This document proposes a new concept for internal combustion engines that uses homogeneous combustion in a porous medium. It introduces porous medium technology, which utilizes the heat transfer and flame propagation properties of highly porous materials like silicon carbide foam. This technology aims to achieve homogeneous mixing, ignition, and combustion within the porous structure to reduce emissions and improve efficiency. Two types of porous medium engines are described - one with periodic contact and one with permanent contact between the working gas and porous medium. The technology offers advantages like very low emissions, higher efficiency, fast combustion, and multi-fuel capability.

1. HOMOGENOUS COMBUSTION IN POROUS
MEDIUM
(A NEW CONCEPT OF I.C. ENGINE )
PREPARED BY:- UMANG TRIVEDI
.

2.  INDEX
I. INTRODUCTION
II. WHY WE NEED IT?
III. HOMOGENEOUS COMBUSTION
IV. POSSIBLE COMBUSTION MODES OF A HOMOGENEOUS CHARGE
V. POROUS MEDIUM TECHNOLOGY
VI. PRINCIPLE OF THE POROUS MEDIUM-ENGINE
VII. POROUS MEDIUM WITH CLOSED CHAMBER
VIII. POROUS MEDIUM WITH OPEN CHAMBER
IX. ADVANTAGES OF PM TECHNOLOGY
X. CONCLUSION
XI. REFRENCES.

3.  INTRODUCTION
Engine is one of the most hot topic where many research has been done and still
many new are been developed.
In that engine we want that which would give non-zero emission , less fuel
consumption to with stand under wild range of speed and load is currently under
research.
Many new things are reached in this field as it has various scope of
development in Porous Medium.
Since a lot of new stuff are developed or its under develoPorous Mediument .
Among them the new research is done in engine with homogeneous
combustion using porous medium Technology.

4.  WHY WE NEED IT?
At present, the emissions of internal combustion engines can only be improved by catalytic
treatments of the exhaust gases.
Such treatments, however, result in high costs and relatively low conversion efficiency.
This suggests that a new combustion technique should be developed to yield improved primary
combustion processes inside the engine with drastically reduced exhaust gas emissions.
So a technique was found which can be used in all engine with the steady state household.
The process of mixture formation, ignition & combustion in conventional engine is not effective
due to the lack of mechanisms for homogenous combustion process.
Two parameters will be required for future internal combustion engine i.e. non-zero emission
level & low fuel consumption.

5. COUNT..
These parameter is strongly dependent on the process of mixture formation &
combustion which are difficult to controlled in a conventional engine combustion
system.
The question is remain unsolved is the method for realization of homogenous
combustion in IC engine, specially if the variable engine operational conditions
are considered.
So here porous medium concept is introduced in order to overcome above
difficulty.
Porous Medium utilize the special features of highly porous media to support
and controlled the mixture formation and combustion process in IC engine.

6.  HOMOGENEOUS COMBUSTION
Homogeneous combustion in an IC engine is defined as a process characterized by a 3D-ignition
of the homogeneous charge with simultaneous-volumetric-combustion.
Hence it ensures a homogeneous temperature field.
According to the definition given above, three steps of the mixture formation and combustion
may be selected that define the ability of a given combustion system to operate as a homogeneous
combustion system:
A. Homogenization of charge.
B. Ignition conditions.
C. Combustion process and temperature field.

7. COUNT…
Four different ignition techniques may be selected:
A. Local ignition (e.g. spark plug).
B. Thermal self-ignition (e.g. compression ignition).
C. Controlled auto-ignition (e.g. low temperature chemical ignition).
D. 3D-thermal Porous Medium -self-ignition (3D-grid-structutre of a high temperature).
The last considered ignition system, has been recently proposed and uses a 3Dstructured porous
medium for the volumetric ignition of homogeneous charge.
The Porous Medium has homogeneous surface temperature over the most of the Porous Medium-
volume, higher than the ignition temperature.
In this case the Porous Medium-volume defines the combustion chamber volume.
Thermodynamically speaking, the porous medium is here characterized by a high heat capacity and
by a large specific surface area.

8.  POSSIBLE COMBUSTION MODES
OF A HOMOGENEOUS CHARGE
1) Homogenous charge with local ignition. 4) Homogeneous charge with 3D-
thermal self-ignition in Porous
Medium-volume
2) Homogeneous charge with compression ignition.
3) Homogeneous charge with controlled auto-ignition

9. The porous medium technology for IC engines means here the utilization of specific features of
a highly porous media for supporting and controlling the mixture formation and combustion
processes in I.C. engines.
 The employed specific features of Porous Medium are directly related to a very effective heat
transfer and very fast flame propagation within the Porous Medium.
The medium used is SiC ceramic foam which looks as shown
in Figure.
 POROUS MEDIUM
TECHNOLOGY

10. COUNT..
 Generally, the most important parameters of Porous Medium for application to engine combustion
technology can be given as follows:
I. Heat capacity,
II. Specific surface area,
III. Heat transport properties,
IV. Transparency for fluid flow,
V. Spray and flame propagation,
VI. Pore sizes, pore density,
VII. Pore structure,
VIII. Thermal resistance of the material,
IX. Mechanical resistance and mechanical properties under heating and cooling conditions

11. COUNT..
For IC engine application, the thermal
resistance of the porous medium is one of
the most important parameter defining its
applicability of a given material to
combustion in engine.
A view of the thermal test of SiC-reactors
for engine application is shown in Fig.

