still a missing piece of the puzzle. Mainly, engineering work still needs to be done to properly integrate the EHPS architecture to achieve safety objectives. The burden is still on systems engineering to propose their own methodology in absence of a standard that addresses the integration complexities of the EHPS. In our previous paper, we outlined an approach for the hazard analysis of the battery system, with an emphasis on TR hazards [1]. In this paper, we will build upon this approach by outlining a PSSA methodology that serves to validate the EHPS architecture by addressing the novelties and the integration complexities between the PBS, EHPS, and the aircraft. This approach is designed to evaluate the robustness of the EHPS in achieving the safety objectives, by detailing a customized requirements validation process. With this approach, we can ensure that a correct and complete set of safety requirements will be derived no matter the aircraft configuration. With this “designing for safety” approach, or in this case: “integrating for safety”, we can be assured a clear pathway to certification.
Hanna, Michael, Walker, Cherizar
High-Efficient and Cost-Effective Three-Way Catalyst Substrate Design for Plug-in Hybrid Electric Vehicle2025-01-85284/1/2025
China 6b regulation was fully implemented since July 2023 with very strict emission standards for HC, NMHC, NOx, and CO. The country is now also in the process of developing China 7 regulation, which will perhaps impose even stricter emission limits and extra criteria pollutants including NH3. Moreover, increasingly strict fuel consumption regulation has been implemented as well and it is highly possible that greenhouse gas emission limits will be included in the China 7 regulation. With the hybrid technology innovation, PHEVs are effective in fuel economy and emission reduction, which are favored by manufacturers and consumers, and leading to a rapid increase in market share. Through the optimization of hybrid architecture and the synergy of electric motors, the operating conditions of the hybrid engine have been optimized, making it more stable and avoiding extreme engine operating conditions compared to traditional ICE, which also provides possibilities for optimizing the after-treatment system design to achieve low cost and high efficiency at the same time. In this study, engine operating conditions and engine out emissions of a PHEV were analyzed through vehicle testing with WLTC cycle in lab. Emission tests were conducted using different catalyst systems to study the impact of different substrate design options including low mass Corning® FLORA® substrates with higher cell density on gaseous pollutant emissions. As a byproduct of secondary reactions on catalysts, the generation of NH3 is closely related to catalyst efficiency. This study also investigated the characteristics of NH3 emissions and proposed appropriate design to reduce NH3 emission. Additionally, the influence of thermal aging conditions on catalyst conversion efficiency was studied to explain the correlation between anti-ageing performance and the substrate design.
Wang, Jiming, Li, Chunbo, Feng, Xiangyu, Chen, Xiaolang, Boger, Thorsten, Tian, Lichen, Hu, Xianli, Zeng, Jun, Tian, Tian, Gao, Bojun, Li, Dacheng, Liu, Shicheng, Jiang, Fajun
Experimental Investigation of Hydrogen or Methane Injection in Active Pre-Chamber on a Lean Combustion Gasoline Engine2025-01-71061/31/2025
With the global promotion of carbon neutrality policies, internal combustion engine (ICE) of traditional fossil fuel is gradually transitioning to carbon neutral fuel ICE, and hybrid dedicated engines are gradually replacing traditional internal combustion engines in the passenger car market. Ultra-lean combustion supported by active pre-chamber is one of the key technologies for achieving high thermal efficient over 45% BTE. However, there are still issues like cold start and PN emissions caused by impingement of liquid fuel injection in pre-chamber, and there is still room for improvement in thermal efficiency by less energy of pilot ignition fuel. Gaseous fuel such as hydrogen or methane have no wetting issues, and can be more easily controlled in terms of the injection amount in pre-chamber, thereby using a less amount of gaseous fuel as the pilot ignition fuel could be a solution. Due to the above situation, this article conducted experiments on a lean burn gasoline engine by injecting hydrogen or methane instead of gasoline into the pre-chamber to ignite the gasoline in the main chamber, and investigate its performance, combustion and emissions. The results show that, there is a best value for both the equivalent calorific value substitution ratio of hydrogen or methane injection in pre-chamber and global lambda, which results in lowest fuel consumption. Due to the fact that hydrogen has a higher activity and none carbon molecule while methane has a lower activity and property of easily generating soot precursors through C1 radicals, the performance of hydrogen and methane injection in the pre-chamber is significantly different: Compared to gasoline injection in pre-chamber, hydrogen injection in pre-chamber can reduce ISFC and significantly decrease PN. Methane injection in pre-chamber increases ISFC and PN, the more retarded the SOI is, the higher the PN results. Hydrogen injection in pre-chamber can breaking through the limitation of ignition angle being too forward of traditional pre-chamber in cold start. This article provides data and solutions for the transition from fossil fuels to carbon neutral fuel step by step.
Liu, Yaodong, Liu, Mingli, He, Zhentao, Li, Xian, Zhao, Chuan, Qian, Dingchao, Qu, Hanshi, Li, Jincheng
Study of Soot Generation in Hybrid Engines during Cold Start and Low-Load Conditions Using an Optical Engine2025-01-70471/31/2025
As regulations regarding vehicle emissions and fuel consumption become increasingly stringent, the development of hybrid power systems is accelerating, primarily due to their benefits in fuel efficiency and reduction of pollutants. Hybrid engines are specially designed to operate optimally at mid to high speeds and loads. But for low-speed low-load conditions, due to the relatively low in-cylinder tumble intensity and lower injection pressure, the fuel-air mixture tends to deteriorate, resulting in an increase in particle number. To enable the engine to reach optimal RPM and load quickly during frequent start-stop cycles, hybrid engines typically set a higher startup engine speed and establish fuel rail pressure more quickly compared to traditional engines. Yet hybrid engines still encounter challenges of soot generation during cold start conditions. Especially in urban driving conditions where the hybrid engine frequently experiences startups and idling, the soot generation problem becomes severe. Understanding the soot generation process under these specific conditions is critical for hybrid engines. This research aims to investigate soot formation process during cold-start and low-speed low-load conditions by examining the in-cylinder spray development and combustion processes. To achieve this, an optical engine has been employed, designed with a combustion system indentical to that of a cutting-edge hybrid engine. Backlit imaging method was used to capture the movement of spray droplets, which provides a clear visualization of how the fuel interacts with the piston top and in-cylinder airflow. High-speed color photography was used to record the flame propagation process and the sooty flame development from the bottom of the combustion chamber. By focusing on these processes, this research finds that for low-speed low-load conditions, the combustion of fuel film, which generates pool fire, is the main source of carbon soot. While for cold-start conditions, combustion of rich pockets in the chamber space is the primary source of soot. Insights gained from this research could inform the design of more efficient hybrid engines that minimize soot emissions, ultimately contributing to cleaner air and more sustainable transportation solutions.
