Downloads

Miao, X., Xu, B., Deng, J., & Li, L. Key Technologies to 50% Brake Thermal Efficiency for Gasoline Engine of Passenger Car. International Journal of Automotive Manufacturing and Materials. 2025. doi: https://doi.org/10.53941/ijamm.2025.100001

Review

Key Technologies to 50% Brake Thermal Efficiency for Gasoline Engine of Passenger Car

Xinke Miao, Bingxin Xu, Jun Deng, and Liguang Li *

School of Automotive Studies, Tongji University, Shanghai 201804, China

* Correspondence: liguang@tongji.edu.cn

Received: 13 August 2024; Revised: 6 December 2024; Accepted: 17 December 2024; Published: 20 January 2025

Abstract: As fuel consumption and emissions regulations become increasingly stringent, various advanced strategies have been proposed to achieve higher efficiency in internal combustion engines. This paper reviews the advancements in thermal efficiency of gasoline engines and analyzes the key technological methods to achieve over 50% brake thermal efficiency (BTE). The technological routes proposed for high-efficiency gasoline engine are primarily focused on high compression ratios and lean combustion combined with novel combustion technologies. Supporting technologies mainly include Atkinson/Miller cycles, intake boosting, exhaust gas re-circulation (EGR), water injection, thermal barrier coatings, friction reduction, structural optimization, and combustion diagnostics and control.

Keywords:

thermal efficiency gasoline engine combustion technologies

1. Introduction

Climate change has increasingly drawn global attention and concern. In 2015, The Paris Agreement was adopted by 196 parties at the UN Climate Change Conference (COP21). The countries and regions voluntarily established energy efficiency and emission reduction targets. The central aim of the Paris Agreement is to hold “the increase in the global average temperature to well below 2 °C above pre-industrial levels” and pursue efforts “to limit the temperature increase to 1.5 °C above pre-industrial levels” [1]. At the Leaders Summit on Climate in 2021, participants announced ambitious climate targets ensuring that nations accounting for half of the world’s economy have now committed to the emission reductions needed globally. The European Union (EU) has stated a target of reducing net greenhouse gas (GHG) emissions by at least 55% by 2030 and a net zero target by 2050, while the United States (US) has pledged to reduce emissions 50% below 2005 levels by 2030 [2]. China has set the “3060 goal”, striving to peak carbon emissions by 2030 and to achieve carbon neutrality by 2060 [3].

Transportation is the second largest source of carbon emissions globally, surpassed only by electricity and heat production, which are categorized as a single source in industrial. According to the statistical results of the International Energy Agency (IEA) [4], the global transportation sector emitted 7.63 billion tons of carbon dioxide (CO2) in 2021, which accounted for 22.7% of the carbon emissions from energy activities. It is evident that to achieve carbon dioxide reduction targets, it is crucial to reduce carbon emissions from transportation. There is an urgent need for the automotive industry to transition towards cleaner, low-carbon technologies. Consequently, many regions around the world have implemented stringent fuel consumption and emission regulations for vehicles. In Europe, major light-duty vehicle (LDV) markets are targeting 95 g/km CO2 by 2020. In the US, the average reduction rate of CO2 emissions for 2017 through 2021 is 3.5 percent per year and 5 percent per year for 2022 through 2025. In China, the fuel consumption standard is 6.9 L/100 km for domestically produced passenger cars, which will be lowered to 4.0 in 2025 and 3.2 in 2030 [5].

In the foreseeable future, energy-saving vehicles are expected to remain the dominant force in the market, with approximately 60% of vehicles predicted to still equipped with internal combustion engines by 2030 [6]. Therefore, improving the efficiency and reducing the emissions of internal combustion engines remains a top priority at this stage, whether for traditional fuel vehicles or hybrid vehicles. The High-Quality Development Plan of Internal Combustion Engine Industry (2021–2035) issued by China Internal Combustion Engine Industry Association aims to set ambitious targets for the industry. One of the key goals is to achieve a brake thermal efficiency (BTE) of 50% for the new generation of gasoline powertrains by 2030 [7].

Over the past decade, the application of various advanced combustion technologies has increased the BTE of gasoline engines from 30–36% [8] to over 45%. Fuel blending is a crucial technology for improving the thermal efficiency of internal combustion engines (ICE). Significant progress has been made in blending gasoline with different fuels such as diesel [912], n-heptane [13,14], ethanol [1518], polyoxymethylene dimethyl ethers (PODE) [1923], hydrogen [24], natural gas [25], and coal to liquid (CTL) [26]. However, this review article focuses solely on research related to gasoline as a fuel. It highlights recent advancements in gasoline engine efficiency and the key technologies used.

2. Advances in High Thermal Efficiency Gasoline Engines

Table 1 summarizes the recent researches on the thermal efficiency of gasoline engines, where the number in the bracket represents the effective compression ratio (εe). The maximum BTE expected for slider-crank engines is about 60% [27]. Yu et al. [28] proposed a technological route to achieve 60% BTE in gasoline engines through numerical simulation and theoretical calculation. However, due to cost constraints, achieving this goal under realistic situations seems quite challenging. In 2019, Japan’s Strategic Innovation Promotion (SIP) Program achieved a BTE of 51.5% for gasoline engine [29]. In the same year, Mazda announced that it had successfully developed a gasoline engine with an indicated thermal efficiency (ITE) of 56% [30].

