Browse Topic: Low temperature combustion (LTC)

Items (380)
Diesel engines are largely used as power units with high fuel efficiency. Conversely, they have an adverse impact on the environment and human health as they emit high NOx and particulate matter emissions. As more stringent regulations for emissions are introduced, low temperature combustion strategy such as Gasoline Compression Ignition evolved and demonstrated the potential to reduce the particulate matter and NOx emissions by operating engines under a Partially Premixed Combustion mode. Therefore, a 0.55 mm single cylinder engine (Gasoline Direct Injection), was tested over range of engine loads with constant speed (1500 rpm) using RON80 without oxygenates. Different operating parameters such as injection, exhaust gas recirculation (EGR) etc. were used to control combustion phasing and mixture stratifications. At low loads, rebreathing of hot exhaust gas produced low levels of NOx and smoke emissions. It reduced NOx by 60% and smoke levels below 0.20 FSN when it is coupled with low
Qahtani, Yasser AlSellnau, MarkYu, Xin
The rising demand for vehicles has increased CO and HC emissions, worsening air quality and contributing to climate change, key issues under the clean development mechanism and UN SDG 13: Climate Action. Reactivity-Controlled Compression Ignition (RCCI) offers a promising solution to reduce PM and NOx while maintaining fuel efficiency. However, the cyclic variation of the RCCI engine remains an underexplored area in control strategies, necessitating further research for optimization in line with sustainable development goals. This study explores the impact of premixing ratios on RCCI engines fueled with butanol and the nature of cyclic variation to know the controllability. Tests were conducted on a single-cylinder diesel engine at 1500 rpm and constant engine load. The experiments reveal that increasing the premixing ratio from 45% to 60% decreases the heat release rate by 15%, Pmax by 10%, and IMEP by 12%. Recurrence Quantitative Analysis (RQA) confirmed strong deterministic
Yadav, Ratnesh KumarMohite, Avadhoot AbasoMaurya, Rakesh Kumar
A numerical investigation has been performed in the current work on reactivity-controlled compression ignition (RCCI), a low-temperature combustion (LTC) strategy that is beneficial for achieving lower oxides of nitrogen (NOx) and soot emission. A light-duty diesel engine was modified to run in RCCI mode. Experimental data were acquired using diesel as HRF (high-reactivity fuel) and gasoline as LRF (low reactivity fuel) to check the accuracy and fidelity of predicted results. Blends of ethanol and gasoline with DTBP (di-tert-butyl peroxide) addition in a small fraction on an energy basis were used in numerical simulations to promote ignitability and reactivity enhancement of PFI charge. Achieving stable, smooth, and gradual combustion in RCCI is challenging at low loads, especially in light-duty engines, due to misfiring and poor combustion stability. DTBP is known for enhancing cetane number and accelerating combustion, and it is mixed in a PFI blend to avoid combustion deterioration
Tripathi, SaurabhKrishnasamy, Anand
Low-temperature heat release (LTHR) is of interest for its potential to help control autoignition in advanced compression ignition (ACI) engines and mitigate knock in spark ignition (SI) engines. Previous studies have identified and investigated LTHR in both ACI and SI engines before the main high-temperature heat release (HTHR) event and, more recently, LTHR in isolation has been demonstrated in SI engines by appropriately curating the in-cylinder thermal state during compression and disabling the spark discharge. Ethanol is an increasingly common component of market fuel blends, owing to its renewable sources. In this work, the effect of adding ethanol to iso-octane (2,2,4-trimethylpentane) blends on their LTHR behavior is demonstrated. Tests were run on a motored single-cylinder engine elevated inlet air temperatures and pressures were adjusted to realize LTHR from blends of iso-octane and ethanol without entering the HTHR regime. The blends were tested with inlet temperatures of 40
White, Samuel PhilipBajwa, Abdullah UmairLeach, Felix
Biogas (60% methane–40% CO2 approximately) can be used in the reactivity-controlled compression ignition (RCCI) mode along with a high-reactivity fuel (HRF). In this work dimethyl ether (DME) that can also be produced from renewable sources was used as the HRF as a move toward sustainable power generation. The two-cylinder turbocharged diesel engine modified to work in the DME–biogas RCCI (DMB-RCCI) mode was studied under different proportions of methane (45–95%) in biogas since the quality of this fuel can vary depending on the feedstock and production method. Only a narrow range of biogas to DME ratios could be tolerated in this mode at each output without misfire or knock. Detailed experiments were conducted at brake mean effective pressures (BMEPs) of 3 and 5 bar at a speed of 1500 rpm and comparisons were made with the diesel–biogas dual-fuel and diesel–biogas RCCI modes under similar methane flow rates while the proportion of CO2 was varied. The DMB-RCCI mode exhibited superior
Gopa Kumar, S.Mohan, AneeshRamesh, A.