Liu, Changye, Man, Xingjia, Cui, Mingli, Liang, Yuanfei, Wang, Shangning, Li, Xuesong
Impact on FEAD Dynamic Performance of Mild Hybrid Engine with Increase in Engine Torque2024-28-020412/5/2024
Front End Accessory Drive (FEAD) systems are used in automobiles to transfer power from the engine-to-engine accessory components such as the alternator, water pump, etc. using a Belt and Tensioner. The emergence of Mild hybrid technologies has led to the replacement of alternator with Belt-driven Integrated Starter-generator (B-ISG). In conventional configuration of FEAD, the power transfer is in single direction but in mild hybrid engine power transfer is bidirectional: tight and slack side of the Belt changes as per Torque assist or Regeneration mode. The presence of an integrated starter-generator (ISG) in a belt transmission places excessive strain on the FEAD System and necessitates checking the dynamic performance of FEAD System thoroughly. Study of Increase in Engine Torque in existing Vehicle was done to understand its effect on various system. This vehicle is Mild Hybrid and consists of Belt-driven Integrated Starter generator system. Increase in Engine torque lead to increase in rotational fluctuation which directly impacts the FEAD System parameters such Belt slip, Belt Tension, etc. This paper presents the impact of increase in Engine Torque on dynamic performance of FEAD system through System performance test on Vehicle. System Performance test measures various parameters of Vehicle and FEAD System during different test patterns which are worst conditions for FEAD. These different Test patterns were identified based on ISG Modes (Assist, Generation and Regeneration) and various parameters such as Rotational fluctuation, ISG Torque, Battery SOC, etc. System performance Test result shows the Belt slip, Belt Tension and Tensioner behavior during ISG Modes (Assist, Generation & Regeneration). Measurement results were compared and analyzed, and it was judged that current FEAD design of the drive system meets the requirements of Engine with increased torque. Influence of increase in damping of Hydraulic Tensioner on FEAD performance parameter was also demonstrated. Approach followed for design verification in this paper have practical engineering significance for design and development of the FEAD System.
Kumar, Aditya, Gupta, Avinash, Bharti, Anil Kant
New 1.5-Liter Hybrid Engine Development with High Brake Thermal Efficiency2024-01-510711/29/2024
The hybrid engines produced by most original equipment manufacturers (OEMs) have been modified to fit within the framework of conventional engine designs. Recently, Geely has introduced a new 1.5-liter (1.5L) inline four-cylinder (I4) TGDI engine, specifically designed to meet the requirements of its innovative, efficient, and intelligent hybrid powertrain architecture. This engine achieves an impressive brake thermal efficiency (BTE) of 44%, as well as high specific torque at 153 Nm/L and high specific power at 67 kW/L. To attain this superior performance, the following technical strategies were implemented: a high compression ratio, the robust Miller cycle, an extended piston stroke-to-bore ratio, an intake port optimized for high tumble, cooled exhaust gas recirculation (EGR), and an advanced high-energy ignition system. Among these, the middle four strategies, in conjunction with piston cooling jets and enhanced exhaust-side cooling, all contribute to improved in-cylinder combustion. This, in turn, effectively mitigates the potential for severe knock and pre-ignition issues that can arise from the high compression ratio. Moreover, reducing friction is a key factor in achieving the 44% BTE. When integrated into Geely’s plug-in hybrid system, this new engine results in a 5.1% decrease in fuel consumption under charge-sustaining conditions, as measured in the WLTC cycle, when compared to the previous-generation engine.
Li, Qiang, Liu, Yang, Zhang, Peiyi, Yan, Pingtao, Li, Hongzhou, Zhu, Yunfeng, Ji, Yan, Li, Minggui, Cui, Boyue
Dynamics of a Variable Speed Hybrid-Electric Helicopter Propulsion SystemF-0080-2024-12525/7/2024
In this paper, a comprehensive dynamic simulation of a parallel hybrid gas-electric single main rotor helicopter involving a motor/generator (MG) pair and a differential planetary gear transmission (PGT) arrangement forming an electronic continuously variable transmission (E-CVT) was performed. This notional hybrid electric helicopter was sized based on a retrofit of a dual engine, 10000 lb, 2500 Hp class helicopter. The total weight added by the electric components was 182 lbs which increased the propulsion system weight from 1184 to 1366 lbs. The simulation results found that at 110 kts cruise, the hybrid electric system enabled a 27% reduction in main rotor rpm which resulted in an 18% reduction in the fuel burn rate. It is concluded that use of an E-CVT parallel hybrid propulsion system offers potential for increased flight range and reduced fuel consumption in medium to large-scale helicopter applications.
