Browse Topic: HCCI engines

Items (1,136)

Simulation Study on EGR Condensate Flow and Uniformity of Each Cylinder in the Intake Manifold

2023-01-703410/30/2023

As engine technology developed continuously, engine with both turbocharging and EGR has been researched due to its benefit on improving the engine efficiency. Nevertheless, a technical issue has raised up while utilizing both turbocharging and EGR at the same time: excess condensed water existed in intake manifold which potentially trigger misfire conditions. In order to investigate the root-cause, a CFD model (conducted by CONVERGE CFD software) was presented and studied in this paper which virtually regenerated intake manifold flow-field with EGR condensed water inside. Based on the simulated results, it concluded that different initial conditions of EGR condensed water could significantly change the amount of water which deposited in each cylinder. Thus, a coefficient of variation of deposited condensed water amount among these cylinders, was marked as the evaluation reference of cylinder misfire. Theoretically, as this coefficient of variation reduced, the EGR condensed water from

Pan, Shiyi, Li, Guanting, Wang, Jinhua, Zhang, Nan, Xu, Zhiqin, Chen, Shanghua, Chen, Jun, Zhao, Shengwei

Numerical Investigations on Formation Process of N ₂ O in Ammonia/Hydrogen Fueled Pre-Chamber Jet Ignition Engine

2023-01-702310/30/2023

Ammonia is used as the carbon-free fuel in the engine, which is consistent with the requirements of the current national dual-carbon policy. However, the great amount of NOx in the exhaust emissions is produced after combustion of ammonia and is one kind of the most tightly controlled pollutants in the emission regulation. Nitrous Oxide (N2O) is a greenhouse gas with a very strong greenhouse effect, so that the N2O emissions needs to be paid close attention. In this paper, the CFD simulation of the N2O formation and emission characteristics during combustion is carried in the ammonia/hydrogen fueled pre-chamber jet ignition engine. The simulation results show that the turbulent kinetic energy (TKE) around the orifices of the pre-chamber is enhanced due to the local temperature difference between the main-chamber and the pre-chamber, and then the residual ammonia/hydrogen fuel in the crevice or near the cylinder wall is trapped in the high temperature zone of the main chamber, leading

Shang, Quanbo, Ji, Meng, Li, Liguang, Deng, Jun

Simulation Study on the Effect of In-Cylinder Water Injection Mass on Engine Combustion and Emissions Characteristics

2023-01-700410/30/2023

The rapid development of the automobile industry has brought energy and environmental issues that scholars are increasingly concerning about. Improving efficiency and reducing emissions are currently two hot topics in the internal combustion engine industry. Direct water injection technology (DWI) can effectively reduce the cylinder temperature, which is due to the absorption of the heat by the injecting liquid water. In addition, lower temperature in the cylinder will reduce the formation of NO. In this paper, a CFD simulation of DWI application in a lean-burning single-cylinder engine with pre-chamber jet ignition was carried out. And the engine was experimentally tested for the simulation model validation. And then the effect of DWI strategy with different injecting water mass on the combustion and emissions characteristics are analyzed. Physically, injected water not only absorbs heat but also provides heat insulation. The results are shown under the rotating speed of 2800 r/min

Guan, Jun, Shang, Quanbo, Hu, Yinuo, Lu, Ye, Li, Liguang, Deng, Jun

A Model-Based Investigation of Electrically Split Turbocharger Systems Capabilities to Overcome the Drawbacks of High-Boost Downsized Engines

2022-01-505207/20/2022

Engine downsizing is one the most common methods of coping with strict emission regulations. However, it must be coupled with complementary systems so that the engine performance would meet the standards. That is why new efficient solutions can pave the way toward this goal. The electric forced-induction system (EFIS) is the emerging replacement for conventional forced-induction systems (FIS), namely, turbochargers and superchargers. The reason behind this replacement is the drawbacks associated with FIS, among them are turbo lag and inefficiency in exhaust gas energy recycling. Electrically split turbocharger (EST) is a form of EFIS which offers a great potential for engine downsizing. In this paper, a new approach to EST utilization for lowering the fuel consumption (FC) without compromising performance has been introduced, through which the augmented degree of freedom enabled by an EST is used to optimize the air-charge boosting. To show the effectiveness of the proposed method, a

Kouhyar, Farzad, Nikzadfar, Kamyar

A Multi-Zone Combustion Model integrated with a fast Tabulated-Chemistry Approach applied for the Simulation of HCCI Engines supplied with Hydrogen or Carbon-Based Fuels

2022-01-045903/29/2022

To meet the stringent regulation imposed by EU and other legislators, various advanced combustion modes for Internal Combustion Engines (ICEs) are currently under investigation. Among those, Homogeneous Charge Compression Ignition (HCCI) appears a promising solution, simultaneously reducing pollutant emission and enhancing thermal efficiency. In this context, the numerical simulation has evolved into a powerful tool to investigate the combustion modes and to develop optimum control strategies, thanks to its greater flexibility and lower cost, if compared with the experiments. To simulate HCCI and other advanced combustion modes, based on charge stratifications in the combustion chamber, a general multi-zone model has been developed and implemented through user coding into a commercial software (GT-Power™). This model is based on a control mass Lagrangian multi-zone approach and it incorporates a procedure based on an off-line tabulation of chemical kinetics (Tabulated Kinetic of

De Bellis, Vincenzo, Malfi, Enrica, Fasulo, Giovanni, Lanotte, Alfredo, Bozza, Fabio

Gasoline-diesel and methanol-diesel fueled reactivity controlled compression ignition (RCCI) engine extended load operation with high compression ratio

2022-01-054803/29/2022

The study presents extended load operation (at 3.4 bar BMEP) of dual fuel combustion mode for light-duty single cylinder compression ignition (CI) engine. The high compression ratio, hot charge dilution (with 30% and 389 K) and dual fuel combustion provides more fuel-air mixing, evaporation and reactivity stratification for obtaining minimum HC and NOx-soot emissions. Without altering the engine configurations the suitability of alternative fuel (Methanol) is investigated for extended engine operation. Gasoline and methanol are selected as low reactivity fuels (LRF) and diesel as high reactivity fuel (HRF) for understanding the dual fuel RCCI combustion. The dual-fuel combustion with charge dilution shows the improved combustion characteristics, increased brake thermal efficiency with minimum emissions for test fuels. The methanol-diesel shows delayed start of combustion, reduced heat release rate, increase in fuel consumption and CO emissions with charge dilution. For gasoline-diesel