The global imperative to develop clean energy solutions has redirected research efforts towards highly efficient combustion engines with ultra-low emissions. This has prompted investigations into alternative combustion concepts, including Low Temperature Combustion (LTC), utilizing environmentally friendly fuels. Within the scope of our research project, we are primarily focused on the development of an innovative combustion concept known as Homogeneous Reactivity-Controlled Compression Ignition (hRCCI), which employs renewable fuels such as ethanol and 1-octanol for a serial hybrid powertrain. The lack of predictive simulations for this concept presents a significant challenge in optimizing the engine's operation. Most of the 1D system simulation models use a non-predictive combustion model for combustion simulations. Due to the dependence on auto-ignition chemistry, a chemistry based hRCCI combustion model for real time computation has been proposed with this work. Based on the
Sundaram, Pravin KumarGrundl, Larissa MichaelaTrapp, Christian
Low temperature combustion (LTC) modes are among the advanced combustion technologies which offer thermal efficiencies comparable to conventional diesel combustion and produce ultra-low NOx and particulate matter (PM) emissions. However, combustion timing control, excessive pressure rise rate and high cyclic variations are the common challenges encountered by the LTC modes. These challenges can be addressed by developing model-based control framework for the LTC engine. In the current study, in-cylinder pressure data for dual-fuel LTC engine operation is analyzed for 636 different operating conditions and the heat release rate (HRR) traces are classified into three distinct classes based on their distinct shapes. These classes are named as Type-1, Type-2 and Type-3, respectively. To this end, HRR traces are analyzed for each class based on start of combustion (CA10), combustion phasing (CA50), burn duration (BD), maximum in-cylinder pressure (Pmax), location of peak pressure (θPmax
Batool, SadafNaber, JeffreyShahbakhti, Mahdi
A numerical investigation of a six-stroke direct injection compression ignition engine operation in a low temperature combustion (LTC) regime is presented. The fuel employed is a gasoline-like oxygenated fuel consisting of 90% isobutanol and 10% diethyl ether (DEE) by volume to match the reactivity of conventional gasoline with octane number 87. The computational simulations of the in-cylinder processes were performed using a high-fidelity multidimensional in-house 3D CFD code (MTU-MRNT) with improved spray-sub models and CHEMKIN library. The combustion chemistry was described using a two-component (isobutanol and DEE) fuel model whose oxidation pathways were given by a reaction mechanism with 177 species and 796 reactions. The key advantage of six-stroke engine operation is the ability to switch the combustion mode among kinetical controlled mode (KCM), kinetically-driven mixing control mode (K-MCM) and mixing controlled mode (MCM) in the second power stroke (PS2) providing a wider
Purushothaman, Ashwin KarthikRa, YoungchulHa, Kyoung PyoZhu, ShengrongUllal, Ankith
Reactivity Controlled Compression Ignition (RCCI) is a promising, high-efficiency, clean combustion mode for diesel engines. One of the significant limitations of RCCI is its higher unburned hydrocarbon (HC) and carbon monoxide (CO) emissions compared to conventional diesel combustion. After-treatment control of HC and CO emissions is difficult to achieve in RCCI because of lower exhaust gas temperatures associated with the low-temperature combustion (LTC) mode of operation. The present study involves combined experimental and computational fluid dynamic (CFD) investigations to develop the most effective HC and CO control strategy for RCCI. A production light-duty diesel engine is modified to run in RCCI mode by introducing electronic port fuel injection with the replacement of mechanical injectors by the CRDI system. Experimental data were obtained using diesel as HRF (High reactive fuel) and gasoline as LRF (low reactive fuel). The combustion simulation was performed using the
Tripathi, SaurabhKrishnasamy, Anand
This study investigates the effects on combustion characteristics of aluminum oxide (Al2O3) nanoparticles as additives for diesel in a constant volume chamber. Depending on the amount of aluminum oxide nanoparticles added, the test fuels are labeled as DA25, DA50, and DA100, which represent 25, 50, and 100 mg of aluminum oxide nanoparticles into 1 L of pure diesel, respectively. The ambient temperature for this experiment ranged from 800 to 1200 K to cover conventional and low-temperature combustion regimes. The oxygen concentration ranged from 21% to 13% to simulate different levels of exhaust gas recirculation (EGR). Based on in-cylinder pressure traces and results of apparent heat release rates, there was an improvement in combustion characteristics with the addition of aluminum oxide nanoparticles. The best combustion characteristics improvement was obtained under 800K/13% oxygen concentration case, where peak combustion pressure and heat release rate increased by 1.84% and 5.42
Ji, HuangchangLee, TimothyZhao, ZhiyuChen, Shengwei
Reactivity-controlled compression ignition (RCCI) engine is an innovative dual-fuel strategy, which uses two fuels with different reactivity and physical properties to achieve low-temperature combustion, resulting in reduced emissions of oxides of nitrogen (NOx), particulate matter, and improved fuel efficiency at part-load engine operating conditions compared to conventional diesel engines. However, RCCI operation at high loads poses challenges due to the premixed nature of RCCI combustion. Furthermore, precise controls of indicated mean effective pressure (IMEP) and CA50 combustion phasing (crank angle corresponding to 50% of cumulative heat release) are crucial for drivability, fuel conversion efficiency, and combustion stability of an RCCI engine. Real-time manipulation of fuel injection timing and premix ratio (PR) can maintain optimal combustion conditions to track the desired load and combustion phasing while keeping maximum pressure rise rate (MPRR) within acceptable limits. In
Punasiya, MohitSarangi, Asish Kumar