DeSmidt, Hans, Ai, Zhisheng
Combustion Development and Efficiency Improvement for Hybrid Engines2024-01-20934/9/2024
In the pursuit of carbon emission reduction, hybridization has emerged as a significant trend in powertrain electrification. As a crucial aspect of hybrid powertrain system development, achieving high brake thermal efficiency (BTE) and a wide operating range with high efficiency are essential for hybrid engines to effectively integrate with the hybrid system. When developing dedicated hybrid engines (DHE), several design considerations come into play. First, in order to make efficient use of available resources and enable engine production on the same assembly line as conventional engines, it is crucial to maintain consistency in key design parameters of the cylinder head and block, thus extending the platform-based design approach. Among the key measures to achieve high BTE, cooled exhaust gas recirculation (EGR) has been extensively explored and proven effective in improving efficiency by mitigating knocking and reducing engine cooling heat loss. Fast combustion, acting as a facilitator, becomes crucial for the system to handle high EGR rates. Therefore, a high-tumble combustion system design is required as an integral part of the hybrid engine to promote rapid combustion. Optimizing the gas exchange system is another crucial aspect in achieving high brake thermal efficiency. Investigation results indicate that through system optimization and trade-offs, optimal matches can be found among EGR rate, cam duration, and compression ratio for a hybrid engine. Furthermore, by optimizing energy management strategy with the hybrid system, the engine operates under high-efficiency regions for the majority of the WLTC test cycle, resulting in reduced fuel consumption. This paper describes the evolution of combustion system design from conventional engines to DHE at SAIC Motor, and presents investigations into the impact of key technical measures on brake thermal efficiency. It also explores the optimization of energy management strategies and their effect on engine operating conditions and fuel consumption of the hybrid vehicle in the WLTC cycle.
Xu, Zheng, Qiu, Jie, Zhang, ZiQing, Cheng, Chuanhui, Zhang, YaJun, Yang, Yang, Wang, Yingzhen, Lu, Yuan, Zhou, Zhou, Li, XiaoYang
Thermal Management Development for a Dedicated Hybrid Engine2024-01-24164/9/2024
The high-efficiency dedicated hybrid engine (DHE) has led to increasingly complex challenges in engine thermal management. On one hand, the high compression ratio of up to 16:1 makes the engine more susceptible to knocking, necessitating meticulous thermal management to mitigate the potential sensitivity to metal temperature. On the other hand, extensive use of external cooled exhaust gas recirculation (EGR) helps reduce knocking and improve thermal efficiency, but it also raises temperature levels and requires additional cooling measures. For the 1.5L DHE developed by SAIC Motor, a split cooling structure was employed in the engine cooling system design, with the cylinder head water jacket and cylinder block water jacket arranged in parallel and equipped with different coolant outlets. By utilizing a dual thermostat to control flow, this design allows for adjustable flow distribution, providing effective cooling to the cylinder head while reducing cooling to the cylinder block. The block thermostat can close the flow of the block water jacket before the water temperature reaches the opening temperature, enabling quick warming of the cylinder block. Furthermore, an electric water pump was employed as an ideal solution for the DHE, eliminating the need for a front-end drive system. This helps reduce parasitic losses due to accessories and improve overall efficiency. As the primary driving source for coolant in the entire cooling system, the electronic water pump plays a crucial role in the overall thermal management system. Specialized control strategies and software have been developed to optimize its performance. This paper presents the development of thermal management, including cooling system design and simulations, as well as test development. It also elaborates on the control strategy development for the electric water pump, which meets the requirements of the engine and vehicle under various environmental and operating conditions.
Xu, Zheng, Xia, QiWei, Peng, Chao, wang, YanJun
Aspects of Engine Lubricant Operating Conditions and Fuel Economy Differentiation; In-Vehicle Comparisons of Standard Internal Combustion Engine with Two Types of Hybrid Electric2024-01-28244/9/2024
Due to the global drive for carbon neutrality, passenger vehicle gasoline engines are transitioning to higher levels of electrification, such as hybrid electric vehicles and plug-in hybrid electric vehicles, HEVs and PHEVs. Compared with conventional internal combustion engine (ICE) vehicles, the HEV or PHEV engine whilst in ICE only operation, typically operates for multiple shorter periods, in turn the engine coolant and lubricant temperatures are lower. Conventional internal combustion engines are often able to yield valuable fuel economy benefits by selecting appropriate engine lubricating oils, typically employing reduced viscosity and suitable additives. There are commercial engine tests available for measurement, often in an engine test cell for precision. Steady state testing is also a simplified option. Such efforts require care, as the accurate measurement is technically and practically challenging. This level of difficulty is again increased by the further complication of vehicle hybridisation, aspects of which are discussed. However, this paper presents comparison data of similar engine technology in different vehicle types, namely ICE and two different types of HEV, with different engine operation strategies, to show an effect on lubricant differentiation for fuel economy. Possible explanations of the results are discussed. Based on field observations, an often highly loaded area of the gasoline direct injection (GDI) ICE is the high-pressure (HP) fuel pump with oil lubricated cam and follower. This often presents a challenge for the engine lubricant. A novel test rig is described, which measures GDI HP fuel pump friction accurately. Further comparison data showing the contribution of this to the engine friction is presented over the transient Worldwide Harmonized Light Duty Transient cycle, WLTC, for both ICE and HEV operation in charge sustaining mode; lubricant friction differentiation in this area is shown. The choice of a relevant drive cycle is important for developing new and existing lubricant products. The range of engine operation strategies controlled by both the vehicle and the driver is much wider for hybrid engines, when compared with standard ICE vehicles. To illustrate aspects of this, some recent on road PHEV data is also presented.
Butcher, Richard, Bradley, Nathan, Jamieson, Matthew, Chambers, Thomas
Simulation Investigation of Turbulent Jet Ignition (TJI) Combustion in a Dedicated Hybrid Engine under Stoichiometric Condition2024-01-21114/9/2024
Turbulent jet ignition (TJI) combustion using pre-chamber ignition can accelerate the combustion speed in the cylinder and has garnered growing interest in recent years. However, it is complicated for the optimization of the pre-chamber structure and combustion system. This study investigated the effects of the pre-chamber structure and the intake ports on the combustion characteristics of a gasoline engine through CFD simulation. Spark ignition (SI) combustion simulation was also conducted for comparison. The results showed that the design of the pre-chamber that causes the jet flame colliding with walls severely worsen the combustion, increasing the knocking intendency, and decrease the thermal efficiency. Compared with SI combustion mode, the TJI combustion mode has the higher heat transfer loss and lower unburned loss. The well-optimized pre-chamber can accelerate the flame propagation with knock suppression. Strong-tumble flow distorts the jet flame propagation, which is not conducive to the development of combustion process. The TJI combustion mode combined with the new designed tumble-swirl intake port can increase the ITE by 0.7 % compared to SI combustion mode under condition of n = 3000 r/min and IMEP ≈ 1.0 MPa.
