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Low-temperature combustion is an emerging engine technology that has the ability to yield low NOx and soot emissions while maintaining high fuel efficiency. Low-temperature combustion strategies include homogeneous charge compression ignition, premixed charge compression ignition, reactivity-controlled compression ignition and partially premixed co...
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... are various LTC strategies, including HCCI, PCCI (also known as partially premixed com- bustion (PPC)) and RCCI. Figure 3 illustrates the evo- lution of these LTC strategies with the focus on their advantages and disadvantages compared to conventional CI and SI strategies. In the LTC strategy, by premixing a significant portion of the fuel and relying on long igni- tion delay (ID) times, high-temperature flame fronts can be avoided, which inhibits NO x formation and reduces heat transfer losses, and the resulting higher ratio of spe- cific heats can further increase efficiency. ...
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... RCCI combustion results indicated that it has sig- nificant potential with more than a 15% improvement in modeled light-duty (LD) vehicle fuel economy. 90 Figure 13 shows the key benefit of the dual-fuel RCCI combustion process over a single-fuel HCCI process. It has the ability to control combustion phas- ing when the operating conditions change. ...
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... GDI injection pressures ranged from 150 to 200 bar, while the CRI pressures ranged from 250 to 500 bar, and the SOI timings ranged from 235° and 2115° ATDC. Figure 23(a) displays the CA50 combustion phasing as a function of SOI timing. 111 Exploring the effect of the oxygen concentration and intake temperature on RCCI combustion efficiency at light load ...
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... earliest injection timings provided relatively long mixing durations, which resulted in reduced amounts of locally rich pockets of diesel fuel, thus weakening the ignition sources along with the increase in the ID, allowing for combustion to retard. Figure 23(b) shows the calculated combustion efficiency for each experi- mental point. It is seen that for an appropriate combus- tion phasing ATDC, the CRI injector provides a 1% increase in combustion efficiency over the GDI injec- tor. ...
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... first study on application of natural gas with the RCCI concept was conducted by Nieman et al. 123 They used the KIVA-3V CFD code in conjunction with the CHEMKIN chemistry tool and the NSGA II algorithm to perform optimization for a wide range of methane-diesel RCCI engine operating conditions. A comparison between the optimum 9-bar IMEP gasoline-diesel HD RCCI strategy and the 9-bar IMEP natural gas-diesel strategy can be seen in Figure 30. The gasoline-diesel RCCI strategy was optimized at a relatively high boost, while the natural gas-diesel strategy utilized low boost. ...
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... and combustion efficiency for RCCI combustion using B20 compared to ULSD. 151 Figure 30. Comparison of optimum 9-bar IMEP gasoline- diesel and natural gas-diesel strategies for RCCI combustion. ...
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... experimentally studied the impact of gas quality in a diesel-compressed natural gas (CNG) RCCI engine. Figure 31 shows the combustion phasing and combus- tion duration for different gas qualities. As can be seen, the start of combustion (SOC) shows little variation for earlier injection. ...
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... piston bowl profile was optimized for RCCI operation to reduce unburned fuel emissions and piston bowl surface area using genetic algorithm (GA) optimization, in conjunc- tion with the KIVA code. Figure 32 compares combus- tion, performance and engine-out emission results for all piston designs at the mentioned operating condi- tions. The pumping mean effective pressure (PMEP) of the RCCI piston was typically lower than the OEM pis- ton in both RCCI and CDC modes, except when there was a drastic difference in intake pressure. ...
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... addition, the high levels of piston- induced mixing that are created by narrow or deep pis- ton bowls increase the heat transfer coefficient and fur- ther add to the heat transfer losses. Therefore, the more quiescent combustion chamber created by the wide or Figure 31. Combustion phasing and combustion duration for different gas qualities at 1800 r/min, 9 bar BMEP. ...
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... bowl is beneficial for PCI strategies. Dempsey et al. 171 investigated the use of a modified piston featur- ing a shallow, flat piston bowl with nearly no squish land in a gasoline-diesel and a methanol-diesel RCCI engines (see Figure 33). Using the modified piston, the GIE of RCCI combustion was significantly improved at light loads due to increases in combustion efficiency and decreases in heat transfer losses. ...
