Slow speed diesel engines are large, , especially tall, and heavy and operate on the two-stroke cycl...
are the largest diesel engines ever built. Engine powers up to 100,000 kw are available from a single engine.
They are tall to allow for long strokes which improve engine efficiency the large physical allow for long
strokes which improve engine efficiency. The large physical size of the engine and components leads to
slow rotational speed with speeds up to 300 rpm considered to be slow. For equivalent power output, the
two-stroke diesel engine is significantly lighter than its com-parable four-stroke relative. This is most
apparent for large power requirements where the two-stroke engine produces much more power for the
same weight.
Large, slow speed, two-stroke marine diesel engines offer the advantages of:
1. Burning poorer quality, cheaper fuel.
2. Providing large power from a single, less complicated machine comprising fewer individual cylinders and moving parts.
3. Having a low rotational speed allowing them to be directly coupled to the propeller and removing the
need for transmission machinery such as clutches and gearboxes etc.
4. Being reversible and thus eliminating the need for reversing gear or controllable pitch propellers.
参考解析:
1. Why the long stroke can improve the engine efficiency?
A. The rotational speed is very fast.
B. The engine is four-stroke engine.
C. The large physical allow for long strokes which improve engine efficiency.
D. For the long stroke is reversible.
2. What is the main reason that the slow speed engine has a low rotational speed?
A. Because it is lighter than other engines.
B. Because it needs the clutches and gearboxes.
C. Because it burns the poorer quality fuel.
D. Because it has large physical size of the engine and components.
3. Compare to four-stroke engine the two-stroke engine has advantage of_______
A. The two-stroke engine is larger than the four-stroke in size.
B. The two-stroke engine, is heavier compare to .the equal out power's four-stroke engine
C. For equivalent heavy, the two-stroke diesel engine can provide more power than its comparable four2stroke relative.
D. The two-stroke engine can use the controllable pitch .propellers.
4. The two-stroke engine has the following advantage except for_______
A. Having more complex moving parts and a few of individual cylinders.
B. It burns cheaper, poorer quality fuel.
C. It can directly couple to propellers.
D. Being reversible and eliminating the reversing gear.