HCCI - AbsoluteAstronomy.com

Homogeneous charge compression ignition (HCCI) is a form of internal combustion

Internal combustion engine

The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...

in which well-mixed fuel

Fuel

Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...

and oxidizer (typically air) are compressed to the point of auto-ignition. As in other forms of combustion

Combustion

Combustion or burning is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species. The release of heat can result in the production of light in the form of either glowing or a flame...

, this exothermic reaction

Exothermic reaction

An exothermic reaction is a chemical reaction that releases energy in the form of light or heat. It is the opposite of an endothermic reaction. Expressed in a chemical equation:-Overview:...

releases chemical energy into a sensible form that can be transformed in an engine into work

Work (thermodynamics)

In thermodynamics, work performed by a system is the energy transferred to another system that is measured by the external generalized mechanical constraints on the system. As such, thermodynamic work is a generalization of the concept of mechanical work in mechanics. Thermodynamic work encompasses...

and heat.

Introduction

HCCI has characteristics of the two most popular forms of combustion used in SI (spark ignition) engines: homogeneous charge spark ignition (gasoline

Gasoline

Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...

engines) and CI engines: stratified charge compression ignition (diesel engine

Diesel engine

A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...

s). As in homogeneous charge spark ignition, the fuel and oxidizer are mixed together. However, rather than using an electric discharge to ignite a portion of the mixture, the density and temperature of the mixture are raised by compression until the entire mixture reacts spontaneously. Stratified charge compression ignition also relies on temperature and density increase resulting from compression, but combustion occurs at the boundary of fuel-air mixing, caused by an injection event, to initiate combustion.

The defining characteristic of HCCI is that the ignition occurs at several places at a time which makes the fuel/air mixture burn nearly simultaneously. There is no direct initiator of combustion. This makes the process inherently challenging to control

Control theory

Control theory is an interdisciplinary branch of engineering and mathematics that deals with the behavior of dynamical systems. The desired output of a system is called the reference...

. However, with advances in microprocessors and a physical understanding of the ignition process, HCCI can be controlled to achieve gasoline engine-like emissions along with diesel engine

Diesel engine

A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...

-like efficiency. In fact, HCCI engines have been shown to achieve extremely low levels of Nitrogen oxide emissions (NO_x) without an aftertreatment catalytic converter

Catalytic converter

A catalytic converter is a device used to convert toxic exhaust emissions from an internal combustion engine into non-toxic substances. Inside a catalytic converter, a catalyst stimulates a chemical reaction in which noxious byproducts of combustion are converted to less toxic substances by dint...

. The unburned hydrocarbon and carbon monoxide emissions are still high (due to lower peak temperatures), as in gasoline engines, and must still be treated to meet automotive emission regulations

Automobile emissions control

Vehicle emissions control is the study and practice of reducing the motor vehicle emissions -- emissions produced by motor vehicles, especially internal combustion engines....

.

Recent research has shown that the use of two fuels with different reactivities (such as gasoline and diesel) can help solve some of the difficulties of controlling HCCI ignition and burn rates. RCCI or Reactivity Controlled Compression Ignition has been demonstrated to provide highly efficient, low emissions operation over wide load and speed ranges *http://www.engr.wisc.edu/news/headlines/2009/Aug03.html.

History

HCCI engines have a long history, even though HCCI has not been as widely implemented as spark ignition or diesel injection. It is essentially an Otto combustion cycle

Otto cycle

An Otto cycle is an idealized thermodynamic cycle which describes the functioning of a typical reciprocating piston engine, the thermodynamic cycle most commonly found in automobile engines....

. In fact, HCCI was popular before electronic spark ignition

Ignition system

An ignition system is a system for igniting a fuel-air mixture. Ignition systems are well known in the field of internal combustion engines such as those used in petrol engines used to power the majority of motor vehicles, but they are also used in many other applications such as in oil-fired and...

was used. One example is the hot-bulb engine

Hot bulb engine

The hot bulb engine, or hotbulb or heavy oil engine is a type of internal combustion engine. It is an engine in which fuel is ignited by being brought into contact with a red-hot metal surface inside a bulb....

which used a hot vaporization chamber to help mix fuel with air. The extra heat combined with compression induced the conditions for combustion to occur. Another example is the "diesel" model aircraft engine

Carbureted compression ignition model engines

Simple compression ignition engines are made for model propulsion, usually model aircraft but also model boats. These are quite similar to the typical glow-plug engine that runs on a mixture of methanol-based fuels with a hot wire filament to provide ignition...

