Intech Power Generator Systems
Diesel engine generaotrs the best choice for your generator needs for
longitivity & efficiency. We guide you why diesel engine generators are better
for all generator applications.
1. Why is diesel a better choice for your generator application? - GAS OR
DIESEL?
We recommend diesels due to their:
-
longevity - think of an 18 wheeler capable of 1,000,000
miles of operation before major service)
-
lower fuel costs (lower fuel consumption per kilowatt
(kW) produced)
-
lower maintenence costs - no spark system, more rugged
and more reliable engine.
Today’s modern diesels are quiet and normally require less
maintenance than comparably sized gas (natural gas or propane) units. Fuel costs
per kW produced with diesels is normally thirty to fifty percent less than gas
units.
1800 rpm water cooled diesel units operate on average 12-30,000 hours before
major maintenance is required. 1800 rpm water cooled gas units normally operate
6-10,000 hours because they are built on a lighter duty gasoline engine block.
3600 rpm air-cooled gas units are normally replaced – not overhauled at 500 to
1500 hours.
Because the gas units burn hotter (higher btu of the fuel) you will see
significantly shorter lives than the diesel units.
2. How does a diesel work?
The main differences between the gasoline engine and the diesel engine are:
-
A gasoline engine intakes a mixture of gas and air,
compresses it and ignites the mixture with a spark. A diesel engine takes in
just air, compresses it and then injects fuel into the compressed air. The
heat of the compressed air lights the fuel spontaneously.
-
A gasoline engine compresses at a ratio of 8:1 to 12:1,
while a diesel engine compresses at a ratio of 14:1 to as high as 25:1. The
higher compression ratio of the diesel engine leads to better efficiency.
-
Gasoline engines generally use either carburetion, in
which the air and fuel is mixed long before the air enters the cylinder, or
port fuel injection, in which the fuel is injected just prior to the intake
stroke (outside the cylinder). Diesel engines use direct fuel injection --
the diesel fuel is injected directly into the cylinder.
Note that the diesel engine has no spark plug, that it
intakes air and compresses it, and that it then injects the fuel directly into
the combustion chamber (direct injection). It is the heat of the compressed air
that lights the fuel in a diesel engine.
The injector on a diesel engine is its most complex component and has been the
subject of a great deal of experimentation -- in any particular engine it may be
located in a variety of places. The injector has to be able to withstand the
temperature and pressure inside the cylinder and still deliver the fuel in a
fine mist. Getting the mist circulated in the cylinder so that it is evenly
distributed is also a problem, so some diesel engines employ special induction
valves, pre-combustion chambers or other devices to swirl the air in the
combustion chamber or otherwise improve the ignition and combustion process.
One big difference between a diesel engine and a gas engine is in the injection
process. Most car engines use port injection or a carburetor rather than direct
injection. In a car engine, therefore, all of the fuel is loaded into the
cylinder during the intake stroke and then compressed. The compression of the
fuel/air mixture limits the compression ratio of the engine -- if it compresses
the air too much, the fuel/air mixture spontaneously ignites and causes
knocking. A diesel compresses only air, so the compression ratio can be much
higher. The higher the compression ratio, the more power is generated.
Some diesel engines contain a glow plug of some sort (not shown in this figure).
When a diesel engine is cold, the compression process may not raise the air to a
high enough temperature to ignite the fuel. The glow plug is an electrically
heated wire (think of the hot wires you see in a toaster) that helps ignite the
fuel when the engine is cold so that the engine can start.
Smaller engines and engines that do not have such advanced computer controls use
glow plugs to solve the cold-starting problem.
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