Top 1000+ Solved Heat Transfer (HT) MCQ Questions Answer
Q. Fluid motion in the natural convection heat transfer between a solid surface and a fluid incontact with it, results from the
a. Existence of thermal boundary layer
b. Temperature gradient produced due to density difference
c. Buoyancy of the bubbles produced at active nucleation site
d. None of these
Q. Nusselt number is the ratio of the
a. Temperature gradient of the wall to that across the entire pipe
b. Temperature difference to the temperature gradient at the wall
c. Heat flux at the wall to that across the entire pipe
d. None of these
Q. Critical value of the __________ number governs the transition from laminar to turbulentflow in free convection heat transfer.
a. Grashoff
b. Reynolds
c. Both 'a' & 'b'
d. Prandtl & Grashoff
Q. Prandtl number is the reciprocal of
a. Thermal diffusivity/Momentum diffusivity
b. Thermal diffusivity × Momentum
c. Thermal diffusivity × Mass diffusivity
d. Mass diffusivity × Momentum diffusivity
Q. In case of parallel flow heat exchanger, the lowest temperature theoretically attainable bythe hot fluid is __________ the outlet temperature of the cold fluid.
a. Equal to
b. More than
c. Less than
d. Either more or less than (depending upon the fluid)
Q. For a multipass shell and tube heat exchanger, the LMTD correction factor is always
a. 1
b. > 1
c. < 1
d. Between 1 & 2
Q. Thermal conductivity of a gas at low density, __________ with increase in temperature.
a. Decreases
b. Increases
c. Remains unchanged
d. May increase or decrease; depends on the gas
Q. Which of the following is the most widely used heat insulating material for pipelinescarrying steam?
a. Tar dolomite bricks followed by asbestos
b. Fireclay refractory followed by aluminium sheet
c. Cotton followed by aluminium foil
d. 85% magnesia cement and glass wool
Q. With increase in temperature, the thermal conductivity of a gas
a. Increases
b. Decreases
c. Remain same
d. May increase or decrease depending on the type of gas
Q. Which area is used in case of heat flow by conduction through a cylinder?
a. Logarithmic mean area
b. Arithmetic mean area
c. Geometric mean area
d. None of these
Q. Pick out the wrong statement.
a. Heat transfer from a hot body to cold body by the emission of heat waves is called radiation
b. Filmwise condensation takes place on non-wettable surfaces
c. The boiling point of a solution is affected by liquid head as well as boiling point elevation
d. None of these
Q. Choose the correct equation.
a. Nu = (Re) (Pr) (Gz)
b. Nu = (Re) (Pr) (St)
c. Nu = (Re) (Pr)
d. Nu = (Pr) (St)
Q. In a heat exchanger, the rate of heat transfer from the hot fluid to the cold fluid
a. Varies directly as the area and the LMTD
b. Directly proportional to LMTD and inversely proportional to the area
c. Varies as square of the area
d. None of these