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... LD MCE RCCI experiments performed at ORNL were guided by CFD, and chemical kinetics modeling performed by Curran et al. 90 focused on an operating point of 2300 r/min, 4.4 bar brake mean effective pressure (BMEP), which is representative of a moderate road load or light acceleration in a LD pas- senger vehicle. These experiments focused on the chal- lenges of implementing RCCI on an MCE, including the importance of cylinder-to-cylinder balancing, Figure 32. Comparison of combustion, performance and engine-out emission results for three piston designs at mentioned operating conditions. ...
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... of combustion, performance and engine-out emission results for three piston designs at mentioned operating conditions. 189 Figure 33. Comparison of the stock GM piston (solid line) and the modified RCCI piston bowls (dashed line) at TDC. 171 Figure 34, regarding HC speciation, there was an increase in aldehyde-, ketone-and gasoline-specific spe- cies such as benzene and toluene in RCCI compared to CDC and diesel PCCI. ...
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... Figure 33. Comparison of the stock GM piston (solid line) and the modified RCCI piston bowls (dashed line) at TDC. 171 Figure 34, regarding HC speciation, there was an increase in aldehyde-, ketone-and gasoline-specific spe- cies such as benzene and toluene in RCCI compared to CDC and diesel PCCI. Moreover, the PM mass emis- sion rate was compared for these three strategies, as seen in Figure 35(a), and the results showed that dual- fuel RCCI PM mass emissions were 40% less than the CDC but two times greater than the diesel PCCI. ...
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... of the stock GM piston (solid line) and the modified RCCI piston bowls (dashed line) at TDC. 171 Figure 34, regarding HC speciation, there was an increase in aldehyde-, ketone-and gasoline-specific spe- cies such as benzene and toluene in RCCI compared to CDC and diesel PCCI. Moreover, the PM mass emis- sion rate was compared for these three strategies, as seen in Figure 35(a), and the results showed that dual- fuel RCCI PM mass emissions were 40% less than the CDC but two times greater than the diesel PCCI. This was attributed to volatile HC accumulating on the filter in dual-fuel RCCI operation. ...
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... was attributed to volatile HC accumulating on the filter in dual-fuel RCCI operation. The RCCI, CDC and PCCI filters are also shown in Figure 35(b). The differ- ent colors of the PM are correlated with the black car- bon (BC) content of the PM, so CDC had the highest BC fraction and RCCI had the least (;1%). ...
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... differ- ent colors of the PM are correlated with the black car- bon (BC) content of the PM, so CDC had the highest BC fraction and RCCI had the least (;1%). In other research, they found that the use of a diesel oxidation catalyst (DOC) was able to reduce the PM mass by nearly 50%, 30% and 6% for RCCI, CDC and PCCI, respectively (see Figure 36). 201 This was again attrib- uted to oxidizing volatile organic compounds with the DOC. ...
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... was possible to operate the engine using RCCI combustion during engine speed transient conditions. Figure 37 compares CDC and RCCI combustion performance between open-and closed-loop operations. For CDC, combustion noise and CA50 follow the steady-state values as CA50 increases with engine speed. ...
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Recently, considerable efforts are made by the engine researches all over the world, focusing primarily on achieving ultra-low emissions of NOx (nitrogen oxides) and soot without any compromise to high thermal efficiency from dual-fuel engine. In this study, combustion performance and engine-out emission of a single cylinder gasoline-diesel dual-fu...
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... Still, considerable scope for improvement in this technology exists which withholds it from widespread adoption. These include hydrocarbon emissions at low and part loads [10], combustion stability [11], high PRR [12], and thermal management for efficient after-treatment [13]. In addition, the diverse production pathways that affect the composition of future fuels, combined with the need for flexible fuel operation, position H 2 in an admixed form as a promising solution to address the identified challenges. ...