Methods

A mixture of fuel and air will ignite when the concentration and temperature of reactants is sufficiently high. The concentration and/or temperature can be increased by several different ways:

High compression ratio
Compression ratio
The 'compression ratio' of an internal-combustion engine or external combustion engine is a value that represents the ratio of the volume of its combustion chamber from its largest capacity to its smallest capacity...
Pre-heating of induction gases
Forced induction
Retained or re-inducted exhaust gases

Once ignited, combustion occurs very quickly. When auto-ignition occurs too early or with too much chemical energy, combustion is too fast and high in-cylinder pressures can destroy an engine. For this reason, HCCI is typically operated at lean

Lean burn

Lean burn refers to the use of lean mixtures in an internal combustion engine. The air-fuel ratios can be as high as 65:1, so the mixture has considerably less fuel in comparison to the stoichiometric combustion ratio ....

overall fuel mixtures.

Advantages

HCCI provides up to a 30-percent fuel savings, while meeting current emissions standards.
Since HCCI engines are fuel-lean, they can operate at a Diesel-like compression ratios (>15), thus achieving higher efficiencies than conventional spark-ignited gasoline engines.
Homogeneous mixing of fuel and air leads to cleaner combustion and lower emissions. Actually, because peak temperatures are significantly lower than in typical spark ignited engines, NO_x
Nitrogen oxide
Nitrogen oxide can refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds:* Nitric oxide, also known as nitrogen monoxide, , nitrogen oxide* Nitrogen dioxide , nitrogen oxide...

levels are almost negligible. Additionally, the premixed lean mixture does not produce soot
Soot
Soot is a general term that refers to impure carbon particles resulting from the incomplete combustion of a hydrocarbon. It is more properly restricted to the product of the gas-phase combustion process but is commonly extended to include the residual pyrolyzed fuel particles such as cenospheres,...

.
HCCI engines can operate on gasoline, diesel fuel, and most alternative fuels.
In regards to gasoline engines, the omission of throttle losses improves HCCI efficiency.

Disadvantages

High in-cylinder peak pressures may cause damage to the engine.
High heat release and pressure rise rates contribute to engine wear.
The autoignition event is difficult to control, unlike the ignition event in spark ignition (SI) and diesel engine
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...

s which are controlled by spark plugs and in-cylinder fuel injectors, respectively.
HCCI engines have a small power range, constrained at low loads by lean flammability limits and high loads by in-cylinder pressure restrictions.
Carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

(CO) and hydrocarbon
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....

(HC) pre-catalyst emissions are higher than a typical spark ignition engine, caused by incomplete oxidation (due to the rapid combustion event and low in-cylinder temperatures) and trapped crevice gases, respectively.

Control

Controlling HCCI is a major hurdle to more widespread commercialization. HCCI is more difficult to control than other popular modern combustion engines, such as Spark Ignition (SI) and Diesel. In a typical gasoline engine, a spark is used to ignite the pre-mixed fuel and air. In Diesel engines, combustion begins when the fuel is injected into compressed air. In both cases, the timing of combustion is explicitly controlled. In an HCCI engine, however, the homogeneous mixture of fuel and air is compressed and combustion begins whenever the appropriate conditions are reached. This means that there is no well-defined combustion initiator that can be directly controlled. Engines can be designed so that the ignition conditions occur at a desirable timing. To achieve dynamic operation in an HCCI engine, the control system

Control system

A control system is a device, or set of devices to manage, command, direct or regulate the behavior of other devices or system.There are two common classes of control systems, with many variations and combinations: logic or sequential controls, and feedback or linear controls...

must change the conditions that induce combustion. Thus, the engine must control either the compression ratio, inducted gas temperature, inducted gas pressure, fuel-air ratio, or quantity of retained or re-inducted exhaust. Several control approaches are discussed below.