12.  PRINCIPLE OF THE POROUS MEDIUM-
ENGINE
The Porous Medium-engine is here defined as an internal combustion engine with the following
processes realized in a porous medium: internal heat recuperation, fuel injection, fuel
vaporization, mixing with air, homogenization of charge, 3D-thermal self ignition followed by a
homogeneous combustion.
Porous Medium-Engine may be classified with respect to the heat recuperation as:
 Engine with periodic contact between Porous Medium and working gas in cylinder (closed chamber).
Engine with permanent contact between Porous Medium and working gas in cylinder (open chamber).
On the other hand, possible positioning of the Porous Medium combustion chamber in engine can be used to
design different engines: A. Cylinder head (Porous Medium is stationary).
B. Cylinder (Porous Medium is stationary).
C. Piston (Porous Medium moves with piston).
One of the most interesting features of Porous Medium -engine is its multi fuel performance.
The Porous Medium-engine concept may be applied to both two and four-stroke cycles.

13.  POROUS MEDIUM WITH CLOSED
CHAMBER
The Porous Medium-engine cycle with a case of
closed Porous Medium chamber, i.e. engine with a
periodic contact between working gas and Porous
Medium-heat recuperator.
At the end of the expansion stroke the valve
controlling timing of the Porous Medium chamber
closes and fuel is injected in the Porous Medium-
volume.
This volume represents in thermodynamic sense a
low pressure chamber and a long time is available
for fuel injection and its vaporization in the Porous
Medium.
These processes may continue through exhaust,
intake and compression strokes

14.  COUNT…
Near the TDC of compression the valve in Porous Medium chamber opens and the compressed air
flows from the cylinder into the hot Porous Medium volume containing fuel vapors.
Very fast mixing of the gaseous charge occurs and the resulting mixture is ignited in the whole Porous
Medium volume.
The resulting heat release process performs simultaneously in the whole Porous Medium volume.
The three essential conditions for a homogeneous combustion are here fulfilled:
I. Homogenization of charge in Porous Medium -volume,
II. 3D-thermal self ignition in Porous Medium ,
III. Volumetric combustion with a homogeneous temperature field in Porous Medium-volume.
 Additionally, the Porous Medium -material deals as a heat capacitor and, hence, controls the
combustion temperature

15.  POROUS MEDIUM WITH OPEN
CHAMBER
The Porous Medium-engine is a combustion system
characterized by a permanent contact between working
gas and Porous Medium-volume, as schematically
shown in Figure
Here, it is assumed that the Porous Medium-
combustion chamber is mounted in the engine head.
During the intake stroke there is a weak influence of
the Porous Medium-heat capacitor on the in-cylinder air
thermodynamic conditions.
Also during the early compression stroke, only a small
amount of air is in contact with hot porous medium
process (non-isentropic compression) increases with
continuing compression, and at the TDC the whole
combustion air is closed in the Porous Medium
volume.

16.  COUNT..
Near the TDC of compression the fuel is injected in to Porous Medium volume
and very fast fuel vaporization and mixing with air occur in 3D-structure of
Porous Medium-volume.
Again, the requested 3D-thermal self-ignition of the resulting mixture follows in
Porous Medium-volume together with a volumetric combustion characterized by
a homogeneous temperature distribution in Porous Medium combustion volume.
Again, all necessary conditions for homogeneous combustion are fulfilled in the
Porous Medium combustion chamber.

17.  ADVANTAGES OF PM TECHNOLOGY
1)Very low emissions level due to homogeneous combustion and controlled temperature in the
PM-combustion zone.
2) Theoretically higher cycle efficiency due to similarity to the Carnot cycle.
3) Very low combustion noise due to significantly reduced pressure peaks.
4) Nearly constant and homogeneous combustion temperature field in the PM- volume.
5) Very fast combustion.
6) Multi-fuel system.
7) May operate with homogeneous charge: from stoichiometric to very lean
mixture compositions.
8) Weak effect of in-cylinder flow structure, turbulence or spray atomization

18.  Conclusion
 There is no doubt that the future of internal combustion engine is related to the homogeneous
combustion process in a wide range of engine operational conditions.
This technique shows potential for a near-zero combustion emissions & Moreover, this kind of
combustion system is less fuel specific.
 the realization of homogeneous combustion in IC engine under variable loads and speeds will
probably require new concepts for mixture formation and controlled ignition conditions under
different engine loads.
And all above it need to be economical dealing with compression temp., compression stroke,
ignition , mixing ratio so still needed to developed in this field.

19.  REFRENCES
1) http://engineringcorner.blogspot.in/2011/09/new-concept-of-ic-engine-with.html.
2) http://www.ijltet.org/wp-content/uploads/2012/07/6.pdf,
3) http://www.geedindia.org/papers/adil_vikas_abhi.pdf