91
In a heat exchanger, floating head is provided to
A)
Facilitate cleaning of the exchanger
B)
Increase the heat transfer area
C)
Relieve stresses caused by thermal expansion
D)
Increase log mean temperature gradient
Answer & Solution
Answer: Option
C
92
Heat transfer rate described by Fourier's law will decrease, if the __________ increases.
A)
Thermal conductivity
B)
Thickness
C)
Temperature difference
D)
Heat transfer area
Answer & Solution
Answer: Option
B
93
In case of a vertical tube evaporator, with increase in the liquor level, the __________ is increased.
A)
Velocity of circulation
B)
Liquor-film co-efficient
C)
Both A and B
D)
Neither A and B
Answer & Solution
Answer: Option
D
94
In forced convection, the heat transfer depends on
A)
Re, Pr
B)
Re, Gr
C)
Mainly Gr
D)
Re only
Answer & Solution
Answer: Option
A
95
The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by
A)
Painting the surface black
B)
Painting the surface white (with aluminium paint)
C)
Giving the surface a mirror finish
D)
Roughening the surface
Answer & Solution
Answer: Option
B
96
The equation, $${{\text{N}}_{{\text{st}}}} = \frac{{\text{f}}}{2},$$ is the __________ analogy.
A)
Colburn
B)
Reynolds
C)
Prandtl
D)
None of these
Answer & Solution
Answer: Option
B
97
The equation, $${{\text{N}}_{{\text{st}}}} \times {\text{N}}_{{\text{pr}}}^{\frac{2}{3}} = \frac{{\text{f}}}{2},$$ is the __________ analogy.
A)
Colburn
B)
Reynolds
C)
Prandtl
D)
None of these
Answer & Solution
Answer: Option
A
98
Controlling heat transfer film co-efficient is the one, which offers __________ resistance to heat transfer.
A)
No
B)
The least
C)
The largest
D)
Lower
Answer & Solution
Answer: Option
C
99
In a shell and tube heat exchanger, putting a longitudinal baffle across the shell, forces the shell side fluid to pass __________ through the heat exchanger.
A)
Once
B)
Twice
C)
Thrice
D)
Four times
Answer & Solution
Answer: Option
B
100
Thermal conductivities of most of the liquids __________ with rise in temperature.
A)
Increases
B)
Decreases
C)
Remains unchanged
D)
May increase or decrease; depends on the liquid
Answer & Solution
Answer: Option
B