ITE BTE ε ( ε e ) λ EGR Rate Displacement/L Cylinder Number Combustion Method
Yu et al. [28]/2019 60% (sim) 17 (14.2) 1.9 54% 1.933 1 HCCI
Ichiro et al. [30]/2019 56% 17.3 1.8 40% SPCCI
Zhao et al. [31]/2024 53% (sim) 17 2.5 0.56 1 APC
Addepalli et al. [32]/2023 53% 46.1% 17 12.4 6 GCI
Hu et al. [33]/2023 52.5% 16 2.4 0.5 1 APC
Zhao et al. [34]/2024 51.6% (sim) 17 2.5 0.56 1 APC
SIP [29]/2019 51.5% 14~17 2 HEI
Our Research Group/2024 51.34% 47% 16.8 2.4 0.5 1 APC
Wang et al. [35]/2023 51% 12.28~16.4 2.24 0.5 1 APC
Li et al. [36]/2020 51% 18 40% 5.3 4 GCI
Zhao et al. [37]/2023 50.3% 46.3% 15.5 2 0.375 1 APC
Liu et al. [38]/2024 50.3% 17 1.9 0.563 1 HEI
Chen et al. [39]/2024 50.1% 12.48~16.4 2.8 0.5 1 APC
Du et al. [40]/2024 50% 46.3% 16.5 2.1 0.5 1 APC
Qian et al. [41]/2023 50% 18 5.3 4 GCI
Peethambaram et al. [42]/2024 49.85% (sim) 16.64 2.23 1.5 1 APC
Dernotte et al./2017 49.70% 16 3.13~3.33 5.886 6 GCI
Wang et al. [43]/2021 49.50% 16 2.25 0.5 1 Corona Ignition
Yu et al. [44]/2017 49.3% 17 2.38~3.13 0.498 4 DICI
48.5% HCCI
Wu et al. [45]/2024 48.5% 18 38% 5.3 4 GCI
Cai et al. [46]/2020 48.2% 17 1.94 0.5 1 Corona Ignition
Sellnau et al. [47]/2016 48.00% 15 1.8 4 GDCI
Wu et al. [48]/2023 48% 18 5.3 4 GCI
Meng et al. [49]/2022 47.62% (sim) 45.05% (sim) 9.48 2 1.8 4 HEI
Gainey et al. [50]/2023 47.60% 16 33% 1.7 4 GCI
Zhang et al. [51]/2023 47.46% (sim) 17.5 40% 0.5 1 SI
Yan et al. [52]/2023 47.4% (sim) 17 0.65 1 PPCI
Pei et al. [53]/2022 47.09% 17 (9.3~12.8) 1.9 0.563 1 HEI
Serrano et al. [54]/2019 47% 13~15 2 0.408 1 APC
Jiang et al. [55]/2019 47% 18 5.3 4 GCI
Vedula et al. [56]/2017 46.8% 12 1.85 0.709 1 APC (DM-TJI)
Zhang et al. [57]/2021 46.8% (sim) 11 20% 6.49 4 GCI
Li et al. [58]/2023 46.28% 17 1.9 0.563 1 HEI
Yuan et al. [59]/2024 46.14% 17 1.5~2.0 0.466 1 APC
Dec et al. [60]/2024 45.5% 16 5.9 6 LTGC-AMFI
Cung et al. [61]/2021 45.3% 22 18% 13 1 GCI
Zheng et al. [62]/2022 45% 12.5~15 1.5 0.5 1 SI
Ikeya et al. [63]/2015 45% (sim) 17 (12.5) 30% 0.626 1 HEI
Xu et al. [20]/2023 45% 16.7 2 4 PPCI
O’Donnell et al. [64]/2023 45% 16 (14.9) 2.38~3.13 5.9 6 HCCI
Lago Sari et al. [65]/2024 44.7% 14.9 6 GCI
Li et al. [66]/2024 44% 15 1.7 2 4 APC
Liu et al. [67]/2024 43.8% 16.5 10% 1.5 4 Passive Pre-Chamber
Bunce et al. [68]/2021 43.6% 13~15 1.7 1.5 3 APC
Sellnau et al. [69]/2019 43.50% 17 2.2 4 GDCI
Li et al. [70]/2023 43.21% 20.3 7.7 6 GCI
Ye et al. [71]/2024 43.1% 13.9~15.8 1 0.375 1 SI
Lee et al. [72]/2017 42.2% (sim) 12.6~15 35% 2 4 Twin Spark Plugs
Mao et al. [73]/2017 42% 16.8 ~1.35 8.42 6 PCC
Osborne et al. [74]/2021 42% 11 1.7 2 4 HEI
Zhang et al. [75]/2021 41% 17 1 0.563 1 SI
Sok et al. [76]/2022 41% 13.1 0.95~1.61 0.343 4 HCCI
Hakariya et al. [77]/2017 40% 13 25% 2.5 4 HEI
Yang et al. [78]/2023 40% 10.5 1.5 4 SI
Zhu [79]/2021 40.5% 16 1.4 1.4 4 HEI
Chao [80]/2019 39.53% 12 15% 1 3 SI
Wang [81]/2022 39.1% 16 2 2 4 APC
Krajnović et al. [82]/2024 37.7% (sim) 12.8 1.6 0.67 1 APC
Lv et al. [83]/2024 37.29% 11.2 1 1.6 4 Passive Pre-Chamber
Table 1. Summary of recent researches on the thermal efficiency of gasoline engines.

According to the data in Table 1, the effect of compression ratio ε and λ on thermal efficiency is shown in Figure 1. It is evident that a high compression ratio combined with lean combustion technology is the main technical route for efficient gasoline engines. Toyota’s Hakariya et al. [77] increased the compression ratio of a 2.5 L naturally aspirated direct injection engine from 10.3 to 13.0, achieving high swirl ratio and high flow coefficient targets by increasing the stroke-to-bore (S/B) ratio and optimizing the intake port design. This resulted in faster combustion and an increase in maximum BTE from 35% to 40%. Similarly, Hyundai’s Lee et al. [72] utilized analogous techniques to raise the compression ratio of a gasoline engine to 14, enhance the intake port design to increase the swirl ratio, and combined dual spark plug ignition with exhaust gas recirculation (EGR), boosting BTE from 38.3% to 42.2%.

Figure 1. Effect of compression ratio ε and λ on thermal efficiency.

Honda’s Ikeya et al. [63] employed a higher S/B ratio, Miller cycle, EGR, high-energy ignition (HEI), which is typically defined as ignition energy exceeding 100 mJ, with 450 mJ applied in this study. Combined with an optimized combustion chamber shape which significantly increased combustion speed and reduced knocking tendency. This approach achieved an effective thermal efficiency of 45% at an engine speed of 2000 r/min, with an S/B ratio of 1.5, a geometric compression ratio of 17, and an effective compression ratio of 12.5. Niizato [84] extended the lean combustion limit using pre-chamber ignition, achieving a maximum λ of 2.7 and a peak ITE of 47.2%.

Geely’s Wang et al. [43] applied high compression ratio technology (ε = 16), high swirl ratio intake ports, small overlap angle intake camshaft, lean combustion technology (λ = 2.0), and a corona ignition system. At 2000 r/min, the engine’s ITE reached 49.5%. Hu et al. [33] extended the lean combustion limit using active pre-chamber (APC) ignition, achieving a peak ITE of 52.5% at λ of 2.4.

In addition to spark-ignition (SI) modes, gasoline compression ignition (GCI) under high compression and lean burn conditions also warrants attention. Delphi’s Sellnau et al. [47,69] developed the second-generation Gasoline Direct Injection Compression Ignition (GDCI) engine with a compression ratio of 15, using an EGR strategy to achieve partial premixed compression ignition across all operating conditions, reaching a maximum ITE of 48%. The third-generation GDCI engine, with a compression ratio of 17, achieved stable combustion with an BTE of 43.5%. The Sandia National Laboratories’ Dernotte et al. [85] achieved a maximum ITE of 49.7% using a double direct-injection (D-DI) strategy to realize low-temperature stratified compression ignition with λ > 3.0 in an engine with a compression ratio of 16.

The SIP Program optimized the combustion system by integrating various technologies, including increasing the engine’s compression ratio and stroke/bore ratio, ultra-lean combustion (λ > 2.0), an HEI system, and in-cylinder water injection, raising the BTE of gasoline engines from 38.5% to 48%. Building on this, they further increased BTE to 51.5% through thermoelectric conversion, improved turbocharging efficiency, and reduced friction losses as shown in Figure 2 [29]. Mazda’s approach primarily involved high compression ratios, lean combustion (λ = 1.8), intake boosting, adiabatic combustion, and spark-controlled compression ignition (SPCCI). Utilizing cylinder pressure sensors for cycle-based in-cylinder combustion diagnostics and control, they boosted the thermal efficiency from 44% to 56% as shown in Figure 3 [30]. Our research group has recently achieved maximum ITE of 51.34% and BTE of 47% at 2800 r/min on a high compression ratio (ε = 16.8) single-cylinder engine. This was accomplished using active pre-chamber (APC) ignition technology for ultra-lean combustion (λ = 2.4) combined with intake boosting and the Miller cycle.

