The controlling heat transfer film coefficient is the one offering the ______________ resistance?
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Answer: C. The largest
Explanation
The controlling heat transfer film coefficient is the one offering the largest resistance. Thermal resistances in series add together to determine the overall heat transfer coefficient. The component with the highest resistance dominates and controls the entire thermal rate. Composite heat transfer systems involve multiple resistances from fluid films and solid walls. An inverse relationship exists between film coefficients and their respective thermal resistances. Identifying the controlling resistance allows engineers to focus enhancement efforts effectively.
Heat exchanger optimization requires locating the dominant film resistance to improve performance. If a gas film offers the highest resistance, increasing liquid velocity provides negligible benefit. Targeting the controlling resistance maximizes energy efficiency and minimizes equipment costs. Zero resistance would mean infinite heat transfer coefficient, which is physically impossible. The least resistance has minimal impact on the overall thermal performance of the system. Lower resistance simply contributes a minor fraction to the total circuit resistance.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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