Top 1000+ Solved Heat Transfer (HT) MCQ Questions Answer
Q. If a single tube pass heat exchanger is converted to two pass, then for the same flow rate,the pressure drop per unit length in tube side will
a. Increase by 1.8 times
b. Decrease by 22
c. Increase by 216
d. Remain unchanged
Q. At what value of Prandtl number, the hydrodynamic and thermal boundary layers of afluid flowing over a heated plate will be identical?
a. 1
b. < 1
c. > 1
d. None of these
Q. A measure of the extent to which viscous heating is important relative to the heat flowresulting from the impressed temperature difference is represented by the __________ number.
a. Condensation
b. Grashoff
c. Stanton
d. Brinkman
Q. Heat flux through several resistances in series in analogous to the current flowing throughseveral
a. Resistances in parallel
b. Capacitors in series
c. Resistances in series
d. None of these
Q. Heat transfer efficiency leading of energy conservation in a heat exchanger can be achieved by
a. Keeping the heat transfer surface clean
b. Enhancing the fluid pumping rate
c. Increasing the tube length
d. None of these
Q. For a counter current heat exchanger with Ti h = 80°C, T°c = 60°C, T°h = 50°C and Ti c = 30°C, 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/dZ2 > 0
b. d 2T/dZ2 = 0
c. d 2T/dZ2 < 0
d. dT/dZ = 0
Q. Which is the most suitable for the concert-ration of highly concentrated solution?
a. Open pan evaporation
b. Long tube vertical evaporator
c. Agitated film evaporator
d. None of these
Q. For gases, the thermal conductivity increases with temperature rise. For liquids, withincrease in concentration, its thermal conductivity generally
a. Decreases
b. Increases
c. Remains unchanged
d. Increases exponentially
Q. A hot liquid is kept in a big room. The logarithm of the numerical value of the temperature difference between the liquid and the room is plotted against time. The plot will be very nearly a/an
a. Ellipse
b. Straight line
c. Parabola
d. Circular arc
Q. With increase in the distance between the heat source and the object receiving the heat, theradiation heat transfer
a. Decreases
b. Increases
c. Increases exponentially
d. Remain unaffected
Q. Prandtl number is the ratio of
a. Mass diffusivity to thermal diffusivity
b. Momentum diffusivity to thermal diffusivity
c. Thermal diffusivity to mass diffusivity
d. Thermal diffusivity to momentum diffusivity
Q. Double pipe heat exchangers are preferably useful, when
a. High viscosity liquid is to be cooled
b. Requirement of heat transfer area is low
c. Overall heat transfer co-efficient is very high
d. A corrosive liquid is to be heated
Q. A hot body will radiate heat most rapidly, if its surface is
a. White & rough
b. Black & rough
c. White & polished
d. Black & polished
Q. Rate of heat transfer by vaporisation from pools of water is affected by the
a. Nature of heating surface and distribution of bubbles
b. Surface tension of water
c. Viscosity of water
d. All (A), (B) and (C)