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17 pages, 5451 KiB  
Article
Study of Efficient and Clean Combustion of Diesel–Natural Gas Engine at High Loads with TAC-HCCI Combustion
by Min Zhang, Wenyu Gu, Zhi Jia and Wanhua Su
Energies 2025, 18(15), 4121; https://doi.org/10.3390/en18154121 - 3 Aug 2025
Viewed by 75
Abstract
This study proposes an innovative Thermodynamic Activity Controlled Homogeneous Charge Compression Ignition (TAC-HCCI) strategy for diesel–natural gas dual-fuel engines, aiming to achieve high thermal efficiency while maintaining low emissions. By employing numerical simulation methods, the effects of the intake pressure, intake temperature, EGR [...] Read more.
This study proposes an innovative Thermodynamic Activity Controlled Homogeneous Charge Compression Ignition (TAC-HCCI) strategy for diesel–natural gas dual-fuel engines, aiming to achieve high thermal efficiency while maintaining low emissions. By employing numerical simulation methods, the effects of the intake pressure, intake temperature, EGR rate, intake valve closing timing, diesel injection timing, diesel injection pressure, and diesel injection quantity on engine combustion, energy distribution, and emission characteristics were systematically investigated. Through a comprehensive analysis of optimized operating conditions, a high-efficiency and low-emission TAC-HCCI combustion technology for dual-fuel engines was developed. The core mechanism of TAC-HCCI combustion control was elucidated through an analysis of the equivalence ratio and temperature distribution of the in-cylinder mixture. The results indicate that under the constraints of PCP ≤ 30 ± 1 MPa and RI ≤ 5 ± 0.5 MW/m2, the TAC-HCCI technology achieves a gross indicated mean effective pressure (IMEPg) of 24.0 bar, a gross indicated thermal efficiency (ITEg) of up to 52.0%, and indicated specific NOx emissions (ISNOx) as low as 1.0 g/kW∙h. To achieve low combustion loss, reduced heat transfer loss, and high thermal efficiency, it is essential to ensure the complete combustion of the mixture while maintaining low combustion temperatures. Moreover, a reduced diesel injection quantity combined with a high injection pressure can effectively suppress NOx emissions. Full article
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19 pages, 2678 KiB  
Article
Simulation-Based Study of NH3/H2-Dual Fueled HCCI Engine Performance: Effects of Blending Ratio, Equivalence Ratio, and Compression Ratio Using Detailed Chemical Kinetic Modeling
by Fatimoh Balogun, Aneesh Vasudev, Alireza Kakoee, Katriina Sirviö and Maciej Mikulski
Processes 2025, 13(7), 2049; https://doi.org/10.3390/pr13072049 - 27 Jun 2025
Viewed by 363
Abstract
Challenges associated with the homogeneous charge combustion ignition (HCCI) concept include combustion phasing control and a narrow operating window. To address the HCCI engine developmental needs, chemical kinetic solvers have been recently included in the commercial engine simulation toolchains like GT-Suite v2024 upward. [...] Read more.
Challenges associated with the homogeneous charge combustion ignition (HCCI) concept include combustion phasing control and a narrow operating window. To address the HCCI engine developmental needs, chemical kinetic solvers have been recently included in the commercial engine simulation toolchains like GT-Suite v2024 upward. This study investigates the feasibility of ammonia (NH3) and hydrogen (H2) as dual fuels in homogenous charge compression ignition (HCCI) engines, leveraging chemical kinetics modeling via GT-Suite software v2024. A validated baseline model was adapted with NH3/H2 injectors and simulated across varying blending ratios (BR), compression ratios (CR), air–fuel equivalence ratios (ER), and engine speeds. Results reveal that adding 10% H2 to NH3 significantly improves ignition. Optimal performance was observed at a CR of 20 and a lean mixture, achieving higher indicated thermal efficiency (about 40%), while keeping the intrinsic advantages of zero-carbon fuel. However, NOx emissions increased with higher ER due to elevated combustion temperatures. The study emphasizes the trade-offs between efficiency and NOx emissions under tested conditions. Finally, despite the single-zone model limitations in neglecting thermal stratification, this study shows that kinetic modeling has great potential for effectively predicting trends in HCCI, thereby demonstrating the promise of NH3/H2 blends in HCCI engines for cleaner and efficient combustion, paving the way for advanced dual-fuel combustion concepts. Full article
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27 pages, 6313 KiB  
Review
Experimental and Simulation Research Progress on the Solidification Structure Evolution of High Chromium Cast Iron
by Longxiao Huang, Yang Liu and Hanguang Fu
Metals 2025, 15(6), 663; https://doi.org/10.3390/met15060663 - 13 Jun 2025
Viewed by 408
Abstract
High-chromium cast irons (HCCIs) have emerged as preferred materials for critical wear-resistant components operating under extreme conditions, owing to their excellent wear resistance, low cost, and good castability. They are widely used in metallurgy, energy, and mechanical engineering industries. The evolution of solidification [...] Read more.
