A Stand-Alone Multi-Zone Model for Combustion in HCCI Engines

2005 ◽  
Author(s):  
Paitoon Kongsereeparp ◽  
Behzad Kashani ◽  
M. David Checkel
Keyword(s):  
Equivalence Ratio ◽  
Homogeneous Charge Compression Ignition ◽  
Residual Fraction ◽  
Zone Model ◽  
Compression Ignition ◽  
Ignition Timing ◽  
Operating Variables ◽  
Hcci Combustion ◽  
Combustion Duration ◽  
Hcci Engines

Because they have the potential for ultra low NOx emissions and high efficiency, Homogeneous Charge Compression Ignition (HCCI) engines have the potential to develop a significant niche. However, a narrow operating range, (bracketed by severe knock and misfire problems), presents a formidable obstacle to developing usable HCCI combustion systems. HCCI combustion is influenced by a complex array of operating variables including fuel octane quality, intake preheating temperature, compression ratio, equivalence ratio, exhaust gas recirculation and engine component temperature. These variables affect the two critical combustion parameters: ignition timing and combustion duration. If these two parameters can be controlled by appropriate settings of the operating variables, a good HCCI combustion scheme could be achieved. Therefore, the theoretical prediction of these two combustion parameters as a function of the key operating variables is necessary for development of HCCI combustion. This paper describes a stand-alone, single-zone and multi-zone combustion model which have been developed for the specific purpose of investigating HCCI combustion control. In the multi-zone model, temperature and composition in each zone were adjusted in order to study the effect of in-homogeneity which is critical to understanding ignition timing and combustion duration in real HCCI engines. The models simulated HCCI combustion using two fuels: hydrogen, (11 species, 23 reactions- from CHEMKIN library), and natural gas, (53 species, 325 reactions- from GRI mech). The capabilities of the two models to predict ignition timing, combustion duration and peak pressure were verified against experimental and simulation results of Fiveland et al [2, 11]. The models were then used to study the effect of different in-homogeneity levels of equivalence ratio, intake temperature and residual fraction. The single zone model could only predict ignition timing while the multi-zone model shows the capability to mimic realistic HCCI combustion phenomena. The study showed that some degree of in-homogeneity is critical to predicting performance of the homogeneous charge compression ignition engine. Further, stratification of equivalence ratio was relatively ineffective at changing combustion while stratification of mixture temperature was very effective. Stratification of the residual fraction proved to be the most promising method of controlling combustion parameters and the mechanism was primarily thermal.

Characterizing the cyclic variability of ignition timing in a homogeneous charge compression ignition engine fuelled with n-heptane/iso-octane blend fuels

2008 ◽  
Vol 9 (5) ◽  
pp. 361-397 ◽  
Author(s):  
M Shahbakhti ◽  
C R Koch
Keyword(s):  
Equivalence Ratio ◽  
Homogeneous Charge Compression Ignition ◽  
Coolant Temperature ◽  
Cyclic Variation ◽  
Compression Ignition ◽  
Ignition Timing ◽  
Compression Ignition Engine ◽  
Hcci Combustion ◽  
Cyclic Variations ◽  
Homogeneous Charge

The cyclic variations of homogeneous charge compression ignition (HCCI) ignition timing is studied for a range of charge properties by varying the equivalence ratio, intake temperature, intake pressure, exhaust gas recirculation (EGR) rate, engine speed, and coolant temperature. Characterization of cyclic variations of ignition timing in HCCI at over 430 operating points on two single-cylinder engines for five different blends of primary reference fuel (PRF), (iso-octane and n-heptane) is performed. Three distinct patterns of cyclic variation for the start of combustion (SOC), combustion peak pressure ( Pmax), and indicated mean effective pressure (i.m.e.p.) are observed. These patterns are normal cyclic variations, periodic cyclic variations, and cyclic variations with weak/misfired ignitions. Results also show that the position of SOC plays an important role in cyclic variations of HCCI combustion with less variation observed when SOC occurs immediately after top dead centre (TDC). Higher levels of cyclic variations are observed in the main (second) stage of HCCI combustion compared with that of the first stage for the PRF fuels studied. The sensitivity of SOC to different charge properties varies. Cyclic variation of SOC increases with an increase in the EGR rate, but it decreases with an increase in equivalence ratio, intake temperature, and coolant temperature.