Hydrogen (H2) admixing in Reactivity Controlled Compression Ignition (RCCI) technology engines is touted to enhance indicated efficiency (ITE>50%), optimize combustion and reduce greenhouse gas emissions. However, many pending issues remain regarding engine durability, nitrogen oxide (NOX) emissions and blending limits. These issues are addressed by employing a novel performance-oriented model which simulates under 3 min, combustion physics with similar predictivity (>95% accuracy) as computational fluid dynamic results. This so-called multizone model is parameterized to real-world operating cycles from a dual-fuel mid-speed marine engine. By considering port-fuel injected H 2 , the simulations show that combustion phasing advances at an average rate of 0.3⁰CA/% H 2 , accompanied by a peak reduction in methane slip of 80% achievable at 25% H 2 energy share. Also, engine control-oriented issues are addressed by demonstrating either intake temperature or diesel fuel share optimization to negate the drawbacks of combustion harshness and NO X emissions, while improving ITE 1-1.5pp over baseline operation. Nomenclature Abbreviations BR Blend ratio CA50 Crank angle at 50% energy released CFD Computational fluid dynamics CHR Cumulative heat release CL Combustion losses HCCI Homogeneous charge compression ignition HRF High reactivity fuel HRR heat release rate iEGR Internal exhaust gas recirculation IMEP indicated mean effective pressure IMEP720 net indicated mean effective pressure IMO International maritime organization ISx Indicated specific quantity (x: fuel, NO X , UHC) ITE Indicated thermal efficiency IVC Intake valve closing LFO Light fuel oil LHV Lower heating value (continued on next column) (continued) Abbreviations LRF low reactivity fuel LTC low temperature combustion MPRR Maximum pressure rise rate MZM Multizone model NG Natural gas NHR net heat released NOX Oxides of nitrogen PCCI Premixed charge compression ignition PMEP pumping mean effective pressure pp Percentage points PRR pressure rise rate RCCI Reactivity controlled compression ignition RMSE root mean square error SE Standard error SOC Start of combustion SOI Start of injection TDC top dead centre TDR Turbulent dissipation rate (continued on next page)
... A significant trend in ANN applications is observed in reactivity-controlled compression ignition engines, as elucidated by Paykani et al. [87]. Their study explores lowtemperature combustion strategies, including reactivity-controlled compression ignition, which uses dual-fuel partially premixed combustion. ...
This paper explores the integration and advancements of artificial neural networks (ANNs) in modeling diesel engine performance, particularly focusing on biodiesel-fueled engines. ANNs have emerged as a vital tool in predicting and optimizing engine parameters, contributing to the enhancement of fuel efficiency and a reduction in emissions. The novelty of this review lies in its critical analysis of the existing literature on ANN applications in biodiesel engines, identifying gaps in optimization and emission control. While ANNs have shown promise in predicting engine parameters, fuel efficiency, and emission reduction, this paper highlights their limitations and areas for improvement, especially in the context of biodiesel-fueled engines. The integration of ANNs with big data and sophisticated algorithms paves the way for more accurate and reliable engine modeling, essential for advancing sustainable and eco-friendly automotive technologies. This research underscores the growing importance of ANNs in optimizing biodiesel-fueled diesel engines, aligning with global efforts towards cleaner and more sustainable energy solutions.
... Elaborating on the development of how new combustion technologies as well as electrification, can further improve the efficiency and emissions performance of internal combustion engines available (Duan et al., 2021;Paykani et al., 2015). These technologies aim to combine the best features of gasoline and diesel engines, achieving high efficiency with low emissions (Vedran & Božica, 2018). ...
The release of carbon emissions into the atmosphere has a negative impact on the environment. Carbon emissions are considered a significant factor in global warming. These harmful emissions trap heat and lead to an increase in the earth's average temperatures, which in turn causes melting polar ice caps, rising sea levels, and severe weather patterns. Fiveseater vehicles represent a significant portion of the global automotive fleet, making their emissions impactful in contributing to these environmental changes. This study investigates the relationship between engine size and CO2 emissions in five-seater vehicles using machine learning algorithms. Linear regression, ElasticNet, and neural networks were applied to a dataset of 38, 500 observations obtained from Kaggle. The study found a significant correlation between engine sizes and CO2 emissions. Factors such as engine displacement and fuel type were analysed and identified as contributors to CO2 emissions. The results indicate that advanced engine technologies such as turbochargers and hybrid systems can mitigate emissions by improving efficiency although the impact varies. These findings highlight the importance of engine downsizing and technological integration to reduce the automotive sector's carbon footprint. This study offers insights that can help guide environmentally-friendly strategies in the automotive industry.
