Combustion
spark plug
In spark ignition engine, the combustion of the air fuel mixture is initiated by a
Nicolas A. Otto
Developed the gasoline engine
self ignition temperature
In compression engine, the combustion of the air fuel mixture is self ignited as a result of compressing the mixture above its
lowest position(BDC)
Initially, both the intake and exhaust valves are closed and the piston is at its
diesel cycle
Is a compression-ignition type of engine
Otto Cycle
Is a spark ignition type of engine
combustion chamber
Most supercharged of turbocharged engines use fuel injection of gasoline directly to
Isentropic Process
Otto Cycle has two constant volume process and two
gas cycles
Spark-Ignition automotive engines, diesel engines, and the conventional gas turbines are devices which operates on . They are also internal combustion engines.
Bore
The Diameter of the piston
Compression Ratio
The efficiency of the otto cycle is dependent only on the
scavenging
The exhaust stroke of the gasoline engine is also known as
Volume process
The heat added in Otto Cycle is during constant
compression ratio of the engine and the specific heat ratio of the working fluid
The thermal efficiency of an ideal otto cycle depends on the
displacement volume
The volume displaced by the piston as it moves between TDC and BDC
volume displacement of the engine
The work output per cycle also depends strongly on the compression ratio as well as the
8.0
Typical compression ratio of otto cycle is
increases
Using monatomic gas, (Helium and Argon) the thermal efficiency of Otto cycle
Reciprocating engines
are classified as a spark-ignition engines or compression ignition engines
Reciprocating engine
basically a piston-cylinder device
Supercharging
blank the engine in otto cycle can increase the power of the cycle but not to increase the efficiency
Rudolf Diesel
developed the diesel engine
constant volume process
diesel cycle has two isentropic, one constant pressure and one
upward
during compression stroke, the piston move , compressing the air fuel mixture
increase
if the specific heat ratio increases, the cycle efficiency will also
increase the efficiency of the engine
increasing the piston diameter or piston stroke of Otto cycle engine will
heat
is added during the constant pressure process
BDC(Bottom Dead Center)
is the position of the piston when it forms the largest volume in the cylinder
TDC(Top Dead Center)
is the position of the piston when it forms the smallest volume in the cylinder
turbocharging
is used in aircraft engines and some automotive engines. In this method, a turbine driven by the exhaust gases is used to provide power to the compressor or blower at the inlet.
engine knock
produces an audible noise
increasing the pressure and temperature
shortly before the piston reaches the highest position, the spark plug fires, of the system
intake valves
the air or air fuel mixture is drawn into the cylinder through the
exhaust valves
the combustion products are expelled from the cylinder through the
stroke of the engine
the distance between the TDC and BDC in which the piston can travel
increasing the pressure ratio
the mean effective pressure of the otto cycle can be increased by increasing the heat transfer into the engine per cycle or by
clearance volume
the minimum volume formed in the cylinder when the piston is at TDC is called
Four-stroke Internal Combustion Engine
the piston executes the complete stroke(two mechanical cycles) within the cylinder, and crankshafts completes two revolutions for each thermodynamic cycles
Autoignition
the premature ignition of the fuel is called
Slightly Above
the pressure in the cylinder is, during the exhaust stroke and slightly below during the intake stroke.
compression ratio
the ratio of the maximum to minimum volume in the cylinder of an internal combustion engine.
specific heat ratio
the second parameter affecting the thermal efficiency of an ideal otto cycle is
25-35 percent
the thermal efficiency of actual spark-ignition engines ranges from about
compression ratio
the thermal efficiency of the car engines has been decreased somewhat as a result of decreased
increases
the thermal efficiency of the otto cycle increases as the compression ratio
4 stroke cycle
the useful output is done during the expansion or compression stroke
less efficient
two stroke engines are generally than four stroke engines because of isentropic expulsion of the exhaust gases and partial expulsion of fresh air fuel mixture and the exhaust gases
simple and inexpensive
two stroke engines are relatively and have high power to weight and power to volume ratios which make them suitable for applications requiring small sizes and weight such as for motorcycles chain saws and lawn mowers
more power
two stroke engines has compared to four stroke engines
two revolutions only
two stroke engines performs intake, compression, and expansion and exhaust srroke in