Residual-effected homogeneous charge compression ignition at a low compression ratio using exhaust reinduction

2003 ◽  
Vol 4 (3) ◽  
pp. 163-177 ◽  
Author(s):  
P. A. Caton ◽  
A. J. Simon ◽  
J. C. Gerdes ◽  
C. F. Edwards
Keyword(s):  
Compression Ratio ◽  
Equivalence Ratio ◽  
Homogeneous Charge Compression Ignition ◽  
Compression Ignition ◽  
Single Digit ◽  
Hcci Combustion ◽  
Actuation System ◽  
Order Of Magnitude ◽  
No Emissions ◽  
Homogeneous Charge

Studies have been conducted to assess the performance of homogeneous charge compression ignition (HCCI) combustion initiated by exhaust reinduction from the previous engine cycle. Reinduction is achieved using a fully flexible electrohydraulic variable-valve actuation system. In this way, HCCI is implemented at low compression ratio without throttling the intake or exhaust, and without preheating the intake charge. By using late exhaust valve closing and late intake valve opening strategies, steady HCCI combustion was achieved over a range of engine conditions. By varying the timing of both valve events, control can be exerted over both work output (load) and combustion phasing. In comparison with throttled spark ignition (SI) operation on the same engine, HCCI achieved 25–55 per cent of the peak SI indicated work, and did so at uniformly higher thermal efficiency. This was accompanied by a two order of magnitude reduction in NO emissions. In fact, single-digit (ppm) NO emissions were realized under many load conditions. In contrast, hydrocarbon emissions proved to be significantly higher in HCCI combustion under almost all conditions. Varying the equivalence ratio showed a wider equivalence ratio tolerance at low loads for HCCI.

Modeling the Effects of Steam-Fuel Reforming Products on Homogeneous Charge Compression Ignition of n-Heptane

2009 ◽  
Author(s):  
Francisco Posada ◽  
Nigel N. Clark ◽  
Aleksandr Kozlov ◽  
Martin Linck ◽  
Dmitri Boulanov ◽  
...  
Keyword(s):  
Species Composition ◽  
Heat Release ◽  
Homogeneous Charge Compression Ignition ◽  
Zone Model ◽  
Compression Ignition ◽  
Ignition Timing ◽  
Fuel Reforming ◽  
Total N ◽  
Temperature Heat ◽  
Homogeneous Charge

Homogeneous Charge Compression Ignition (HCCI) offers benefits of high efficiency with low emissions, but suffers load range limitations and control issues. A method to improve control of HCCI was numerically investigated based on two separate fuel streams with different autoignition characteristics to regulate timing and heat release at specific operational conditions. In this numerical study n-heptane was selected as the primary fuel, and the secondary fuel was defined as a reformed product of n-heptane (RG). The reformed fuel species composition was experimentally determined based on steam/n-heptane reforming process at a steam/carbon mole ratio of 2:1. In addition to H2 and CO, the reformed fuel stream was composed of CH4, CO2, H2O and non-reformed n-heptane. A single zone model using a detailed chemical kinetic mechanism was implemented on CHEMKIN to study the effects of base fuel and steam-fuel reforming products on the ignition timing and heat release characteristics. The study was performed considering the reformed fuel species composition at total n-heptane conversion (stoichiometric) and also at the composition corresponding to a specific set of operational reforming temperatures. The computational model confirmed that the reformed products have a strong influence on the low temperature heat release (LTHR) region, affecting the onset of the high temperature heat release (HTHR). The ignition timing was proportionally delayed with respect to the baseline fuel case when higher concentrations of reformed gas were used.

Effects of Fuel Octane Number on Homogeneous Charge Compression Ignition (HCCI) Combustion with Rapid Compression Machine

2012 ◽  
Vol 455-456 ◽  
pp. 339-343
Author(s):  
You Kun Wang ◽  
Peng Cheng ◽  
Yun Kai Wang ◽  
Hua Li ◽  
Ying Nan Guo
Keyword(s):  
Octane Number ◽  
Homogeneous Charge Compression Ignition ◽  
Maximum Pressure ◽  
Compression Ignition ◽  
Rapid Compression Machine ◽  
Hcci Combustion ◽  
Combustion Duration ◽  
Rapid Compression ◽  
Start Of Combustion ◽  
Homogeneous Charge

The effects of fuel octane number (RON) on homogeneous charge compression ignition (HCCI) combustion were studied under different combustion boundary conditions on a rapid compression machine. The results show that the maximum pressure raise rate and maximum combustion temperature decreased as the RON increased while the start of combustion is delayed and the combustion duration is shortened at the same time.