... Market fuels have been considered irreplaceable, so the focus in developing Internal Combustion Engines (ICEs) has been entirely on the engine itself [4][5][6]. Despite continuous improvements over the last decades, which span from innovative combustion techniques [7][8][9][10] and new combustion control strategies [11][12][13], to more accurate and costeffective sensors [14][15][16] and pre-and after-treatment technologies [17,18], a change in approach is now required due to urgency of the climate crisis. In a new paradigm, the fuel and engine should be codeveloped as a system to make ICEs a sustainable option for the future of transportation [2,19]. ...
The practical use of hydrogen as a fuel for Internal Combustion Engines (ICEs) poses unresolved challenges. However, many issues concerning combustion control and emissions do not originate from the fuel itself but rather from the inevitable interference of lubricant oil in the combustion process. This study investigates the catalytic action of lubricant oil to elucidate certain pre-ignition events in hydrogen ICEs that are not yet fully understood. In pursuit of this goal, a numerical tool is developed, which can also contribute to improving the design of future powertrains. In the first part of the work, a reduced chemical model named the "HyLube" reaction mechanism was developed for investigating hydrogen-lubricant interactions. A single surrogate species, i.e., n-hexadecane (n-C 16 H 34), was selected to mimic the chemical properties of lubricant oil, based on prior research. Extensive validation using experimental data from the literature demonstrated the accuracy and reliability of the model. With 133 species and 2074 reactions, the kinetic mechanism is well-suited for integration into CFD simulations of engines. In the second part, using the "HyLube" mechanism, predictions were made to determine if lubricant oil contamination affects hydrogen ICE operation. Zero-dimensional simulations quantified the impact of adding the lubricant oil surrogate to H 2 /air mixtures on charge reactivity across a range of engine-like thermodynamic conditions, encompassing compression ratio and equivalence ratio variations. The findings indicated significant effects, especially at lower temperatures, suggesting potential hazards before combustion initiation.
... Furthermore, RCCI operation is characterised by high pressure rise rate (PRR) and peak cylinder pressure (P max ) levels [1] which limit high-load operation. Under part-and low-load conditions, unburnt hydrocarbons (UHC) and CO emissions become an issue [9]. ...
... The net cumulative heat release (CHR) is computed from the raw pressure trace, shown in Fig. 6b. For tuning the model to case C, a value of 3.8 is selected for HRF λ 10 , and ζ ∇ is determined based on seeding the remaining fuel among zones 1 to 9 according to Eq. (9). Thus, the piston and head boundary zones (11 and 12) are not seeded with HRF. ...
... In order to map the CFD-derived profile onto the zones of UVATZ, it first needs to be discretized, respecting the total mass of injected fuel. The basis is a routine similar to the previously utilised Eq. (9). Considering the exponential trend from Fig. 12b, modifications are made to the relation, as shown in Eq.14. ...
... Low temperature combustion contributes to low heat loss and thereby to the increase in the thermal efficiency of the engine [63]. Another benefit of the 'low temperature combustion' is that it can lead to low levels of NOx emissions which may help to meet regulation levels for so-called criteria pollutants [64][65][66]. The RCCI mode also offers some flexibility in the fuels used within the combustion process [64]. ...
... Another benefit of the 'low temperature combustion' is that it can lead to low levels of NOx emissions which may help to meet regulation levels for so-called criteria pollutants [64][65][66]. The RCCI mode also offers some flexibility in the fuels used within the combustion process [64]. ...
