If average heat transfer co-efficient is ha and the local coefficient at the end of the plate is hl then in case of heat transfer to a fluid flowing over a flat plate, heated over its entire length________________?
Correct answer: D. ha = 2hl
- A. ha = hl
- B. ha = 0.75 hl
- C. ha = 0.5 hl
- D. ha = 2hl
Explanation
For laminar flow over a flat plate, the local coefficient varies approximately as x⁻¹ᐟ². Averaging this variation from the leading edge to the plate end gives an average coefficient equal to twice the coefficient at the end.
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