Liu, Shang, Lin, Zhelong, Qi, Yunliang, Lu, Guoxiang, Wang, Bo, Liu, Yang, Wang, Zhi
High-Precision Modeling and Online Validation of a 200kW-Class Series Hybrid Power System in Aviation2023-01-709712/31/2023
Taking into account the high rotor speed of the generator and the trend of high voltage in direct current microgrids in high-power aviation hybrid propulsion systems, a hybrid power system with a power of 200 kilowatts (kW), a voltage of 540 volts (V), and a rated generator speed of 10500 r/min was established. Anticipating the demands of future high-power system tests, a matching simulation model was developed. The paper discusses various aspects including model construction, test design, and result validation, proposing an overall control strategy for series hybrid aviation propulsion systems – utilizing lithium-ion batteries to stabilize grid voltage and using the turboshaft-generator unit as the primary power source to meet the main power demands of the electric propulsion system. The established model consists of four modules: turboshaft engine, power generator, voltage-stabilizing battery, and electric motor/propeller. These modules are independently controlled and are unified into a microgrid through a direct current bus. In the designed cases, the simulation data including generator speed, gas turbine speed, grid voltage, and component power were compared and analyzed against experimental data. The results indicate that both steady-state and dynamic errors of the simulation are controlled within 10%. This implies that the constructed simulation model accurately replicates the operational state of the 200 kW-level series hybrid aviation propulsion system. It serves as a pre-research platform for testing system control strategies and developing new control algorithms. Finally, the feasibility of a strategy to appropriately increase the power of the turboshaft-generator set and maintain battery output power fluctuations within 0 kW was validated within the simulation system, providing a reference for future experiments.
Diao, Bo, Li, Po, Zhu, Jianfeng, Huang, Guochen, She, Yunfeng, Xing, Yaoren
Simulation Study on High Expansion Ratio Dedicated Hybrid Engine for Hybrid Commercial Vehicle Application2023-01-700510/30/2023
The fuel economy and emission of the hybrid vehicle depend largely on the selected engine. And the dedicated hybrid engine (DHE) can be controlled to operate in the optimal operating range because DHE can be decoupled from the vehicle transmission system. The main purpose of this paper is to improve the thermal efficiency of the diesel engine under common operating conditions combined with high compression ratio (CR) and early or late intake valve closing (IVC) angle. According to the vehicle road spectrum data, the optimal operating range of the engine is determined to be 1200-1400 rpm and 70%-90% load. Then CR and IVC angle are optimized by using the calibrated one-dimensional thermodynamic model of the engine under limited peak combustion pressure (Pmax). The results show that the adjustment of IVC angle and CR can control the thermal state at the end of compression stroke. The combination of CR and IVC angle can achieve the optimal fuel consumption improvement. The minimum brake special fuel consumption (BSFC) is reduced from 189.2 g/kWh to 184 g/kWh. Based on the thermal process analysis of internal combustion engines, the effects of CR, IVC, and boost pressure on engine performance are analyzed. The improvement of thermal efficiency caused by higher CR would be compensated by the decrease of combustion constant degree. What is more, early or late IVC angle can reduce combustion phase loss and gas exchange loss. Further, a more efficient turbocharger can be matched to achieve higher thermal efficiency.
Wang, Xiaosa, Lin, Zhiqiang, Wang, Hu, He, Hua, Wang, Xiaohui, Liang, Depu
An Experimental Study on Soot Particles Size Distribution and Nanostructure Evolution at Different Tailpipe Positions of a Dedicated Hybrid Engine2023-01-700310/30/2023
Hybrid vehicles, compared to pure fossil fuel vehicles, have added power battery pack, high-power electric motors. The space of the aftertreatment is limited, so the layout position of the aftertreatment system must be optimized. Meanwhile, the European 7 emission standard reduces the particulate number (PN) limit particles size from 23nm to 10nm, presenting new challenges for the aftertreatment system. The focus of this study is to investigate the variations in particles size distribution and nanostructure of soot particles during the exhaust along a dedicated hybrid engine aftertreatment system (catalyst carrier free). Four operating conditions were selected for the test, namely 2000 r/min-0.2 MPa, 2000 r/min-0.8 MPa, 4500 r/min-0.2 MPa, and 4500 r/min-0.8 MPa. The particles sampling points are before Three-way catalyst (TWC), after TWC, and after gasoline particulate filter (GPF). Engine Exhaust Particle Sizer (EEPS) was used to analyze the changes in particle modal distribution, transmission electron microscope (TEM) was used to analyze the nanostructure of particles, and Raman spectroscopy was used to analyze the degree of nanostructure order. The results show that with the exhaust transport, the total PN decreased by an average of about 64.4% under each operating condition. Taking the 4500 r/min-0.8 MPa as an example, the proportion of nucleation mode particles decreased from sampling points 1 to 3, the proportion of accumulation mode increased, the average diameter of primary particle increased by 20.3%, the fringe separation distance increased by 2.3%, the fringe tortuosity increased by 2.6%, the fringe length decreased by 2.6%, the fractal dimension increased by 11.2%, the degree of disorder of particles increased.
Fu, Jiale, Hu, Zhiyuan, Fang, Liang, Lou, Diming, Tan, Piqiang, Yin, Qi
Hybrid Operation Characteristics and Their Impact on Engine Oil Requirements2023-32-01729/29/2023
With the increasing regulatory stringency on emission reduction and efficiency improvement, the automotive industry has experienced a significant shift in the hardware platform. Among technology candidates, hybrid technology is still considered one of the most viable approaches to meet the regulation requirement (both emission and efficiency) at an affordable cost to both the customer and the manufacturer. New engine operating characteristics are expected in hybrid applications which would potentially result in different performance requirements for the engine oil. Therefore, it is crucial to understand those characteristics of a hybrid powertrain, from which the insights of fluid requirements can be derived. A hybrid vehicle test study was conducted to evaluate the engine operation of different kinds of hybrid platforms. The hybrid operation has been well characterized by thoroughly analyzing parameters on each engine. The temperature profile from each hybrid powertrain was evaluated and used to illustrate the impact of the driving cycle on fluid properties. It was found that the driving cycle is a very effective tool to deepen technical understanding of the interactive operation between the internal combustion (IC) engine and electric motor in a hybrid powertrain. This interactive operation will ultimately determine the engine performance and fluid working environment. Based on the acquired knowledge and insights from the vehicle testing, a controlled engine study was conducted to understand the impact of different operating parameters on fuel and water dilution under various engine operating conditions. Oil analysis results indicate that oil samples generated from the engine tests contain a wide range of water and fuel dilution levels, representative of the oil samples found in a real-world application. In addition, performance testing conducted on the oil samples provided greater understanding of hybrid engine operation on fluid performance requirements.