Variable compression ratio

There are several methods for modulating both the geometric and effective compression ratio. The geometric compression ratio can be changed with a movable plunger at the top of the cylinder head. This is the system used in "diesel" model aircraft engines

Model engine

In radio-controlled modeling, a model engine is an internal combustion engine used to power a radio-controlled aircraft, radio-controlled car, radio-controlled boat, free flight and control line aircraft, and tether car models also use these engines....

. The effective compression ratio can be reduced from the geometric ratio by closing the intake valve either very late or very early with some form of variable valve actuation (i.e. variable valve timing

Variable valve timing

In internal combustion engines, variable valve timing , also known as Variable valve actuation , is a generalized term used to describe any mechanism or method that can alter the shape or timing of a valve lift event within an internal combustion engine...

permitting Miller cycle

Miller cycle

In engineering, the Miller cycle is a combustion process used in a type of four-stroke internal combustion engine. The Miller cycle was patented by Ralph Miller, an American engineer, in the 1940s.- Overview :...

). Both of the approaches mentioned above require some amounts of energy to achieve fast responses. Additionally, implementation is expensive. Control of an HCCI engine using variable compression ratio strategies has been shown effective.
The effect of compression ratio on HCCI combustion has also been studied extensively.

Variable induction temperature

In HCCI engines, the autoignition event is highly sensitive to temperature. Various methods have been developed which use temperature to control combustion timing. The simplest method uses resistance heaters to vary the inlet temperature, but this approach is slow (cannot change on a cycle-to-cycle basis).
Another technique is known as fast thermal management (FTM). It is accomplished by rapidly varying the cycle to cycle intake charge temperature by rapidly mixing hot and cold air streams.
It is also expensive to implement and has limited bandwidth associated with actuator energy.

Variable exhaust gas percentage

Exhaust gas can be very hot if retained or re-inducted from the previous combustion cycle or cool if recirculated through the intake as in conventional EGR

Exhaust gas recirculation

In internal combustion engines, exhaust gas recirculation is a nitrogen oxide emissions reduction technique used in petrol/gasoline and diesel engines. EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. In a gasoline engine, this inert exhaust...

systems. The exhaust has dual effects on HCCI combustion. It dilutes the fresh charge, delaying ignition and reducing the chemical energy and engine work. Hot combustion products conversely will increase the temperature of the gases in the cylinder and advance ignition. Control of combustion timing HCCI engines using EGR has been shown experimentally.

Variable valve actuation

Variable valve actuation (VVA) has been proven to extend the HCCI operating region by giving finer control over the temperature-pressure-time history within the combustion chamber. VVA can achieve this via two distinct methods:

Controlling the effective compression ratio: A variable duration VVA system on intake can control the point at which the intake valve closes. If this is retarded past bottom dead center (BDC), then the compression ratio will change, altering the in-cylinder pressure-time history prior to combustion.
Controlling the amount of hot exhaust gas retained in the combustion chamber: A VVA system can be used to control the amount of hot internal exhaust gas recirculation (EGR) within the combustion chamber. This can be achieved with several methods, including valve re-opening and changes in valve overlap. By balancing the percentage of cooled external EGR with the hot internal EGR generated by a VVA system, it may be possible to control the in-cylinder temperature.

While electro-hydraulic and camless VVA systems can be used to give a great deal of control over the valve event, the componentry for such systems is currently complicated and expensive. Mechanical variable lift and duration systems, however, although still being more complex than a standard valvetrain, are far cheaper and less complicated. If the desired VVA characteristic is known, then it is relatively simple to configure such systems to achieve the necessary control over the valve lift curve. Also see variable valve timing

Variable valve timing

Variable fuel ignition quality

Another means to extend the operating range is to control the onset of ignition and the heat release rate by manipulating the fuel itself. This is usually carried out by adopting multiple fuels and blending them "on the fly" for the same engine . Examples could be blending of commercial gasoline and diesel fuels , adopting natural gas or ethanol ". This can be achieved in a number of ways;

Blending fuels upstream of the engine: Two fuels are mixed in the liquid phase, one with low resistance to ignition (such as diesel fuel) and a second with a greater resistance (gasoline), the timing of ignition is controlled by varying the compositional ratio of these fuels. Fuel is then delivered using either a port or direct injection event.
Having two fuel circuits: Fuel A can be injected in the intake duct (port injection) and Fuel B using a direct injection (in-cylinder) event, the proportion of these fuels can be used to control ignition, heat release rate as well as exhaust gas emissions.

