The critical radius 'r' of insulation on a pipe is given by____________________?
Correct answer: B. r = k/h
- A. r = 2k/h
- B. r = k/h
- C. r = k/2h
- D. r = h/k
Explanation
For a cylindrical pipe, the critical insulation radius is obtained by balancing the increase in outer convection area against the added conduction resistance, giving r_c = k/h. The expression 2k/h applies to a sphere, not a cylinder.
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