Chaudhari, Vasudev D., Deshmukh, Dr. Devendra

Understanding the impact of heat of vaporization on ɸ-sensitivity of toluene & ethanol reference fuels

2022-01-061803/29/2022

The low-temperature combustion (LTC) concept as a basis for high-efficiency, low-emission combustion technologies is getting more attentions among researchers and automotive industries. The modern engines which are working based on the (LTC) concept have specific fuel requirements. Fuel ɸ-sensitivity is a key factor to be considered for tailoring fuels for these engines. Fuel with high ɸ-sensitivity are more responsive to fuel or thermal stratifications, since the auto-ignition properties of different air-fuel mixtures of these fuels, with different equivalence ratio (ɸ) are more diverse. This diversity provide a smoother heat release rate in stratified condition. In this study a modified Cooperative Fuel Research (CFR) engine for homogeneous-charge compression ignition (HCCI) combustion is used to investigate the pressure sensitivity of 12 different toluene–ethanol reference fuels (TERFs) in three research octane number (RON) groups of 63, 84, and105. In this study, the effect of

Alemahdi, Nika, Garcia, Antonio, Boufaim, Emma, Aferiatd, Giulia, Tuner, Martin

Conceptual model for the start of combustion timing in the range from RCCI to conventional dual fuel

2022-01-055603/29/2022

In the challenge to reduce CO2, NOx and PM emissions, the application of natural gas or biogas in engines is a viable approach. In heavy duty and marine, either a conventional dual fuel (CDF), or a reactivity controlled compression ignition (RCCI) approach is feasible on existing diesel engines. In both technologies a pilot diesel injection is used to ignite the premixed natural gas. However, the influence of injection-timing and -pressure on the start of combustion timing (SOC) is opposite between the two. For every single operating point these relations can be explained by a detailed CFD simulation, but an intuitive overall explanation is lacking. This makes it difficult to incorporate both modes into one engine application, using a single controller. In an experimental campaign by the authors, on a medium speed engine, the lowest emissions were found to be very close to the SOC corresponding to the transition from RCCI to CDF. This highlights the relevance of having one overall

Merts, Menno, Fogué Robles, Alvaro, Monsalve-Serrano, Javier, Garcia, Antonio, Lundgren, Marcus, Verhelst, Sebastian

Development and validation of an EHN mechanism for fundamental and applied chemistry studies

2022-01-054603/29/2022

Autoignition enhancing additives have been used for years to enhance the ignition quality of diesel fuel, with 2-ethylexyl 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, Dario, Dec, John

METHODOLOGICAL APPROACHES TO CONTROL HC AND CO EMISSIONS DURING COLD CONDITIONS

2022-01-054403/29/2022

Diesel Engines are known for its low fuel consumption and at the same time for higher emission formation (NOx, HC, CO and SOOT). Meeting Emission and CO2 targets simultaneously become tough challenge for the Combustion Engineer. HCCI and PCCI combustion concepts allow the reduction of NOx and Soot simultaneously to very low levels with help of Exhaust gas re-circulation (EGR) while maintaining the CO2 emissions advantage of a diesel Engine But due to the low Combustion temperatures, HC and CO will rise drastically, especially when the catalyst bed temperature is not enough to reach light-off temperature to initiate the after-treatment process. This condition will become serve in Lower Engine temperatures (Cold condition) due to the heterogeneous nature of Diesel Combustion and also affects the BSFC of an Engine. At first multiple injection strategies (Pilot quantity and Pilot separation) has been studied to control both HC and CO by increasing the global combustion temperature. In

Mutta, Surendranath

Describing the Auto-Ignition Quality in Small, Air Cooled, Two Stroke Engines

2022-32-006301/09/2022

Auto-ignition quality is one of the most important properties in gasoline. Auto-ignition quality is today described by the Motor Octane Number (MON) and the Research Octane Number (RON). For modern, light duty, gasoline engines it has been quite well established that RON is the most accurate number. However, no study has been performed on hand held forest and garden products, such as chainsaws. Is the auto-ignition quality best described in the same way for these engines as for light duty engines? In this paper, a matrix of six different fuels with different combinations of MON and RON values were tested on a Husqvarna 550 XP Mark II, a modern air cooled, sequential stratified scavenging 2-stroke chainsaw engine. Ignition timing sweeps were performed and knock limited spark advance (KLSA) were calculated. Then the data has been analyzed with a multi-variate analysis of KLSA against both MON and RON to try to determine how MON and RON should be combined to best describe the anti-knock

Risberg, Per, Elm, Thomas, Bergman, Mikael, Hellquist, Fredrik, Karvo, Anna, Tripathi, Rupali

CO2 emission benefits of Homogeneous Charge Compression Ignition and Direct Injection Compression Ignition combustion

2021-26-042309/22/2021

The aim of the paper is to provide an assessment of the Homogeneous Charge Compression Ignition (HCCI) combustion, compared to a well-established alternative such as Direct Injection Compression Ignition (DICI) combustion, under the criteria of CO2 emission reduction potential. The assessment is performed by reviewing the relevant literature and analyzing the commercial products available on the market that are featuring these two technologies. DICI engines have demonstrated in the real world the ability to deliver top fuel conversion efficiencies of about 50%, and fuel conversion efficiencies largely in excess of 40% over the most part of the load and speed range. Research-only HCCI engines have delivered fuel efficiencies well below 40% in the very few carefully selected map points where they working during carefully performed laboratory experiments. As a further contribution, the model of a reference DICI diesel engine is modified to accommodate port fuel injection (PFI) of n

Boretti, Alberto

Experimental Investigation of Cyclic Variation of Heat Release Dynamics of HCCI Combustion Engine

