Transient Air/Fuel Ratio Control in SI Engines

2002 ◽  
Author(s):  
R. Cipollone ◽  
M. Sughayyer
Keyword(s):  
Fuel Injection ◽  
Control Strategies ◽  
Dynamical Behavior ◽  
Transport Processes ◽  
Injection System ◽  
Intake Manifold ◽  
Fuel Ratio ◽  
Wide Range ◽  
Si Engines ◽  
System Effectiveness

Mixture strength control system effectiveness depends on its capacity to deal with air and fuel transport processes inside the intake manifold: the prediction of air mass flow to the engine cylinders and the compensation for the fuel lag during engine transients. These issues are all likely to be of extreme importance with the transient air/fuel ratio control strategies. This paper introduces an innovative model-based air/fuel ratio control strategy for SI engines. It is based on a previously published modeling approach for the air dynamics inside intake manifolds, which is based on the formulation of the mass, momentum and energy conservation equations and named as Method Of Interconnected Capacities. The proposed strategy uses a fuel compensator that is based on a macroscopical modeling of the fuel film dynamical behavior inside the intake manifold, which is derived from the Aquino model. A wide range of severe transient tests obtained from the experimentation of a single-cylinder research engine (type AVL 5401), equipped with port-fuel injection system, is presented. The results obtained have proved the effectiveness of the proposed strategy in controlling the air/fuel ratio in SI engines in a better way compared to the traditional control systems.

Numerical Investigation on LNG Injection in a SI-ICE

2018 ◽  
Author(s):  
Gianluca Pasini ◽  
Stefano Frigo ◽  
Marco Antonelli ◽  
Maria Berardi
Keyword(s):  
Natural Gas ◽  
Fossil Fuels ◽  
Fuel Injection ◽  
Engine Performance ◽  
Peak Torque ◽  
Cryogenic Liquid ◽  
Volumetric Efficiency ◽  
Injection System ◽  
Intake Manifold ◽  
Si Engines

Since the beginning of this century, Liquefied Natural Gas (LNG) has been attracting more and more attention as a cleaner energy alternative to other fossil fuels, mainly due to the possibility to transport it over longer distances than natural gas in pipelines and lower environmental impact than other liquid fuels. It is expected that this trend in the use of LNG will lead to steady increases in demand over the next few decades. At present, in the automotive sector, natural gas is employed as fuel in spark-ignited (SI) engines in the gas phase (CNG) adopting port-fuel injection system (PFI) in the intake manifold, with the main result of reducing CO2 emissions by up to 20%, compared with gasoline operation. However, SI engines which are operated in this manner suffer loss of peak torque and power due to a reduction in volumetric efficiency. Direct-Injection (DI) inside the cylinder can overcome this drawback by injecting CNG after intake valve closure. Another strategy could be the injection of natural gas in the liquid phase, both in PFI or DI mode. The injected fuel evaporation cools down the intake air; increasing the charge density with a substantial improvement in the engine volumetric efficiency and delivered power. However, at present, injection systems dedicated to cryogenic injection of natural gas are still in the prototype state. In the present study, the volumetric efficiency and performance of a turbocharged, LNG fuelled SI-ICE were numerically analysed both in the cases of DI and PFI modes and compared with the results of a conventional CNG system. Various fuel injection timings and injector position were analysed. The engine performance was evaluated by means of a one-dimensional model developed with the simulation program GT-Power, while the verification of the LNG-air mixture characteristics was carried out with the commercial code Aspen HYSIS. The numerical activity has shown that gaseous DI, before inlet valves closing, gives the worst result since methane, once injected into the cylinder, expands hindering the entry of air. On the other side, liquid PFI represents the best configuration to maximize the volumetric efficiency and therefore the engine power. All the technological issues related to a cryogenic liquid methane injection system were not taken into consideration in this study.

scholarly journals An Experimental and Modeling Study of HCCI Combustion Using n-Heptane

