Mechanical Engineering - Steam Boilers and Engines - Discussion

Discussion Forum : Steam Boilers and Engines - Section 1 (Q.No. 9)
9.
Which of the following statement is correct for a compound steam engine ?
The cost of the engine, for the same power and economy, is more than that of a simple steam engine.
The forces in the working parts are increased as the forces are distributed over more parts.
The ratio of expansion is reduced, thus reducing the length of stroke.
The temperature range per cylinder is increased, with corresponding increase in condensation.
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
2 comments Page 1 of 1.

Scientist atanu pal said:   5 years ago
A compound steam engine unit is a type of steam engine where steam is expanded in two or more stages.

A typical arrangement for a compound engine is that the steam is first expanded in a high-pressure (HP) cylinder,

Then having given up heat and losing pressure, it exhausts directly into one or more larger-volume low-pressure (LP) cylinders.

Multiple-expansion engines employ additional cylinders, of progressively lower pressure, to extract further energy from the steam.

It Invented in 1781, this technique was first employed on a Cornish beam engine in 1804. Around 1850, compound engines were first introduced into Lancashire textile mills.
(3)

Balu said:   8 years ago
It seems given answer is correct.

'The complete expansion of the steam occurs across multiple cylinders and, as there is less expansion in each cylinder, less heat is lost by the steam in each. This reduces the magnitude of cylinder heating and cooling, making higher expansion ratios practical and increasing the efficiency of the engine".
(1)

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