2021-01-117009/21/2021

Homogenous charge compression ignition (HCCI) combustion emerged as a potential technique for reducing automotive pollution. Controlling the combustion timing at different engine operating conditions is one of the major challenges for the commercial application of HCCI combustion engines. To control HCCI ignition timing, it is often necessary to know the characteristics of HCCI cyclic variations. In this study, cyclic combustion variations in an HCCI engine are analyzed. Combustion stability and cycle-to-cycle variations of HCCI combustion parameters were investigated on a modified four-stroke diesel engine. The experiments were conducted by varying intake air temperatures and relative air-fuel ratios at constant engine speed. In the steady-state engine operating condition, in-cylinder pressure signals of 2000 consecutive engine combustion cycles are acquired for each test condition. From this large volume of experimental data collected, cyclic variations of various combustion

Singh, Ajay, Maurya, Rakesh Kumar

Combustion, Performance and Emission Characteristics of Early Direct Injection Compression Ignition Engine with Varying Oxy Hydrogen Gas Concentration

2021-01-117109/21/2021

Early Direct Injection Homogeneous Charge Compression Ignition is one of the clean combustion technologies which reduces the oxides of nitrogen and soot emissions significantly. However, this strategy suffered from drawbacks of fuel spray impingement on cylinder walls, excessive carbon monoxide, and unburnt hydrocarbon emissions, and lower thermal efficiency than conventional diesel combustion in CI engines. A novel attempt has been made in this experimental research work to address the above-said issues by injection of oxy hydrogen gas as a fuel additive to diesel in stationary Compression Ignition engine. This gas was injected into the intake manifold where it premixes with the incoming air. Experiments were conducted at a constant rpm of 1500 and load was varied from 0 to 75%. The diesel was injected by common rail direct injector 45 Before Top Dead Center which ensured an almost homogenous mixture of air, oxy hydrogen gas, and diesel. Due to the presence of hydrogen, the increased

Bhave, Nikhil Aniruddha, Gupta PhD, Mahendra, Joshi PhD, Sandeep

Validation of Kinetic Mechanisms against Various Ignition Delay Data and the Development of Ignition Delay Correlations for Ethanol, Natural Gas, and Primary Reference Fuel Blends under Homogeneous Charge Compression Ignition Conditions

03-15-03-001709/21/2021

Homogeneous Charge Compression Ignition (HCCI) is a promising advanced combustion concept with high efficiencies and low emissions. Chemical kinetic mechanisms and ignition delay correlations (IDCs) are often applied to simulate HCCI combustion. However, a large number of mechanisms and correlations are not developed specifically for HCCI conditions, i.e., lean mixtures and usually with significant residual gas fractions (RGF). To address this issue, a two-part study is conducted. First, experimental ignition delay time (IDT) data from literature under typical HCCI conditions is collected. Then, thirteen widely applied mechanisms for ethanol, natural gas, and primary reference fuel (PRF) blends of isooctane and n-heptane are validated by running constant-volume simulations. Their performance and accuracy are evaluated. Second, the mechanism with the highest accuracy for each fuel is used to generate IDCs for HCCI conditions. For each fuel, simulations were performed to cover a wide

Zhou, Yingcong, Lawler, Benjamin

A Computational Investigation of PPCI-Diffusion Combustion Strategy at Full Load in a Light-Duty GCI Engine

2021-01-051404/06/2021

A two-stage PPCI-diffusion combustion process recently showed good potential to enable clean and fuel-efficient gasoline compression ignition (GCI) combustion at medium-to-high loads. By conducting closed-cycle 3-D CFD combustion analysis, a further step was undertaken in this work to evaluate and optimize the PPCI-diffusion combustion strategy at a full load operating point (2000rpm-23.5 bar IMEPcc) while keeping engine-out NOx below 1 g/kWh. The light-duty GCI engine used in this investigation featured a custom-designed piston bowl geometry at a 17.0 compression ratio (CR), a high pressure diesel fuel injection system, and advanced single-stage turbocharging. A split fuel injection strategy was used to enable the two-stage PPCI-diffusion combustion process. First, the injector spray pattern and swirl ratio effects were evaluated. In-cylinder air utilization and the PPCI-diffusion combustion process were notably influenced by the closed-cycle combustion system design. Among the

Zhang, Yu, Sellnau, Mark

Lean-Stratified Combustion System with Miller Cycle for Downsized Boosted Application - Part I

2021-01-045804/06/2021

Automotive manufacturers relentlessly explore engine technology combinations to achieve reduced fuel consumption under continued regulatory, societal and economic pressures. For example, technologies enabling advanced combustion modes, increased expansion to effective compression ratio, and reduced parasitics continue to be developed and integrated within conventional and hybrid propulsion strategies across the industry. A high-efficiency gasoline engine capable for use in conventional or hybrid electric vehicle platforms is highly desirable. This paper is the first to two papers describing the development of a combustion system combining lean-stratified combustion with Miller cycle for downsized boosted applications. The work was completed under a multi-year US DOE project. The goal was to define a light-duty engine package capable of achieving a 35% fuel economy improvement at US Tier 3 emission standards over a naturally aspirated stoichiometric baseline vehicle. A multi-mode

Solomon, Arun, Battiston, Paul, Sczomak, David

Is the camshaft being timed out?

20AUTP11_0911/01/2020

Development of electric vehicle motors, power controls and batteries, seemingly dominate the automotive industry's forward thinking, yet R&D of internal combustion engine technologies in its many forms continues. That is underlined by the U.K.'s Brunel University establishment of a new future-powertrain research program centering on intelligent valving technology and the eventual replacement of the conventional camshaft by electric actuators. Brunel's Centre for Advanced Powertrain and Fuels (CAPF) has installed Camcon Automotive's SCI (Single Cylinder Intelligent Valve) technology development system, which the company regards as supporting upcoming emissions regulations and reducing ICE costs. CAPF director, Prof. Hua Zhao, said of the potential for Camcon Automotive's intelligent valve technology: “Its flexibility and superior controllability will enable the development of the next generation powertrain with very high efficiency, low carbon and zero environmental impact emissions.”

An Analytical Approach for Calculating Instantaneous Multilayer-Coated Wall Surface Temperature in an Engine

2020-01-016004/14/2020

Thermal swing coatings that have low volumetric heat capacity and low thermal conductivity are attractive because they have the potential to significantly reduce heat transfer to the combustion chamber walls. This paper presents an analytical method for determining the exact solution of the time-resolved wall temperature during the engine cycle for any number of coating layers and properties using the Laplace transformed heat diffusion equation. The method relies only on material properties and the past heat flux history, and represents the exact solution of the heat diffusion equation. The analytical nature of the solution enables fast computation and, therefore, application to system-level optimization calculations. The model relies on an assumption of one-dimensional heat flow, and constant material properties. The major advantage of this approach compared to the standard finite difference approach, wherein the wall is finely discretized, is that there is no approximation and the

Koutsakis, G., Ghandhi, J.B.

