The most effective technique for raising Carnot engine efficiency involves____________________?
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Answer: D. decrease lower temperature
Explanation
Carnot efficiency is calculated using the absolute temperatures of the heat source and the heat sink reservoirs. Lowering the sink temperature reduces the fraction of wasted energy rejected to the ambient environment significantly. Mathematical analysis shows that decreasing the lower temperature yields a larger efficiency gain than raising the source temperature. The maximum thermal efficiency of any heat engine is limited by the temperatures of its operating reservoirs. Carnot efficiency equals one minus the ratio of the absolute sink temperature to the absolute source temperature. Materials science limitations often restrict how high engineers can raise the maximum source operating temperature.
Increasing the higher temperature raises efficiency, but material metallurgical limits restrict how far it can go. Decreasing the higher temperature would actually reduce the overall thermal efficiency of the Carnot engine. Increasing the lower sink temperature degrades engine performance by increasing the fraction of rejected heat.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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