Figure 2. Technical route to achieve 51.5% BTE in the SIP Program (Adapted with permission from Ref. [29], 2019, SIP Program).

Figure 3. Technical route for Mazda to achieve 56% ITE (Reprinted with permission from Ref. [30], 2019, Mazda).

Summarize the technologies from Table 1 that achieve an ITE of over 50% for gasoline engines, as presented in Table 2. It highlights the key advancements that enable engines to achieve over 50% brake thermal efficiency (BTE), with an emphasis on the synergies between combustion methods and supporting technologies. High compression ratios, lean combustion, and intake boosting emerge as foundational elements across various modes such as HCCI, GCI, APC, and SPCCI, while technologies like EGR, variable effective compression ratio, thermal barrier coatings, water injection play complementary roles in addressing challenges like knock suppression, heat loss, and combustion stability. In addition, friction reduction is a technique that increases the efficiency without changing the combustion in the cylinder. By systematically analyzing the Table 2, it becomes evident that these technologies form an essential framework for achieving future efficiency targets.

Combustion Method HCCI [28] GCI [32,36,41] SPCCI [30] HEI [29,38] APC [ 31,3335,37,39,40]
High Compression Ratio
Lean Combustion
Intake Boosting
Exhaust Gas Recirculation
Variable Effective Compression Ratio (e.g., Atkinson/Miller cycle)
Enhanced Air Flow
Thermal Barrier Coatings
Friction Reduction
Water Injection
High Pressure Injection
Enhanced Mechanical Strength
Table 2. The main technologies on the high thermal efficiency of gasoline engines.

3. Key Technologies for High Thermal Efficiency Gasoline Engines

3.1. Theoretical Analysis

The actual combustion process in an engine is complex, but theoretical/numerical analysis can provide suitable pathways toward assessing the performance boundaries of the engine and provide optimized directions for subsequent design and research. The main energy transfer losses are summarized in Equation (1) to describe the relationship between various efficiencies of the internal combustion engine (ICE).

η B r a k e = η C o m b u s t i o n η T h e r m o d y n a m i c η G a s E x c h a n g e η M e c h a n i c a l (1)

where ηBrake refers to the brake thermal efficiency, ηCombustion refers to the combustion efficiency, ηThermodynamic refers to the thermodynamic efficiency, ηGasExchange refers to the gas exchange efficiency and ηMechanical refers to the mechanical efficiency.

In a conventional ICE, ηCombustion, ηGasExchange, and ηMechanical are usually higher than 90%, reflecting their relatively high performance under typical conditions. However, further improvements in these areas, such as optimizing combustion processes or reducing mechanical losses, can still contribute meaningfully to achieving maximum BTE. Among these efficiencies, ηThermodynamic is typically the lowest, with a theoretical limit of about 60%. Therefore, in the theoretical analysis, a notable focus is placed on improving ηThermodynamic due to its significant potential for enhancing overall efficiency. Meanwhile, to maintain the universality of the calculation results, the heat transfer loss and time loss in ηThermodynamic are not considered in the theoretical analysis. Equation (2) represents the calculation of ηOtto, which corresponds to the theoretical ηThermodynamic of gasoline engines:

η O t t o = 1 - 1 ε γ - 1 (2)

where ηOtto refers to the Otto cycle efficiency, γ refers to the specific heat ratio, and ε refers to the compression ratio. Equation (2) clearly reveals the effects of γ and ε on ηOtto. Figure 4 presents the curves illustrating Equation (2).

Figure 4. The curves of Otto cycle thermal efficiency.

Moreover, an appropriate combustion phase and a shorter combustion duration can enhance ηThermodynamic, bringing it closer to the theoretical limit of ηOtto [85].

From a thermodynamic perspective, improving ηThermodynamic can primarily be approached in three ways:

(1) Maximizing the engine’s compression ratio as much as possible.

(2) Ensuring the working fluid has a high specific heat ratio.

(3) Organizing combustion efficiently to enhance the isochoric heat addition, thus approaching the theoretical cycle efficiency.

3.2. Technical Routes

Theoretical analysis indicates that the higher the compression ratio, the higher the theoretical thermal efficiency of a gasoline engine. However, as the compression ratio increases, the temperature and pressure at the end of compression also increase, which leads to a greater tendency for knocking. To mitigate knocking, it is necessary to employ technologies such as lean combustion, exhaust gas recirculation (EGR), and water injection [66,86] into the engine to lower the in-cylinder temperature. At the meantime, lean combustion can increase the specific heat ratio γ by increasing the excess air coefficient λ, thus further improving thermal efficiency. For example, studies have shown that in an engine with a compression ratio of 16, increasing λ from 1.0 to 1.4 can result in an approximate 3% absolute improvement in thermal efficiency, considering the variation of γ with temperature [87].

In light of recent studies, the combination of high compression ratios and lean combustion emerges as the most prominent and effective technological strategy for achieving high thermal efficiency in gasoline engines. However, as the air-fuel mixture becomes increasingly lean, ignition difficulties, misfiring, and combustion instability can arise. Therefore, to support lean combustion at high compression ratios, it is necessary to explore novel combustion modes.

Combustion modes are principally categorized into spark ignition and compression ignition technologies. Compression ignition technologies encompass homogeneous charge compression ignition (HCCI) [44,64], partially premixed compression ignition (PPCI) [20,21,52], reactivity-controlled compression ignition (RCCI) [14,26], stratified charge compression ignition (SCCI) [13] and intelligent charge compression ignition (ICCI) [88,89]. Spark ignition technologies are further subdivided into thermal plasma ignition and non-thermal plasma ignition. Thermal plasma ignition methods include HEI [24,38], multiple spark ignition [72,90], multi-electrode ignition [91,92], pre-chamber ignition [93,94], and laser ignition [95], whereas non-thermal plasma ignition techniques involve corona ignition [96,97], microwave-assisted ignition [98,99], and nanosecond pulse ignition [100,101]. The advantages and disadvantages of the main ignition technologies are compared in Table 3. Among them, pre-chamber ignition technology, particularly active pre-chamber ignition, not only effectively increases the ignition energy compared to other ignition methods but also enhances in-cylinder turbulence, making lean combustion ignition leaner and more stable. Significant progress has been made in recent years [33,42,54].

Spark Ignition Technologies Ignition Ability Reliability Complexity Cost
Thermal Plasma High Energy Ignition Moderate High Moderate Moderate
Multiple Spark Ignition Low High Low Low
Multi-electrode Ignition Low High Low Low
Pre-chamber Ignition High High Moderate Moderate
Laser Ignition High Low High Very High
Non-thermal Plasma Corona Ignition Moderate Moderate Moderate High
Microwave-assisted Ignition Low High High High
Nanosecond Pulse Ignition Low High Moderate High
Table 3. Characteristics of the main ignition technologies.

When the effective compression ratio cannot be further increased due to limitations such as knock tendency, the Atkinson/Miller cycle [78,102] can be used to improve the engine’s thermal efficiency. This is achieved by using variable valve timing to create a higher expansion ratio while maintaining an effective compression ratio suitable for stable operation. Additionally, research into thermal barrier coatings technologies [50,103] can make the actual combustion cycle closer to the ideal cycle. Some studies have also used monatomic gases, such as argon [104,105], as the working medium to increase the specific heat ratio and thus improve efficiency. However, such approaches face significant challenges in practical applications due to the cost and complexity of using monatomic gases as the intake charge.