High-chromium cast irons (HCCIs) have emerged as preferred materials for critical wear-resistant components operating under extreme conditions, owing to their excellent wear resistance, low cost, and good castability. They are widely used in metallurgy, energy, and mechanical engineering industries. The evolution of solidification microstructure directly governs the final properties of HCCIs, making the in-depth investigation of their solidification behavior of great significance. This paper provides a comprehensive review of recent experimental and simulation-based advances in understanding the solidification microstructure evolution of HCCIs. The effects of alloy composition, cooling rate, and inoculation treatments on microstructure development and phase distribution during solidification are critically analyzed. Furthermore, the application of simulation techniques—including thermodynamic modeling, phase-field method, cellular automata, and finite element analysis—is discussed in detail, highlighting their roles in revealing the mechanisms of microstructural evolution. Finally, the current challenges and potential future research directions in the study of the solidification behavior of high-chromium cast irons are outlined. Full article
(This article belongs to the Special Issue Calphad Tools for the Metallurgy of Solidification)
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22 pages, 8377 KiB  
Article
Study on the Corrosion and Wear Mechanism of a Core Friction Pair in Methanol-Fueled Internal Combustion Engines
by Wenjuan Zhang, Hao Gao, Qianting Wang, Dong Liu and Enlai Zhang
Materials 2025, 18(9), 1966; https://doi.org/10.3390/ma18091966 - 25 Apr 2025
Cited by 1 | Viewed by 510
Abstract
With the global shift in energy structure and the advancement of the “double carbon” strategy, methanol has gained attention as a clean low-carbon fuel in the engine sector. However, the corrosion–wear coupling failure caused by acidic byproducts, such as methanoic acid and formaldehyde, [...] Read more.
With the global shift in energy structure and the advancement of the “double carbon” strategy, methanol has gained attention as a clean low-carbon fuel in the engine sector. However, the corrosion–wear coupling failure caused by acidic byproducts, such as methanoic acid and formaldehyde, generated during combustion severely limits the durability of methanol engines. In this study, we employed a systematic approach combining the construction of a corrosion liquid concentration gradient experiment with a full-load and full-speed bench test to elucidate the synergistic corrosion–wear mechanism of core friction pairs (cylinder liner, piston, and piston ring) in methanol-fueled engines. The experiment employed corrosion-resistant gray cast iron (CRGCI), high chromium cast iron (HCCI), and nodular cast iron (NCI) cylinder liners, along with F38MnVS steel and ZL109 aluminum alloy pistons. Piston rings with DLC, PVD, and CKS coatings were also tested. Corrosion kinetic analysis was conducted in a formaldehyde/methanoic acid gradient corrosion solution, with a concentration range of 0.5–2.5% for formaldehyde and 0.01–0.10% for methanoic acid, simulating the combustion products of methanol. The results showed that the corrosion depth of CRGCI was the lowest in low-concentration corrosion solutions, measuring 0.042 and 0.055 μm. The presence of microalloyed Cr/Sn/Cu within its pearlite matrix, along with the directional distribution of flake graphite, effectively inhibited the micro-cell effect. In high-concentration corrosion solutions (#3), HCCI reduced the corrosion depth by 60.7%, resulting in a measurement of 0.232 μm, attributed to the dynamic reconstruction of the Cr2O3-Fe2O3 composite passive film. Conversely, galvanic action between spherical graphite and the surrounding matrix caused significant corrosion in NCI, with a depth reaching 1.241 μm. The DLC piston coating obstructed the permeation pathway of formate ions due to its amorphous carbon structure. In corrosion solution #3, the recorded weight loss was 0.982 mg, which accounted for only 11.7% of the weight loss