Compression ignition engines used in heavy-duty applications are typically powered by diesel fuel. The high energy density and feedstock abundance provide a continuing source for the immense energy demand. However, the heavy-duty transportation sector is challenged with lowering greenhouse gas and combustion by-product emissions, including carbon dioxide, nitrogen oxides, and particulate matter. The continuing development of engine management and combustion strategies has proven the ability to meet current regulations, particularly with higher fuel injection pressure. Nonetheless, a transition from diesel to a renewable alternative fuel source will play a significant role in reducing greenhouse gases while maintaining the convenience and energy density inherent in liquid fuels. Dimethyl ether is a versatile fuel that possesses combustion properties suitable for compression ignition engines and physical properties helpful for clean combustion. The higher volatility of DME may permit
Leblanc, SimonWang, LinyanSandhu, Navjot SinghYu, XiaoZheng, Ming
Electrification of transport, together with the decarbonization of energy production are suggested by the European Union for the future quality of air. However, in the medium period, propulsion systems will continue to dominate urban mobility, making mandatory the retrofitting of thermal engines by applying combustion modes able to reduce NOx and PM emissions while maintaining engine performances. Low Temperature Combustion (LTC) is an attractive process to meet this target. This mode relies on premixed mixture and fuel lean in-cylinder charge whatever the fuel type: from conventional through alternative fuels with a minimum carbon footprint. This combustion mode has been subject of numerous modelling approaches in the engine research community. This study provides a theoretical comparative analysis between multi-zone (MZ) and Transported probability density function (TPDF) models applied to LTC combustion process. The generic thermo-kinetic balances for both approaches have been
Maroteaux, FadilaMancaruso, EzioPommier, Pierre-LinVaglieco, Bianca Maria
Chemical-kinetics-based multizone models (MZM) are effective tools for performance-oriented simulations of low-temperature combustion concepts. It demonstrates a better trade-off between simulation speed and predictivity than both high-fidelity computational fluid dynamics (CFD) and low-fidelity data-driven models. This study applies a newly developed MZM, referred to as UVATZ, to simulate reactivity-controlled compression ignition (RCCI) combustion, fueled by natural gas (NG) and diesel. In such a concept, in-cylinder conditions at intake valve closing (IVC) largely define the kinetically dominated combustion predictions. To secure IVC predictions accurately, UVATZ is for the first time coupled with a detailed air/fuel path dynamics model created in commercial engine modeling software (GT-Suite), forming a 1D simulation framework. The direct coupling enables information exchange of initial and boundary conditions between the two models including IVC and EVO thermodynamic state, wall
Kakoee, AlirezaVasudev, AneeshSmulter, BenHyvonen, JariMikulski, Maciej
One of the main challenges in internal combustion engine design is the simultaneous reduction of all engine pollutants like carbon monoxide (CO), total unburned hydrocarbons (THC), nitrogen oxides (NOx), and soot. Low-temperature combustion (LTC) concepts for compression ignition (CI) engines, e.g., premixed charged compression ignition (PCCI), make use of pre-injections to create a partially homogenous mixture and achieve an emission reduction. However, they present challenges in the combustion control, with the usage of in-cylinder pressure sensors as feedback signal is insufficient to control heat release and pollutant emissions simultaneously. Thus, an additional sensor, such as an ion-current sensor, could provide further information on the combustion process and effectively enable clean and efficient PCCI operation. This study performed experiments in a high-temperature, high-pressure, constant-flow combustion vessel to verify the ion-current application for premixed charge
Golc, DominikEsposito, StefaniaPitsch, HeinzBeeckmann, Joachim
Using renewable fuels is a reliable approach for decarbonization of combustion engines. iso-Butanol and n-butanol are known as longer chain alcohols and have the potential of being used as gasoline substitute or a renewable fraction of gasoline. The combustion behavior of renewable fuels in modern combustion engines and advanced combustion concepts is not well understood yet. Low-temperature combustion (LTC) is a concept that is a basis for some of the low emissions-high efficiency combustion technologies. Fuel ɸ-sensitivity is known as a key factor to be considered for tailoring fuels for these engines. The Lund ɸ-sensitivity method is an empirical test method for evaluation of the ɸ-sensitivity of liquid fuels and evaluate fuel behavior in thermal. iso-Butanol and n-butanol are two alcohols which like other alcohol exhibit nonlinear behavior when blended with (surrogate) gasoline in terms of RON and MON. In this study, first the Lund ɸ-sensitivity numbers of iso-butanol and n-butanol
Alemahdi, NikaGarcia, AntonioTuner, Martin
This paper is the first of three papers stemming from a dual fuel Chrysler prototype engine which uses both diesel and gasoline direct injection running at stoichiometric conditions, as part of a project to explore the viability of incorporating an engine platform which utilizes low temperature combustion regimes into a modern automotive application. The combustion system used high rates of EGR while maintaining combustion stability by using high charge motion intake port and a high energy ignition system. The engine ran highly dilute SI combustion at low loads, Diesel Assisted Spark Ignition at medium loads and a transition to Diesel Micro Pilot ignition at medium to high load. This paper explores diesel assisted spark ignited combustion at medium loads 6.5 bar to 12.7 bar BMEP. The second paper will explore the use of diesel micro-pilot ignition at high loads 10.6 bar to 14.5 bar BMEP and the third paper to be published in 2024 will explore fuel property effects (mainly Cetane and
Church, WilliamMcConnell, Steven