Garelick, Kenneth, Shao, Huifang, Hidetaka, Hoshino, Li, Yanfei, Shuai, Shijin
2024 Toyota Land Cruiser returning to its roots23AUTP09_139/1/2023
After three years away from the U.S. market with its range-topping SUV, the Land Cruiser, Toyota unveiled the redesigned 2024 Land Cruiser in Salt Lake City on Aug. 1. The model, long known around the world for its durability and offroad credentials, arrives with the SUV competition hotter than ever. The company said the new model will start at around $55,000. The new Land Cruiser has just one engine option, the i-Force Max turbo 2.4-L four-cylinder hybrid that generates 326 hp and 465 lb-ft (630 Nm) that is routed through an 8-speed automatic transmission. All models are equipped with what Toyota classifies as a “full-time four-wheel-drive system” with a lockable center differential and an electronically controlled 2-speed transfer case to impart high- and low-range capability. Also standard is a lockable rear differential to apportion power in a 50/50 ratio across the rear axle.
Clonts, Chris
Modeling and Experimental Validation of a Hybrid Electric Propulsion System for Naval Applications2023-24-01318/28/2023
Focusing on coastal or inland navigation cities, where emissions from ships are not negligible concerning global ones, the possibility of reducing exhaust gas pollution would have more benefits for public health and air quality. Therefore, in recent years, increasing attention on environmental sustainability is driving the shipbuilding industry towards greener propulsion based on full-electric or hybrid-electric propulsion systems. This work is presented a parallel hybrid system composed of two electric motors, one internal combustion engine, and lithium battery storage. All motors are coupled to the propeller through a specially designed transmission system based on the High Sliding Gear theory (HSG). The hybrid-electric propulsion system is designed to extender the battery pack durability, ensuring a smooth profile of the required current, through the complementary action of the batteries and the internal combustion engine. Then, the overall performance of the hybrid propulsion system is verified by laboratory experimentations, also testing the energy storage system. A fast boat (yacht) is chosen as a simulation case where a lumped parameters model is coupled with map-based motors obtained from experimental test activities performed on this hybrid propulsion system. This model is also validated by the available performance data obtained during an experimental campaign where has been emulated a typical propeller load. The results show the feasibility of this hybrid architecture, in terms of performance and sustainable maritime transport. Furthermore, the simulation results confirm the experimental performance, proving to be a good tool for system development in terms of energy management.
Marialto, Renato, Brando, Gianluca, Dannier, Adolfo, Sementa, Paolo, Cardone, Massimo, Fornaro, Enrico
An MPC-Based Strategy for Managing Energy in Hybrid Powertrains of Fast Boats2023-24-00258/28/2023
In the shipbuilding industry, the employment of hybrid propulsion systems is increasingly common on-board vessels for making more eco-sustainable boat traffic in marine waters. Energy management systems are required to ensure the culling of fuel consumption and the preservation of batteries by monitoring their state of charge in hybrid powertrains, coupled with the possibility of performing the sea path desired by a driver unit. A Model Predictive Control (MPC) supervisor is proposed in the present work for managing a marine parallel-hybrid propulsion system in terms of handling the state of charge of batteries and the driving cycle imposed by the boat driver. Specifically, the MPC is employed to avoid excessive electric energy consumption observable as a reduced loss in terms of the state of charge of batteries by selecting the best amount of command torques related to two electric motors and one internal combustion engine of the considered powertrain. A lumped parameters model of a fast boat coupled with map-based motors belonging to the considered hybrid propulsion system is employed for making tests functional to evaluate the performance of the proposed supervisor based on an MPC in terms of energy management capabilities. The proposed approach can be employed for preliminary design purposes of hybrid propulsion systems for naval applications. Specifically, two propulsors featured by different hybridization factors are compared, demonstrating the possibility of recharging batteries only for a lower hybridization factor based on the chosen waterway. The low computational load related to the proposed MPC demonstrates its suitability to manage naval hybrid propulsion systems in real-time. Therefore, this type of supervisor can be included in electronic control units of fast boats.
Tordela, Ciro, Fornaro, Enrico
Energy Management System of Fuel Cell Electric Vehicles Based on Stochastic Model Predictive Control and Markov Chains2023-24-00248/28/2023
In the mobility industry, Fuel Cell Electric Vehicle (FCEV) combines fuel cell technology with batteries, allowing to overcome some limitations of Battery Electric Vehicles (BEVs), such as the high recharging time and the high battery mass for applications requiring a high amount of energy (e.g., bus and heavy-duty vehicles). FCEVs have the possibility to collect several information from Intelligent Transportation Systems (ITSs) with relevant potential for vehicle efficiency improvement. Indeed, an online vehicle speed prediction inherently considering real-life factors such as traffic flow, driving path and driving style, allows for novel designs of Energy Management Systems (EMSs) for the optimal operations of the hybrid propulsion system. In such context, this paper proposes an EMS based on Stochastic Model Predictive Control with Learning (SMPCL) to optimize the hydrogen consumption of a Fuel Cell Electric Vehicle (FCEV), while guaranteeing the fulfillment of constraints on battery state of charge (SOC) and available power ranges, as well as maximizing the lifetime of fuel cell and battery. The proposed approach combines a scenario-based Stochastic Model Predictive Control (SMPC) for the propulsion system optimization with novel fuzzy Markov Chains (MCs) for short-term vehicle speed prediction. The effectiveness of this approach has been evaluated considering real driving speed acquisitions of a city bus operating in Turin (Italy) in different traffic flows and with different drivers. For comparison, several algorithms have been applied to a high-fidelity simulation plant representative of the FCEV propulsion system developed in GT-SUITE. The results show that SMPCL allows for relevant reduction of hydrogen consumption compared to classic rule-based approach, while getting also important benefits in terms of fuel cell and battery lifetimes. Moreover, hydrogen consumption is very close to the results of a global offline optimization algorithm used as benchmark (i.e., Dynamic Programming). Finally, next steps will include experimental validation of proposed approach on a real propulsion system in a test bench located in Turin (Italy).
