#### Heat Transfer

1

Heat transfer co-efficient (h) for a fluid flowing inside a clean pipe is given by h = 0.023 K/D ((Dvp)/(mu))^0.8 . ((C_(p mu))/(K))^0.4
This is valid for the value of NRe equal to

A. . < 2100
B. 2100-4000
C. > 4000
D. > 10000

2
( N_(Re) . N_(Pr))  (D/L) is called the __________ number
A. Peclet
B. Stanton
C. Graetz
D. none of these

3
For a counter current heat exchanger with Tih = 80^circC, T^circc= 60^circC, T^circh = 50^circC andTic = 30^circC, and the temperature difference between the two streams being the same everywhere along Z, the direction of flow of hot fluid. The temperature profile should satisfy

A. (d^2T)/(dZ^2) > 0
B. (d^2T)/(dZ^2) = 0
C. (d^2T)/(dZ^2) < 0
D. (dT)/(dZ) = 0

4

Fouling factor for a heat exchanger is given by (where, U1 = heat transfer co-efficient of dirty surface U2 = heat transfer co-efficient of clean surface)

A. U_1 - U_2
B. 1/U_1 - 1/U_2
C. 1/U_2 - 1/U_1
D. U_2 - U_1

5

In case of surface condensers, a straight line is obtained on plotting 1/U    vs__________ on an ordinary graph paper.

A. 1/overline(V) - 0.8
B. overline(V) - 0.8
C. overline(V) - 2
D. 1/overline(V) - 2