Compound steam engine: choose the correct statement about advantages/design features. Context: Compounding expands steam in multiple cylinders to improve economy and reduce temperature range per cylinder. Select the correct statement for a compound steam engine.
Mechanical Engineering
Steam Boilers and Engines
Difficulty: Easy
Choose an option
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AFor the same power and economy, the cost of the engine is more than that of a simple steam engine.
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BThe forces in working parts are increased since forces are distributed over more parts.
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CThe ratio of expansion is reduced, thus reducing the length of stroke.
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DThe temperature range per cylinder is increased, increasing condensation.
Answer
Correct Answer: For the same power and economy, the cost of the engine is more than that of a simple steam engine.
Explanation
ConceptCompound engines divide expansion across multiple cylinders (HP→IP→LP), improving efficiency and reducing thermal stresses. They are generally more costly than simple engines of the same power due to added cylinders and components.
Why the others are incorrect
- Forces are shared across stages; they are not “increased” as per Option B.
- Overall expansion ratio is increased, not reduced (Option C).
- Per-cylinder temperature range is decreased, reducing condensation (Option D).