Alfieri, Vincenzo, Binetti, Giulio, Ruotolo, Romualdo, Gandino, Edoardo
An Energy Management Strategy for Aeronautical Hybrid Propulsion Systems Based on an MPC Supervisor2023-24-00268/28/2023
In the last decades, the requirement related to the reduction of energy waste has been focused on the aeronautical field for decreasing CO2 emissions in propulsion systems, coupled with the possibility of improving their ecological sustainability. Performance of hybrid electric aircraft are affected by the sizes and weights of propulsion systems typically constituted of internal combustion engines and electric motors. Therefore, the correct design of propulsive architectures is fundamental to ensure a desired state of charge target level of batteries compliant with the flight plan provided by a driver unit. A Linear Time Variant Model Predictive Control (LTV-MPC) strategy for energy management purposes of an aeronautical hybrid powertrain is proposed in the present work. The MPC, designed as a supervisor, provides the best trade-off between command torques of motors belonging to a parallel-hybrid propulsion system to guarantee the final state of charge as close as possible to the initial one. Furthermore, the MPC ensures the following of the target flight plan, typically called mission, imposed by the driver. A lumped parameters dynamical model of an 8-seat aircraft is presented for testing the capability of the proposed LTV-MPC to manage a hybrid powertrain composed of an internal combustion engine and an electric motor described by maps. The proposed LTV-MPC supervisor is suitable to be employed in the aeronautical field to handle, in real-time, hybrid propulsion systems thanks to its reduced computational effort coupled with its capability to reduce CO2 emissions.
Fornaro, Enrico, Tordela, Ciro
Analyzing the Usage of Wankel Engine Technology in Future Automotive Powertrains13-05-02-00098/4/2023
The Wankel engine is an eccentric rotary internal combustion engine known for its simplicity, compactness, reliability, and efficiency. However, issues related to sealing, efficiency, and emissions have hindered its widespread use. Recent advancements in sealing technology, novel designs, material coatings, and alternative fuels have addressed some of these problems, leading to improvements in Wankel engine performance. This study examines these advancements in Wankel engine technology and proposes three potential applications for future automotive use. The first application involves utilizing a Wankel engine with a continuously variable transmission to replace the powertrain in conventional vehicles. The second application suggests replacing the engine in a series-parallel electric-hybrid architecture with a Wankel engine. Lastly, the third application explores using a Wankel engine as a range extender for electric vehicles. To evaluate the benefits in terms of fuel consumption for different drive cycles, each of these applications was modeled using the Future Automotive System Technology Simulator (FASTSim). The models were assessed with both standard Wankel engines and those incorporating recent advancements. The results indicate a potential reduction in fuel consumption when utilizing improved Wankel engine designs compared to traditional piston-based engines. However, it should be noted that these improved Wankel engines still face significant challenges regarding hydrocarbon emissions. Furthermore, the study identified a promising application for Wankel engines as range extenders in electric vehicles, suggesting their potential to enhance the overall efficiency of electric transportation.
Mittal, Vikram, Shah, Rajesh, Przyborowski, Alexandra
Combined Physical and ANN-Based Engine Model of a Turbo-Charged DI Gasoline Engine with Variable Valve Timing2023-01-01944/11/2023
High-efficient simulations are mandatory to manage the ever-increasing complexity of automotive powertrain system and reduce development time and costs. Integrating AI methods into the development process provides an ideal solution thanks to massive increase in computational power. Based on an 1D physical engine model of a turbo-charged direct injection gasoline engine with variable valve timing (VVT), a high-performance hybrid simulation model has been developed for increasing computing performance. The newly developed model is made of a physics-based low-pressure part including intake and exhaust peripheries and a neural-network-based high-pressure part for combustion chamber calculations. For the training and validation of the combustion chamber neural networks, a data set with 10.5 million operating points was generated in a short time thanks to the parallelizable combustion chamber simulations in stand-alone mode. The data set covers wide variation ranges of boundary and operating conditions in the combustion chamber including variable valve timings. A special neural network structure was configurated, which consists of five interconnected gated recurrent unit (GRU) sub-networks for calculating mass fuel burned, pressure values, the peak pressure position, NO emissions as well as knock condition. To form a whole working cycle simulation within GT-SUITE, the neural networks were converted into a functional mock-up unit (FMU), which is connected with the physics-based low-pressure part through FKFS RapidCylinder®. A performance evaluation of the hybrid engine model shows that, the mean deviations of brake torque, MFB50 and NO emissions compared to the physics-based reference mode are respectively 0.529%, 0.048°CA and 32.67ppm over the whole engine characteristic map, indicating an equal calculation quality. While maintaining the calculation accuracy, the neural networks with FMU connections realize a combustion chamber calculation 5- to 10-fold faster than real-time and an acceleration of the whole engine calculation of up to 80% compared to the completely physics-based simulation.