Beyond improving thermodynamic efficiency, mechanical efficiency can be enhanced through friction reduction technologies [106,107]. Optimizing intake and exhaust systems [74,108] and employing intake boosting technologies [109] can increase gas exchange efficiency. Furthermore, besides using novel combustion technologies, optimizing combustion chamber design [110] and utilizing combustion diagnostics and control technologies [111,112] can enhance combustion efficiency.

In summary, as shown in Figure 5, the main technological routes to achieve a BTE of over 50% include the following steps: designing engines with a geometric compression ratio not exceeding 20 and optimizing the intake and combustion chamber structures. Implementing Miller cycles through Variable Valve Timing (VVT). Utilizing intake boosting technologies in conjunction with novel combustion technologies, such as with an active pre-chamber ignition, to achieve ultra-lean combustion with a lambda greater than 2. Further enhancing efficiency with thermal barrier coatings and low-friction lubrication technologies. Finally, ensuring stable and reliable combustion through advanced combustion diagnostics and control technologies.

Figure 5. The main technological routes to achieve a BTE of over 50%.

4. Conclusions and Perspectives

This paper presents a review on the advancements in thermal efficiency of gasoline engines and analyzes the key technological methods to achieve over 50% brake thermal efficiency (BTE). Based on existing research and theoretical analysis, the feasible technological routes for achieving high thermal efficiency in gasoline engines has been proposed.

The technological routes involve high compression ratios with optimizing geometric structures, implementing Miller cycles with VVT, utilizing intake boosting and novel combustion technologies for ultra-lean combustion (λ > 2.0), enhancing efficiency with thermal barrier coatings and low-friction lubrication, and ensuring reliable combustion through advanced diagnostics and control technologies.

However, issues related to material strength, emission control, cost, and reliability still require ongoing research and development.

Author Contributions: Conceptualization and methodology, L.L., J.D., X.M., B.X.; literature review and resources, X.M., B.X.; writing, X.M.; editing, L.L., J.D., X.M., B.X.; funding acquisition, L.L. and J.D. All authors have read and agreed to the published version of the manuscript.

Funding: This research was funded by the Natural Science Foundation of China [Grant Number 52076153] and the Shanghai Science and Technology Program (grant numbers 22ZR1463000).

Institutional Review Board Statement: Not applicable.

Informed Consent Statement: Not applicable.

Data Availability Statement: Not applicable.

Conflicts of Interest: The authors declare no conflict of interest.

