# Chemical Engineering - Heat Transfer

### Exercise :: Heat Transfer - Section 6

16.

Overall heat transfer co-efficient of a particular tube is U1. If the same tube with some dirt deposited on either side has coefficient U2, then

 A. U1 = U2 B. U2 > U1 C. U1 > U2 D. U1 = dirt factor - U2

Explanation:

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17.

In SI units, thermal conductivity is expressed in

 A. Watt/m.°K B. Watt/m2. °K C. Watt/m2. °K D. Watt/m4. °K

Explanation:

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18.

Boiling point of a solution according to Duhring's rule is a linear function of the __________ of water.

 A. boiling point (at the same pressure) B. viscosity C. density D. thermal conductivity

Explanation:

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19.

The overall resistance for heat transfer through a series of flat resistance, is the __________ of the resistances.

 A. average B. geometric mean C. product D. sum

Explanation:

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20.

At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe ?

 A. 0.5 B. < 0.5 C. > 0.6 D. < 0.1