Environmental Engineering Reference
In-Depth Information
Table 11.2
Characteristics of medium speed four-stroke marine diesel engines
Engine
parameters
Physical properties
Operation
parameters
The number of revolutions is between 300 and 900 rpm. The average piston
speed ranges from 8 to 9 m s -1 (from 26.2 to 29.5 ft s -1 ). The cylinder
diameter is usually between 200 mm and 640 mm (7.9 and 25.2 in)
Performance
The power range is from 100 to 2,150 kW (from 134 to 2,883 HP) per
cylinder
The average pressure ranges from 200 9 10 5
Pa (4.18 9 10 5
lbf ft -2
Pressure range
or
2.901 psi) to 290 9 10 5
Pa (6.10 9 10 5
lbf ft -2
or 4.210 psi)
Table 11.3
Characteristics of high speed four-stroke marine diesel engines
Engine
parameters
Physical properties
Operation
parameters
The number of revolutions is over 900 rpm and the average piston speed is
between 9 and 11 m s -1 (29.5 and 36.7 ft s -1 ). The cylinder piston stroke
volume reaches from 0.266 to 0.55 dm 3 (from 9.3 9 10 -3 to
19.4 9 10 -3 ft 3 ). There are three, four, six, and eight cylinder versions
designed ''in-line'' and in a ''V'' shape
Future
development
The most important possibilities are increasing the fuel injection pressure,
using variable preinjection time, applying adjustable swirl, and mass of
intake air and introducing adjustable swirl and angle of injected fuel into
the combustion chamber and regulating the ignition point depending on
the exhaust gas quality
operating engine speed between 900 and 2,300 rpm. Similar to the medium speed
engine, the ignition pressure is approximately 200 9 10 5
Pa, i.e., 4.18 9 10 5
lbf ft -2 or 2,901 psi [ 15 ].
There is no sharp differentiation between medium and high speed marine diesel
engine (see Table 11.3 ).
Medium speed four-stroke marine engines are particularly advantageous at
lower speeds and lower partial loads. High speed four-stroke engines are used on
sport and lifeboats, and on specific smaller ships.
Gas turbines are used on ferries and navy ships, and provide higher speeds and
power ranges. They have the highest SFC under marine engines [ 16 ].
11.3 Main Operation Characteristics of Marine
Diesel Engines
11.3.1 Charging Marine Diesel Engines
Charging any diesel engine with air increases its performance without increasing
its speed by more than 50%. The efficiency of a turbocharger directly influences
Search WWH ::




Custom Search