Direct Injection: PCCI or PPCI Combustion

Compression Ignition Direct Injection (CIDI) combustion is a well-established means of controlling ignition timing and heat release rate and is adopted in Diesel engines combustion. Partially Pre-mixed Charge Compression Ignition (PPCI) also known as Premixed Charge Compression Ignition (PCCI) is a compromise between achieving the control of CIDI combustion but with the exhaust gas emissions of HCCI, specifically soot . On a fundamental level, this means that the heat release rate is controlled preparing the combustible mixture in such a way that combustion occurs over a longer time duration and is less prone to knocking. This is done by timing the injection event such that the combustible mixture has a wider range of air/fuel ratios at the point of ignition, thus ignition occurs in different regions of the combustion chamber at different times - slowing the heat release rate. Furthermore this mixture is prepared such that when combustion occurs there are fewer rich pockets thus reducing the tendency for soot formation . The adoption of high EGR and adoption of diesel fuels with a greater resistance to ignition (more "gasoline like") enables longer mixing times prior to ignition and thus fewer rich pockets thus resulting in the possibility of both lower soot emissions and NOx

High peak pressures and heat release rates

In a typical gasoline or diesel engine, combustion occurs via a flame. Hence at any point in time, only a fraction of the total fuel is burning. This results in low peak pressures and low energy release rates. In HCCI, however, the entire fuel/air mixture ignites and burns nearly simultaneously resulting in high peak pressures and high energy release rates. To withstand the higher pressures, the engine has to be structurally stronger and therefore heavier. Several strategies have been proposed to lower the rate of combustion. Two different fuels, with different autoignition properties, can be used to lower the combustion speed.
However, this requires significant infrastructure to implement. Another approach uses dilution (i.e. with exhaust gases) to reduce the pressure and combustion rates at the cost of work production.

Power

In both a spark ignition engine and diesel engine

Diesel engine

A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...

, power can be increased by introducing more fuel into the combustion chamber. These engines can withstand a boost in power because the heat release rate in these engines is slow. However, in HCCI engines the entire mixture burns nearly simultaneously. Increasing the fuel/air ratio will result in even higher peak pressures and heat release rates. In addition, many of the viable control strategies for HCCI require thermal preheating of the charge which reduces the density and hence the mass of the air/fuel charge in the combustion chamber, reducing power. These factors make increasing the power in HCCI engines challenging.

One way to increase power is to use fuels with different autoignition properties. This will lower the heat release rate and peak pressures and will make it possible to increase the equivalence ratio. Another way is to thermally stratify the charge so that different points in the compressed charge will have different temperatures and will burn at different times lowering the heat release rate making it possible to increase power.
A third way is to run the engine in HCCI mode only at part load conditions and run it as a diesel or spark ignition engine at full or near full load conditions.
Since much more research is required to successfully implement thermal stratification in the compressed charge, the last approach is being studied more intensively.

Emissions

Because HCCI operates on lean mixtures, the peak temperatures are lower in comparison to spark ignition (SI) and Diesel engines. The low peak temperatures prevent the formation of NO_x. This leads to NO_x emissions at levels far less than those found in traditional engines. However, the low peak temperatures also lead to incomplete burning of fuel, especially near the walls of the combustion chamber. This leads to high carbon monoxide and hydrocarbon emissions. An oxidizing catalyst would be effective at removing the regulated species because the exhaust is still oxygen rich.

Difference from Knock

Engine knock or pinging

Engine knocking

Knocking in spark-ignition internal combustion engines occurs when combustion of the air/fuel mixture in the cylinder starts off correctly in response to ignition by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front.The...

occurs when some of the unburnt gases ahead of the flame in a spark ignited engine spontaneously ignite. The unburnt gas ahead of the flame is compressed as the flame propagates and the pressure in the combustion chamber rises. The high pressure and corresponding high temperature of unburnt reactants can cause them to spontaneously ignite. This causes a shock wave to traverse from the end gas region and an expansion wave to traverse into the end gas region. The two waves reflect off the boundaries of the combustion chamber and interact to produce high amplitude standing waves.