References

  1. United Nations. The Paris Agreement. 2015. Available online: https://unfccc.int/process-and-meetings/the-paris-agreement (accessed on 12 December 2015).
  2. Leaders Summit on Climate. 2021. Available online: https://www.state.gov/leaders-summit-on-climate/ (accessed on 22 April 2021).
  3. Carbon Neutrality in China. 2020. Available online: https://chinaeucn.com/carbon-neutrality-china/ (accessed on 22 September 2020).
  4. IEA. Energy Statistics Data. 2024. Available online: https://www.iea.org/data-and-statistics (accessed on 25 July 2024).
  5. Dahham, R.Y.; Wei, H.; Pan, J. Improving Thermal Efficiency of Internal Combustion Engines: Recent Progress and Remaining Challenges. Energies 2022, 15, 6222. https://doi.org/10.3390/en15176222.
  6. China-SAE. Technology Roadmap for Energy Saving and New Energy Vehicles 2.0; China Machine Press: Beijing, China, 2021.
  7. China Internal Combustion Engine Industry Association. High-Quality Development Plan for internal Combustion Engine Industry (2021–2035); China Internal Combustion Engine Industry Association: Shanghai, China, 2021.
  8. Boretti, A.A. Energy Recovery in Passenger Cars. J. Energy Resour. Technol. 2012, 134, 022203. https://doi.org/10.1115/1.4005699.
  9. Long, W.; Li, B.; Cao, J.; Meng, X.; Tian, J.; Cui, J.; Tian, H. Effects of dual-direct injection parameters on performance of fuel Jet Controlled Compression Ignition mode on a high-speed light duty engine. Fuel 2019, 235, 658–669. https://doi.org/10.1016/j.fuel.2018.08.043.
  10. Suo, G.; Lu, L. Experimental Study on Performance and Emissions of Gasoline-Diesel Dual Fuel Low Temperature Combustion. Trans. Csice 2017, 35, 509–515.
  11. Tong, L.; Wang, H.; Zheng, Z.; Reitz, R.; Yao, M. Experimental study of RCCI combustion and load extension in a compression ignition engine fueled with gasoline and PODE. Fuel 2016, 181, 878–886. https://doi.org/10.1016/j.fuel.2016.05.037.
  12. Li, Z.; Li, J.; Huang, G.; Zhang, Y.; He, Z.; Qian, Y.; Lu, X. A methodology for stratified-charge preparation via low-reactivity fuel multi-injection strategy in intelligent charge compression ignition (ICCI) mode. Fuel 2021, 289, 119751. https://doi.org/10.1016/j.fuel.2020.119751.
  13. Ji, L.; Lü, X.; Ma, J.; Huang, C.; Han, D.; Huang, Z. Experimental Study on Influencing Factors of iso-Octane Thermo-atmosphere Combustion in a Dual-Fuel Stratified Charge Compression Ignition (SCCI) Engine. Energ Fuel 2009, 23, 2405–2412. https://doi.org/10.1021/ef8009537.
  14. Liu, H.; Ma, G.; Ma, N.; Zheng, Z.; Huang, H.; Yao, M. Effects of charge concentration and reactivity stratification on combustion and emission characteristics of a PFI-DI dual injection engine under low load condition. Fuel 2018, 231, 26–36. https://doi.org/10.1016/j.fuel.2018.05.027.
  15. Zhang, Y.; Wu, H.; Mi, S.; Zhao, W.; He, Z.; Qian, Y.; Lu, X. Comprehensive optimization of a diesel-E85 engine over the full operating range using the Taguchi method in intelligent charge compression ignition (ICCI) mode. Fuel 2023, 332, 126042. https://doi.org/10.1016/j.fuel.2022.126042.
  16. Liu, S.; Lin, Z.; Zhang, H.; Fan, Q.; Lei, N.; Wang, Z. Experimental study on combustion and emission characteristics of ethanol-gasoline blends in a high compression ratio SI engine. Energy 2023, 274, 127398. https://doi.org/10.1016/j.energy.2023.127398.
  17. Splitter, D.; Wissink, M.; DelVescovo, D.; Reitz, R.D. RCCI Engine Operation Towards 60% Thermal Efficiency; SAE: Warrendale, PA, USA, 2013.
  18. Peng, Q.; Rockstroh, T.; Hall, C. The impact of fuel and injection strategy on combustion characteristics, emissions and efficiency in gasoline compression ignition operation. Fuel 2022, 318, 123548. https://doi.org/10.1016/j.fuel.2022.123548.
  19. Ding, B.; Wang, Y.; Bai, Y.; Xie, M.; Chen, J. Effects of PODE substitution rate and fuel injection timing on combustion, emission characteristic and energy balance in PODE-gasoline dual direct-injection engine. Energy 2024, 294, 130840. https://doi.org/10.1016/j.energy.2024.130840.
  20. Xu, G.; Duan, H.; Cai, Y.; Li, Y.; Jia, M. Potential of the reverse-reactivity controlled compression ignition (R-RCCI) combustion for maintaining ultra-low emissions and enhanced thermal efficiency. Energy 2023, 280, 128249. https://doi.org/10.1016/j.energy.2023.128249.
  21. Duan, H.; Jia, M.; Li, Y.; Wang, T. A comparative study on the performance of partially premixed combustion (PPC), reactivity-controlled compression ignition (RCCI), and RCCI with reverse reactivity stratification (R-RCCI) fueled with gasoline and polyoxymethylene dimethyl ethers (PODEn). Fuel 2021, 298, 120838. https://doi.org/10.1016/j.fuel.2021.120838.
  22. Wang, H.; Tong, L.; Zheng, Z.; Yao, M. Experimental Study on High-Load Extension of Gasoline/PODE Dual-Fuel RCCI Operation Using Late Intake Valve Closing. SAE Int. J. Engines 2017, 10, 1482–1490. https://doi.org/10.4271/2017-01-0754.
  23. Wang, H.; Zhong, X.; Mi, S.; Yao, M. Numerical investigation on the combustion characteristics of PODE3 gasoline RCCI and high load extension. Fuel 2020, 263, 116366. https://doi.org/10.1016/j.fuel.2019.116366.
  24. Fan, G.; Zheng, Z.; Li, L. Effect of hydrogen injection coupled with high-energy ignition on the combustion stability of a lean-burn gasoline engine. Int. J. Hydrog. Energy 2024, 49, 602–620. https://doi.org/10.1016/j.ijhydene.2023.08.2940360-3199.
  25. Xu, Y.; Zhang, Y.; Gong, J.; Su, S.; Wei, Z. Combustion behaviours and emission characteristics of a retrofitted NG/gasoline duel-fuel SI engine with various proportions of NG-gasoline blends. Fuel 2020, 266, 116957. https://doi.org/10.1016/j.fuel.2019.116957.
  26. Zhang, H.; Sun, W.; Guo, L.; Yan, Y.; Li, J.; Lin, S.; Wang, Q.; Sun, Y. An experimental study of using coal to liquid (CTL) and diesel as pilot fuels for gasoline dual-fuel combustion. Fuel 2021, 289, 119962. https://doi.org/10.1016/j.fuel.2020.119962.
  27. Daw, C.S.; Graves, R.L.; Caton, J.A.; Wagner, R.M. Summary Report on the Transportation Combustion Engine Efficiency Colloquium Held at USCAR, March 3 and 4, 2010; Office of Scientific and Technical Information (OSTI): Oak Ridge, TN, USA, 2010.
  28. Yu, H.; Su, W. Numerical study on the approach for super-high thermal efficiency in a gasoline homogeneous charge compression ignition lean-burn engine. Int. J. Engine Res. 2019, 22, 1329–1341. https://doi.org/10.1177/1468087419889248.
  29. Cross-Ministerial Strategic Innovation Promotion (SIP) Program, Innovative Combustion Technology (2019). Available online: https://www.jst.go.jp/sip/dl/k01/k01_seika2019.pdf (accessed on 29 January 2019).