This paper is the second of three papers stemming from a dual fuel Chrysler prototype engine which uses both diesel and gasoline direct injection running at near-stoichiometric conditions, as part of a project to explore the viability of incorporating an engine platform which utilizes low temperature combustion regimes into a modern automotive application. The combustion system was designed to tolerate high rates of EGR while maintaining combustion stability by using high charge motion intake port and a high energy ignition system. The engine ran on highly dilute SI combustion at low loads, Diesel Assisted Spark Ignition at medium loads and a transition to Diesel Micro Pilot ignition at medium to high load. The first paper explored the use of Diesel Assisted Spark Ignited at moderate loads 6.5 bar to 12.7 bar BMEP and the third paper to be published in 2024 will explore fuel property effects (mainly Cetane and Octane) through the use of alternative fuels. This paper explores the use of
Church, WilliamMcConnell, Steven
An experimental test bed study was conducted in a 3.8-liter diesel common rail engine with a gasoline port injection to evaluate the aftertreatment strategy in low- and high-reactive fuel. The selection of diesel oxidation catalyst (DOC) and precious group metal (PGM) content is critical for low-temperature combustion (LTC) (dual fuel) to control hydrocarbon (HC) and carbon monoxide (CO) emissions. Three DOCs with different PGM contents were tested along with different dual-fuel compositions to understand their effectiveness and particle mass composition. The chemical composition of exhaust particles from the engine out and DOC out are compared. An increase in low-reactive fuel (D15G85) and an increase in PGM content highlights a significant reduction in particle mass (PM) from 31 mg/kWhr to 2 mg/kWhr. The major reduction in particle size distribution observed with high PGM loading is 40 nm with a dual-fuel configuration of D15G85 as the best approach to meet emission standards
Barman, JyotirmoyDeshmukh, Devendra Laxmanrao
A comprehensive study was conducted in an experimental engine, on the combustion/emissions characteristics of Partially Premixed Combustion (PPC) with either n-butanol or ethanol at either 30% or 40% Port Fuel Injection (PFI) by mass, and Conventional Diesel Combustion (CDC) was used to compare the performance of each PPC test conducted. It was found in the combustion analysis that PPC with either n-butanol or ethanol had several advantageous combustion characteristics compared to CDC, such as Peak Pressure Rise Rate (PPRR, bar/CAD), Ringing Intensity (RI, MW/m2), and Apparent Heat Release Rate (AHRR). As the load was increased, Low Temperature Heat Release (LTHR) and Negative Temperature Coefficient (NTC) regions were extended for PPC with n-butanol when comparing PPC with ethanol. Although PPC consisted of 30% and 40% low-reactivity PFI fuel by mass, combustion pressure was observed to have similar peak values with CDC experiments. It was found that as the PFI percentage
Soloiu, ValentinCarapia, CesarSmith, RichardWeaver, AmandaParker, LilyBrock, DillanMckinney, LeviMolina, GustavoIlie, Marcel
Reactivity controlled compression ignition (RCCI) is a potential low-temperature combustion (LTC) technique for running intrinsically efficient compression ignition engines while reducing the oxides of nitrogen (NOx) and particulate matter (PM) emissions. However, poor low-load combustion efficiency is a major challenge in the RCCI strategy. In this work, a combination of injection strategy and cold and hot exhaust gas recirculation (EGR) strategies were investigated to improve the low-load combustion efficiency of a production light-duty compression ignition engine operating in the gasoline-diesel dual-fuel RCCI mode. The engine was operated at a low load of 3 bar gross indicated mean effective pressure and at an engine speed of 1500 rpm with wide ranges of single and multiple fuel injection strategies. Significant improvement in combustion efficiency was achieved by targeting the directly injected diesel fuel in the piston lip region. Multiple fuel injection strategy in which more
Khedkar, Nikhil DilipSarangi, Asish K.
Strict measures in emission regulations constantly lead researchers to technologies that are cleaner, renewable, and energy conversion efficient. Reactivity controlled compression ignition (RCCI), which is a low-temperature combustion (LTC) mode, is a promising technology providing simultaneously low nitrogen oxides (NOx) and soot emissions without reduction in engine thermal efficiency. However, the fact that the operating range is still not wide enough compared to conventional engines is one of the most challenging obstacles to RCCI engines. In this study the effects of the premixed ratio (PR) on engine operating range and emissions were investigated experimentally. A compression ignition (CI) engine was modified to be run in RCCI mode. Gasoline and diesel fuels were used as fuel pair in the experiments. The engine was operated at three different PRs of PR25, PR50, and PR75. It was found that the widest operating ranges and minimum brake specific fuel consumption (BSFC) values were
Şahin, FatihHalis, SerdarYıldırım, EmreAltın, MuratBalaban, FethiSolmaz, HamitYücesu, H. Serdar
High thermal efficiency and low engine-out emissions including nitrogen oxides (NOx) and particulate matter (PM) make low-temperature combustion (LTC) favorable for use in engine technologies. Homogeneous charge compression ignition (HCCI), partially premixed charge compression ignition (PPCI), and reactivity controlled compression ignition (RCCI) are among the common LTC modes. These three LTC modes can be achieved on the same dual-fuel engine platform; thus, an engine controller can choose the best LTC mode for each target engine load and speed. To this end, a multi-mode engine controller is needed to adjust the engine control variables for each LTC mode. This article presents a model-based control development of a 2.0-liter multi-mode LTC engine for cycle-to-cycle combustion control. The engine is equipped with port fuel injectors (PFI) and direct injectors (DI). All combustion modes are achieved with dual fuels (iso-octane and n-heptane) under naturally aspirated conditions. Using
Batool, SadafNaber, JeffreyShahbakhti, Mahdi