A similar ignition process occurs in HCCI. However, rather than part of the reactant mixture being ignited by compression ahead of a flame front, ignition in HCCI engines occurs due to piston compression. In HCCI, the entire reactant mixture ignites (nearly) simultaneously. Since there are very little or no pressure differences between the different regions of the gas, there is no shock wave propagation and hence no knocking. However at high loads (i.e. high fuel/air ratios), knocking is a possibility even in HCCI.

Simulation of HCCI Engines

The development of computational models for simulating combustion and heat release rates of HCCI engines has required the advancement of detailed chemistry models . This is largely because ignition is most sensitive to chemical kinetics rather than turbulence/spray or spark processes as are typical in direct injection compression ignition or spark ignition engines. Computational models have demonstrated the importance of accounting for the fact that the in-cylinder mixture is actually in-homogeneous, particularly in terms of temperature. This in-homogeneity is driven by turbulent mixing and heat transfer from the combustion chamber walls, the amount of temperature stratification dictates the rate of heat release and thus tendency to knock . This limits the applicability of considering the in-cylinder mixture as a single zone resulting in the uptake of 3D computational fluid dynamics codes such as Los Alamos National Laboratory's

Los Alamos National Laboratory

Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...

KIVA

KIVA (software)

KIVA is a family of Fortran-based Computational Fluid Dynamics software developed by Los Alamos National Laboratory . The software predicts complex fuel and air flows as well as ignition, combustion, and pollutant-formation processes in engines...

CFD

CFD may refer to:Science and computing* Computational fluid dynamics, a branch of fluid dynamics* Counterfactual definiteness, the ability, quantum mechanics, to consider results of unperformed measurements* Cfengine Daemon, the process that runs Cfengine...

code and faster solving probability density function modelling codes .

Prototypes

As of August 2007 there were no HCCI engines being produced in commercial scale. However several car manufacturers have fully functioning HCCI prototypes.

General Motors
General Motors
General Motors Company , commonly known as GM, formerly incorporated as General Motors Corporation, is an American multinational automotive corporation headquartered in Detroit, Michigan and the world's second-largest automaker in 2010...

has demonstrated HCCI with a modified Family II engine
GM Family II engine
The Family II is a straight-4 piston engine that was originally developed by Opel in the early 1970s. It was used in the Opel Ascona and Opel Kadett and their corresponding sister models the Vauxhall Cavalier and Vauxhall Astra...

installed in Opel Vectra
Opel Vectra
The Opel Vectra is a large family car that was engineered and produced by Opel. In the United Kingdom, the car was sold under the Vauxhall marque as the Vauxhall Cavalier and later as the Vauxhall Vectra, from 1995 onwards...

and Saturn Aura
Saturn Aura
The Saturn Aura is a mid-size car produced under the Saturn brand of American automaker General Motors. It debuted as a concept car at the North American International Auto Show in January 2005. The production model of the Aura was shown at the 2006 New York Auto Show in April, with production...

. GM is also researching smaller Family 0 engines for HCCI applications. GM has used KIVA
KIVA (software)
KIVA is a family of Fortran-based Computational Fluid Dynamics software developed by Los Alamos National Laboratory . The software predicts complex fuel and air flows as well as ignition, combustion, and pollutant-formation processes in engines...

in the development of direct-injection, stratified charge gasoline engines as well as the fast burn, homogeneous-charge gasoline engine.
Mercedes-Benz
Mercedes-Benz
Mercedes-Benz is a German manufacturer of automobiles, buses, coaches, and trucks. Mercedes-Benz is a division of its parent company, Daimler AG...

has developed a prototype engine called DiesOtto
DiesOtto
The Mercedes-Benz DiesOtto is an experimental automobile engine that “is said to incorporate the benefits of a diesel engine, but runs on regular old unleaded.”...