... On the other hand, using direct injection for both fuels is another promising solution. Avoiding wall wetting with early diesel injection remains an ongoing challenge, however [21]. Unlike other dual-fuel processes, HCII performs only one late diesel injection set at 12° before top dead center (BTDC), as shown in a study by Yu et al. [22]. ...
div class="section abstract"> Dual-fuel engines powered by renewable fuels provide a potential solution for reducing the carbon footprint and emissions of transportation, contributing to the goal of achieving sustainable mobility. The investigation presented in the following uses a dual-fuel engine concept running on biogas (referred to as CNG in this paper) and the e-fuel polyoxymethylene dimethyl ether (OME). The current study focuses on the effects of exhaust gas rebreathing and external exhaust gas recirculation (EGR) on emissions and brake thermal efficiency (BTE).
A four-cylinder heavy-duty engine converted to dual-fuel operation was used to conduct the engine tests at a load point of 1600 min-1 and 9.8 bar brake mean effective pressure (BMEP). The respective shares of high reactivity fuel (HRF, here: OME) and low reactivity fuel (LRF, here: CNG) were varied, as were the external and internal EGR rates and their combinations. CNG was injected into the intake manifold to create a homogeneous air-fuel mixture, while OME was introduced as a pilot injection directly into the combustion chamber. Results showed an increase in total hydrocarbons (THC) and carbon monoxide (CO) emissions, while nitric oxide (NOx) emissions were significantly reduced compared to diesel operation. Soot emissions were completely mitigated due to the absence of direct carbon bonds in both CNG and OME. For the initial stage of the study, exhaust gas rebreathing was implemented on only one exhaust valve through a second event lift. For the second part of the study, the second event lift was also installed on the other exhaust valve. At a substitution rate of 50 % CNG, THC emissions could be lowered by up to 35 %, CO emissions by up to 50 % and NOx emissions by up to 18 % with the use of internal EGR. The combination of internal and external EGR reduced emissions even further.
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... Airflow control, with a near stoichiometric [∅-1] airfuel ratio for SI engine, fuel flow control, with a lean [∅<1] air-fuel ratio for CI engine, and fuel flow control, often with a lean [∅≤1] air-fuel ratio or charge dilution for HCCI engine. The impact of three engines on exhaust emissions is as follows: increase NOx and CO2 at SI; reduce CO2 but increase NOx and PM at CI; and decrease NOx, CO2, and PM but increase HC and CO at HCCI [71]. The working principle of the HCCI engine depends on the four-stroke Otto cycle. ...
Renewable energy should be used instead of fossil fuels owing to the negative impact of fossil fuels on both humans and the environment, as well as the toxic emissions of carbon dioxide, unburned hydrocarbons, and nitrogen oxide. Studies investigated the consideration of using alternative fuel that is renewable, sustainable, and eco-friendly, especially because of the huge demand for energy, the decline, and the environmental initiatives to decrease the usage of petroleum sources. The addition of oxyhydrogen [HHO] to biodiesel and diesel blends can enhance characteristics; however, there is a concern about raising nitrogen oxide levels, which can have negative impacts on human lives and the environment, contributing to the increase of chronic respiratory conditions, acid rain occurrences, and global warming. Hence, it has been proposed that these issues can potentially be resolved by employing a homogeneous charge compression ignition engine fueled by a mixture of oxyhydrogen gas and biodiesel/diesel fuel to reduce nitrogen oxide until it is negligible. Recent research efforts have discussed the combination of oxyhydrogen gas with biodiesel and diesel blends in an HCCI engine. These studies were performed to obtain the characteristics that result in an improvement in the values of performance parameters like brake thermal efficiency [BTE], brake specific fuel consumption [BSFC], exhaust gas temperature [EGT or Texh.], and volumetric efficiency [ηvol.]. Furthermore, combustion parameters that include peak cylinder pressure [PCP], heat release rate [HRR], mean gas temperature [MGT], ignition delay [ID], and combustion duration [CD] were observed. In addition, exhaust emissions parameters such as nitrogen oxide [NOx], carbon monoxide [CO], unburned hydrocarbon [UHC or HC], carbon dioxide [CO2], exhaust oxygen [EO] or oxygen rate [O2], and smoke opacity [soot] were measured.