Simultaneous reduction of engine pollutants (e.g., CO, THC, NOx, and soot) is one of the main challenges in the development of new combustion systems. Low-temperature combustion (LTC) concepts in compression ignition (CI) engines like premixed charged compression ignition (PCCI) make use of pre-injections to create a partly homogenous mixture. In the PCCI combustion regime, a direct correlation between injection and pollutant formation is no longer present because of long ignition delay times. In LTC combustion systems, the in-cylinder pressure sensor is normally used to help the combustion control. However, to allow the control of PCCI engines, new sensor concepts are investigated to obtain additional information about the PCCI combustion for advanced controller structures. In LTC combustion systems like gasoline-controlled autoignition (GCAI) concepts, the application of ion current sensors enables additional monitoring of the combustion process with real-time capability. In analogy
Golc, DominikEsposito, StefaniaLoffredo, FrancescaPitsch, HeinzBeeckmann, Joachim
With low-temperature combustion engine research reaching an applicable level, physics-based control-oriented models regain attention. For reactivity controlled combustion concepts, chemical kinetics-based multizone models have been proven to reproduce the governing physics for performance-oriented simulations. They offer accuracy levels similar to high-fidelity computational fluid dynamics (CFD) models but with a fraction of their computational effort. Nevertheless, state-of-the-art reactivity controlled compression ignition (RCCI) simulations with multizone model toolchains still face challenges related to predictivity and calculation speed. This study introduces a new multizone modelling framework that addresses these challenges. It includes a C++ code, deeply integrated with open-source, thermo-kinetic libraries, and coupled to an industry standard 1-D modelling framework. Incorporating a predictive turbulence mixing model, it aims to eliminate dependence on CFD-based initialisation
Vasudev, AneeshCafari, AlbertoAxelsson, MartinMikulski, MaciejHyvonen, Jari
A commercially available fuel, E85, a blend of ~85% ethanol and ~15% gasoline, can be a viable substitute for fossil fuels in internal combustion engines in order to achieve a reduction of the greenhouse gas (GHG) emissions. Ethanol is traditionally made of biomass, which makes it a part of the food-feed-fuel competition. New processes that reuse waste products from other industries have recently been developed, making ethanol a renewable and sustainable second-generation fuel. So far, work on E85 has focused on spark ignition (SI) concepts due to high octane rating of this fuel. There is very little research on its application in CI engines. Alcohols are known for low soot particle emissions, which gives them an advantage in the NOx-soot trade-off of the compression ignition (CI) concept. Therefore, the main objective of this research is to experimentally characterise the impact of E85 on performance and emissions of a heavy-duty (HD) direct ignition compression ignition (DICI) engine
Novakovic, MajaTuner, MartinGarcia, AntonioVerhelst, Sebastian
Gasoline compression ignition using a single gasoline-type fuel has been shown as a method to achieve low-temperature combustion with low engine-out NOx and soot emissions and high indicated thermal efficiency. However, key technical barriers to achieving low temperature combustion on multi-cylinder engines include the air handling system (limited amount of exhaust gas recirculation) as well as mechanical engine limitations (e.g. peak pressure rise rate). In light of these limitations, high temperature combustion with reduced amounts of exhaust gas recirculation appears more practical. Furthermore, for high temperature Gasoline compression ignition, an effective aftertreatment system allows high thermal efficiency with low tailpipe-out emissions. In this work, experimental testing was conducted on a 12.4 L multi-cylinder heavy-duty diesel engine operating with high temperature gasoline compression ignition combustion using EEE gasoline. Engine testing was conducted at an engine speed
Pamminger, MichaelAddepalli, Srinivasa KrishnaScarcelli, RiccardoWallner, Thomas
Homogeneous charged compression ignition (HCCI) engine is a low-temperature combustion (LTC) strategy with higher thermal efficiency and ultra-low NOx and particulate matter emission. Syngas is a renewable and clean alternative fuel that has gained researchers' interest, and it is one of the alternatives to fossil fuels. Syngas can be a suitable fuel for HCCI Engines due to their characteristics of high flame speed, lower flammability limits, and low auto-ignition temperatures. This paper presents the crank angle-based exergy analysis of syngas fuelled HCCI engines. Energy and exergy analysis is essential for the better performance and utilization of the HCCI engine. The syngas HCCI engine is numerically simulated in this study using a stochastic reactor model (SRM). In SRM models, physical parameters are described by a probability density function (PDF), and these parameters do not vary within the combustion chamber. Thus, the spatial distribution (due to local inhomogeneity) of the
Saxena, Mohit RajRanjane, VishwajeetMaurya, Rakesh Kumar
Premixed Charge Compression Ignition (PCCI) is a promising LTC strategy to reduce NOx and soot emissions without relying on after-treatment devices. One major drawback of PCCI is high HC and CO emissions resulting from fuel-wall impingement due to early injection of diesel. Narrow-angle direct injection (NADI) helps reduce the wall wetting of fuel. But it is effective only at lower loads. At mid and higher loads, it increases soot and CO emissions in small-bore engines due to the formation of fuel-rich pockets in the piston bowl region. This problem is addressed using a split injection strategy in the present work. A 3-D CFD model is developed and validated with experimental data at two load conditions. Simulations are performed using CONVERGE CFD software. Split injection strategies are explored using wide (148 deg) and narrow (88 deg) spray included angles. The investigations concluded that a main injection of 20 deg bTDC and 30 deg bTDC were optimal for wide and narrow spray
V, PradeepKrishnasamy, Anand