observed with the CKS piston coating. Following a 1500 h bench test, the combination of the HCCI cylinder liner and DLC-coated piston ring significantly reduced the wear depth. The average wear amounts at the top and bottom dead centers were 5.537 and 1.337 μm, respectively, representing a reduction of 67.7% compared with CRGCI, where the wear amounts were 17.152 and 4.244 μm. This research confirmed that the HCCI ferrite–Cr carbide matrix eliminated electrochemical heterogeneity, while the DLC piston coating inhibited abrasive wear. Together, these components reduced the wear amount at the top dead center on the push side by 80.1%. Furthermore, mismatches between the thermal expansion coefficients of the F38MnVS steel piston (12–14 × 10−6/°C) and gray cast iron (11 × 10−6/°C) resulted in a tolerance exceeding 0.105 mm in the cylinder fitting gap after 3500 h of testing. Notably, the combination of a HCCI matrix and DLC coating successfully maintained the gap within the required range of 50–95 μm. Full article
(This article belongs to the Special Issue Research on Performance Improvement of Advanced Alloys)
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28 pages, 9191 KiB  
Review
Research Progress on Alloying of High Chromium Cast Iron—Austenite Stabilizing Elements and Modifying Elements
by Shiqiu Liu and Li Liang
Crystals 2025, 15(3), 210; https://doi.org/10.3390/cryst15030210 - 22 Feb 2025
Cited by 2 | Viewed by 959
Abstract
High chromium cast iron (HCCI) is widely used in the manufacturing of equipment parts in the fields of mining, cement, electric power, metallurgy, the chemical industry, and paper-making because of its excellent wear and corrosion resistance. Although the microstructure and properties of HCCI [...] Read more.
High chromium cast iron (HCCI) is widely used in the manufacturing of equipment parts in the fields of mining, cement, electric power, metallurgy, the chemical industry, and paper-making because of its excellent wear and corrosion resistance. Although the microstructure and properties of HCCI can be modified by controlling the casting and heat treatment process, alloying is still the most basic and important method to improve the properties of HCCI. There are about 14 common alloying elements in HCCI, among which nickel, copper, and manganese are typical austenite stabilizing elements, which can increase austenite content and matrix electrode potential. The addition of elements such as silicon, nitrogen, boron, and rare earth (RE) is often small, but it has a significant effect on tailoring the microstructure, thereby improving wear resistance and impact toughness. It was thought that after years of development, the research on the role of the above elements in HCCI was relatively complete, but in the past 5 to 10 years, there has been a lot of new research progress. Moreover, the current development situation of HCCI is still relatively extensive, and there are still many problems regarding the alloying of HCCI to be further studied and solved. In this paper, the research results of austenitic stabilizing elements and modifying elements in HCCI are reviewed. The existing forms, distribution law of these elements in HCCI, and their effects on the microstructure, hardness, wear resistance, and corrosion resistance of HCCI are summarized. Combined with the current research situation, the future research and development direction of HCCI alloying is prospected. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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11 pages, 7141 KiB  
Article
Microstructural Insights into Solid Particle Erosion in a High-Chromium Cast Iron
by Alessio Suman, Annalisa Fortini and Nicola Zanini
Metals 2025, 15(1), 6; https://doi.org/10.3390/met15010006 - 26 Dec 2024
Viewed by 959
Abstract
Solid particle erosion (SPE) significantly limits the service life of High-Chromium Cast Irons (HCCIs), widely used in power generation and mining industries. This study investigates how microstructural features influence the erosion resistance of a Fe-Cr-C cast iron, focusing on the interplay between particle [...] Read more.