Effects of exhaust gas recirculation in homogeneous charge compression ignition engines

2000 ◽  
Vol 1 (3) ◽  
pp. 269-279 ◽  
Author(s):  
M Nakano ◽  
Y Mandokoro ◽  
S Kubo ◽  
S Yamazaki
Keyword(s):  
Homogeneous Charge Compression Ignition ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Compression Ignition ◽  
Ignition Timing ◽  
Auto Ignition ◽  
Significant Difference ◽  
Hcci Engines ◽  
Gas Recirculation ◽  
Homogeneous Charge

Ignition control is an important issue in homogeneous charge compression ignition (HCCI) engines, which have the advantages of low NOx emission and high thermal efficiency. In this study, the effect of the exhaust gas recirculation (EGR) on the ignition control of HCCI engines is discussed using an engine cycle simulation in which a homogeneous mixture is assumed. Auto-ignition of 65 per cent iso-octane + 25 per cent toluene + 10 per cent n-heptane, which is used as a fuel to evaluate the characteristics of a gasoline-like fuel, is represented by a detailed reaction model. The dilution by EGR delays the ignition timing when the charged gas temperature is not changed by EGR. The temperature rise of the charged gas promotes auto-ignition. Based on these characteristics, it was suggested that the ignition timing could be controlled by EGR with temperature control, when the amount of fuel supply is constant. This control method can also be applied to control of the air-fuel ratio (A/F) in the cylinder while maintaining the optimum ignition timing. In spite of the difference in the A/F and the EGR ratios, no significant difference was found in the pressure rise rate at combustion and the NOx emission when the ignition timing was the same.

Effects of N2 and CO2 mixing on ignition and combustion in a homogeneous charge compression ignition engine operated on dimethyl ether

2005 ◽  
Vol 6 (5) ◽  
pp. 423-431 ◽  
Author(s):  
W Sahashi ◽  
A Azetsu ◽  
C Oikawa
Keyword(s):  
Heat Release ◽  
Co Oxidation ◽  
Homogeneous Charge Compression Ignition ◽  
Exhaust Gas ◽  
Compression Ignition ◽  
Ignition Timing ◽  
Cool Flames ◽  
Combustion Duration ◽  
Co Emission ◽  
Homogeneous Charge

The control of ignition timing and combustion duration over a wide range of engine speeds and loads in a homogeneous charge compression ignition (HCCI) engine is one of the barriers to the realization of this type of engine. Application of exhaust gas recirculation (EGR) is a promising option to control ignition timing, extend combustion duration, and suppress knock-like combustion. In this study, the effects of the mixing of N2 and CO2, major components of exhaust gas, with the fuel-air mixture on the heat release of the cool flames and the emission characteristics of CO were investigated by experiment and computation. The heat release of the cool flames was reduced with N2 mixing; however, it increased with CO2 mixing. From the systematic experiments and chemical kinetic computations, it was confirmed that the amount of heat release from the cool flames depends strongly on the concentration of O2 at the onset of cool flame. The dominant pathway for CO oxidation is the reaction of CO + OH = CO2 + H, where the H atoms produced react with O2 molecules and produce OH + O or HO2. The CO oxidation becomes active as the branching rate to OH + O is increasing. However, the branching rate to HO2 was increased with the addition of CO2 into the mixture, resulting in higher CO emission. Though the mixing of CO2 is effective in suppressing knock-like combustion owing to its small specific heat ratio and large heat capacity, it has an inferior effect on CO emission.

scholarly journals Performance and Emission Parameters of Homogeneous Charge Compression Ignition (HCCI) Engine: A Review

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3557 ◽  
Author(s):  
M. Mofijur ◽  
M.M. Hasan ◽  
T.M.I. Mahlia ◽  
S.M. Ashrafur Rahman ◽  
A.S. Silitonga ◽  
...  
Keyword(s):  
Homogeneous Charge Compression Ignition ◽  
Engine Performance ◽  
Spark Ignition ◽  
Emission Characteristics ◽  
Compression Ignition ◽  
Combustion Mode ◽  
Performance And Emission ◽  
Hcci Combustion ◽  
Hcci Engines ◽  
Homogeneous Charge

Strict emission regulations and demand for better fuel economy are driving forces for finding advanced engines that will be able to replace the conventional internal combustion engines in the near future. Homogeneous charge compression ignition (HCCI) engines use a different combustion technique; there are no spark plugs or injectors to assist the combustion. Instead, when the mixtures reach chemical activation energy, combustion auto-ignites in multiple spots. The main objective of this review paper is to study the engine performance and emission characteristics of HCCI engines operating in various conditions. Additionally, the impact of different fuels and additives on HCCI engine performance is also evaluated. The study also introduces a potential guideline to improve engine performance and emission characteristics. Compared to conventional compression ignition and spark ignition combustion methods, the HCCI combustion mode is noticeably faster and also provides better thermal efficiency. Although a wide range of fuels including alternative and renewable fuels can be used in the HCCI mode, there are some limitation/challenges, such as combustion limited operating range, phase control, high level of noise, cold start, preparation of homogeneous charge, etc. In conclusion, the HCCI combustion mode can be achieved in existing spark ignition (SI) engines with minor adjustments, and it results in lower oxides of nitrogen (NOx) and soot emissions, with practically a similar performance as that of SI combustion. Further improvements are required to permit extensive use of the HCCI mode in future.