Autoignition enhancing additives have been used for years to enhance the ignition quality of diesel fuel, with 2-ethylhexyl nitrate (EHN) being the most common additive. EHN also enhances the autoignition reactivity of gasoline, which has advantages for some low-temperature combustion techniques, such as Sandia’s Low-Temperature Gasoline Combustion (LTGC) with Additive-Mixing Fuel Injection (AMFI). LTGC-AMFI is a new high-efficiency and low-emissions engine combustion process based on supplying a small, variable amount of EHN into the fuel for better engine operation and control. However, the mechanism by which EHN interacts with the fuel remains unclear. In this work, a chemical-kinetic mechanism for EHN was developed and implemented in a detailed mechanism for gasoline fuels. The combined mechanism was validated against shock-tube experiments with EHN-doped n-heptane and HCCI engine data for EHN-doped regular E10 gasoline. Simulations showed a very good match with experiments. EHN
Lopez Pintor, DarioDec, John
Reactivity Controlled Compression Ignition (RCCI) is a low temperature combustion regime that has demonstrated ultra-low NOx and soot while achieving high thermal efficiency. RCCI uses a low reactivity premixed charge which is ignited via direct injection of a high reactivity fuel. The aim is to create a nearly homogeneous charge but maintain control over the combustion timing via the ratio between the premixed and direct injected fuel, hence controlling global reactivity via reactivity gradients in-cylinder. RCCI combustion with gasoline as the premixed fuel and diesel as the high reactivity fuel has shown good combustion timing controllability. However, RCCI with alcohol fuels, in which pure alcohol is the low reactivity premixed fuel and the alcohol doped with a reactivity enhancer is the direct injected high reactivity fuel, has shown a lack of control over the combustion timing, which is undesirable. This study attempts to regain control over the timing of combustion by using the
Chowdhury, MusharratDempsey, Adam
Among the new low temperature combustion modes, Reactivity-Controlled Compression Ignition (RCCI) offers a low NOx-soot trade off (keeping a relatively high engine efficiency). Also, RCCI permits the introduction of a renewable fuel with a lower CO2 direct emission such as short-chains alcohols. For this work, methanol and diesel fuel were used as low and high reactivity fuels, respectively. A 1.3 L single-cylinder engine, with a cylinder volume usual in medium- and heavy-duty truck and bus engines, was used in this work. The engine was operated at an engine speed of 1600 rpm and 25% load (representing one of the 13-mode test on medium duty trucks), which results in an indicated mean effective pressure of 5.2 bar. The effects of methanol substitution ratio (MSR) at 20 and 35% on performance and pollutant emissions was investigated and compared to conventional diesel combustion (CDC). The main target of the work is to find an optimum point according to a defined objective function for
Rodriguez-Fernandez, JoséHernandez, Juan J.Ramos, ÁngelBarba, JavierDomínguez Pérez, Víctor M.Horcajada Torres, ÓscarCasero-Alonso, VíctorRodríguez-Aragón, Licesio J.
In the past years, stringent emission regulations for Internal Combustion (IC) engines produced a large amount of research aimed at the development of innovative combustion methodologies suitable to simultaneously reduce fuel consumption and engine-out emissions. Previous research demonstrates that the goal can be obtained through the so-called Low Temperature Combustions (LTC), which combine the benefits of compression-ignited engines, such as high compression ratio and unthrottled lean operation, with a properly premixed air-fuel mixture, usually obtained injecting gasoline-like fuels with high volatility and longer ignition delay. Gasoline Partially Premixed Combustion (PPC) is a promising LTC technique, mainly characterized by the high-pressure direct-injection of gasoline and the spontaneous ignition of the premixed air-fuel mixture through compression, which showed a good potential for the simultaneous reduction of fuel consumption and emissions in CI engines. Despite its
Ravaglioli, VittorioPonti, FabrizioSilvagni, GiacomoMoro, DavideStola, FedericoDe Cesare, Matteo
Progressively stringent emission regulations and increasing regulatory demands on fuel economy have led to advanced combustion development. Low temperature combustion (LTC), specifically homogenous charge compression ignition (HCCI), is a promising technology for reducing exhaust emissions and improving efficiency. However, its operating range is limited to low load without boosting and EGR, due to low volumetric efficiency and high pressure rise rates. In addition, effectively controlling the combustion phasing is another challenge in realizing the associated combustion gains. In this work, advanced valve control mechanisms known as continuously variable valve duration (CVVD) and continuously variable valve timing (CVVT) were used for both intake and exhaust valvetrains to enable negative valve overlap (NVO) for trapping hot exhaust residuals and to promote multipoint simultaneous ignition. Heat release phasing was controlled by varying the fueling scheme and by adjusting the amount
Zhu, ShengrongJoo, Nahm RohHollowell, JeffreyHa, Kyoung-PyoShirley, MarkFantin, NickolasWagh, Mayuri
Homogeneous charge compression ignition (HCCI) combustion is low-temperature combustion (LTC) mode that offers an alternative to conventional combustion modes. The advantages of HCCI combustion include high conversion efficiency and low NOx emissions. On the other hand, a direct control mechanism for combustion phasing control is not attainable as in conventional SI (spark ignition) or CI (compression ignition) engines. This limits the HCCI operational range and provides one of the biggest challenges in HCCI mode commercial implementation. High heat release rates and knock initiation limit the high load operation, whereas combustion instabilities limit the low load operation. In this context, this paper explores the use of water injection technique to control the combustion phasing and expand the load of an ethanol HCCI engine. The experiments were conducted on a three-cylinder diesel engine, where all the exhaust gases from a diesel cylinder were used to achieve the HCCI combustion in
Telli, Giovani D.Rocha, Luiz A.O.Zulian, Guilherme Y.Lanzanova, Thompson D.M.Martins, Mario E.S.