, with controlled auto ignition. It was displayed in its F 700
Mercedes-Benz F700
The Mercedes-Benz F700 is a concept car produced by Mercedes-Benz. It was first revealed to the public at the 2007 Frankfurt motor show.-DiesOtto engine:...

concept car at the 2007 Frankfurt Auto Show.
Volkswagen
Volkswagen
Volkswagen is a German automobile manufacturer and is the original and biggest-selling marque of the Volkswagen Group, which now also owns the Audi, Bentley, Bugatti, Lamborghini, SEAT, and Škoda marques and the truck manufacturer Scania.Volkswagen means "people's car" in German, where it is...

are developing two types of engine for HCCI operation. The first, called Combined Combustion System or CCS, is based on the VW Group 2.0-litre diesel engine but uses homogeneous intake charge rather than traditional diesel injection. It requires the use of synthetic fuel
Synthetic fuel
Synthetic fuel or synfuel is a liquid fuel obtained from coal, natural gas, oil shale, or biomass. It may also refer to fuels derived from other solids such as plastics or rubber waste. It may also refer to gaseous fuels produced in a similar way...

to achieve maximum benefit. The second is called Gasoline Compression Ignition or GCI; it uses HCCI when cruising and spark ignition when accelerating. Both engines have been demonstrated in Touran
Volkswagen Touran
The Volkswagen Touran is a compact MPV based on a vertically-stretched fifth generation Volkswagen Golf Mk5, and sold in Europe and other select markets. It was launched in 2003 to fill a gap in Volkswagen's model lineup, below the Sharan large MPV...

prototypes, and the company expects them to be ready for production in about 2015.
In May 2008, General Motors gave Auto Express
Auto Express
Auto Express is a weekly motoring magazine sold in the United Kingdom published by Dennis Publishing. The Editor-in-Chief is Steve Fowler.Launched in September 1988, its 1000th issue was published on 20 February 2008. It's only weekly competitor in Britain is the long established Autocar...

access to a Vauxhall Insignia prototype fitted with a 2.2-litre HCCI engine, which will be offered alongside their ecoFLEX range of small-capacity, turbocharged petrol and diesel engines when the car goes into production. Official figures are not yet available, but fuel economy is expected to be in the region of 43mpg with carbon dioxide emissions of about 150 grams per kilometre, improving on the 37mpg and 180g/km produced by the current 2.2-litre petrol engine. The new engine operates in HCCI mode at low speeds or when cruising, switching to conventional spark-ignition when the throttle is opened.
In October 2005, the Wall Street Journal reported that Honda
Honda
is a Japanese public multinational corporation primarily known as a manufacturer of automobiles and motorcycles.Honda has been the world's largest motorcycle manufacturer since 1959, as well as the world's largest manufacturer of internal combustion engines measured by volume, producing more than...

was developing an HCCI engine as part of an effort to produce a next generation hybrid car.
Oxy-Gen Combustion, a UK-based Clean Technology company, has produced a full-load HCCI concept engine with the aid of Michelin and Shell http://www.oxy-gencombustion.com

Other Applications of HCCI Research

To date there have only been few prototype engines running in HCCI mode however the research efforts invested into HCCI research have disseminated into/resulted in direct advancements in fuel and engine development. Examples are;

PCCI/PPCI combustion - A hybrid of HCCI and conventional diesel combustion offing more control over ignition and heat release rates with lower soot and NOx emissions .
Advancements in fuel modelling - HCCI combustion is driven mainly by chemical kinetics rather than turbulent mixing or injection, this reduces the complexity of simulating the chemistry which results in fuel oxidation and emissions formation. This has led to increasing interest and development of chemical kinetics which describe hydrocarbon oxidation.
Fuel blending applications- Due to the advancements in fuel modelling, it is now possible to carry out detailed simulations of hydrocarbon fuel oxidation, enabling simulations of practical fuels such as gasoline/diesel and ethanol . Engineers can now blend fuels virtually and determine how they will perform in an engine context.

Introduction

History

Methods

Advantages

Disadvantages

Control

Variable compression ratio

Variable induction temperature

Variable exhaust gas percentage

Variable valve actuation

Variable fuel ignition quality

Direct Injection: PCCI or PPCI Combustion

High peak pressures and heat release rates

Power

Emissions

Difference from Knock

Simulation of HCCI Engines

Prototypes

Other Applications of HCCI Research

See also

External links

Further reading