2009 ◽  
Vol 132 (2) ◽  
Author(s):  
Hongsheng Guo ◽  
W. Stuart Neill ◽  
Wally Chippior ◽  
Hailin Li ◽  
Joshua D. Taylor
Keyword(s):  
Low Temperature ◽  
Internal Combustion Engines ◽  
Fuel Injection ◽  
Combustion Process ◽  
Injection System ◽  
Intake Manifold ◽  
Strong Impact ◽  
Oxides Of Nitrogen ◽  
Hcci Combustion ◽  
Modeling Study

Homogeneous charge compression ignition (HCCI) is an advanced low-temperature combustion technology being considered for internal combustion engines due to its potential for high fuel conversion efficiency and extremely low emissions of particulate matter and oxides of nitrogen (NOx). In its simplest form, HCCI combustion involves the auto-ignition of a homogeneous mixture of fuel, air, and diluents at low to moderate temperatures and high pressure. Previous research has indicated that fuel chemistry has a strong impact on HCCI combustion. This paper reports the preliminary results of an experimental and modeling study of HCCI combustion using n-heptane, a volatile hydrocarbon with well known fuel chemistry. A Co-operative Fuel Research (CFR) engine was modified by the addition of a port fuel injection system to produce a homogeneous fuel-air mixture in the intake manifold, which contributed to a stable and repeatable HCCI combustion process. Detailed experiments were performed to explore the effects of critical engine parameters such as intake temperature, compression ratio, air/fuel ratio, engine speed, turbocharging, and intake mixture throttling on HCCI combustion. The influence of these parameters on the phasing of the low-temperature reaction, main combustion stage, and negative temperature coefficient delay period are presented and discussed. A single-zone numerical simulation with detailed fuel chemistry was developed and validated. The simulations show good agreement with the experimental data and capture important combustion phase trends as engine parameters are varied.

A New Hybrid Air Blast Nozzle for Advanced Gas Turbine Combustors

2000 ◽  
Author(s):  
Adel Mansour ◽  
Michael Benjamin ◽  
Erlendur Steinthorsson
Keyword(s):  
Gas Turbine ◽  
Thermal Management ◽  
Fuel Injection ◽  
Injection System ◽  
Operating Pressure ◽  
Air Blast ◽  
Pressure Drops ◽  
Fuel Delivery ◽  
Wide Range ◽  
Atomization Performance

The push towards higher specific fuel consumption and smaller, lighter packaging for aerospace gas turbine engines has resulted in large increases in engine operating pressure and temperature. This is a trend that is expected to continue, and as a result, thermal management of the hot engine section including the fuel nozzle, combustor, and turbine has emerged as a critical technology area requiring further development. For the fuel injection system, nozzle thermal management, turndown ratio, and atomization performance while maintaining correct combustor aerodynamics are the most important performance features that necessitate optimization. Significant advances in fuel injection concepts are required to meet the increasingly demanding combustor requirements. Complex heat-shielded designs are often required to reduce nozzle wetted-wall temperatures and prevent the formation of carbonaceous deposits within the fuel delivery passages. To support the development of advanced combustors and address these increasing performance demands, Parker has developed a new Hybrid Air Blast nozzle. Advanced analytical and experimental design tools were applied to reduce the cut-and-try approach previously used in nozzle development. The developed hybrid air blast design achieved excellent atomization performance over a wide range of fuel flow rates and air pressure drops. Thermal analysis of the nozzle showed that the wetted wall temperatures were reduced considerably when compared to previous designs operating at the same conditions. Eight-port circumferential spray patternation results were outstanding with the patternation factor at various values of liquid flow rate ranging between 0.12 and 0.18. This patternation factor is a significant improvement over those of current state-of-the-art injectors that are typically of the order of 0.25.

scholarly journals RME CO-COMBUSTION WITH HYDROGEN IN COMPRESSION IGNITION ENGINE: PERFORMANCE, EFFICIENCY AND EMISSIONS / SLĖGINIO UŽDEGIMO VARIKLIO ENERGINIŲ, EFEKTYVUMO IR DEGINIŲ EMISIJOS RODIKLIŲ TYRIMAS NAUDOJANT RAPSŲ METILESTERĮ IR VANDENILĮ