The carbon-neutral biodiesel is a promising renewable substitute for fossil diesel that renders the traditional oxides of nitrogen-particulate matter (NOx-PM) trade-off into a unidirectional NOx control problem. Low-temperature combustion (LTC) modes such as homogenous charge compression ignition (HCCI) are attractive for obtaining ultra-low NOx and PM emissions. Studies on utilizing biodiesel fuel for HCCI combustion mode are sparsely available. Moreover, biodiesel emulsions in the HCCI combustion mode have not been attempted so far. Based on this premise, the present work explored the potential to utilize biodiesel and its emulsions having 20% and 25% water by volume under HCCI operating conditions. Biodiesel was prepared from a non-edible Karanja oil. The biodiesel emulsions were prepared using a heated magnetic stirrer apparatus with 3% by volume of the raw Karanja oil as a surfactant. A production light-duty diesel engine is modified to run in external mixture preparation based
Gowrishankar, SudarshanKrishnasamy, AnandJ, Pradeep Bhasker
Low Temperature Combustion (LTC) is an emerging technology that offers an alternative to conventional spark and compression ignition. A highly discussed LTC mode is homogeneous charge compression ignition (HCCI), which consists in a combustion of a highly diluted well-mixed charge at the end of compression stroke, when the charge reaches the auto-ignition state. Since HCCI is an LTC mode, it can result in low NOX emissions with an indicated efficiency comparable to a diesel engine. Otherwise, there are some challenges to overcome such as achieving high loads without knocking and combustion timing control. Several methods to control the combustion had been investigated, between them, the injection of water may be useful to extend HCCI knock free operation and to enable combustion phasing control. This work investigated the influence of water injection in the intake of an ethanol HCCI cylinder from a converted diesel generator set. The EGR, used in HCCI, was obtained via total
Zulian, Guilherme Y.do Prado F., Lincoln M.Garlet, Roberto A.Martins, Mario E. S.Lanzanova, Thompson D. M.Telli, Giovani D.
Over the last years, automotive industries drove a great amount of research in the field of advanced combustion techniques minimizing carbon dioxide emissions. The so-called Low-Temperature Combustions (LTC), characterized by the self-ignition of highly premixed air-fuel mixtures, represent a promising solution to achieving high efficiency and ultralow emissions of nitrogen oxides (NOx) and particulate matter. Among these, gasoline Partially Premixed Combustion (PPC), obtained through the high-pressure direct injections of gasoline, showed a good potential for the simultaneous reduction of pollutants and emissions in compression ignited engines. However, when multiple injections per cycle are performed (with hydraulic-assisted needle opening), combustion stability might be compromised by the wave effects in the hydraulic system, which produce incoherence between the requested and injected fuel. This work presents a model-based pressure waves reconstruction strategy, based on a control
Silvagni, GiacomoRavaglioli, VittorioPonti, FabrizioCorti, EnricoRaggini, LorenzoScocozza, GuidoStola, FedericoDe Cesare, Matteo
The stringent emission regulations for Internal Combustion Engines (ICEs) spawned a great amount of research in the field of innovative combustion approaches characterized by high efficiency and low emissions. Previous research demonstrate that such promising techniques, named Low-Temperature Combustion (LTC), combine the benefits of Compression Ignition (CI) engines, such as high compression ratio and unthrottled lean mixture, with low engine-out emissions using a properly premixed air-fuel mixture. Due to longer ignition delay and high volatility compared to diesel, gasoline-like fuels show good potential for the generation of a highly premixed charge, which is needed to reach LTC characteristics. In this scenario, gasoline Partially Premixed Combustion (PPC), characterized by the high-pressure direct injection of gasoline, showed good potential for the simultaneous reduction of pollutants and emissions in CI engines. However, previous research on gasoline CI highlight that a key
Ravaglioli, VittorioPonti, FabrizioSilvagni, GiacomoMoro, DavideStola, FedericoDe Cesare, Matteo
Premixed charged compression ignition (PCCI) is a promising low temperature combustion strategy for achieving a simultaneous reduction of oxides of nitrogen (NOx) and soot emissions in diesel engines. However, early direct injection results in a significant penalty in fuel economy, high unburned hydrocarbon (HC), and carbon monoxide (CO) emissions, especially in small-bore diesel engines. In the present work, computational fluid dynamic (CFD) investigations are carried out in a small-bore diesel engine using a commercial CFD software, CONVERGE. The computational models are validated with experimental results at two different load conditions, 20% and 40% of rated load. The validated models are used to carry out parametric investigations on the effects of fuel injection parameters, namely the start of fuel injection timing, injection pressure, and spray cone angle on PCCI combustion. The fuel-air equivalence ratio, temperature, and emission contours are used to get more insight into the
Pradeep, VKrishnasamy, Anand
Prior research studies have investigated a wide variety of gasoline compression ignition (GCI) injection strategies and the resulting fuel stratification levels to maintain control over the combustion phasing, duration, and heat release rate. Previous GCI research at the US Department of Energy’s Oak Ridge National Laboratory has shown that for a combustion mode with a low degree of fuel stratification, called “partial fuel stratification” (PFS), gasoline range fuels with anti-knock index values in the range of regular-grade gasoline (~87 anti-knock index or higher) provides very little controllability over the timing of combustion without significant boost pressures. On the contrary, heavy fuel stratification (HFS) provides control over combustion phasing but has challenges achieving low temperature combustion operation, which has the benefits of low NOX and soot emissions, because of the air handling burdens associated with the required high exhaust gas recirculation rates. This work
Curran, ScottSzybist, JamesKaul, BrianEaster, JordanSluder, Scott