Pre-design Investigation of Resonant Frequency Effects on Gas Exchange Efficiencies of a One-kW Natural-Gas Linear Engine Alternator

2020-01-048804/14/2020

Performance of a natural gas two-stroke engine incorporated in a 1-kW free-piston oscillating Linear Engine Alternator (LEA) - a household electricity generator - was investigated under different resonant frequencies for pre-design phase purposes. To increase the robustness, power density, and thermal efficiencies, the crank mechanism in free-piston LEA is omitted and all moving parts of the generator operate at a fixed resonant frequency. Flexure springs are the main source of the LEA’s stiffness and the mass-spring dynamics dominates the engine’s speed. The trade-off between the engine’s performance, mass-spring system limits, and power and efficiency targets versus the LEA speed is very crucial and demands a careful investigation specifically at the concept design stages to find the optimum design parameters and operating conditions. CFD modeling was performed to analyze the effects of resonant frequency on the engine’s gas exchange behavior. To take combustion effects into account

Zamani Meymian, Nima, Darzi, Mahdi, Johnson, Derek, Famouri, Parviz

Is the “K Value” of an Engine Truly Fuel Independent?

2020-01-0615-TEST-REC04/14/2020

The octane appetite of an engine is frequently characterised by the so-called K value. It is usually assumed that K is dependent only on the thermodynamic conditions in the engine when knock occurs. In this work we test this hypothesis: further analysis was conducted on experimental results from SAE 2019-01-0035 in which a matrix of fuels was tested in a single cylinder engine. The fuels consisted of a relatively small number of components, thereby simplifying the analysis of the chemical kinetic proprieties. Through dividing the original fuel matrix into subsets, it was possible to explore the variation of K value with fuel properties. It was found that K value tends to increase slightly with RON. The explanation for this finding is that higher RON leads to advanced ignition timing (i.e. closer to MBT conditions) and advanced ignition timing results in faster combustion because of the higher pressures and temperatures reached in the thermodynamic trajectory. The Livengood-Wu integral

Cracknell, Roger, Kassai, Masaharu, Shiraishi, Taisuke, Festa, Andrea, Gail, Sandro, Aradi, Allen, Shibuya, Masahiko

Exergy Based Optimal Controller Design of a Spark-Ignition Internal Combustion Engine

2020-01-025004/14/2020

Internal combustion engine (ICE) control techniques have been developed with only the first law of thermodynamics in mind, e.g. improving thermal efficiency, tracking specific load requirements, etc. The first law of thermodynamics does not account for the losses in work potential that are caused due to the in-cylinder high temperature thermodynamic processes irreversibilities. For instance, up to 25% of fuel exergy or fuel availability may be lost to irreversibilities during the combustion process. The second law of thermodynamics states that not all energy in an energy source is available to do work; its application evaluates the maximum available energy in that source after accounting for the losses caused by the irreversibilities. Therefore, including the exergy in an optimal engine control algorithm may lead to improved ICE thermal efficiencies. In this work, a model predictive controller (MPC) is developed based on the first and second laws of thermodynamics to control a detailed

Abotabik, Muataz, Meyer, Rick, Proctor, Christopher

Isobaric Combustion at a Low Compression Ratio

2020-01-079704/14/2020

In a previous study, it was shown that isobaric combustion cycle, achieved by multiple injection strategy, is more favorable than conventional diesel cycle for the double compression expansion engine (DCEE) concept. In spite of lower effective expansion ratio, the indicated efficiencies of isobaric cycles were approximately equal to those of a conventional diesel cycle. Isobaric cycles had lower heat transfer losses and higher exhaust losses which are advantageous for DCEE since additional exhaust energy can be converted into useful work in the expander. In this study, the performance of low-pressure isobaric combustion (IsoL) and high-pressure isobaric combustion (IsoH) in terms of gross indicated efficiency, energy flow distribution and engine-out emissions is compared to the conventional diesel combustion (CDC) but at a relatively lower compression ratio of 11.5. The experiments are conducted in a Volvo D13C500 single-cylinder heavy-duty engine using standard EU diesel fuel. The

Dyuisenakhmetov, Aibolat, Goyal, Harsh, Ben Houidi, Moez, Babayev, Rafig, Badra, Jihad, Johansson, Bengt

Is the “K Value” of an Engine Truly Fuel Independent?

04/14/2020

The octane appetite of an engine is frequently characterised by the so-called K value. It is usually assumed that K is dependent only on the thermodynamic conditions in the engine when knock occurs. In this work we test this hypothesis: further analysis was conducted on experimental results from SAE 2019-01-0035 in which a matrix of fuels was tested in a single cylinder engine. The fuels consisted of a relatively small number of components, thereby simplifying the analysis of the chemical kinetic proprieties. Through dividing the original fuel matrix into subsets, it was possible to explore the variation of K value with fuel properties. It was found that K value tends to increase slightly with RON. The explanation for this finding is that higher RON leads to advanced ignition timing (i.e. closer to MBT conditions) and advanced ignition timing results in faster combustion because of the higher pressures and temperatures reached in the thermodynamic trajectory. The Livengood-Wu integral

Cracknell, Roger, Kassai, Masaharu, Shiraishi, Taisuke, Festa, Andrea, Gail, Sandro, Aradi, Allen, Shibuya, Masahiko

Nonlinear Identification Modeling for PCCI Engine Emissions Prediction Using Unsupervised Learning and Neural Networks

2020-01-055804/14/2020

Premixed charged compression ignition (PCCI) is an advanced combustion strategy, which has the potential to achieve ultra-low nitrogen oxide and soot emissions at high thermal efficiencies. PCCI combustion is characterized by a complex nonlinear chemical-physical process, which indicates that a physical description involves significant development times and also high computation cost. This paper presents a method to use cylinder pressure data and engine operations parameters for prediction of PCCI engine emissions by unsupervised learning and nonlinear identification techniques. The proposed method first uses principal component analysis (PCA) to reduce the dimension of the cylinder-pressure data. Based on the PCA analysis, a multi-input multi-out model was developed for nitrogen oxide and soot emission prediction by multi-layer perceptron (MLP) neural network. Before the training process, a second principal component analysis was done to reduce the input dimension with hyper