Solid particle erosion (SPE) significantly limits the service life of High-Chromium Cast Irons (HCCIs), widely used in power generation and mining industries. This study investigates how microstructural features influence the erosion resistance of a Fe-Cr-C cast iron, focusing on the interplay between particle kinetic energy and carbide features, i.e., carbide volume fraction (CVF). Erosion tests, conducted per ASTM G76 standards, revealed that substrates with similar CVFs exhibited varying damage levels, even at consistent particle kinetic energies. The findings underscored that impact conditions have a greater influence on erosion resistance than CVF alone, emphasizing the critical role of carbide morphology and distribution in mitigating damage. This work provides valuable insights for optimizing HCCIs to enhance material performance and durability in demanding erosive environments by tailoring carbide distribution to specific operational conditions. Full article
(This article belongs to the Special Issue Design, Processing and Characterization of Metals and Alloys)
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10 pages, 2335 KiB  
Article
Microstructure Formation and Dry Reciprocating Sliding Wear Response of High-Entropy Hypereutectic White Cast Irons
by Willian Martins Pasini, Wojciech Polkowski, Tomasz Dudziak, Carlos Alexandre dos Santos and Vinicius Karlinski de Barcellos
Metals 2025, 15(1), 4; https://doi.org/10.3390/met15010004 - 26 Dec 2024
Viewed by 769
Abstract
White cast irons (WCI) are widely used in industries requiring high wear resistance due to their microstructure consisting of hard carbides dispersed within a metallic matrix. This study focuses on developing wear-resistant multi-component hypereutectic high chromium cast irons, merging concepts of high entropy [...] Read more.
White cast irons (WCI) are widely used in industries requiring high wear resistance due to their microstructure consisting of hard carbides dispersed within a metallic matrix. This study focuses on developing wear-resistant multi-component hypereutectic high chromium cast irons, merging concepts of high entropy alloys with the conventional metallurgy of white cast irons, specifically exploring the influence of carbide-forming elements such as V, Mo, and Ni on solidification behavior, microstructure, and wear performance. The research investigates the solidification process of the alloys using Computer-Aided Cooling Curve Analysis (CA-CCA) and characterizes the microstructures through X-ray diffraction (XRD) and scanning electron microscopy (SEM). The wear behavior of the developed alloys is evaluated through reciprocating sliding wear tests, revealing the impact of varying chemical compositions on wear resistance. The results demonstrate that high-entropy white cast iron (HEWCI), particularly those enriched with carbide-forming elements, exhibit superior abrasion resistance compared to conventional high-chromium cast irons. The alloy with 2 Mo and 4 V content showed the best performance, presenting the lowest wear rate (61.5% lower than HCCI alloy) and CoF (values ranging from 0.20 to 0.22) due to the highest concentration of V carbides. Full article
(This article belongs to the Special Issue Casting Alloy Design and Characterization—2nd Edition)
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25 pages, 5327 KiB  
Article
Optimization of Energy Management Strategy for Series Hybrid Electric Vehicle Equipped with Dual-Mode Combustion Engine Under NVH Constraints
by Shupeng Zhang, Hongnan Wang, Chengkai Yang, Zeping Ouyang and Xiaoxin Wen
Appl. Sci. 2024, 14(24), 12021; https://doi.org/10.3390/app142412021 - 22 Dec 2024
Cited by 2 | Viewed by 1585
Abstract
Energy management strategies (EMSs) are a core technology in hybrid electric vehicles (HEVs) and have a significant impact on their fuel economy. Optimal solutions for EMSs in the literature usually focus on improving fuel efficiency by operating the engine within a high efficiency [...] Read more.