... Airflow control, with a near stoichiometric [∅-1] airfuel ratio for SI engine, fuel flow control, with a lean [∅<1] air-fuel ratio for CI engine, and fuel flow control, often with a lean [∅≤1] air-fuel ratio or charge dilution for HCCI engine. The impact of three engines on exhaust emissions is as follows: increase NOx and CO2 at SI; reduce CO2 but increase NOx and PM at CI; and decrease NOx, CO2, and PM but increase HC and CO at HCCI [71]. The working principle of the HCCI engine depends on the four-stroke Otto cycle. ...
Renewable energy should be used instead of fossil fuels owing to the negative impact of fossil fuels on both humans and the environment, as well as the toxic emissions of carbon dioxide, unburned hydrocarbons, and nitrogen oxide. Studies investigated the consideration of using alternative fuel that is renewable, sustainable, and eco-friendly, especially because of the huge demand for energy, the decline, and the environmental initiatives to decrease the usage of petroleum sources. The addition of oxyhydrogen [HHO] to biodiesel and diesel blends can enhance characteristics; however, there is a concern about raising nitrogen oxide levels, which can have negative impacts on human lives and the environment, contributing to the increase of chronic respiratory conditions, acid rain occurrences, and global warming. Hence, it has been proposed that these issues can potentially be resolved by employing a homogeneous charge compression ignition engine fueled by a mixture of oxyhydrogen gas and biodiesel/diesel fuel to reduce nitrogen oxide until it is negligible. Recent research efforts have discussed the combination of oxyhydrogen gas with biodiesel and diesel blends in an HCCI engine. These studies were performed to obtain the characteristics that result in an improvement in the values of performance parameters like brake thermal efficiency [BTE], brake specific fuel consumption [BSFC], exhaust gas temperature [EGT or Texh.], and volumetric efficiency [ηvol.]. Furthermore, combustion parameters that include peak cylinder pressure [PCP], heat release rate [HRR], mean gas temperature [MGT], ignition delay [ID], and combustion duration [CD] were observed. In addition, exhaust emissions parameters such as nitrogen oxide [NOx], carbon monoxide [CO], unburned hydrocarbon [UHC or HC], carbon dioxide [CO2], exhaust oxygen [EO] or oxygen rate [O2], and smoke opacity [soot] were measured.
... This value determines the time of the combustion process in the engine. However, in RCCI/HCCI (homogeneous charge compression ignition) and LTC (low temperature combustion) [224,225] engines this parameter does not affect the combustion process [226]. In DF engines, it is crucial to correctly calculate the heat release ratio, which is described in the following sections. ...
This paper presents a theoretical analysis of the selected properties of HCNG fuel calculations and a literature review of the other fuels that allow the storage of ecologically produced hydrogen. Hydrogen has the most significant CO2 reduction potential of all known fuels. However, its transmission in pure form is still problematic, and its use as a component of fuels modified by it has now become an issue of interest for researchers. Many types of hydrogen-enriched fuels have been invented. However, this article will describe the reasons why HCNG may be the hydrogen-enriched fuel of the future and why internal combustion (IC) piston engines working on two types of fuel could be the future method of using it. CO2 emissions are currently a serious problem in protecting the Earth’s natural climate. However, secondarily, power grid stabilization with a large share of electricity production from renewable energy sources must be stabilized with very flexible sources—as flexible as multi-fuel IC engines. Their use is becoming an essential element of the electricity power systems of Western countries, and there is a chance to use fuels with zero or close to zero CO2 emissions, like e-fuels and HCNG. Dual-fuel engines have become an effective way of using these types of fuels efficiently; therefore, in this article, the parameters of hydrogen-enriched fuel selected in terms of relevance to the use of IC engines are considered. Inaccuracies found in the literature analysis are discussed, and the essential properties of HCNG and its advantages over other hydrogen-rich fuels are summarized in terms of its use in dual-fuel (DF) IC engines.