Wei, Jingsi, Liu, Mingjia, Angerbauer, Michael, Yang, Qirui, Xu, Hanjun, Grill, Michael, Kulzer, André, Chen, Ceyuan
Increasing Engine Efficiency with Hydrogen Assisted Lean Burn Operation on a Small Bore, Long Stroke DISI Engine2023-01-02464/11/2023
Internal combustion engines fall under increased environmental and social pressure. However, they will still play an important role in future transport, especially in hybrid propulsion systems. As a consequence, efficiency of SI engines has to be further increased. Lean burn operation provides a promising way to reach this target. An extremely downsized SI single cylinder research engine is used for the investigations. The engine features a stroke-to-bore ratio of 1.5, leading to higher piston speeds and hence increased tumble motion. The resulting increase in turbulent flame speed supports sufficient combustion performance of diluted mixtures. Although the mentioned provisions increase combustion stability for lean burn operation the reachable relative air/fuel ratio is limited. In order to extend the lean burn capabilities of the engine (λ ≥ 2.0) and further exploit the efficiency advantages of this combustion process the engine is upgraded with a hydrogen port fuel injection. With its high laminar flame speeds and low demanded ignition energy, hydrogen acts as a good combustion enhancer in order to achieve the aforementioned targets. The conducted measurements show that small amounts of hydrogen are sufficient to reach relative air/fuel ratios of λ ≥ 2.0 for all investigated operating points. The increase in lean burn operation is accompanied by an increase of the indicated efficiency. The investigations reveal furthermore that efficiency does not peak with the highest reachable relative air/fuel ratio. This results in the highest achieved indicated efficiency of ηi = 45.6% at a relative air/fuel ratio of λ = 1.9.
Wenz, Erich, Eilts, Peter
Q&A23TOFHP04_174/1/2023
As part of its path to carbon neutrality, Kubota Engine engineers have developed a new 3.8-liter hydrogen engine that was introduced at CONEXPO 2023 in Las Vegas. The 4-cylinder spark-ignited engine employs port fuel-injection and provides 85 kW (114 hp), which is the output required for a 45-kVA generator, the company notes. Kotaro Shiozaki, PR manager, Industrial Engine at Kubota Corp., said that hybrid powertrains also are an effective solution for reducing CO2 from industrial engines, and he's confident they will be more than just an interim solution. Kubota displayed three hybrid solutions: a P0 micro-hybrid that will be available later this year, a P1 hybrid that provides brief periods of motor assist when high output is required and a P2 hybrid engine scheduled for production in 2025 that offers electric-motor drive.
Gehm, Ryan
ENGINE OIL PUMP PERFORMANCE AND DURABILITY TEST PROCEDURESUSCAR46 (Current)3/23/2023
SAE/USCAR-46 defines test methods and outputs for engine oil pump bench testing. Performance and durability testing are the primary focus of this standard. This is written to specifically address testing of electronically controlled variable displacement pumps but can be adapted to mechanically controlled pumps and other pump technologies as needed. This standard outlines critical inputs and outputs in order to perform the testing and report results, but does not specifically set the acceptance standards or pass/fail criteria. Acceptance criteria must be set by the customer.
USCAR
A Coupling Architecture for Remotely Validating Powertrain Assemblies14-12-02-00153/15/2023
Among the myriad of potential hybrid powertrain architectures, selecting the optimal for an application is a daunting task. Whenever available, computer models greatly assist in it. However, some aspects, such as pollutant emissions, are difficult to model, leaving no other option than to test. Validating plausible options before building the powertrain prototype has the potential of accelerating the vehicle development even more, doing so without shipping components around the world. This work concerns the design of a system to virtually couple—that is, avoiding physical contact—geographically distant test rigs in order to evaluate the components of a powertrain. In the past, methods have been attempted, either with or without assistance of mathematical models of the coupled components (observers). Existing methods are accurate only when the dynamics of the systems to couple are slow in relation to the communication delay. Also, existing methods seem to overlook the implications of operating a distributed system without a common time frame. In order to overcome the inherent latency arising from long-range communication, the proposed design combines two features: The exploitation of synchronized clocks for the simultaneous introduction of setpoint commands and the use of observers generated through machine learning algorithms. This novel design is subsequently tested in two scenarios: A simple one, involving the virtual coupling of two parts of an elementary device formed by three rotating inertias, and a more complex one, the coupling between an internal combustion engine and an electric motor/generator as representative of a series or parallel hybrid powertrain. Although the results are heavily influenced by the quality of the data-generated observers, the architecture improves the fidelity of the coupling by nearly an order of magnitude compared to the alternative of directly transmitting the signals. It also opens a niche application that leverages the accuracy of low-fidelity models.
Ametller, Adria, Brace, Chris
Electric Hybrid Propulsion SystemTBMG-474972/1/2023
Allison Transmission Indianapolis, IN 317-242-5000
Development of A 1.5L High-Efficiency and High-Specific-Power Hybrid Engine2022-01-706210/28/2022
Although the brake thermal efficiency of the state-of-the-art Atkinson-cycle hybrid engines have reached 41%, such engines typically have a low specific power. The ideal hybrid engines for SUVs should have a high thermal efficiency as well as a high specific power. Jiangling Motors recently developed a 4-cylinder, 1.5L TGDI hybrid Miller engine for powering mid-size SUVs, which has achieved 42% brake thermal efficiency, 19.3-bar BMEP, and 73.3-kW/L specific power. The engine has a high compression ratio, a long stroke, and is equipped with a low-pressure EGR system. It can operate with the stoichiometric mixture on the full engine map, with the help of the water-cooled exhaust manifold and the intelligent thermal management system.
Liu, Yong, Liao, Shanbin, Zheng, Yuewei, Chen, Bin, Miao, Ruigang, Zeng, Cuiwei, Ouyang, Xianlin, Cai, Xingqi, Yang, Yanhua, Zeng, Honglian, Cao, Liming, Teng, Ho
Hybrid Propulsion SystemsTBMG-4677810/1/2022
Benchmark Space Systems Burlington, VT 678-576-6126
Realistic Steady State Performance of an Electric Turbo-Compound Engine for Hybrid Propulsion System2022-24-00159/16/2022
The efficiency of Hybrid Electric Vehicles (HEVs) may be substantially increased if the unexpanded exhaust gas energy is efficiently recovered and employed for vehicle propulsion. This can be accomplished employing a properly designed exhaust gas turbine connected to a suitable generator whose output electric energy is stored in the vehicle storage system; a new hybrid propulsion system is hence delineated, where the power delivered by the main engine is combined to the power produced by the exhaust gas turbo-generator: previous studies, carried out under some simplifying assumptions, showed potential vehicle efficiency increments up to 15% with respect to a traditional turbocharged engine. Given the power target of the required exhaust gas turbo-generator, no commercial or reference product could be considered: on account of this, in the preliminary evaluations, the turbine efficiency was assumed constant. In this paper instead the authors present the result of new evaluations performed by adequately considering the real efficiency of the exhaust gas turbine, which was designed and calculated by means of simple yet effective 1D approach, and validated by means of 3D CFD analysis. The 1D design and evaluation methodology, characterized by short calculation time, revealed sufficiently accurate compared to the result obtained by the time-consuming CFD simulations; the exhaust gas turbine efficiency was hence calculated for each required operating condition and used to compute the expected real efficiency of the compound engine; as a final result, it was found that, compared to a traditional turbocharged engine of the same rated power (73.5 kW), the realistic compound engine exhibit efficiency increments between 5% and 15%, depending on the output power.