Energy management strategies (EMSs) are a core technology in hybrid electric vehicles (HEVs) and have a significant impact on their fuel economy. Optimal solutions for EMSs in the literature usually focus on improving fuel efficiency by operating the engine within a high efficiency range, without considering the drivability, which is affected by noise–vibration–harshness (NVH) constraints at low vehicle speeds. In this paper, a dual-mode combustion engine was implemented in a plug-in series hybrid electric vehiclethat could operate efficiently either at low loads in homogeneous charge compression ignition (HCCI) mode or at high loads in spark ignition (SI) mode. An equivalent consumption minimization strategy (ECMS) combined with a dual-loop particle swarm optimization (PSO) algorithm was designed to solve the optimal control problem. A MATLAB/Simulink simulation was performed using a well-calibrated model of the target HEV to validate the proposed method, and the results showed that it can achieve a reduction in fuel consumption of around 1.3% to 9.9%, depending on the driving cycle. In addition, the operating power of the battery can be significantly reduced, which benefits the health of the battery. Furthermore, the proposed ECMS-PSO is computationally efficient, which guarantees fast offline optimization and enables real-time applications. Full article
(This article belongs to the Special Issue Recent Developments in Electric Vehicles)
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7 pages, 1705 KiB  
Proceeding Paper
Study of the Negative Work Area in the p-V Diagram of an HCCI Engine
by Csaba Tóth-Nagy
Eng. Proc. 2024, 79(1), 22; https://doi.org/10.3390/engproc2024079022 - 4 Nov 2024
Viewed by 813
Abstract
Homogeneously charged compression ignition is a promising combustion process that is proven to increase combustion efficiency and decrease exhaust emissions when compared to Otto or Diesel engine efficiencies and emissions. The HCCI process can be considered an advancement on the path to sustainability. [...] Read more.
Homogeneously charged compression ignition is a promising combustion process that is proven to increase combustion efficiency and decrease exhaust emissions when compared to Otto or Diesel engine efficiencies and emissions. The HCCI process can be considered an advancement on the path to sustainability. However, improper control of the start of combustion causes the efficiency of the engine to drop significantly. The reason for this efficiency drop is that an early start of combustion causes the piston on the upward stroke to experience increased cylinder pressure after the combustion process is complete. The piston must further compress the cylinder content until it reaches the top dead center. During this process, the piston still experiences an increased gas force on the way towards TDC, having to invest extra disadvantageous work into the compression stroke, causing a negative work area in the pressure–volume diagram of the engine. The present study introduces the negative work area in the p-V diagram of an HCCI engine. It describes the phenomenon and explores the reasons behind it. It also investigates some of the factors affecting the negative work area in the p-V diagram. Full article
(This article belongs to the Proceedings of The Sustainable Mobility and Transportation Symposium 2024)
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14 pages, 2147 KiB  
Article
Performance of a Methanol-Fueled Direct-Injection Compression-Ignition Heavy-Duty Engine under Low-Temperature Combustion Conditions
by Mark Treacy, Leilei Xu, Hesameddin Fatehi, Ossi Kaario and Xue-Song Bai
Energies 2024, 17(17), 4307; https://doi.org/10.3390/en17174307 - 28 Aug 2024
Cited by 2 | Viewed by 1744
Abstract
Low-temperature combustion (LTC) concepts, such as homogeneous charge compression ignition (HCCI) and partially premixed combustion (PPC), aim to reduce in-cylinder temperatures in internal combustion engines, thereby lowering emissions of nitrogen oxides (NOx) and soot. These LTC concepts are particularly attractive for [...] Read more.
