For the duration of the summer, we completely instrumented a small engine given to us by a private company to convert it to run completely on natural gas. During the summer we installed all sorts of instrumentation including thermo couplesr, CO2 sensors, High preforming heaters, fabricated a simple intake system. The importance Of doing this is because we needed to know exactly what is going on with the engine and monitor even the slightest change. when trying to run an engine on a different fuel source all the temperatures and pressures in different chambers have to be at an specific point so in instrumenting the engine is a mandatory task. At this point the engine is running well but there seems to be some discrepancies between the meters on installed on the engine. After some further calculations then we may be able to get the engine up and running for a small amount of time.
2. HOW THE TYPICAL ENGINE WORKS
Pulls air and fuel into the cylinder
Closes the cylinder and compresses the air
and fuel mixture to around 150 psi at “top
dead center”.
A spark plug ignites the pressurized mixture
which causes a small explosion to push
down on a piston turning the crankshaft.
The remaining CO2 gases exit through the
exhaust and the cycle repeats.
3. CONCEPT: WHAT IS HCCI?
HCCI stands for Homogenous Charge Combustion Ignition
and how this works is when you heat a fuel air mixture in a
chamber to a certain temperature it will auto-ignite. This
process is similar to the “knocking” of an engine. The
difference between knocking and HCCI is the rate of energy
release. Knocking is more spontaneous and has a higher
peak pressure in a Pressure vs. Volume diagram. HCCI has
a slower and more controlled auto ignition.
4. GOAL
Successfully convert a standard gasoline
operated engine to work with Compressed
natural gas.
Transition the engine to operate with
compressed natural gas without the aid of a
spark plug i.e. auto-combustion.
5. CONCEPT
Lower the U.S dependency of oil products from
foreign countries
Natural Gas Abundance
Cut loses to make natural gas cheaper than it
already is
Put power plant in car
Power plants already use natural gas t o power
generators that supply electricity
Modeling
8. AIR FLOW METER
Air Flow Meter: Used to find the flow rate of
the air that is going into the intake system
after the flow Straightener
9. THERMOCOUPLES
Monitor the temperatures of all different
parts of the engine. They are places on
Exhaust ports,
The intake manifold,
Measure oil tem through dipstick, ambient air
temp,
Intake air temp
11. ENCODER
Reads out all the crank angles and rpm’s of
the engine to the third decimal place. With
the encoder we can tell exactly where the
piston in the chamber.
12. DAMPENER
Being that this engine is a V twin there are a
lot of pressure pulsations coming through the
intake system. The dampener resonates the
pulsations over a larger area.
13. EGR (EXHAUST GAS RECIRCULATION)
Re-circulating exhaust gas back into the
intake manifold then mixing it with fresh air
and fuel steadies the rate of release during
auto ignition.
14. WHAT WE ACCOMPLISHED
Over the course of the last 2 months we have
successfully instrumented the engine
debugged it and everything is now currently
operational, with all sensors, meters working,
the engine is running smoothly and our
software is showing reading accurate
readings.
15. DIFFICULTIES
Working in an engine that has many sensors
and meters attached to it is a very difficult task
because things have to be constantly changed,
takes off, drilled, welded, machined,
dimensioned etc. With a group of 8 people, in
the beginning it was a shoving match of elbows
and tools.
Ordering parts gave us a great deal of difficulty
because they were either high precision parts
that can not be bought in store or
communication issues between departments.
16. Theoretical
Properties of an NGE
combustion chamber
Intake
and Exhaust valves
are closed
Looking at different stages
of piston
Air compressed inside the
chamber
MODELING AND FLUENT ANALYSIS
17. STEP PROCESS
Step 1. Compression of air in closed chamber
Provided some insight into modeling.
Step 2. Compression of methane and air closed chamber
This will provide information on mixture interaction during compression.
Step 3. Develop thermal model (temperature distribution on walls and volume) for methane/air
mixture along with pressure and temperature.
Very important step as will provide information on our computing capabilities and
temperature distribution within the chamber (hot spots)
Step 4. Redo the step 3 with EGR and heated air as inputs.
This will change all the dynamics of the modeling that we will have done thus far and
require high computing power.
Step 5. Use thermal model from step 4 as initial conditions and run the simulation again.
The final step before combustion modeling. Results will give some approximation on
developing HCCI combustion.
will
