Ignition control in the hcci combustion

Not all gasoline engines need spark plugs to ignite their fuel. In a conventional internal combustion engine ICE cycle, a mixture of air, spark and fuel come together over the course of four strokes to create power and move a vehicle forward. Diesel engines do not require spark plugs to ignite the mixture and produce combustion.

Ignition control in the hcci combustion

Bridget Cunningham October 4, Environmental demands for greater fuel efficiency and lower emissions have sparked an interest in finding an alternative to traditional spark- and compression-ignition engines.

While homogeneous charge compression ignition HCCI engines offer a viable solution, significant challenges like maintaining control of ignition timing still remain. But as transportation and other technologies using these engines have evolved, greater emphasis has been placed on reducing the emissions and improving the efficiency of fuel engines.

Ignition control in the hcci combustion

This has not only prompted the optimization of conventional engines, but it has also encouraged the search for alternative engine types that could better meet growing environmental demands. One of the suggested alternatives is HCCI engines. Testing an automotive HCCI engine.

Image by Combustion Research Facility. HCCI is a type of internal combustion in which auto-ignition of a homogeneous fuel-oxidant mixture is reached by a compression process.

HCCI (Homogeneous-Charge Compression Ignition) | NISSAN | TECHNOLOGICAL DEVELOPMENT ACTIVITIES

When compared to conventional engine types, HCCI engines have a lower operation temperature and generate a simultaneous combustion in the entire volume of the combustion chamber. Due to its uniform combustion process and relatively low temperature, the HCCI process emits less NOx and produces a cleaner exhaust.

In this sense, HCCI engines deliver the best of both worlds, balancing the emissions of a gasoline-style engine with the efficiency of a diesel-style engine.

While this technology shows great promise, there are some important challenges to overcome — one of which is ignition timing. In traditional engines, modifying the combustion timing is rather easy via engine control modules.

The flameless combustion process of HCCI, however, makes maintaining control over the process a much more difficult task. While forming such a mixture with conventional diesel fuel is quite difficult small droplets in airnatural gas fuels all-gas phase are able to quickly reach uniform conditions in the cylinder.

These fuels are therefore a viable option for HCCI. With this in mind, we chose to consider the combustion of methane for our example. In this particular case, the methane combustion takes place under lean conditions, which means that an excess of oxidizer is supplied.

Model Methane HCCI Combustion to Optimize Engine Ignition Control

To describe the reaction kinetics and thermodynamics of this mechanism, we used the GRI Importing the respective data files into the Reaction Engineering interface in COMSOL Multiphysics made it easy to set up and access the necessary data for our problem.

The model itself consists of a combustion cylinder featuring a perfectly mixed batch system of variable volume.

This predefined reactor type is available as an option in the Reaction Engineering interface. The figures below show the engine cylinder as well as the key geometric parameters in its design.

The combustion cylinder and its respective geometric parameters. In this case, D is 13 cm, Lc is Note that the speed of the engine is rpm. When calculating the cylinder volume as a function of the crank angle, the piston is shown to initially be at the bottom dead center. The angle is therefore defined as zero at the top dead center.

Plot depicting the cylinder volume combustion chamber as a function of the crank angle.

Homogeneous charge compression ignition - Wikipedia RCCI uses in-cylinder fuel blending with at least two fuels of different reactivity and multiple injections to control in-cylinder fuel reactivity to optimize combustion phasing, duration and magnitude. The process involves introduction of a low reactivity fuel into the cylinder to create a well-mixed charge of low reactivity fuel, air and recirculated exhaust gases.
HCCI (Homogeneous-Charge Compression Ignition) | NISSAN | TECHNOLOGICAL DEVELOPMENT ACTIVITIES Nissan is developing this technology for commercial use. Characteristics of HCCI The system features lower-temperature combustion compared to ordinary gasoline engines, resulting in nearly no NOx emissions.

Simulating the Compression and Ignition of Fuel in an HCCI Engine We can begin by looking at our analysis of the cylinder pressure as a function of time when the mixture of methane and air undergoes compression and ignites.compression ignition, and expands the range of ignition combustion by a maximum of three times compared to the conventional method.

The fuel efficiency of Spark-Assisted HCCI was verified, with results indicating a decrease of 16% in steady-state fuel. In addition. it will be necessary to accurately control ignition timing.

and (3) Exhaust gas purification performance is poor in the lean environment. ignition timing can be easily controlled by control of the spark timing of the plugs.

Reactivity Controlled Compression Ignition (RCCI) RCCI is a dual fuel engine combustion technology that was developed at the University of Wisconsin-Madison Engine Research Center laboratories. RCCI is a variant of Homogeneous Charge Compression Ignition (HCCI) that provides more control over the combustion process and has the potential to dramatically lower fuel use and emissions. In an HCCI engine (which is based on the four-stroke Otto cycle), fuel delivery control is of paramount importance in controlling the combustion process. On the intake stroke, fuel is injected into each cylinder's combustion chamber via fuel injectors mounted directly in the cylinder head. Ignition Control for HCCI. Project ID – ace_18_edwards. K. Dean Edwards Robert M. Wagner Charles E. A. Finney Ignition delay [ms] CRADA between ORNL and Delphi » Incorporate SA-HCCI combustion model into GT-Power and calibrate with engine data.

as in the case of SI and conventional HCCI. until finally a hot flame that generates CO2 from CO is produced. Reactivity Controlled Compression Ignition (RCCI) RCCI is a dual fuel engine combustion technology that was developed at the University of Wisconsin-Madison Engine Research Center laboratories.

RCCI is a variant of Homogeneous Charge Compression Ignition (HCCI) that provides more control over the combustion process and has the potential . HCCI is the ultimate combustion method for achieving both CO2 reduction and clean exhaust using auto-ignition of gasoline, as in a diesel engine.

Ignition control in the hcci combustion

Nissan is developing this technology for commercial use. While homogeneous charge compression ignition (HCCI) engines offer a viable solution, significant challenges like maintaining control of ignition timing still remain.

With simulation tools like the COMSOL Multiphysics® software, you can analyze the combustion process of an HCCI engine and gain deeper insight into ways to advance ignition control. One challenge with Homogeneous Charge Compression Ignition (HCCI) engines is the need for good timing control of the combustion.

The HCCI engine differs from spark ignition engines and compression ignition engines, since it can only run in open-loop at low load.

The main advantages of the HCCI engine are the very low NOx exhaust emissions and fairly high efficiency, close to that of compression .

Model Methane HCCI Combustion to Optimize Engine Ignition Control | COMSOL Blog