The document discusses Homogeneous Charge Compression Ignition (HCCI) engines. HCCI engines compress the fuel-air mixture to the point of auto-ignition, requiring no spark plug. This allows for lower emissions and improved fuel efficiency compared to traditional engines. However, auto-ignition is difficult to control precisely. Various methods are used to control the combustion timing, such as variable compression ratios or induction temperatures. HCCI engines also have a smaller adjustable power range than traditional engines. Major automakers are researching HCCI as a promising future technology.

1. Homogeneous Charge Compression
Ignition (HCCI) Engines

2. Contents
 Need of HCCI
 HCCI Engine Concept
 Advantage & Challenges related to HCCI
 Future Aspects.

3. Solution
• Hybrid Vehicles
• Fuel Cells
• HCCI Engines
• GDI Engine
• Low Emissions Technologies
• New Materials
• Advanced Design Simulations
• Efficient Electronics and Electrical Devices

4. What is an HCCI Engine?
• HCCI is a form of internal
combustion in which the fuel
and air are compressed to the
point of auto ignition.
• That means no spark is required
to ignite the fuel/air mixture
• Creates the same amount of
power as a traditional engine,
but uses less fuel.
Traditional combustion
(left) uses a spark to
ignite the mixture. HCCI
(right) uses piston
compression for a more
complete ignition.

5. How Does It Work?
• A given concentration of fuel and
air will spontaneously ignite
when it reaches its auto-ignition
temperature.
• The concentration/temperature
can be controlled several ways:
– High compression ratio
– Preheating of induction gases
– Forced induction
– Retaining or reintroducing exhaust
gases
Click here for a nice
animation of an HCCI
engine in action!

6. The Challenges Facing Us…
• Emission (NOx & Soot)
• Fuel Economy
Fuel Consumption is increased by more than 10 % in last 7 years
UrbanUrban
PollutionPollution

7. Traditional combustion (left) uses a spark to ignite the mixture. HCCI (right) uses piston
compression for a more complete ignition.
• Unlike conventional engines, the combustion occurs
simultaneously throughout the volume rather than in a flame
front.
• This important attribute of HCCI allows combustion to occur at
much lower temperatures, dramatically reducing engine-out
emissions of NOx
SI Engine HCCI

8. WORKING OF HCCI ENGINE

9. Comparison with other engines

10. FOUR STROKE ENGINE
Suction Stroke.
Compression Stroke.
Combustion Stroke.
Exhaust Stroke.

11. SUCTION STROKE:
Fuel air mixture intake take place.

12. Compression Stroke: Piston moves from bottom
dead centre totop dead centre

13. COMBUSTION STROKE:

14. EXHAUST STROKE: Removal of exhaust gases
takes place.

15. Advantages
• Can achieve up to 15% fuel
savings
• Lower peak temperature
leads to cleaner
combustion/lower emissions
• Can use gasoline, diesel, or
most alternative fuels
HCCI automobiles could
reduce greenhouse gas
emissions

16.  POTENTIAL
1. High efficiency, no knock limit on
compression ratio..
2. Low PM emissions, no need for PM filter.
3. HCCI provides up to a 15-percent fuel
savings, while meeting current emissions
standards.
4. HCCI engines can operate on gasoline,
diesel fuel, and most alternative fuels.
5. In regards to CI engines, the omission of
throttle losses improves HCCI efficiency.

17. Disadvantages
• Higher cylinder peak
pressures may damage the
engine
• Auto-ignition is difficult to
control
• HCCI Engines have a
smaller power range
Prototype HCCI car from Saturn

18.  BARRIERS
1. The auto-ignition event is difficult to control,
unlike the ignition event in spark -ignition(SI)
and diesel engines which are controlled by
spark plugs and in-cylinder fuel injectors,
respectively.
2. HCCI engines have a small power range,
constrained at low loads by lean flammability
limits and high loads by in-cylinder pressure
restrictions
3. High HC and CO emissions.