2018 ◽  
Vol 10 (0) ◽  
pp. 1-9
Author(s):  
Romualdas Juknelevičius
Keyword(s):  
Combustion Process ◽  
Engine Performance ◽  
Fuel Mixture ◽  
Common Rail ◽  
Injection System ◽  
Intake Manifold ◽  
Compression Ignition Engine ◽  
Common Rail Injection System ◽  
Wide Range ◽  
The Rich

The article presents the test results of the single cylinder CI engine with common rail injection system operating on biofuel – Rapeseed Methyl Ester with addition supply of hydrogen. The purpose of this investigation was to examine the influence of the hydrogen addition to the biofuel on combustion phases, engine performance, efficiency, and exhaust emissions. HES was changed within the range from 0 to 44%. Hydrogen was injected into the intake manifold, where it created homogeneous mixture with air. Tests were performed at both fixed and optimal injection timings at low, medium and nominal engine load. After analysis of the engine bench tests and simulation with AVL BOOST software, it was observed that lean hydrogen – RME mixture does not support the flame propagation and efficient combustion. While at the rich fuel mixture and with increasing hydrogen fraction, the combustion intensity concentrate at the beginning of the combustion process and shortened the ignition delay phase. AVL BOOST simulation performed within the wide range of HES (16–80%) revealed that combustion intensity moves to the beginning of combustion with increase of HES. Decrease of CO, CO2 and smoke opacity was observed with increase of hydrogen amounts to the engine. However, increase of the NO concentration in the engine exhaust gases was observed. Santrauka Straipsnyje pateikti tyrimo rezultatai, gauti atlikus bandymą vieno cilindro slėginio uždegimo variklyje su biodegalais – rapsų metilesterį (RME) ir vandenilį. Biodegalai įpurškiami akumuliatorine įpurškimo sistema „Common rail“. Šio tyrimo tikslas – ištirti, kaip vandenilis veikia biodegalų degimą, variklio veikimą, jo efektyvumą ir deginių susidarymą. Vandenilio energinė dalis degimo mišinyje buvo keičiama nuo 0 iki 44 %. Vandenilis buvo tiekiamas įsiurbimo fazės metu įsiurbimo kanalu į degimo kamerą, kurioje jis, susimaišęs su oru, sudaro homogeninį mišinį. Bandymai buvo atliekami nekeičiant įpurškimo kampo, nustačius optimalų įpurškimo kampą esant žemai, vidutinei ir nominaliai variklio apkrovai. Išnagrinėjus variklio bandymų rezultatus ir sumodeliavu AVL BOOST programa, buvo pastebėta, kad, esant liesam vandenilio ir RME mišiniui, liepsnos plitimas yra lėtas, mišinys dega neveiksmingai. Tačiau riebus degalų mišinys ir padidinta vandenilio energijos dalis užtikrina degimo intensyvumą degimo proceso pradžioje ir sutrumpina uždegimo gaišties trukmę. AVL BOOST modeliavimas, atliktas plačiu vandenilio energijos dalies diapazonu (16–80 %), patvirtino teiginį, kad degimas tampa intensyvesnis degimo pradžioje dėl padidinto vandenilio kiekio. Didinant vandenilio kiekį, buvo pastebėta, kad išmetamosiose dujose sumažėjo CO, CO2 ir kietųjų dalelių, tačiau padidėjo NO koncentracija.

Transient air-fuel ratio control of a multi-point injection engine with an integration-type ultrasonic flowmeter

2001 ◽  
Vol 215 (3) ◽  
pp. 385-391
Author(s):  
J. Kim ◽  
T. Kang ◽  
S. K. Kauh
Keyword(s):  
Fuel Injection ◽  
Spark Ignition Engine ◽  
Ultrasonic Flowmeter ◽  
Intake Manifold ◽  
Air Mass ◽  
Fuel Ratio ◽  
Throttle Valve ◽  
Fuel Model ◽  
Model Control ◽  
Point Injection