A Two Zone Model of a Single Cylinder HCCI Engine for Control Applications

2008 ◽  
Author(s):  
Varun Tandra ◽  
Nilabh Srivastava
Keyword(s):  
Zone Model ◽  
Ignition Timing ◽  
Control Laws ◽  
Single Cylinder ◽  
First Law Of Thermodynamics ◽  
Hcci Engine ◽  
Hcci Combustion ◽  
Hcci Engines ◽  
Computationally Intensive ◽  
Peak Pressures

This paper presents a first step towards developing a physics-based two-zone model of a single cylinder HCCI engine. Previously control laws were derived by using single zone mathematical models of HCCI combustion; although certain multi-zone models were reported, they were found too complex and unwieldy for the development of fast and efficient controllers for HCCI engines. The present work outlines the modeling approach of a single-cylinder two-zone HCCI engine by incorporating the first law of thermodynamics and temperature and concentration inhomogeneities within the cylinder in order to better predict peak pressures and combustion timings. The results showed good conformity when compared with the computationally intensive multi-zone models. A comparative analysis between the single zone and two-zone models, in the context of predicting cylinder pressures, temperatures, ignition timing is also discussed. Moreover, the effect of external parameters such as speed, and EGR were also evaluated.

scholarly journals Development of a 0D multi-zone model for fast and accurate prediction of homogeneous charge compression ignition (HCCI) engine

2021 ◽  
Vol 312 ◽  
pp. 07006
Author(s):  
Giovanni Fasulo ◽  
Fabio Bozza ◽  
Enrica Malfi ◽  
Luigi Teodosio
Keyword(s):  
Equivalence Ratio ◽  
Homogeneous Charge Compression Ignition ◽  
Fuel Mixture ◽  
Numerical Approach ◽  
Computational Effort ◽  
Zone Model ◽  
Pure Hydrogen ◽  
Compression Ignition ◽  
Hcci Engine ◽  
Homogeneous Charge

Homogeneous Charge Compression Ignition (HCCI) is a promising advanced combustion mode, featured by both high thermal efficiency and low emissions. In this context, a 0D multi-zone model has been developed, where the thermal stratification in the combustion chamber has been taken into account. The model is based on a control mass Lagrangian multi-zone approach. In addition, a procedure based on a tabulated approach (Tabulated Kinetic of Ignition - TKI) has been developed, to perform an accurate and fast prediction of the air/fuel mixture auto-ignition. This methodology allows combining the accuracy of detailed chemistry with a negligible computational effort. The tabulated procedure has been preliminarily verified through the comparison with the results of a commercial software (GT-Power™). In this assessment, single zone simulations have been performed comparing the TKI strategy to a conventional chemical kinetics one, in four different cases at varying the intake temperature and the equivalence ratio. Then, the proposed 0D multi-zone model has been validated against experimental data available in the literature. The analyses are carried out with reference to an HCCI engine fuelled with pure hydrogen and working in a single operating point, namely 1500 rpm, 2.2 bar IMEP and with a fuel/air equivalence ratio of 0.24. Three different temperatures, i.e., 373, 383, and 393 K, have been considered for the intake air. The experimental/numerical comparisons of pressure cycles and burn rates proved that the proposed numerical approach can reproduce the experiments with good accuracy, without the need for case-by-case tuning.

Experimental and Numerical Study on Auto-Ignition and Combustion of Homogeneous Charge Compression Ignition Fueled With Dimethyl Ether

2005 ◽  
Author(s):  
Ma-Ji Luo ◽  
Zhen Huang ◽  
De-Gang Li
Keyword(s):  
Diesel Engine ◽  
Dimethyl Ether ◽  
Homogeneous Charge Compression Ignition ◽  
Numerical Study ◽  
National Laboratory ◽  
Zone Model ◽  
Compression Ignition ◽  
Hcci Combustion ◽  
Key Species ◽  
Homogeneous Charge

Experimental study of the autoignition and combustion characteristics of homogeneous charge compression ignition (HCCI) was carried out on a modified diesel engine fuelled with Dimethyl ether (DME) fuel. Numerical simulations were also performed by using the detailed chemical kinetic mechanism of DME oxidation proposed by American Lawrence Livermore National Laboratory (LLNL). The experimental results indicate that HCCI combustion with DME fuel can be realized in diesel engine with a few modifications, and it has a two-stage heat release characteristics. The emissions of HCCI combustion with DME fuel can be characterized by free of smoke and near zero NOx. The simulation results suggest that the single-zone model can accurately predict the ignition timings, including the low temperature ignition and high temperature ignition. The variations of key species (such as H2O2, CH2O, OH, HCO, CH, etc) with crank angle during fuel oxidation and the effects of engine operating parameters on HCCI combustion can also be analyzed by numerical simulation.

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