Low-temperature combustion (LTC) concepts, such as homogeneous charge compression ignition (HCCI) and partially premixed combustion (PPC), aim to reduce in-cylinder temperatures in internal combustion engines, thereby lowering emissions of nitrogen oxides (NOx) and soot. These LTC concepts are particularly attractive for decarbonizing conventional diesel engines using renewable fuels such as methanol. This paper uses numerical simulations and a finite-rate chemistry model to investigate the combustion and emission processes in LTC engines operating with pure methanol. The aim is to gain a deeper understanding of the physical and chemical processes in the engine and to identify optimal engine operation in terms of efficiency and emissions. The simulations replicated the experimentally observed trends for CO, unburned hydrocarbons (UHCs), and NOx emissions, the required intake temperature to achieve consistent combustion phasing at different injection timings, and the distinctively different combustion heat release processes at various injection timings. It was found that the HCCI mode of engine operation required a higher intake temperature than PPC operation due to methanol’s low ignition temperature in fuel-richer mixtures. In the HCCI mode, the engine exhibited ultra-low NOx emissions but higher emissions of UHC and CO, along with lower combustion efficiency compared to the PPC mode. This was attributed to poor combustion efficiency in the near-wall regions and engine crevices. Low emissions and high combustion efficiency are achievable in PPC modes with a start of injection around a crank angle of 30° before the top dead center. The fundamental mechanism behind the engine performance is analyzed. Full article
(This article belongs to the Special Issue Towards Climate Neutral Thermochemical Energy Conversion)
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16 pages, 3531 KiB  
Article
Combustion Test for the Smallest Reciprocating Piston Internal Combustion Engine with HCCI on the Millimeter Scale
by Huichao Shang, Li Zhang, Zhigang Tang, Jinlin Han, Yingzhang Wang and Tao Zhang
Appl. Sci. 2024, 14(16), 7359; https://doi.org/10.3390/app14167359 - 21 Aug 2024
Viewed by 1289
Abstract
Micro reciprocating piston internal combustion engines are potentially desirable for high-energy density micro power sources. However, complex subsystem functions hinder the downsizing of reciprocating piston internal combustion engines. The homogeneous charge compression-ignition (HCCI) combustion mode requires no external ignition system; it contributes to [...] Read more.
Micro reciprocating piston internal combustion engines are potentially desirable for high-energy density micro power sources. However, complex subsystem functions hinder the downsizing of reciprocating piston internal combustion engines. The homogeneous charge compression-ignition (HCCI) combustion mode requires no external ignition system; it contributes to structural simplification of the reciprocating piston internal combustion engines under a micro space constraint but has not been adequately verified at the millimeter scale. The study used a millimeter-scale HCCI reciprocating piston internal combustion engine fueled by a mixture of kerosene, ether, castor oil, and isopropyl nitrate for combustion investigation. The test engine with a displacement of 0.547 cc is the smallest reciprocating piston internal combustion engine known to have undergone in-cylinder combustion diagnosis. It is observed that the HCCI combustion mode at the millimeter scale can realize stable combustion with excellent cooperation for the thermodynamic cycle under appropriate structural and operating conditions, which is essentially not inferior to those in conventional-sized reciprocating piston internal combustion engines. This finding helps the next step of scaling down reciprocating piston internal combustion engines. Full article
(This article belongs to the Section Applied Thermal Engineering)
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26 pages, 6187 KiB  
Article
Controllability of Pre-Chamber Induced Homogeneous Charge Compression Ignition and Performance Comparison with Pre-Chamber Spark Ignition and Homogeneous Charge Compression Ignition
by Josip Krajnović, Sara Ugrinić, Viktor Dilber and Darko Kozarac
Appl. Sci. 2024, 14(15), 6451; https://doi.org/10.3390/app14156451 - 24 Jul 2024
Cited by 1 | Viewed by 951
Abstract
This paper presents an experimental and numerical evaluation of the pre-chamber induced HCCI combustion concept (PC-HCCI) in terms of engine performance, emissions, and controllability. In this concept, a spark-initiated combustion in the pre-chamber is utilized to trigger the kinetically controlled combustion of an [...] Read more.