  30. Hirose, I. Our Way Toward the Ideal Internal Combustion Engine for Sustainable Future. In Proceedings of the 28th Aachen Colloquium Automobile and Engine Technology, Aachen, Germany, 7–9 October 2019.
  31. Zhao, D.; An, Y.; Hu, J.; Pei, Y.; Sun, J.; Zhang, Z. Study of turbulent jet ignition based on synergy of airflow to achieve 53% indicated thermal efficiency for hybrid ultra-lean burning engines. In Powertrain Systems for a Sustainable Future; CRC Press: Boca Raton, FL, USA, 2023; pp. 139–149.
  32. Addepalli, S.K.; Pamminger, M.; Scarcelli, R.; Wallner, T. Modeling the impact of the fuel injection strategy on the combustion and performance characteristics of a heavy-duty GCI engine. Int. J. Engine Res. 2023, 25, 24–46. https://doi.org/10.1177/14680874231206650.
  33. Hu, K.; Chao, Y.; Hu, Y.; Ma, J.; Cheng, H.; Wei, H.; Li, S. Experimental Study of the Prechamber of High Thermal Efficiency Lean Burn Engine. Chin. Intern. Combust. Engine Eng. 2023, 44, 84–89.
  34. Zhao, D.; Pei, Y.; An, Y.; Hu, J.; Zhang, Z.; Sun, J.; Gao, D. Evaluation of the turbulent hot jet flame characteristics for achieving high thermal efficiency of hybrid engine. Appl. Therm. Eng. 2024, 236, 121611. https://doi.org/10.1016/j.applthermaleng.2023.121611.
  35. Wang, B.; Xie, F.; Hong, W.; Du, J.; Chen, H.; Li, X. Extending ultra-lean burn performance of high compression ratio pre-chamber jet ignition engines based on injection strategy and optimized structure. Energy 2023, 282, 128433. https://doi.org/10.1016/j.energy.2023.128433.
  36. Li, Z.; Xia, J.; Jiang, C.; He, Z.; Qian, Y.; Zhu, L.; Lu, X. Experimental study on wide load operation of gasoline compression ignition engine: Real distillate gasoline versus primary reference fuel. Fuel 2020, 277, 118211. https://doi.org/10.1016/j.fuel.2020.118211.
  37. Zhao, Z.; Qi, Y.; Wang, Z. Thermal efficiency optimization of a single cylinder gasoline engine based on active jet ignition. Int. J. Engine Res. 2023, 25, 835–849. https://doi.org/10.1177/14680874231208346.
  38. Liu, Z.; Zheng, Z. The effect of ignition energy on the lean combustion limitation in high compression ratio engines. Energy 2024, 301, 131591. https://doi.org/10.1016/j.energy.2024.131591.
  39. Chen, H.; Qi, H.; Jiang, X.; Du, J.; Ye, L.; Zhang, Z. Effect of Pre-Chamber Structure Parameters on Lean-Burn Characteristics for a Gasoline Engine. Trans. Csice 2024, 42, 106–113.
  40. Du, J.; Qi, H.; Chen, H.; Li, Y.; Zhan, W.; Jiang, X.; Wu, W.; Zhang, Z. Pre-Chamber Combustion System Development for an Ultra-Lean Gasoline Engine; SAE Technical Paper; SAE: Warrendale, PA, USA, 2024.
  41. Qian, Y.; Wu, H.; Mi, S.; Zhao, W.; Zhou, D.; Lu, X. High-efficiency combustion of gasoline compression ignition (GCI) mode with medium-pressure injection of low-octane gasoline under wide engine load conditions. Appl. Energy Combust. Sci. 2023, 15, 100179. https://doi.org/10.1016/j.jaecs.2023.100179.
  42. Peethambaram, M.R.; Zhou, Q.; Waters, B.; Pendlebury, K.; Fu, H.; Haines, A.; Hale, D.; Hu, T.; Zhang, J.; Wu, X.; et al. Combustion Analysis of Active Pre-Chamber Design for Ultra-Lean. Engine Operation. SAE Int. J. Engines 2024, 17, 705–720. https://doi.org/10.4271/03-17-05-0040.
  43. Wang, Z.; Zhang, H.; Hu, K.; Li, L.; Wei, H.; Li, S.; Wang, R. Experimental Research on the Effect of Ultra-lean Combustion on the Gasoline Engine Performance. Small Intern. Combust. Engine Veh. Tech. 2021, 50, 9–12.
  44. Yu, L.; Li, Y.; Li, B.; Liu, H.; Wang, Z.; He, X.; Shuai, S. Comparative Study on Gasoline HCCI and DICI Combustion in High Load Range with High Compression Ratio for Passenger Cars Application. SAE Int. J. Fuels Lubr. 2017, 10, 710–717. https://doi.org/10.4271/2017-01-2257.
  45. Wu, H.; Mi, S.; Qian, Y.; Zhang, Y.; Zhao, W.; Lu, X. Investigation of injection parameters coupled with fuel reactivity on combustion and emissions in dual direct-injection GCI engine. Int. J. Engine Res. 2024, 25, 1281–1298. https://doi.org/10.1177/14680874241229489.
  46. Cai, W.; Xu, H.; Ma, S.; Wang, Y. Experiment on a Homogeneous Lean Burn Gasoline Engine with High-Energy Ignition. Trans. Csice 2020, 38, 298–303.
  47. Sellnau, M.; Foster, M.; Moore, W.; Sinnamon, J.; Hoyer, K.; Klemm, W. Second Generation GDCI Multi-Cylinder Engine for High Fuel Efficiency and US Tier 3 Emissions. SAE Int. J. Engines 2016, 9, 1002–1020.
  48. Wu, H.; Zhang, Y.; Mi, S.; Zhao, W.; He, Z.; Qian, Y.; Lu, X. A methodology for regulating fuel stratification and improving fuel economy of GCI mode via double main-injection strategy. Front. Energy 2023, 17, 678–691. https://doi.org/10.1007/s11708-022-0859-z.
  49. Meng, S.; Wu, Z.; Han, Z.; Wang, Y.; Lyu, M.; Kong, D. Modeling Analysis of Thermal Efficiency Improvement up to 45% of a Turbocharged Gasoline Engine; SAE Technical Paper; SAE: Warrendale, PA, USA, 2022.
  50. Gainey, B.; Gandolfo, J.; Yan, Z.; Vedpathak, K.; Kumar, R.; Jordan, E.H.; Sellnau, M.; Filipi, Z.; Lawler, B. A two-material thermal barrier coating spatially tailored for high-efficiency GCI combustion. Int. J. Engine Res. 2023, 25, 156–169. https://doi.org/10.1177/14680874231194386.
  51. Zhang, Z.; Zheng, Z. Numerical simulation of the effects of the EGR ratio and ignition timing on a supercharged and high compression ratio hybrid gasoline engine. Fuel 2023, 341, 127695. https://doi.org/10.1016/j.fuel.2023.127695.
  52. Yan, Z.; Levi, A.; Zhang, Y.; Sellnau, M.; Filipi, Z.; Lawler, B. A numerical evaluation and guideline for thermal barrier coatings on gasoline compression ignition engines. Int. J. Engine Res. 2023, 24, 2206–2222. https://doi.org/10.1177/14680874221114534.
  53. Pei, Y.; Zhang, Q.; Peng, Z.; An, Y.; Shi, H.; Qin, J.; Zhang, B.; Zhang, Z.; Gao, D. Thermal efficiency improvement of lean burn high compression ratio engine coupled with water direct injection. Energy Convers. Manag. 2022, 251, 114969. https://doi.org/10.1016/j.enconman.2021.114969.
  54. Serrano, D.; Zaccardi, J.-M.; Müller, C.; Libert, C.; Habermann, K. Ultra-Lean Pre-Chamber Gasoline Engine for Future Hybrid Powertrains. SAE Int. J. Adv. Curr. Pract. Mobil. 2019, 2, 607–622. https://doi.org/10.4271/2019-24-0104.
  55. Jiang, C.; Li, Z.; Liu, G.; Qian, Y.; Lu, X. Achieving high efficient gasoline compression ignition (GCI) combustion through the cooperative-control of fuel octane number and air intake conditions. Fuel 2019, 242, 23–34. https://doi.org/10.1016/j.fuel.2019.01.032.
  56. Vedula, R.T.; Song, R.; Stuecken, T.; Zhu, G.G.; Schock, H. Thermal efficiency of a dual-mode turbulent jet ignition engine under lean and near-stoichiometric operation. Int. J. Engine Res. 2017, 18, 1055–1066. https://doi.org/10.1177/1468087417699979.