19. The Future of HCCI
• The future of HCCI looks
promising
• Major companies such as
GM, Mercedes-Benz, Honda,
and Volkswagen have
invested in HCCI research.
• Preliminary prototype figures
show that HCCI cars can
achieve in the area of 43
mpg

20. HCCI CONCEPT

21. Starting HCCI engines
 Charge does not readily auto ignite cold
engines.
 Early proposal was to start in SI mode
and run in HCCI mode.
 It involves the risk of knocking and
cylinder failure at high compression
ratios.
 Now intake air pre-heating with HE and
burner system allows startup in HCCI
mode with conventional starter.

22. Control methods of HCCI combustion
 The spontaneous and simultaneous combustion
of fuel-air mixture need to be controlled.
 No direct control methods possible as in SI or CI
engines.
 Various control methods are:
 Variable compression ratio
 Variable induction temperature
 Variable valve actuation

23. Control methods of HCCI combustion
 Variable compression ratio method
 The geometric compression ratio can
be changed with a movable plunger
at the top of the cylinder head. This
concept used in “diesel” model
aircraft engine.

24.  Variable induction temperature
 The simplest method uses
resistance heater to vary inlet
temperature. But this method is
slow
 Now FTM (Fast Thermal
Management) is used. It is
accomplished by rapidly varying the
cycle to cycle intake charge
temperature by rapid mixing.

25. FTM system
Rapid mixing of cool and hot intake air
takes place achieving optimal temperature
as demanded and hence better control.

26. Control methods of HCCI combustion
 Variable valve actuation (VVA)
 This method gives finer control
within combustion chamber
 Involves controlling the effective
pressure ratio. It controls the point
at which the intake valve closes. If
the closure is after BDC, the
effective volume and hence
compression ratio changes.

27. Control methods of HCCI combustion

28. Dual mode transitions
 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
overall fuel mixtures
 This restricts engine operation at high
loads

29. Dual mode transitions
 Practical HCCI engines will need to
switch to a conventional SI or diesel
mode at very low and high load
conditions due to dilution limits
 Two modes:
 HCCI-DI dual mode
 HCCI-SI dual mode

30. SI mode transitions
 It equips VVA and spark ignition system
 Operates in HCCI mode at low to medium
loads and switches into SI mode at higher
loads
 Transition is not very stable and smooth

31. DI-HCCI
 Long ignition delay and rapid mixing are
required to achieve diluted homogeneous
mixture.
 Combustion noise and NOx emissions were
reduced substantially without an increase in
PM.
 Combustion phasing is controlled by injection
timing.
 Thus DI-HCCI proves to be promising
alternative for conventional HCCI with good
range of operation.

32. Recent developments in HCCI
 Turbo charging initially proposed to
increase power
 Challenges for turbo charging
1. Exhaust gas temperatures low (300 to
350 °c) because of high compression
ratio.
2. Post turbine exhaust gas temperature
must be high enough to preheat intake
fuel-air mixture in HE.
3. Low available compressor pressure
ratio.

33.  The exhaust has dual effects on HCCI
combustion.
 It dilutes the fresh charge, delaying ignition
and reducing the chemical energy and
engine work.
 Reduce the CO and HC emissions
Recent developments in HCCI

34. HCCI prototypes
 General Motors has demonstrated Opel
Vectra and Saturn Aura with modified
HCCI engines.
 Mercedes-Benz has developed a prototype
engine called Dies Otto, with controlled
auto ignition. It was displayed in its F 700
concept car at the 2007 Frankfurt Auto
Show

35.  Volkswagen 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 homogenous intake charge rather
than traditional diesel injection. It requires the
use of synthetic fuel 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 prototypes, and the
company expects them to be ready for
production in about 2015.

36. Works Cited
• “Homogeneous Charge Compression Ignition”
http://en.wikipedia.org/wiki/Homogeneous_Char
ge_Compression_Ignition November, 2008.
• “New HCCI Engine”
http://videos.howstuffworks.com/multivu/3284-
new-hcci-engine-video.htm November, 2008
• “GM Takes New Combustion Technology Out of
the Lab and Onto the Road”
http://www.gm.com/experience/fuel_economy/
news/2007/adv_engines/new-combustion-
technology-082707.jsp