This paper presents an experimental and numerical evaluation of the pre-chamber induced HCCI combustion concept (PC-HCCI) in terms of engine performance, emissions, and controllability. In this concept, a spark-initiated combustion in the pre-chamber is utilized to trigger the kinetically controlled combustion of an ultra-lean mixture in the main combustion chamber. The experimental measurements were performed on a single-cylinder engine with a custom-made active pre-chamber. A high compression ratio of 17.5 was used, which limits the maximum achievable engine load due to high knocking tendency but enables both standard PCSI combustion (flame propagation) at very high dilution levels and HCCI combustion at reasonable intake temperatures. The analysis of combustion characteristics and the resulting performance is performed at indicated mean effective pressures (IMEPs) of 3.5 and 3.0 bars, and three different intake temperatures of 80 °C, 90 °C, and 100 °C. The variation in engine load was achieved by adjusting the excess air ratio in the main chamber. On each combination of intake temperature and engine load, a spark sweep and an injected PC fuel mass sweep were performed to obtain the highest indicated efficiency while satisfying the restrictions in terms of combustion stability and knock intensity. It was shown that, unlike in a conventional HCCI engine, the combustion phasing can be directly and reliably controlled by adjusting either spark timing or the reactivity of the pre-chamber mixture, ensuring adequate combustion stability and eliminating potential misfires. A similar indicated efficiency as with conventional HCCI combustion was obtained, while the NOx emissions, although slightly elevated, are still insignificant. Compared to PCSI combustion at the same engine load, a 4-percentage-point increase in indicated efficiency and two times lower NOx emissions were achieved. Compared to the most efficient PCSI operating point, it was 1 percentage point lower, indicating that efficiency was achieved, but the specific NOx emissions are reduced by approximately 70%. Most importantly, very similar performance was obtained with significant variations in intake temperature, proving the reliability and adaptability of this combustion concept. Full article
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18 pages, 6027 KiB  
Article
The Effect of Combustion Phase According to the Premixed Ethanol Ratio Based on the Same Total Lower Heating Value on the Formation and Oxidation of Exhaust Emissions in a Reactivity-Controlled Compression Ignition Engine
by Se-Hun Min and Hyun-Kyu Suh
Fire 2024, 7(7), 258; https://doi.org/10.3390/fire7070258 - 19 Jul 2024
Viewed by 1517
Abstract
A compression ignition engine generates power by using the auto-ignition characteristics of fuel injected into the cylinder. Although it has high fuel efficiency, it discharges a lot of exhaust emissions such as NOX and PM. Therefore, there is much ongoing research aiming [...] Read more.
A compression ignition engine generates power by using the auto-ignition characteristics of fuel injected into the cylinder. Although it has high fuel efficiency, it discharges a lot of exhaust emissions such as NOX and PM. Therefore, there is much ongoing research aiming to reduce the exhaust emissions by using the technologies applied in this regard, such as PCCI, HCCI, etc. However, these methods still discharge large exhaust emissions. The RCCI method, which combines the spark ignition method and compression ignition method, is attracting attention. So, in this work, the objective of this study is to numerically investigate the effect of combustion phase according to the premixed ethanol ratio based on the same total heating value in-cylinder by changing the initial air composition on the formation and oxidation of exhaust emissions in the RCCI engine. The heating value of the premixed ethanol ratio varied from 0% to 40% based on the same total lower heating value in-cylinder in steps of 10%. It was assumed that the ethanol introduced into the cylinder through the premixing chamber was evaporated, and the initial air composition in the cylinder was changed and set. It was revealed that when the premixed ratio based on the same total lower heating value was increased, the introduced fuel amount into the crevice volume with advancing the start of energizing timing was decreased, which increased the peak cylinder pressure. In addition, the ignition delay was also longer due to the low cylinder temperature by the evaporation latent heat of the ethanol, which reduced the compression loss, so the IMEP value was increased. The rich equivalence ratio had a narrow distribution in the cylinder, which caused a reduction in cylinder temperature, so the NO formation amount was reduced. The ISCO value increased the increase in premixed ethanol ratio based on the same total lower heating value in-cylinder because the flame propagation of ethanol by combustion of diesel did not work well, and the CO formed by combustion was slowly oxidized due to the cylinder’s low temperature as a result of the evaporation latent heat of ethanol. From these results, the optimal operating conditions for simultaneously reducing the exhaust emissions and improving the combustion performance were judged such that the start of energizing timing was BTDC 23 deg, and the premixed ethanol ratio based on the same total lower heating value in-cylinder was 40%. Full article
(This article belongs to the Special Issue Ignition Mechanism and Advanced Combustion Technology)
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15 pages, 7073 KiB  
Article
Numerical Simulation of Infiltration Behavior of ZTAP/HCCI Composites
by Xu He, Yu Lu, Xiangming Li, Mojin Zhou and Yehua Jiang
Crystals 2024, 14(4), 355; https://doi.org/10.3390/cryst14040355 - 10 Apr 2024
Cited by 1 | Viewed by 1216
Abstract
According to statistics, 80% of failed components in mechanical equipment are caused by various types of wear and corrosion. Therefore, in order to reduce material loss, research on wear-resistant materials is urgent. In order to solve the difficulty of directly observing the infiltration [...] Read more.