Pan, Wang, Korkmaz, Metin, Beeckmann, Joachim, Pitsch, Heinz

Validation of Computational Models for Isobaric Combustion Engines

2020-01-080604/14/2020

The focus of this study is to aid the development of the isobaric combustion engine by investigating multiple injection strategies at moderately high pressures. A three-dimensional (3D) commercial computational fluid dynamics (CFD) code, CONVERGE, was used to conduct simulations. The validation of the isobaric combustion case was carried out through the use of a single injector with multiple injections. The computational simulations were matched to the experimental data using methods outlined in this paper for different multiple injection cases. A sensitivity analysis to understand the effects of different modeling components on the quantitative prediction was carried out. First, the effects of the kinetic mechanisms were assessed by employing different chemical mechanisms, and the results showed no significant difference in the conditions under consideration. Next, different liquid fuel properties were examined, and it was found that the physical properties of the fuels have a notable

Aljabri, Hammam H., Babayev, Rafig, Liu, Xinlei, Badra, Jihad, Johansson, Bengt, Im, Hong G.

Combined Experimental/Numerical Study of the Soot Formation Process in a Gasoline Direct-Injection Spray in the Presence of Laser-Induced Plasma Ignition

2020-01-029104/14/2020

Combustion issued from an eight-hole, direct-injection spray was experimentally studied in a constant-volume pre-burn combustion vessel using simultaneous high-speed diffused back-illumination extinction imaging (DBIEI) and OH* chemiluminescence. DBIEI has been employed to observe the liquid-phase of the spray and to quantitatively investigate the soot formation and oxidation taking place during combustion. The fuel-air mixture was ignited with a plasma induced by a single-shot Nd:YAG laser, permitting precise control of the ignition location in space and time. OH* chemiluminescence was used to track the high-temperature ignition and flame. The study showed that increasing the delay between the end of injection and ignition drastically reduces soot formation without necessarily compromising combustion efficiency. For long delays between the end of injection and ignition (1.9 ms) soot formation was eliminated in the main downstream charge of the fuel spray. However, poorly atomized and

Tagliante, Fabien, Sim, Hyung S., Pickett, Lyle M., Nguyen, Tuan, Skeen, Scott

Machine Learning Techniques for the Prediction of Combustion Events in Cooperative Fuel research Engine (CFR) at Homogeneous Charge Compression Ignition (HCCI) conditions.

2020-01-113204/14/2020

This research assesses the capability of data-science models to predict the combustion events occurring for certain input conditions in Cooperative Fuel Research Engine (CFR) at Homogeneous Charge Compression Ignition (HCCI) conditions. The experimental data from CFR engine of University of Michigan (UM), operated at different input conditions for various gasoline type fuels was utilized for the study. The current study developed a capable machine learning framework to predict the auto-ignition propensity of a fuel under HCCI conditions. The combustion events happening at HCCI conditions in CFR engine are primarily classified into four different classes depending on the combustion phasing and pressure rise during the combustion in engine. The classes are: no ignition, normal combustion, high MPRR and early CA 50. Two machine learning (ML) models, K-nearest neighbors and Support Vector Machines, are compared for their classification capabilities of combustion events. Seven conditions

Angikath Shamsudheen, Fabiyan, Yalamanchi, Kiran, Yoo, Kwang Hee, Voice, Alexander, Boehman, Andre, Sarathy, Mani

Measurements and Correlations of Local Cylinder-Wall Heat-Flux Relative to Near-Wall Chemiluminescence across Multiple Combustion Modes

2020-01-080204/14/2020

Minimizing heat transfer (HT) losses is important for both improving engine efficiency and increasing exhaust energy for turbocharging and exhaust aftertreatment management, but engine combustion system design to minimize these losses is hindered by significant uncertainties in prediction. Empirical HT correlations such as the popular Woschni model have been developed and various attempts at improving predictions have been proposed since the 1960s, but due to variations in facilities and techniques among various studies, comparison and assessment of modelling approaches among multiple combustion modes is not straightforward. In this work, simultaneous cylinder-wall temperature and OH* chemiluminescence high-speed video are all recorded in a single heavy-duty optical engine operated under multiple combustion modes. The cylinder-wall HT is derived from the measured transient temperature and compared with Woschni HT correlation predictions using both bulk and estimated local gas

Li, Zheming, Musculus, Mark, Shechtman, Zachary

Assessment of the Ignition System Requirement on Diluted Mixture Spark Engines

2020-01-111604/14/2020

In order to face the new challenges, spark ignition engines are evolving by following some strategies and technologies. Among them, alternative combustion processes based on the dilution of the homogeneous mixture, either with fresh air or with Exhaust Gas Recirculation (EGR), are being explored. In a higher or lower extent, these changes modify in-cylinder thermodynamic conditions during the engine operation (pressure, temperature and gas composition) thus conditioning the spark ignition system requirements that will have to evolve to become more reliable and powerful. In this framework, an experimental study on the effect of the key in-cylinder conditions on the ignition system performance has been carried out in a single-cylinder spark-ignition (SI) research engine. The study includes EGR, lambda and energizing time sweeps to assess the behavior of the engine in different operating conditions. Furthermore, various Insulated-Gate Bipolar Transistors (IGBT) and spark plugs have been

Molina, Santiago, Martin, Jaime, Novella, Ricardo, Gomez-Soriano, Josep, Padilla, Jose

A New Efficient Combustion Method for ICEs

2020-01-131404/14/2020

The best known methods for combustion in Internal Combustion Engines (ICEs) are: Spark Ignition (SI), Compression Ignition (CI) and Homogeneous Charge Compression Ignition (HCCI). Each of these combustion methods has well known limitations for efficiency and clean exhaust. This paper presents a new method of combustion, called Entry Ignition (EI) that overcomes some of these limitations. EI burns a homogeneous fuel air mixture at constant pressure with combustion occurring at the inlet where the unburned mixture flows into the combustion chamber. Combustion results from the unburned mixture mixing with the much hotter burned gases already in the combustion chamber. EI can operate in a conventional piston-type engine, with the only major change being in the valving. EI’s efficiency gain results from the following. Firstly, EI is not subject to “knocking” and so can operate at CI-level compression ratios or higher. Secondly, EI allows lean burn, which improves efficiency for basic

Cheeseman, Peter C.