For controlling oxides of nitrogen (NOx) and particular matter (PM) emissions from diesel engines, various fuel and combustion mode modification strategies are investigated in the past. Low temperature combustion (LTC) is an alternative combustion strategy that reduces NOx and PM emissions through premixed lean combustion. Dual fuel reactivity-controlled compression ignition (RCCI) is a promising LTC strategy with better control over the start and end of combustion because of reactivity and equivalence ratio stratification. However, the unburned hydrocarbon (HC) and carbon monoxide (CO) emissions are significantly higher in RCCI, especially at part-load conditions. The present work intends to address this shortcoming by utilizing oxygenated alternative fuels. Considering the limited availability and higher cost, replacing conventional fuels completely with alternative fuels is not feasible. Based on this premise, oxygenated alternative fuel blends, viz. methanol and Karanja biodiesel
Nemade, PushpakKrishnasamy, Anand
Extensive experimental investigations done over a decade in different engine types demonstrated the capability of achieving high efficiency along with low levels of oxides of nitrogen (NOx) and soot emissions with low temperature combustion (LTC) modes. However, the commercial application of LTC strategies requires several challenges to be addressed, including precise ignition timing control, reducing higher unburned hydrocarbon (UHC) and carbon monoxide (CO) emissions. The lower exhaust gas temperatures with LTC operation pose severe challenges for after-treatment control systems. Among the available LTC strategies, Reactivity Controlled Compression Ignition (RCCI) has emerged as the most promising strategy due to better ignition timing control with higher thermal efficiency. Nevertheless, the complexity of engine system hardware due to the dual fuel injection system and associated controls, high HC and CO emissions are the major limiting factors in RCCI. Homogeneous Charge with
chaurasiya, rishabhKrishnasamy, Anand
The research on reducing emissions from automotive engines through modifications in the combustion mode and the fuel type is gaining momentum because of the increasing contribution to global warming by the transportation sector. The combustion and emission formation in the advanced low temperature combustion (LTC) engine strategies are susceptible to fuel molecular composition and properties. Ignition timing in LTC strategies is primarily controlled by fuel composition and associated chemical kinetics. Thus, tailoring of fuel properties is required to address the limitations of LTC in terms of lack of control on ignition timing and narrow engine operating load range. Utilizing fuel blends and additives such as nanoparticles is a promising approach to achieving targeted fuel property. An improved understanding of fundamental processes, including fuel evaporation, is required due to its role in fuel-air mixing and emission formation in LTC. In the present work, evaporation
Gupta, Saurabh KumarKrishnasamy, Anand
Substantial fuel economy improvements for light-duty automotive engines demand novel combustion strategies. Low temperature combustion (LTC) demonstrates potential for significant fuel efficiency improvement; however, control complexity is an impediment for real-world transient operation. Spark-assisted compression ignition (SACI) is an LTC strategy that applies a deflagration flame to generate sufficient energy to trigger autoignition in the remaining charge. Operating a practical engine with SACI combustion is a key modeling and control challenge. Current models are not sufficient for control-oriented work such as calibration optimization, transient control strategy development, and real-time control. This work describes the process and results of developing a fast-running control-oriented model for the autoignition phase of SACI combustion. A data-driven model is selected, specifically artificial neural networks (ANNs). The models are trained to an experimentally-validated one
Robertson, DennisPrucka, Robert
The aim of this paper is to computationally investigate the combustion behavior and energy recovery processes of a six-stroke gasoline compression ignition (6S-GCI) engine that employs a continuously variable valve duration (CVVD) technique, under highly diluted, low-temperature combustion (LTC) conditions. The effects of variation of parameters concerning injection spray targeting (number of fuel injector holes. injector nozzle size and spray included angle) and combustion chamber geometry (piston bowl design) are analyzed using an in-house 3D CFD code coupled with high-fidelity physical sub-models with the Chemkin library in conjunction with a skeletal chemical kinetics mechanism for a 14-component gasoline surrogate fuel. The foundation of this study stems from the authors previous works, regarding the effects of the change in various operating parameters on the overall performance of 6S-GCI engine, which show that both kinetically-controlled mode of combustion (KCM) and mixing
Rajput, OudumbarRa, YoungchulPurushothaman, Ashwin KarthikHa, Kyoung-Pyo
With the increasing demand of emission reductions from the automotive industry, advanced after-treatment strategies have been investigated to overcome the challenges associated with meeting increasingly stringent emission regulations. Ongoing investigations on low temperature combustion (LTC) strategies are being researched to meet future emission regulations, however, the lowered exhaust temperature presents an even greater issue for exhaust after-treatment due to the change in combustion modes. Catalyst temperature is critical for the catalytic ability to maintain effective conversion efficiency of regulated emissions. The use of periodic flow reversal has shown benefits of maintaining catalyst temperature by alternating the exhaust flow direction through the catalytic converter, reducing the catalyst sensitivity to inlet gas temperature fluctuations. Cyclically alternating the exhaust flow direction can produce a thermal wave, elevating the central catalyst temperature above the
Hesketh, CavanLiang, LiSandhu, Navjot SinghHan, XiaoyeWang, MeipingZheng, Ming
Environmental pollution as a result of improper disposal of agricultural and food industry waste has been a concern lately. In the present study, an attempt has been made to produce energy from these wastes. Biodiesel produced from residual cooking oil (RCOB) and hexanol produced from agricultural waste have been investigated as alternatives to petroleum-based fossil fuels in a dual-fuel low-temperature combustion engine. Hexanol was injected in the inlet port at 3 bar injection pressure whereas RCOB was injected directly inside the combustion chamber using a common rail direct injection system. The proportion of Hexanol to RCOB was varied from 40% to 60% at rated load. The operating parameters such as intake air temperature, exhaust gas recirculation (EGR) quantity along with multiple injection timing, duration, quantity, and pressure were optimized for lower oxides of nitrogen (NOx) and smoke emissions. Intake air temperature of 40 °C, EGR rate of 30 %, and direct injection timings
Thomas, Justin JacobNagarajan, GovindanVR, SabuSharma, Vikas
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