Top 1000+ Solved Heat Transfer (HT) MCQ Questions Answer
Q. Dittus-Boelter equation cannot be used for molten metals mainly due to its very low
a. Prandtl number
b. Grashoff number
c. Thermal conductivity
d. Viscosity
Q. Baffle spacing
a. Is not the same as baffle pitch
b. Should be less than one fifth the diameter of the shell
c. Should be less than the inside diameter of the shell
d. None of these
Q. Which of the following is unimportant in forced convection?
a. Reynolds number
b. Prandtl number
c. Grashoff number
d. None of these
Q. The purpose of floating head in a heat exchanger is to
a. Avoid buckling of tubes
b. Provide support for tubes
c. Decrease the pressure drop
d. Facilitate its lengthening, if needed
Q. Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by thetube length/diameter ratio, if the flow is in the __________ zone.
a. Laminar
b. Transition
c. Both 'a' & 'b'
d. Highly turbulent
Q. Mechanical recompression evaporation is used in the production of
a. Alcohol
b. Distilled water
c. Salt
d. Fruits jam
Q. Pick out the wrong statement.
a. Swenson-Walker crystalliser is a batch crystalliser
b. Super saturation of the solution is the driving potential for a crystal growth
c. The liquor left after the removal of crystals from a solution is called mother liquor
d. The first stage of crystal formation is called nucleation
Q. The outlet temperature of cooling water in a heat exchanger is generally not allowed to exceed above 50°C in industrial practice mainly to avoid
a. Its evaporation loss
b. Excessive corrosion
c. Uneconomic LMTD
d. Decrease in heat exchanger efficiency
Q. The number of kg vaporised per kg of steam fed to the evaporator is defined as
a. Capacity
b. Rate of evaporation
c. Economy
d. Rate of vaporisation
Q. Vacuum is generally maintained in the vapour space of an evaporator mainly to
a. Get economical temperature difference by using moderate pressure steam
b. Facilitate forward feeding in multiple effect evaporation
c. Concentrate heat sensitive materials
d. Achieve very high concentration of the final product
Q. Three solid objects of the same material and of equal mass-a sphere, a cylinder (length = diameter) and a cube are at 500°C initially. These are dropped in a quenching bath containing a large volume of cooling oil each attaining the bath temperature eventually. The time required for 90% change in temperature is the smallest for
a. Cube
b. Cylinder
c. Sphere
d. Equal for all the three
Q. With increase in porosity, the thermal conductivity of a solid substance
a. Increases
b. Decreases
c. Remains unchanged
d. May increase or decrease; depends on the solid
Q. Which of the following forced convection heat transfer equation accounts for the liquidviscosity effect for viscous liquids?
a. Dittus-Boelter equation
b. Sieder-Tate equation
c. Nusselt equation
d. None of these
Q. Which type of heat exchanger is preferred for heavy heat loads?
a. Double pipe
b. Plate fine
c. Series and parallel set of shell and tube
d. None of these