Optimization of Intake Port and Pentroof Angle for Simultaneous Reduction of Fuel Consumption and Exhaust Emissions in a GDI Engine

03-13-03-002002/04/2020

This article aims to identify the best combination of intake port angle (IPA) and cylinder head pentroof angle (PA) of a gasoline direct injection (GDI) engine to achieve a simultaneous reduction in the fuel consumption and the exhaust emissions using computational fluid dynamics (CFD) and optimization techniques. The present study is carried out on a single-cylinder, four-stroke GDI engine. The design space is bound by the range of the IPA (35°, 80°) and the PA (5°, 20°). The initial data set consists of 80 design points, which are generated using the uniform Latin hypercube (ULH) algorithm. CFD simulations were carried out at all the points in the initial data set using CONVERGE at engine speed of 2,000 rev/min and the overall equivalence ratio of 0.7 ± 0.05. A prediction model based on the support vector machine algorithm is generated between the design inputs and the output parameters viz., indicated specific fuel consumption (ISFC), hydrocarbon (HC), nitric oxides (NOx), and soot

Saw, Om Prakash, Addepalli, Srinivasa Krishna, Mallikarjuna, J.M.

Effects of positive or negative dwell times of split injection on diesel spray development and mixture formation processes

2019-32-059601/24/2020

An investigation on the effect of dwell time of split injection on a diesel spray evolution and mixture formation process was carried out. A commercial 7-hole injector were used in the experiment to eliminate the possible discrepancies on the spray with single-hole research injector. Laser absorption scattering (LAS) technique was implemented for the measurement of the temporal evolution of fuel evaporation and mixture concentration. The diesel surrogate fuel consists of n-tridecane and 2.5% of 1-methylnaphthalene in volume basis was used. The total amount of fuel injected was initially fixed to 5.0 mg/hole. A split ratio of 9: 1 in mass basis was selected according to the results obtained from a previous study. The dwell time was varied from 120 µs to a negative value of −50 µs. The effects of negative dwell time was not ideal for lean mixture formation when compared to zero or positive dwell time conditions. The collision of the spray tail of the first injection and the head of the

Kim, Jaeheun, Kakami, Shinichi, Nishida, Keiya, Ogata, Yoichi

Study on Robust Fuel Performance with Differing Fuel Types in a 2-Stroke CAI Combustion Engine

01/24/2020

This study sought to achieve robust combustion with the differing fuel types and levels of fuel quality that are present in various areas of the world. The tests used the 2-stroke controlled auto ignition (CAI) engine from our earlier report [1], which was proven to have potential as an efficient, clean engine for diesel fuel. This study verified whether efficient, clean CAI combustion of gasoline fuel could be achieved with the same basic structure and engine system. Diesel and gasoline have very different volatility, viscosity and ignition characteristics, all of which significantly affect combustion in an engine. It is particularly necessary in CAI combustion to adjust the ignition timing according to the fuel used, as the difference in auto-ignition temperature from gasoline and diesel affects the CAI ignition timing. This issue was addressed by conducting experiments with a test engine to determine how the ignition timing is affected by the equivalent ratio, compression ratio and

Kurata, Mashu, Okubo, Masami, Yamada, Yoshikazu, Kitano, Sho

Energy Release Characteristics inside a Spark-Ignition Engine with a Bowl-in-Piston Geometry

2020-01-5003-TEST-REC01/16/2020

The conversion of compression ignition (CI) internal combustion engines to spark-ignition (SI) operation by adding a spark plug to ignite the mixture and fumigating the fuel inside the intake manifold can increase the use of alternative gaseous fuels (e.g., natural gas) in heavy-duty applications. This study proposed a novel, less-complex methodology based on the inflection points in the apparent rate of heat release (ROHR) that can identify and separate the fast-burning stage inside the piston bowl from the slower combustion stage inside the squish region (a characteristic of premixed combustion inside a diesel geometry). A single-cylinder 2L CI research engine converted to natural gas SI operation provided the experimental data needed to evaluate the methodology, at several spark timings, equivalence ratios, and engine speeds. The results indicated that the end of the bulk combustion traditionally defined as the location of 90% energy release was not greatly affected by the change in

Liu, Jinlong, Dumitrescu, Cosmin Emil

Energy Release Characteristics inside a Spark-Ignition Engine with a Bowl-in-Piston Geometry

01/16/2020

The conversion of compression ignition (CI) internal combustion engines to spark-ignition (SI) operation by adding a spark plug to ignite the mixture and fumigating the fuel inside the intake manifold can increase the use of alternative gaseous fuels (e.g., natural gas) in heavy-duty applications. This study proposed a novel, less-complex methodology based on the inflection points in the apparent rate of heat release (ROHR) that can identify and separate the fast-burning stage inside the piston bowl from the slower combustion stage inside the squish region (a characteristic of premixed combustion inside a diesel geometry). A single-cylinder 2L CI research engine converted to natural gas SI operation provided the experimental data needed to evaluate the methodology, at several spark timings, equivalence ratios, and engine speeds. The results indicated that the end of the bulk combustion traditionally defined as the location of 90% energy release was not greatly affected by the change in

Liu, Jinlong, Dumitrescu, Cosmin Emil

Chemical kinetic mechanisms for HCCI combustion of wet ethanol with exhaust gas recirculation

2019-36-029301/13/2020

This work compares the accuracy of in-cylinder pressure and apparent heat release rate (AHRR) diagrams to the experimental data and the use of different chemical kinetics models applied to the GT-Power® software. The engine computational model is based on a naturally aspirated diesel engine with three cylinders, one of them modified to operate with hydrous ethanol with port fuel injection and HCCI combustion achieved with hot exhaust gas recirculation (EGR) of the Diesel cylinders. Operating points chosen to perform the comparison to experimental tests were 1800 rpm, 300 kPa of indicated mean effective pressure and fuels with 10% and 20% of water-in-ethanol by volume. The kinetic mechanisms for ethanol oxidation evaluated were the detailed NUI Galway and a Skeletal model based on it. With either model, cylinder pressure diagrams were not very different from the experimental values. The detailed mechanism was, on average, 9 times slower to process each case than the Skeletal mechanism

Herzer, Filipe A., Fagundez, Jean L. S., Martins, Mario E. S., Salau, Nina P. G.