  57. Zhang, L.; Wang, H.; Zhong, X.; Han, X.; Wang, M.; Zheng, Z.; Yao, M. Study on the influence mechanism of mixture stratification on GCI combustion and the compound injection strategy under high load operation. Energy Sci. Eng. 2021, 9, 2434–2448. https://doi.org/10.1002/ese3.997.
  58. Li, Z.; Qin, J.; Pei, Y.; Zhong, K.; Zhang, Z.; Sun, J. The Lean-Burn Limit Extending Experiment on Gasoline Engine with Dual Injection Strategy and High Power Ignition System. Energies 2023, 16, 5662. https://doi.org/10.3390/en16155662.
  59. Yuan, S.; Wei, H.; Zhang, Y.; Liu, X.; Ma, X.; Ding, J.; Hu, K.; Lū, X.; Ma, J.; Zhao, F. Geely's Lean-burn Gasoline Engine with Brake Thermal Efficiency of 46%. In Lecture Notes in Electrical Engineering; Springer Nature: Singapore, 2024; pp. 1079–1098.
  60. Dec, J.E.; Lopez Pintor, D.; Vijayagopal, R. Practical low-temperature gasoline combustion for very high efficiency off-road, medium- and heavy-duty engines. Int. J. Engine Res. 2024, 25, 1691–1707. https://doi.org/10.1177/14680874241244550.
  61. Cung, K.; Moiz, A.A.; Smith, E.M.; Bitsis, D.C.; Michlberger, A.; Briggs, T.; Miwa, J. Gasoline compression ignition (GCI) combustion of pump-grade gasoline fuel under high compression ratio diesel engine. Transp. Eng. 2021, 4, 100066. https://doi.org/10.1016/j.treng.2021.100066.
  62. Zheng, Z.; Huang, Z.; Wang, T.; Wang, L.; Chen, H.; Chen, W. Influence of Heat Transfer of Combustion Chamber Wall on the Performance of Gasoline Engine Based on Polishing Technology under Different Compression Ratio and Air-Fuel Ratio. Int. J. Automot. Technol. 2022, 23, 1055–1063. https://doi.org/10.1007/s12239-022-0092-0.
  63. Ikeya, K.; Takazawa, M.; Yamada, T.; Park, S.; Tagishi, R. Thermal Efficiency Enhancement of a Gasoline Engine. SAE Int. J. Engines 2015, 8, 1579–1586.
  64. O'Donnell, P.C.; Lawler, B.; Lopez-Pintor, D.; Sofianopoulos, A. Effects of injection pressure and timing on low load low temperature gasoline combustion using LES. Appl. Therm. Eng. 2023, 232, 121001. https://doi.org/10.1016/j.applthermaleng.2023.121001.
  65. Lago Sari, R.; Zhang, Y.; Merritt, B.; Kumar, P.; Shah, A. Combining Gasoline Compression Ignition and Powertrain Hybridization for Long-Haul Applications. Energies 2024, 17, 1099. https://doi.org/10.3390/en17051099.
  66. Li, Y.; Wu, W.; Li, Y.; Chen, H.; Zhang, Z.; Du, J. Study on Lean Combustion Characteristics of Gasoline Direct Injection Engines with Jet Ignition and Intake Water Injection Technologies. Chin. Intern. Combust. Engine Eng. 2024, 45, 8–17.
  67. Liu, S.; Lin, Z.; Qi, Y.; Lu, G.; Wang, B.; Liu, Y.; Wang, Z. Simulation Investigation of Turbulent Jet Ignition (TJI) Combustion in a Dedicated Hybrid Engine under Stoichiometric Condition; SAE Technical Papers; SAE: Warrendale, PA, USA, 2024.
  68. Bunce, M.; Peters, N.; Pothuraju Subramanyam, S.K.; Blaxill, H.; Gao, J.; Choi, E. The Impact of Advanced Fuels and Lubricants on Thermal Efficiency in a Highly Dilute Engine. SAE Int. J. Adv. Curr. Pract. Mobil. 2021, 3, 2540–2553. https://doi.org/10.4271/2021-01-0462.
  69. Sellnau, M.; Foster, M.; Moore, W.; Sinnamon, J.; Hoyer, K.; Klemm, W. Pathway to 50% Brake Thermal Efficiency Using Gasoline Direct Injection Compression Ignition. SAE Int. J. Adv. Curr. Pract. Mobil. 2019, 1, 1581–1603. https://doi.org/10.4271/2019-01-1154.
  70. Li, Y.; Zhang, S.; Wang, H.; Chen, Y.; Li, B.; Yao, M. Experimental Investigations on Optimization Control Strategies of Gasoline Compression Ignition Combustion with High Compression Ratio at Low Loads. Chin. Intern. Combust. Engine Eng. 2023, 44, 33.
  71. Ye, T.; Wang, L.; Cao, Y. Experimental Study on Effect of Intake Port Water Injection on Engine Combustion Performance. Mech. Sci. Technol. Aerosp. Eng. 2024, 43, 45–53.
  72. Lee, B.; Oh, H.; Han, S.; Woo, S.; Son, J. Development of High Efficiency Gasoline Engine with Thermal Efficiency over 42%; SAE: Warrendale, PA, USA, 2017.
  73. Mao, B.; Wang, Q.; Liu, J.; Liu, H.; Zheng, Z.; Yao, M. Effects of gasoline viscosity and injection pressure on the performance and emissions of a multi-cylinder partially premixed combustion engine. In Proceedings of the 9th International Conference on Modeling and Diagnostics for Advanved Engine Systems (COMODIA 2017), Okayama, Japan, 25–28 July 2017.
  74. Osborne, R.; Lane, A.; Turner, N.; Geddes, J.; Atkins, P.; Pohorelsky, L.; Gidney, J.; Cleeton, J. A New Generation Lean Gasoline Engine for Premium Vehicle CO2 Reduction; SAE Technical Papers; SAE: Warrendale, PA, USA, 2021.
  75. Zhang, Q.; Pei, Y.; An, Y.; Peng, Z.; Qin, J.; Shi, H.; Zhang, B.; Zhang, Z.; Gao, D. Study of water direct injection on knock control and combustion process of a high compression ratio GDI engine. Fuel 2021, 306, 121631. https://doi.org/10.1016/j.fuel.2021.121631.
  76. Sok, R.; Kusaka, J. Experimental Investigation of Direct Fuel Injection Into Low-Oxygen Recompression Interval in a Homogenous Charge Compression Ignition Engine. J. Energy Resour. Technol.-Trans. Asme 2022, 144, 012301. https://doi.org/10.1115/1.4052470.
  77. hakariya, M.; Toda, T.; Sakai, M. The New Toyota Inline 4-Cylinder 2.5 L Gasoline Engine; SAE Technical Papers; SAE: Warrendale, PA, USA, 2017.
  78. Yang, H.; Zhang, L.; Liu, J.; Fu, J.; Shen, D.; Yuan, Z. Development and Validation of a Variable Displacement Variable Compression Ratio Miller Cycle Technology on an Automotive Gasoline Engine. Energies 2023, 16, 4480. https://doi.org/10.3390/en16114480.
  79. Zhu, D. SI/HCCI Ion Current Characteristics and Combustion Diagnosis and Control Based on Ion Current/Cylinder Pressure Synergy for High Compression Ratio Gasoline Engine; Tongji University: Shanghai, China, 2021.
  80. Chao, Y. SI/HCCI Combustion Optimization and Incycle Closed Loop Control for High Compression Ratio Gasoline Engine; Tongji University: Shanghai, China, 2019.
  81. Wang, J. Research on Lean Limit Expansion of Gasoline Engine Based on Pre-Chamber Ignition; Tongji University: Shanghai, China, 2022.
  82. Krajnović, J.; Sjerić, M.; Tomić, R.; Kozarac, D. A novel concept of active pre-chamber engine with a single injector—The passive main chamber approach. Appl. Therm. Eng. 2024, 250, 123509. https://doi.org/10.1016/j.applthermaleng.2024.123509.
  83. Lv, Y.; Feng, S.; Luo, J.; Liu, Q.; Li, L.; Kang, Z. Effect of key structure parameters of passive pre-chamber on in-cylinder combustion processes and emissions within a gasoline engine. Case Stud. Therm. Eng. 2024, 59, 104467. https://doi.org/10.1016/j.csite.2024.104467.
  84. Niizato, T. Honda Powertrain Strategy and ICE Technology for the Future. In Proceedings of the in SAE 2018 High Efficiency IC Engine Symposium, Detroit, MI, USA, 8–9 April 2018.