Pipitone, Emiliano, Caltabellotta, Salvatore, Beccari, Stefano, Lanzafame, Rosario, Mauro, Stefano, Brusca, Sebastian
Freevalve: Control and Optimization of Fully Variable Valvetrain-Enabled Combustion Strategies for High Performance Engines2022-01-10668/30/2022
With ever stricter legislative requirements for CO2 and other exhaust emissions, significant efforts by OEMs have launched a number of different technological strategies to meet these challenges such as Battery Electric Vehicles (BEVs). However, a multiple technology approach is needed to deliver a broad portfolio of products as battery costs and supply constraints are considerable concerns hindering mass uptake of BEVs. Therefore, further investment in Internal Combustion (IC) engine technologies to meet these targets are being considered, such as lean burn gasoline technologies alongside other high efficiency concepts such as dedicated hybrid engines. Hence, it becomes of sound reason to further embrace diversity and develop complementary technologies to assist in the transition to the next generation hybrid powertrain. One such approach is to provide increased valvetrain flexibility to afford new degrees of freedom in engine operating strategies. Freevalve is an electro-hydraulic-pneumatic valve actuation system enabling independent control of IC engine valves, conceptualized by Koenigsegg’s Freevalve AB. Developed primarily in line with increasingly strict emissions legislations over the past two decades, the cam-less engine technology has demonstrated significant potential, offering 20% decreased fuel consumption and 60% less cold start emissions on an average drive cycle. Adopting a software-based, data-driven, statistical approach, this paper provides a review of the most recent valve operating strategies enabled by the Fully Variable Valvetrain (FVVT) engine technology. It provides a case study for peak performance using the “Ultra Boost for Economy” (Ultraboost) project’s engine as a state-of-the-art advanced valvetrain control benchmark. The One-Dimensional physics-based models are created in GT-Suite to comparatively demonstrate potential benefits of Freevalve compared to industry-standard common camshaft technologies. In addition to mitigating arising environmental concerns, preliminary findings have demonstrated that new degrees-of-freedom enabled by the FVVT IC engine technology, Freevalve, present significant potential to improve the full load curve of performance-focused engines, particularly at the low-medium engine speed range.
Elmagdoub, Abdelrahman Waleed Mohamed, Möller, Andreas, Carlson, Urban, Brace, Chris, Akehurst, Sam, Turner, James, Zhang, Nic
Architecture Examples for Electrified Propulsion AircraftAIR8678 (Current)8/1/2022
The application of electric power for aircraft propulsion can take a variety of forms, ranging from partial electric to full electric. The introduction of electric engines to drive propulsors, along with the variety of available methods to generate electricity and store energy offers great degree of new design freedom for next-generation aircraft and aircraft architectures. This newfound design freedom exposes a need within the aviation industry to establish a common design language for electrified propulsion. While this need for a common design language is recognized, the intent of this document is to encourage innovation, providing reference architectures as a launching point for future work in this area. This document will describe potential electrified propulsion architectures and provide examples. While providing these example architectures, this document will develop common definitions for the elements of the architectures by defining: 1 The elements of electrified propulsion architectures, including any dedicated power generation and distribution systems as well as energy storage elements. 2 The interfaces to/from the electrified propulsion system. 3 The interfaces within the electrified propulsion system. 4 Electrical energy management and storage architecture of an electrified propulsion system. While capturing these architectures and elements, this document will serve as a reference point for future works of SAE and provide aerospace industry guidance. It is recognized that the high power density associated with electrified propulsion will require an advanced thermal management system (TMS). It is expected that, in practice, there will be a great degree of implementation-specific variation in TMS solutions for the elements of an electrified propulsion system. Although thermal management is an intrinsic requirement applicable to most, if not all, elements of an electrified propulsion system, TMS is outside the scope of this document, which is intended to describe six example electrified propulsion architectures.
E-40 Electrified Propulsion Committee
Assessment of Components Sizing and Energy Management Algorithms Performance for a Parallel PHEV2022-37-00156/14/2022
In Plug in hybrid electric vehicles (PHEVs), the management of the main drivetrain components and the shift between pure electric and hybrid propulsion is decided by the on-board energy management system (EMS). The EMS decisions have a direct impact on CO2 emissions and need to be optimized to achieve as low emissions as possible. This paper presents optimization methods for EMS algorithms of a parallel P2 PHEV. Two different supervisory control algorithms are examined, employing simulations on a validated PHEV platform. An Equivalent Consumption Minimization Strategy (ECMS) algorithm is implemented and compared to a rule-based one, the latter derived by back-engineering of available experimental data. The different EMS algorithms are analyzed and compared on an equal basis in terms of distance, demanded energy and state of charge levels over different driving cycles. A sensitivity analysis on component sizing interaction with algorithm performance is conducted to check robustness of conclusions. The study shows that the ECMS algorithm can adapt the energy management strategy over the component variations, as no fuel consumption (FC) change exceeded 5%. The performance of the rule-based algorithm is affected by the component size variations as they resulted FC changes up to 26%. In that case recalibration would be necessary in order to maintain the fuel economy performance. The outcome of the study could support the selection of the appropriate EMS algorithm considering both FC and optimization robustness, accounting for individual components size.
Aletras, Nikolaos, Doulgeris, Stylianos, Samaras, Zissis, Ntziachristos, Leonidas
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