Practice Test: Question Set - 01
1. Pick out the wrong statement.
- (A) The
value of hydrostatic head increases with increase in vacuum in the effect in a
multiple effect evaporator system
- (B) Entering
velocity of the liquid in the tubes of natural circulation evaporators is in
the range of 0.3 to 0.9 metre/second
- (C) Duhring's
plot is used for calculating the concentration of solution
- (D) In a
multiple effect evaporation system, the number of effects is limited by the
total boiling point rise
2. In a shell and tube heat exchanger,
- (A) The
temperature drops in the two fluids and the wall are proportional to individual
resistances
- (B) The
temperature drop is inversely proportional to the resistance across which the
drop occurs
- (C) There
is no relationship between temperature drop and resistance
- (D) The
relationship is not generalised
3. (NGr × NPr) is called the __________ number.
- (A) Graetz
- (B) Rayleigh
- (C) Nusselt
- (D) Stanton
4. Which of the following has maximum thermal conductivity at the same temperature?
- (A) Steel
- (B) Petrol
- (C) Air
- (D) All
have the same conductivity
5. A concentric double pipe heat exchanger as compared to the shell and tube heat exchanger for the same heat load requires
- (A) Less
heating surface
- (B) More
space
- (C) Lower
maintenance cost
- (D) None
of these
6. Maximum water velocity in tubes of a 1-2 shell and tube heat exchanger may be around __________ meters/second.
- (A) 1
- (B) 10
- (C) 20
- (D) 30
7. For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it
- (A) Decreases
the pressure drop
- (B) Decreases
the outlet temperature of cooling medium
- (C) Increases
the overall heat transfer coefficient
- (D) None
of these
8. A tank painted with which of the following colored paints, would heat up maximum by radiation from sun?
- (A) Yellow paint
- (B) White
paint
- (C) Black paint
- (D) Grey
paint
9. Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100°C and the inside heat transfer co-efficient is ‘3k/l’. If the wall temperature on the outside is held at 25°C, what is the inside wall temperature in degree centigrade?
- (A) 35.5
- (B) 43.75
- (C) 81.25
- (D) 48.25
10. Three materials A, B and C of equal thickness and of thermal conductivity of 20, 40 & 60 kcal/hr. m. °C respectively are joined together. The temperature outside of A and C are 30°C and 100°C respectively. The interface between B and C will be at a temperature of __________ °C.
- (A) 40
- (B) 95
- (C) 70
- (D) 50
11. A graph between __________ is called Wilson plot.
- (A) (1/U) Vs. (1/v0.8)
- (B) (1/v0.8) Vs. U
- (C) v0.8 Vs
. U
- (D) (1/U) Vs. (1/V)
12. The thermal radiation emitted by a body is proportional to Tn, where T is its absolute temperature. The value of 'n' is exactly 4 for
- (A) Black
painted bodies only
- (B) All
bodies
- (C) Polished
bodies only
- (D) A
black body
13. For a laminar flow of fluid in a circular tube, 'h1' is the convective heat transfer co-efficient at velocity 'V1'. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is
- (A) 1.26 h1
- (B) 0.794 h1
- (C) 0.574 h1
- (D) 1.741 h1
14. Pick out the correct statement.
- (A) 1
kcal/hr.m.°C is equal to 1 BTU/hr. ft.°F
- (B) In
steady state heat conduction, the only property of the substance which
determines the temperature distribution, is the thermal conductivity
- (C) In
unsteady state heat conduction, heat flows in the direction of temperature rise
- (D) In
heat transfer by forced convection, Grashoff number is very important
15. Evaporation by thermo compression results in the
- (A) Saving
of steam
- (B) Realization
of multiple effect economy in a single effect
- (C) Both (a) and
(b)
- (D) None
of these