  85. Reader, G.T.; Asad, U.; Zheng, M. Energy efficiency trade-off with phasing of HCCI combustion. Int. J. Energy Res. 2013, 37, 200–210. https://doi.org/10.1002/er.1900.
  86. Xu, J.; Zhou, Z.; Jiang, L.; Zhou, H.; Zhang, C. Influence of Inlet Water Injection on Energy Conservation and Emission of Gasoline Engine. Int. J. Automot. Technol. 2023, 24, 935–943. https://doi.org/10.1007/s12239-023-0076-8.
  87. Caton, J.A. Quantification of Efficiency Gains for Dilute IC Engines due to Increases of the Ratio of Specific Heats. In Proceedings of the ASME 2014 Internal Combustion Engine Division Fall Technical Conference, Columbus, IN, USA, 19–22 October 2014.
  88. Qian, Y.; Mi, S.; Wu, H.; Zhang, Y.; Li, Z.; Lu, X. Towards high efficiency of intelligent charge compression ignition (ICCI) engine by optimizing the high-reactivity fuel injection strategies under medium-high loads. Fuel 2023, 335, 127037. https://doi.org/10.1016/j.fuel.2022.127037.
  89. Qian, Y.; Zhang, Y.; Mi, S.; Wu, H.; Li, Z.; Lu, X. Efficient and clean combustion of intelligent charge compression ignition (ICCI) engine at low load conditions. Fuel 2023, 332, 126002. https://doi.org/10.1016/j.fuel.2022.126002.
  90. Bakhshi, M.; Pritanshu, R.; Shukla, A. Numerical investigation on effect of spark plug configuration on performance in an engine cylinder. FME Trans. 2023, 51, 585–594. https://doi.org/10.5937/fme2304585m.
  91. Yu, S.; Zheng, M. Future gasoline engine ignition: A review on advanced concepts. Int. J. Engine Res. 2020, 22, 1743–1775. https://doi.org/10.1177/1468087420953085.
  92. Han, X.; Yu, S.; Tjong, J.; Zheng, M. Study of an innovative three-pole igniter to improve efficiency and stability of gasoline combustion under charge dilution conditions. Appl. Energy 2020, 257, 113999. https://doi.org/10.1016/j.apenergy.2019.113999.
  93. Toulson, E.; Schock, H.J.; Attard, W.P. A Review of Pre-Chamber Initiated jet ignition Combustion Systems; SAE Technical Papers; SAE: Warrendale, PA, USA, 2010.
  94. Alvarez, C.E.C.; Couto, G.E.; Roso, V.R.; Thiriet, A.B.; Valle, R.M. A review of prechamber ignition systems as lean combustion technology for SI engines. Appl. Therm. Eng. 2018, 128, 107–120. https://doi.org/10.1016/j.applthermaleng.2017.08.118.
  95. Pavel, N.; Bärwinkel, M.; Heinz, P.; Brüggemann, D.; Dearden, G.; Croitoru, G.; Grigore, O.V. Laser ignition—Spark plug development and application in reciprocating engines. Prog. Quantum Electron. 2018, 58, 1–32. https://doi.org/10.1016/j.pquantelec.2018.04.001.
  96. Ricci, F.; Martinelli, R.; Dal Re, M.; Grimaldi, C.N. Comparative analysis of thermal and non-thermal discharge modes on ultra-lean mixtures in an optically accessible engine equipped with a corona ignition system. Combust. Flame 2024, 259, 113123. https://doi.org/10.1016/j.combustflame.2023.113123.
  97. Suess, M.; Guenthner, M.; Schenk, M.; Rottengruber, H.S. Investigation of the potential of corona ignition to control gasoline homogeneous charge compression ignition combustion. Proc. Inst. Mech. Eng. Part D J. Automob. Eng. 2011, 226, 275–286. https://doi.org/10.1177/0954407011416905.
  98. DeFilippo, A.C. Microwave-Assisted Ignition for Improved Internal Combustion Engine Efficiency. Ph.D. Thesis, University of California, Berkeley, CA, USA, 2013.
  99. Hwang, J.; Kim, W.; Bae, C.; Choe, W.; Cha, J.; Woo, S. Application of a novel microwave-assisted plasma ignition system in a direct injection gasoline engine. Appl. Energy 2017, 205, 562–576. https://doi.org/10.1016/j.apenergy.2017.07.129.
  100. Shiraishi, T.; Urushihara, T.; Gundersen, M. A trial of ignition innovation of gasoline engine by nanosecond pulsed low temperature plasma ignition. J. Phys. D Appl. Phys. 2009, 42, 135208. https://doi.org/10.1088/0022-3727/42/13/135208.
  101. Balmelli, M.; Farber, R.; Merotto, L.; Soltic, P.; Bleiner, D.; Franck, C.M.; Biela, J. Experimental Analysis of Breakdown With Nanosecond Pulses for Spark-Ignition Engines. IEEE Access 2021, 9, 100050–100062. https://doi.org/10.1109/ACCESS.2021.3095664.
  102. Huang, Z.; Wang, L.; Wang, T.; Shen, K. Effects of Dilution Combustion and Miller Cycle on the Performance of Gasoline Engine. Int. J. Automot. Technol. 2022, 23, 511–519. https://doi.org/10.1007/s12239-022-0047-5.
  103. Uchida, N. A review of thermal barrier coatings for improvement in thermal efficiency of both gasoline and diesel reciprocating engines. Int. J. Engine Res. 2020, 23, 3–19. https://doi.org/10.1177/1468087420978016.
  104. Wang, C.; Jin, S.; Deng, J.; Ding, W.; Tang, Y.; Li, L. Future High-Efficiency and Zero-Emission Argon Power Cycle Engines: A Review. Int. J. Automot. Manuf. Mater. 2023, 2, 2. https://doi.org/10.53941/ijamm.2023.100002.
  105. Wang, C.; Jin, S.; Deng, J.; Li, L. An Innovative Argon/Miller Power Cycle for Internal Combustion Engine: Thermodynamic Analysis of its Efficiency and Power Density. Automot. Innov. 2023, 6, 76–88. https://doi.org/10.1007/s42154-022-00208-x.
  106. Skjoedt, M.; Butts, R.; Assanis, D.N.; Bohac, S.V. Effects of oil properties on spark-ignition gasoline engine friction. Tribol. Int. 2008, 41, 556–563. https://doi.org/10.1016/j.triboint.2007.12.001.
  107. Wong, V.W.; Tung, S.C. Overview of automotive engine friction and reduction trends–Effects of surface, material, and lubricant-additive technologies. Friction 2016, 4, 1–28. https://doi.org/10.1007/s40544-016-0107-9.
  108. Wang, W.; Liang, Y.; Zuo, Z.; Jia, B.; Wang, W. Effects of multitype intake structures on combustion performance of different opposed-piston engines. Appl. Therm. Eng. 2023, 235, 121438. https://doi.org/10.1016/j.applthermaleng.2023.121438.
  109. Ricardo, M.-B.; Apostolos, P.; Yang, M. Overview of boosting options for future downsized engines. Sci. China Technol. Sci. 2011, 54, 318–331. https://doi.org/10.1007/s11431-010-4272-1.
  110. Hasan, A.O.; Al-Rawashdeh, H.; Ala′a, H.; Abu-jrai, A.; Ahmad, R.; Zeaiter, J. Impact of changing combustion chamber geometry on emissions, and combustion characteristics of a single cylinder SI (spark ignition) engine fueled with ethanol/gasoline blends. Fuel 2018, 231, 197–203. https://doi.org/10.1016/j.fuel.2018.05.045.
  111. Miao, X.; Li, L.; Wang, S.; Wang, J.; Deng, J. Prediction and control of knock at high load boundary for HCCI engine based on neural network. Fuel 2023, 333, 126421. https://doi.org/10.1016/j.fuel.2022.126421.
  112. Wang, J.; Shi, J.; Deng, J.; Miao, X.; Liu, Y.; Pan, S.; Li, L. Misfire and knock detection based on the ion current inside a passive pre-chamber of gasoline engine. Fuel 2021, 311, 122528. https://doi.org/10.1016/j.fuel.2021.122528.

Most read articles by the same author(s)