Explore topic-wise MCQs in Heat Transfer.

This section includes 69 Mcqs, each offering curated multiple-choice questions to sharpen your Heat Transfer knowledge and support exam preparation. Choose a topic below to get started.

51.

The rate of heat transfer for a plane wall of homogenous material with constant thermal conductivity is given by

A. Q = kA (t₁-t₂)/δ
B. Q = 2kAx/ δ
C. Q = 2kAδx
D. Q = 2k/δ x
Answer» B. Q = 2kAx/ δ
52.

The mean thermal conductivity evaluated at the arithmetic mean temperature is represented by

A. km = k0 [1 + β (t1 – t2)/2].
B. km = k0 [1 + (t1 + t2)/2].
C. km = k0 [1 + β (t1 + t2)/3].
D. km = k0 [1 + β (t1 + t2)/2].
Answer» E.
53.

A pipe carrying steam at 215.75 degree Celsius enters a room and some heat is gained by surrounding at 27.95 degree Celsius. The major effect of heat loss to surroundings will be due to

A. Conduction
B. Convection
C. Radiation
D. Both conduction and convection
Answer» D. Both conduction and convection
54.

A plane slab of thickness 60 cm is made of a material of thermal conductivity k = 17.45 W/m K. Let us assume that one side of the slab absorbs a net amount of radiant energy at the rate q = 530.5 watt/m². If the other face of the slab is at a constant temperature t₂ = 38 degree Celsius. Comment on the temperature with respect to the slab?

A. 87.5 degree Celsius
B. 32 degree Celsius
C. 47.08 degree Celsius
D. 32.87 degree Celsius
Answer» D. 32.87 degree Celsius
55.

A composite wall is made of two layers of thickness δ₁ and δ₂ having thermal conductivities k and 2k and equal surface area normal to the direction of heat flow. The outer surface of composite wall are at 100 degree Celsius and 200 degree Celsius. The minimum surface temperature at the junction is 150 degree Celsius. What will be the ratio of wall thickness?

A. 1:1
B. 2:1
C. 1:2
D. 2:3
Answer» D. 2:3
56.

If we increase the thickness of insulation of a circular rod, heat loss to surrounding due to

A. Convection and conduction increases
B. Convection and conduction decreases
C. Convection decreases while that due to conduction increases
D. Convection increases while that due to conduction decreases
Answer» E.
57.

For the same amount of fabrication material and same inside capacity, the heat loss is lowest in

A. Sphere
B. Cylinder
C. Rectangle
D. Cube
Answer» C. Rectangle
58.

Which is true regarding a complete rectangular furnace?

A. 6 walls, 12 edges and 6 corners
B. 0 walls, 2 edges and 4 corners
C. 6 walls, 12 edges and 8 corners
D. 2 walls, 6 edges and 8 corners
Answer» D. 2 walls, 6 edges and 8 corners
59.

Three metal walls of same thickness and cross sectional area have thermal conductivities k, 2k and 3k respectively. The temperature drop across the walls (for same heat transfer) will be in the ratio

A. 3:2:1
B. 1:1:1
C. 1:2:3
D. Given data is insufficient
Answer» B. 1:1:1
60.

The shape factor for complete rectangular furnace isWhere a, b and c are the inside dimensions and d x is the wall thickness

A. 2/ d x (a b + b c + c a) + 4 (0.64) (a + b +c) + 8 (0.45) d x
B. 2/ d x (a b + b c + c a) + 4 (0.44) (a + b +c) + 8 (0.35) d x
C. 2/ d x (a b + b c + c a) + 4 (0.34) (a + b +c) + 8 (0.25) d x
D. 2/ d x (a b + b c + c a) + 4 (0.54) (a + b +c) + 8 (0.15) d x
Answer» E.
61.

If β is greater than zero, then choose the correct statement with respect to given relationk = k0 (1 +β t)

A. k doesn’t depends on temperature
B. k depends on temperature
C. k is directly proportional to t
D. Data is insufficient
Answer» D. Data is insufficient
62.

For an object i.e. spherical the value of critical radius would be

A. 2k/3h
B. 3k/h
C. 2k/h
D. k/h
Answer» D. k/h
63.

Maximum value of critical radius is

A. 0.01 m
B. 0.04 m
C. 0.06 m
D. 0.0001 m
Answer» B. 0.04 m
64.

An electric cable of aluminum (k = 240 W/ m degree) is to be insulated with rubber (k = 6 W/ square meter degree). If the cable is in air (h = 6 W/square meter degree). Find the critical radius?

A. 80 mm
B. 160 mm
C. 40 mm
D. 25 mm
Answer» E.
65.

Find the heat flow rate through the composite wall as shown in figure. Assume one dimensional flow and takek 1 = 150 W/m degreek 2 = 30 W/m degreek 3 = 65 W/m degreek 4 = 50 W/m degreeAB = 3 cm, BC = 8 cm and CD = 5 cm. The distance between middle horizontal line from the top is 3 cm and from the bottom is 7 cm

A. 1173.88 W
B. 1273.88 W
C. 1373.88 W
D. 1473.88 W
Answer» C. 1373.88 W
66.

A steel pipe of 20 mm inner diameter and 2 mm thickness is covered with 20 mm thick of fiber glass insulation (k = 0.05 W/m degree). If the inside and outside convective coefficients are 10 W/m² degree and 5 W/m² degree, calculate the overall heat transfer coefficient based on inside diameter of pipe. In the diagram, the diameter of small circle is 20 mm

A. 1.789 W/m² degree
B. 2.789 W/m² degree
C. 3.789 W/m² degree
D. 4.789 W/m² degree
Answer» C. 3.789 W/m² degree
67.

In Cartesian coordinates the heat conduction equation is given by

A. d²t/dx² + d²t/dy2 + d²t/dz2 + q g = (1/α) (d t/d T)
B. 2d²t/dx² + d²t/dy2 + d²t/dz2 + 34q g = (d t/d T)
C. d²t/dx² + 3d²t/dy2 + d²t/dz2 = (1/α) (d t/d T)
D. 4d²t/dx² + d²t/dy2 + d²t/dz2 + 1/2q g = (1/α) (d t/d T)
Answer» B. 2d²t/dx² + d²t/dy2 + d²t/dz2 + 34q g = (d t/d T)
68.

The oven of an electric store, of total outside surface area 2.9 m² dissipates electric energy at the rate of 600 W. The surrounding room air is at 20 degree Celsius and the surface coefficient of heat transfer between the room air and the surface of the oven is estimated to be 11.35 W/m² degree. Determine the average steady state temperature of the outside surface of the store

A. 38.22 degree Celsius
B. 48.22 degree Celsius
C. 58.22 degree Celsius
D. 68.22 degree Celsius
Answer» B. 48.22 degree Celsius
69.

The accompanying sketch shows the schematic arrangement for measuring the thermal conductivity by the guarded hot plate method. Two similar 1 cm thick specimens receive heat from a 6.5 cm by 6.5 cm guard heater. When the power dissipation by the wattmeter was 15 W, the thermocouples inserted at the hot and cold surfaces indicated temperatures as 325 K and 300 K. What is the thermal conductivity of the test specimen material?

A. 0.81 W/m K
B. 0.71 W/m k
C. 0.61 W/m K
D. 0.51 W/m K
Answer» C. 0.61 W/m K