for IC engine

2.  Introduction
 CI Engines Formation of CO in
 Emissions Control
 Historical outline of HCCI combustion
 The advantages of HCCI engines
 Working principle of the HCCI engine
technology
 Current application of HCCI y
 Experimental studies
 Conclusion
 reference

3.  During the 1940s air pollution as a problem was
first recognized in the Los Angeles basin.
 Two causes of this were the large population
density and the local weather conditions.
 Smoke and other pollutants combined with fog to
form smog.
 In 1966 HC and CO emission limits were
introduced.
 By making more fuel efficient engines and with the
use of exhaust after treatment, emissions per
vehicle of HC, CO, and NOx were reduced by
about 95% during the 1970s and 1980s.

4. 4
Anatomy of Catalytic Converter for CI Engines
•All catalytic converters are built in a honeycomb or pellet geometry to expose the
exhaust gases to a large surface made of one or more noble metals: platinum,
palladium and rhodium.
•Rhodium used to remove N and platinum used to remove HC and CO.

5.  The mean air-fuel mixture present in the combustion
chamber per cycle is far leaner in the diesel engine than
in the SI engine.
 Due to a lack of homogeneity of the mixture built up by
stratification, however, extremely “rich” local zones are
exist.
 This produces high CO concentrations that are reduced
to a greater or lesser extent by post-oxidation.
 When the excess-air ratio increases, dropping
temperatures cause the post-oxidation rate to be
reduced.
 The reactions “freeze up”.
 However, the final CO concentrations of diesel engines
therefore are far lower than in SI engines.
 The basic principles of CO formation, however, are the
same as in SI engine.

6.  Three basic methods used to control engine
emissions:
 1)Engineering of combustion process -advances in
fuel injectors, oxygen sensors, and on-board
computers.
 2) Optimizing the choice of operating parameters -
two Nox control measures that have been used in
automobile engines are spark retard and EGR.
 3) After treatment devices in the exhaust system -
catalytic converter.

7.  HCCI combustion was discovered as an alternative
way for two stroke engines. A first study on such
type of combustion process was made by in 1979
[1]. This completely new type of combustion
adopted to the piston engines has been called
Active-Thermo Atmosphere Combustion as a
promising alternative for existing spark and diesel
engines. The drawbacks of two stroke engines are
a high residuals emissions at low and partially
loads, and the tendency to run on (knock effect)
when the engine is stopped.

8.  Apart from that the up to date spark ignition
engines fitted with a three way catalyst can be
regarded as a very clean engines, problem
appears during part load conditions. Low efficiency
at partial load results from pumping losses. It
follows from specific SI engine load control. SI
engine is controlled by changing air flow rate. The
air flow through venturi throat is throttled by
reducing the flow area. Suffering the consequence
of throttling, pumping losses increase during the
gas exchange and considerable amount of work
produced by the engine must be used for
scavenging.

9.  The HCCI concept, which is proposed as an
ultimate method of lean burn, is completely
different from other conventional combustion
concepts like spark or compression ignition.
In the HCCI engine homogeneous mixture is
created and it depends on solution in the
intake system or inside the cylinder.
Homogeneous charge or air is drawn into the
cylinder during suction stroke and
compressed to high enough temperature and
pressure.

10.  At present two engines run in HCCI mode are
commercially available in the world. First of them is
delivered by Nissan fitted with new technology
combustion called MK Combustion System,
second is developed by Honda called AR
Combustion System.
 The ”MODULATED KINETICS” – MK – system,
developed by Nissan [38] (see figure 2),
incorporated in a regular CIDI engine using diesel
fuel. At light load, the engine operates with high
swirl ratio, high EGR quantity and retarded
injection timing.

11.  This piece of work presents the results of the tests
of engine, during which distribution of fuel
 between the direct injection system and port
injection system was changed.
 For each test the constant injection and ignition
timing and the stoichiometric composition of
 the mixture was maintained. The direct injection
timing was determined in preliminary tests
 at 281° CA before TDC, which means direct
injection of fuel during the intake stroke.

12.  The carried-out simulations of the engine working
with fuel injection only into the intake
 manifold and dual-injection of fuel gave the
following conclusions:
 • Obtaining with the dual-injection of fuel the
same mixture composition, which occurred
 with indirect injection, requires a slightly larger
amount of fuel. This fact points to improve
 of volumetric efficiency for the engine working with
dual-injection in those simulation
 conditions.

13. On the basis of the results of carried out
considerations the following conclusions
can be presented:
• The outcome of computational part of
the work are convergent with the
experimental research results. This
confirms the proper design of the model
and indicates the its further use.

14.  [1] Kedzia, R., Okoński, A., „Układy paliwowe systemów
wtryskowych silników z zapłonem
 iskrowym”, Poradnik Serwisowy Nr 1/2002, Instalator Polski,
Warsaw 2002, Poland
 [2] Kochersberger, K., Hyde, K. W., Emsen, R., Parker, R. G.,
„An Evaluation of the 1910
 Wright Vertical Four Aircraft Engine”, AIAA-2001-3387,
American Institute of Aeronautics
 and Astronautics, Reston 2001, United States of America
 [3] Mason, F. K., „Messerschmitt Bf-109B,C,D,E in Luftwaffe &
Foreign Service”, Aircam
 Aviation Series No. 39 (Vol.1), Osprey Publishing Limited,
ISBN 0-85045-152-3 Berkshire
 1973, United Kingdom