Effects of Piston Bowl Diameter on Combustion Characteristics of a Natural gas/Diesel Dual Fuel Engine

2019-01-217312/19/2019

Natural gas/diesel dual fuel engines have potential for a high thermal efficiency and low NOx emissions. However, they have the disadvantages of high unburned species emissions and lower thermal efficiencies at low loads (at low equivalence ratio). A way to solve this problem is to properly distribute the pilot fuel vapor in a natural-gas premixture. The combustion chamber geometry affects the combustion process since it influences the distribution of the pilot fuel vapor. This study investigates the influence of injection conditions and the piston bowl geometry on the performance and emissions of a dual fuel engine. Experiments were carried out using two pistons with different bowl diameters, 52 mm and 58 mm, at single-and two-stage diesel-fuel injection. The results show that the larger bowl provides lower hydrocarbon emissions at a lower equivalence ratio in the case of single-stage injection. For two-stage injection, the influence of the bowl diameter depends on the timing of the

Takizawa, Keigo, Tanaka, Hidetake, Horibe, Naoto, Ishiyama, Takuji, Sako, Takahiro

Spark Assisted Compression Ignition Engine with Stratified Charge Combustion and Ozone Addition

2019-01-225312/19/2019

Performance and emissions characteristics for stratified charge spark assisted compression ignition (SACI) with 30 ppm of added ozone (O3) were explored in a single-cylinder, optically accessible, spray-guided, research engine. For the present study, intake pressure and temperature were fixed at 1.0 bar and 42°C respectively, with a range of engine loads (1.5 – 5.5 bar indicated mean effective pressure) and speeds (800 – 1600 revolutions per minute) explored. Fuel stratification achieved by a late-cycle injection of ~ 10–25% of the total fuel was used to maintain stable operation at lower engine loads. For each condition spark timing, second injection SOI, and fuel split ratio between the main and second injection were optimized to maximize engine performance while maintaining nitrogen oxide emissions (NOx) below 5 g/kg-fuel. Ozone addition was found to decrease specific fuel consumption by up to 9%, with across the board improvement in combustion stability relative to similar

Biswas, Sayan, Ekoto, Isaac

Analysis of Reaction Mechanism Preparing Hot Ignition Observed in Homogeneous Compression of n-Heptane Air Mixture

2019-01-234812/19/2019

Multi-stage heat releases in homogenous charge compression ignition (HCCI) near the ignition threshold are analyzed in this study. Motored engine experiments are conducted with exhaust gas analysis by Fourier transform infrared spectrometer under hot ignition suppressed condition, in order to provide a deeper insight into the ignition mechanism of n-heptane. By increasing intake temperature from room temperature, heat release of low temperature oxidation (LTO) can be observed. Moreover, second heat release was observed after primary heat release of LTO, which increases rapidly with increasing intake temperature within narrow range below the high temperature oxidation (HTO) threshold. The mechanism of HTO preparation reaction is discussed.

Safwan bin Mazelan, Muhammad, Tezaki, Atsumu, Thapa, Sahadev

Measurements and modeling of ozone enhanced compression ignition in a rapid compression machine and optically-accessible engine

2019-01-225412/19/2019

For the present study, an ultraviolet light absorption diagnostic was used to measure O3 concentration during the compression stroke of a rapid compression machine and an optically-accessible research engine. Charge oxygen concentration, initial temperature, and equivalence ratio were varied; neat iso-octane was used for fueled experiments. Measurements were compared to single-zone chemical kinetic simulation results. Rapid thermally induced O3 decomposition was observed near top dead center. Ozone decomposition advanced when the charge temperature was increased, oxygen concentration was reduced, or fuel was added. While the model well-captures the experimental trends, for unfueled conditions the temporal prediction of O3 decomposition is generally too far retarded.

Seignour, Nicolas, Ekoto, Isaac, Foucher, Fabrice, Moreau, Bruno

Detection of engine knock using speed oscillations in a single-cylinder spark-ignition engine

2019-01-220612/19/2019

In the present work, the possibility of engine knock detection is investigated based on in-cycle speed data, which is readily available to the ECU. Experiments were conducted at 3000 rpm with wide-open throttle condition in a single-cylinder, air-cooled, port-fuel-injection spark-ignition engine at different levels of knocking. It was found that amplitude of speed oscillations increased with the knock intensity for considered window with the size of 100 crank angle degree, starting from the top dead center of compression. The proposed knock indicators based on in-cycle speed oscillations were found to be able to identify the knock-limited spark timings at different operating conditions. Results showed that the amplitude of speed oscillations, derived from in-cycle speed data with resolution of six crank angle degree, could also be used to quantify the knock. The knock frequency based on speed oscillations also showed a sharp increase at the onset of knock. Cycle by cycle knock

Bhaskar, Kiran, Jose, Jubin V, Mittal, Mayank, Ramesh, A

Effects of ratio and dwell of split injection on fuel spray and mixture formation process under evaporating, non-reacting condition

2019-01-232312/19/2019

The effects of split injections of a diesel spray was evaluated in a constant volume chamber under evaporating, non-reacting condition. Laser absorption scattering (LAS) technique was utilized for the mixture concentration measurement, using a diesel surrogate fuel consists of n-tridecane and 2.5% of 1-methylnaphthalene in volume basis. While fixing the total injected fuel mass of 5.0 mg/hole, the effects of split ratio in mass basis and the dwell time (or injection interval) were investigated. Among the split ratios conducted in the current study (3,7, 5:5 and 7:3), the split ratio of 7:3 was the optimum for lean mixture formation regarding the overall distribution of the equivalence ratio at end-of-injection (EOI) timing. The air entrainment wave at the EOI timing of the first injection allowed the fuel at the vicinity of the nozzle to become leaner at a faster rate. It was thought that, the split ratio of 7:3 provided an adequate amount of fuel quantity and vapor penetration to fit

Kim, Jaeheun, Kakami, Shinichi, Nishida, Keiya, Ogata, Yoichi

Wall Heat Transfer Modeling Based on the Energy Equation For Zero Dimensional Engine Simulation

2019-01-231312/19/2019

ABSTRACT It was important for predicting wall heat flux to apply wall heat transfer model by taking into account of the behavior of turbulent kinetic energy and density change in wall boundary layer. Although energy equation base wall heat transfer model satisfied above requirements, local physical amounts such as turbulent kinetic energy in near wall region should be applied. In this study, in order to predict wall heat transfer by zero dimensional analysis, how to express wall heat transfer by using mean physical amounts in engine combustion chamber was considered by experimental and numerical approaches.

