For turbulent flow in a tube, the heat transfer co-efficient is obtained from the DittusBoelter correlation. If the tube diameter is halved and the flow rate is doubled, then the heat transfer co-efficient will change by a factor of
A)1
B)1.74
C)6.1
D)37

Question

Quizplus · Accepted Answer

The Dittus-Boelter equation for turbulent flow is Nu = 0.023Re^0.8Pr^n. Halving the diameter increases Re by a factor of 2, and doubling the flow rate increases Re by another factor of 2, making Re increase by a factor of 4. Therefore, the heat transfer coefficient increases by 4^0.8 = 6.1.

For Turbulent Flow in a Tube, the Heat Transfer Co-Efficient