a) Flow of thermal energy from low-temperature reservoir to high-temperature reservoir
b) Flow of energy in the form of heat from high-temperature reservoir to low-temperature reservoir
c) Flow of thermal energy irrespective of reservoir temperature
d) None of the above
Q.2.
Which of the following is a method of heat transfer?
a) Convection
b) Radiation
c) Conduction
d) All of the mentioned
Q.3.
Heat transfer takes place according to which of the following law?
a) Newton’s second law of motion
b) First law of thermodynamics
c) Newton’s law of cooling
d) Second law of thermodynamics
Q.4.
Which of the following is the rate of heat transfer unit?
a) Watt
b) Pascal
c) Joule
d) Newton
Q.5.
Which of the following is an example of steady-state heat transfer?
a) Electric bulb cools down by the surrounding atmosphere
b) Chilling effect of cold wind on a warm body
c) Boilers and turbines
d) Cooling of I.C engine
Q.6.
Which way is heat transfer believed to take place in a long, hollow cylinder that is kept at consistent but varied temperatures on its inner and outer surfaces?
a) Unpredictable
b) Radial only
c) No heat transfer takes place
d) Axial only
Q.7.
Which of the following is correct regarding one dimensional heat transfer?
a) Steady – f (x, y, t), Unsteady – f (x)
b) Steady – f (y, z), Unsteady – f (y)
c) Steady – f (x, t), Unsteady – f (x)
d) Steady – f (x), Unsteady – f (x, t)
Q.8.
A person prefers to sit by a fire during the cold winter months. Which of the following heat transfer types gives him with the most heat?
a) Convection and radiation together
b) Radiation will provide quick warmth
c) If it is near the fire, convection sounds good
d) Conduction from the fire
Q.9.
On which of the following does convective heat transfer coefficient doesn’t depend?
a) Orientation of solid surface
b) Time
c) Surface area
d) Space
Q.10.
In liquids and gases, heat transmission is primarily caused by
a) Convection
b) Radiation
c) Conduction
d) Conduction as well as convection
Q.11.
For conduction heat transfer, the heat energy propagation will be minimal for __________
a) Copper
b) Air
c) Water
d) Lead
Q.12.
Amm diameter egg roll (k = 1 W/m degree) is roasted with the help of microwave heating. For good quality roasting, it is desired that temperature at the center of roll is maintained atdegree Celsius when the surrounding temperature isdegree Celsius. What should be the heating capacity in W/m 3 of the microwave if the heat transfer coefficient on the surface of egg roll isW/m2 degree?
a) 613.31 k W/m3
b) 93.31 k W/m3
c) 6713.31 k W/m3
d) 213.31 k W/m3
Q.13.
The rate of heat transfer for a plane wall of homogenous material with constant thermal conductivity is given by which of the following equation?
a) Q = 2k/δ x
b) Q = 2kAδx
c) Q = kA (t1-t2)/δ
d) Q = 2kAx/ δ
Q.14.
The appropriate rate equation for convective heat transfer between a surface and adjacent fluid is prescribed by which law?
a) Newton’s law of cooling
b) Kirchhoff’s law
c) Newton’s first law
d) Wein’s displacement law
Q.15.
A wire of radius 3 mm and 1.m length is to be maintained atdegree Celsius by insulating it by a material of thermal conductivity 0.W/m K. The temperature of surrounding isdegree Celsius with heat transfer coefficient 8.5 W/ m2 K. Find percentage increase in heat loss due to insulation?
a) 124.23 %
b) 100.00 %
c) 12.55 %
d) 134.46 %
Q.16.
Why fins are provided on a heat transfer surface?
a) Pressure drop of the fluid should be minimized
b) Increase turbulence in flow for enhancing heat transfer
c) Surface area is maximum to promote the rate of heat transfer
d) Increase temperature gradient so as to enhance heat transfer
Q.17.
A heating unit is made in the form of a vertical tube ofmm outside diameter and 1.2 m height. The tube is fitted withsteel fins of rectangular section with heightmm and thickness 2.5 mm. The temperature at the base of fin isdegree Celsius, the surrounding air temperature isdegree Celsius and the heat transfer coefficient between the fin as well as the tube surface and the surrounding air is 9.5 W/m2 K. If thermal conductivity of the fin material isW/m K, find the amount of heat transferred from the tube without fin
a) 118.44 W
b) 98.44 W
c) 8.44 W
d) 908.44 W
Q.18.
What is the rate of heat transfer from the fin in case of fin insulated at the tip?
a) (h P k)1/2 (t 0 – t a) tan h ml
b) (h P A)1/2 (t 0 – t a) tan h ml
c) (h P k A)1/2 (t 0 – t a) tan h ml
d) (h k A)1/2 (t 0 – t a) tan h ml
Q.19.
Consider the following statements pertaining to heat transfer through fins
a) i and ii
b) iii and iv
c) i and iv
d) ii and iii
Q.20.
In which of the following cases provision of fins on a given heat transfer surface will be more effective?
a) Fewer but thin fins
b) Large number of thin fins
c) Large number of thick fins
d) Fewer but thick fins
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