Harada, Yuji, Uchida, Kenji, Yamashita, Hiroyuki

A Study on Higher Thermal Efficiency and Lower Cooling Loss in Diesel Engine

2019-01-228312/19/2019

The purpose of this study is to achieve thermal efficiency improvement and cooling loss reduction of a diesel engine with a combustion concept of earlier evaporation, higher entrainment, and compact spray flame. In order to realize this concept, the paper focused on two-component fuel (nC5H12/nC10H22) with high evaporation. In this paper, the effects of two-component fuel on thermal efficiency and exhaust characteristics are examined by using single cylinder diesel engine. In addition, spray characteristics are revealed in an optically accessible chamber and combustion characteristics are revealed by using RCEM.

Fujikawa, Shoya, Arai, Naoyuki, Iwamoto, Seiya, Nishiura, Kohsuke, Matsumura, Eriko, Senda, Jiro

Numerical study of wall heat transfer inside a combustion chamber under conventional diesel combustions and low temperature combustion conditions

2019-01-231412/19/2019

The engine simulations using computational fluid dynamics (CFD) commercial code ANSYS-Forte is employed to study the effects of in-cylinder combustion on heat transfer through the combustion chamber walls. In this numerical study, three different combustion regimes are explored and compared. A conventional diesel combustion (CDC) and low temperature combustion (LTC) with early and late injection conditions are investigated. To simulate the velocity field in the computational domain, the renormalization group (RNG) k-ε turbulence model Is chosen. Also, a detailed chemistry CHEMKIN Pro package is implemented in a combustion model to calculate the reaction mechanism for the engine simulations. To obtain predicted heat flux results from three different combustion regimes, the available heat transfer wall model including temperature wall function and gas density variation is applied. To model validation, the simulated results is validated against experimental data from N14 engines which are

Kaewbumrung, Mongkol, Plengsa-ard, Chalermpol

Development of Non-equilibrium Plasma and Combustion Integrated Model for Reaction Analysis

2019-01-234912/19/2019

Control of self-ignition timing in a HCCI engine is still a major technical issue. Recently, the application of a non-equilibrium plasma using repetitively discharge has been proposed as the promising technology. However, non-equilibrium plasma reaction in higher hydrocarbon fuel mixture is very complicated. Hence, there have been few calculation reports considering a series of reactions from non-equilibrium plasma production to high temperature oxidation process. In this study, 0-dimensional numerical simulation model was developed in which both reactions of plasma chemistry and high temperature oxidation combustion was taken into account simultaneously. In addition, an ODEs solver has been applied for the reduction of calculation time in the simulation. By comparing calculation results with experiment such as self-ignition timing, the validity of the developed numerical model has been evaluated.

Horikoshi, Masahiro, Tanaka, Tatsuya, Okihama, Keisuke, Kon, Yohei, Takana, Hidemasa

Fuel Flexibility Study of a Compression Ignition Engine at High Loads

2019-01-219312/19/2019

Engine experiments were performed on a single-cylinder heavy-duty engine at relatively high loads to investigate the regions where the combustion characteristics are unchanged regardless of the fuel octane number. Primary Reference Fuels (PRFs) and three different commercial fuels with RON values ranging from 0 to 100 were tested in this study. A sweep of net indicated mean effective pressure (IMEPNet) of 5 to 20 bar, absolute intake pressure of 1.5 to 2.8 bar, exhaust gas recirculation (EGR) of 0 to 40%, and fuel injection pressure of 700 to 1400 bar were performed to investigate the combustion characteristics, ignition delay time, combustion duration, efficiency, and emissions. At the highest load point (IMEPNet = 20 bar), all the fuels burn as in conventional diesel combustion. Despite the wide range of octane numbers, all fuels had similar ignition delay time, combustion duration, indicated efficiency, and emissions at 10 to 20 bar IMEPNet. It follows that CI mode is the only

AlRamadan, Abdullah S., Houidi, Moez Ben, Nyrenstedt, Gustav, Johansson, Bengt

Evaluation of Cycle Variation of SWACER-like Knocking Using 3D SI Combustion Simulation

2019-01-220812/19/2019

Cyclic variation on heavy knocking was reproduced using 3D SI combustion simulation with RANS / LES turbulence models and detailed kinetic mechanisms. A 0.66 liter, inline 3 cylinder gasoline engine operated at 1200 rpm, WOT was mainly investigated. It was revealed that the combination of RANS, Liu mech. and calculation over multiple cycles worked well. Detailed process of heavy-knock was also suggested and it was thought that SWACER-like mechanism had concerned. RANS could describe typical behavior of heavy-knock within the first 3 cycle calculation and it showed good agreement with both the actual engine measurement and LES calculation result.

Kuroki, Tomonori, Shima, Yuta, Ono, Yasuhisa, Serizawa, Takeshi

Comparison of heat losses at the impingement point and in between two impingement points in a diesel engine using phosphor thermometry

2019-01-218512/19/2019

In-cylinder heat losses in diesel engines reduce engine efficiency significantly and account for a considerable amount of injected fuel energy. A great part of the heat losses during diesel combustion presumably arises from the impingement of the flame. The present study compares the heat losses at the point where the flame impinges onto the piston bowl wall and the heat losses between two impingement points. Measurements were performed in a full metal heavy-duty diesel engine with a small optical access through a removed exhaust valve. The surface temperature at the impingement point of the combusting diesel spray and at a point in between two impingement points was determined using phosphor thermometry. The dynamic heat fluxes and the heat transfer coefficients which result from the surface temperature measurements are estimated. Simultaneous cylinder pressure measurements and high-speed videos are associated to individual surface temperature measurements. Thus each surface

Binder, Christian, Matamis, Alexios, Richter, Mattias, Norling, Daniel

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