According to statistics, 80% of failed components in mechanical equipment are caused by various types of wear and corrosion. Therefore, in order to reduce material loss, research on wear-resistant materials is urgent. In order to solve the difficulty of directly observing the infiltration process of liquid metal in preform, this study first conducted infiltration experiments on liquid metal in ZTA ceramic particle preform at different pouring temperatures, and then used Fluent software to numerically simulate the infiltration behavior of liquid metal in preform. By changing parameters such as pouring temperature and infiltration pressure, the influence of these parameters on the penetration depth of liquid metal in prefabricated structures was determined. The research results indicate that when the pouring temperatures are 1420 °C, 1570 °C, 1720 °C, and 1870 °C, the infiltration depths are 4 mm, 8 mm, 11 mm, and 15 mm; when the casting infiltration pressures are 7620 Pa, 15,240 Pa, 22,860 Pa, and 30,480 Pa, the infiltration depths are 10 mm, 16 mm, 20 mm, and 22 mm. The simulation results of the pouring temperature on the infiltration depth are basically consistent with the experimental results. Full article
(This article belongs to the Special Issue Modern Technologies in the Manufacturing of Metal Matrix Composites)
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18 pages, 3970 KiB  
Article
Experimental Study of a Homogeneous Charge Compression Ignition Engine Using Hydrogen at High-Altitude Conditions
by Andrés David Morales Rojas, Sebastián Heredia Quintana and Iván Darío Bedoya Caro
Sustainability 2024, 16(5), 2026; https://doi.org/10.3390/su16052026 - 29 Feb 2024
Cited by 2 | Viewed by 2719
Abstract
One of the key factors of the current energy transition is the use of hydrogen (H2) as fuel in energy transformation technologies. This fuel has the advantage of being produced from the most primary forms of energy and has the potential [...] Read more.
One of the key factors of the current energy transition is the use of hydrogen (H2) as fuel in energy transformation technologies. This fuel has the advantage of being produced from the most primary forms of energy and has the potential to reduce carbon dioxide (CO2) emissions. In recent years, hydrogen or hydrogen-rich mixtures in internal combustion engines (ICEs) have gained popularity, with numerous reports documenting their use in spark ignition (SI) and compression ignition (CI) engines. Homogeneous charge compression ignition (HCCI) engines have the potential for substantial reductions in nitrogen oxides (NOx) and particulate matter (PM) emissions, and the use of hydrogen along with this kind of combustion could substantially reduce CO2 emissions. However, there have been few reports using hydrogen in HCCI engines, with most studies limited to evaluating technical feasibility, combustion characteristics, engine performance, and emissions in laboratory settings at sea level. This paper presents a study of HCCI combustion using hydrogen in a stationary air-cooled Lombardini 25 LD 425-2 modified diesel engine located at 1495 m above sea level. An experimental phase was conducted to determine the intake temperature requirements and equivalence ratios for stable HCCI combustion. These results were compared with previous research carried out at sea level. To the best knowledge of the authors, this is the first report on the combustion and operational limits for an HCCI engine fueled with hydrogen under the mentioned specific conditions. Equivalence ratios between 0.21 and 0.28 and intake temperatures between 188 °C and 235 °C effectively achieved the HCCI combustion. These temperature values were, on average, 100 °C higher than those reported in previous studies. The maximum value for the indicated mean effective pressure (IMEPn) was 1.75 bar, and the maximum thermal efficiency (ITEn) was 34.5%. The achieved results are important for the design and implementation of HCCI engines running solely on hydrogen in developing countries located at high altitudes above sea level. Full article
(This article belongs to the Topic Advanced Engines Technologies)
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