An integration-type flowmeter, composed of an ultrasonic flowmeter and an integration circuit, is used to measure the air mass for transient air-fuel ratio (AFR) control of a port fuel injection (PFI) spark ignition engine. Also, the air mass and required fuel mass in the cylinder are accurately calculated for precise AFR control. The proposed method can significantly improve the accuracy of measuring air mass inducted through a throttle valve. Air mass passing into a cylinder is estimated using the measured air mass at the throttle valve and intake manifold pressure. A simple two-constant fuel model is used for a dynamic fuel model. Control parameters from the air and fuel dynamics are applied to minimize AFR excursions, and a four-cylinder, 1.51 PFI engine was used to demonstrate this AFR control strategy. Results show that the AFR followed a command value with a peak error of 4 per cent during throttle transients at various operating points.

A Novel Method to Estimate Parameters of the Wall-Wetting Fuel Model in MPFI Engines for Cold Start and Warm Up Conditions

2004 ◽  
Author(s):  
M. Shahbakhti ◽  
M. Ghafuri ◽  
A. R. Aslani ◽  
A. Sahraeian ◽  
S. A. Jazayeri ◽  
...  
Keyword(s):  
Fuel Injection ◽  
Cold Start ◽  
Spark Ignition Engine ◽  
Intake Manifold ◽  
Exhaust Emission ◽  
Model Parameters ◽  
Transfer Model ◽  
Fuel Film ◽  
Warm Up ◽  
Fuel Ratio

In order to fulfill the LEV/ULEV exhaust emission standards, it is necessary to have a precise control of air fuel ratio under transient conditions especially during cold start and warm up periods. The objective in this study was to estimate parameters of a fuel delivery model and use them to provide a correct fuel injection compensation strategy. In this study, fuel transfer characteristics of intake port of a typical fuel-injected spark ignition engine have been determined for engine warm-up conditions following cold starts at temperature down to −15°C and extending to fully-warmed-up conditions, using a method based upon perturbing fuel injection rate and recording AFR (Air Fuel Ratio) response. Since there was no cold chamber available to perform tests in cold start conditions, a new method was utilized to simulate cold start conditions. This method can be used on any PFI engine with closed valve injection strategy. Following the estimation of fuel transfer model parameters, the variation of fuel film deposit factor (X), fuel film evaporation time constant (τf) and transport delay to oxygen sensor (ΔT) parameters over a range of temperatures, engine speeds and intake manifold pressures have been evaluated, providing a good insight to define transient fuel compensation requirements for cold start and warm up conditions.

A study on the injection characteristics of a liquid-phase liquefied petroleum gas injector for air-fuel ratio control

2005 ◽  
Vol 219 (8) ◽  
pp. 1037-1046 ◽  
Author(s):  
Hansub Sim ◽  
Kangyoon Lee ◽  
Namhoon Chung ◽  
Myoungho Sunwoo
Keyword(s):  
Liquid Phase ◽  
Fuel Injection ◽  
Injection Pressure ◽  
Vapour Phase ◽  
Injection Rate ◽  
Injection System ◽  
Driving Voltage ◽  
Liquefied Petroleum Gas ◽  
Fuel Temperature ◽  
Fuel Ratio

Liquefied petroleum gas (LPG) is widely used as a gaseous fuel in spark ignition engines because of its considerable advantages over gasoline. However, the LPG engine suffers a torque loss because the vapour-phase LPG displaces a larger volume of air than do gasoline droplets. In order to improve engine power as well as fuel consumption and air-fuel ratio control, considerable research has been devoted to improving the LPG injection system. In the liquid-phase LPG injection systems, the injection rate of an injector is affected by the fuel temperature, injection pressure, and driving voltage. When injection conditions change, the air-fuel ratio should be accurately controlled in order to reduce exhaust emissions. In this study, correction factors for the fuel injection rate are developed on the basis of fuel temperature, injection pressure, and injector driving voltage. A compensation method to control the amount of injected fuel is proposed for a liquid-phase LPG injection control system. The experimental results show that the liquid-phase LPG injection system works well over the entire range of engine speeds and load conditions, and the air-fuel ratio can be accurately controlled by using the proposed compensation algorithm.

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