Chemical Engineering  Heat Transfer
Exercise :: Heat Transfer  Section 6
16. 
Overall heat transfer coefficient of a particular tube is U_{1}. If the same tube with some dirt deposited on either side has coefficient U_{2}, then 
A. 
U_{1} = U_{2}  B. 
U_{2} > U_{1}  C. 
U_{1} > U_{2}  D. 
U_{1} = dirt factor  U_{2} 
Answer: Option A
Explanation:

17. 
In SI units, thermal conductivity is expressed in 
A. 
Watt/m.°K  B. 
Watt/m^{2}. °K  C. 
Watt/m^{2}. °K  D. 
Watt/m^{4}. °K 
Answer: Option A
Explanation:

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 
Answer: Option A
Explanation:

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 
Answer: Option D
Explanation:

20. 
At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe ? 
Answer: Option C
Explanation:
