Heat Transfer Questions and Answers Part-1

1. Unit of the rate of heat transfer is
a) Joule
b) Newton
c) Pascal
d) Watt

Answer: d
Explanation: Unit of heat transfer is Joule but the rate of heat transfer is joule per second i.e. watt.

2. How many types of convection process are there?
a) One
b) Three
c) Four
d) Two

Answer: b
Explanation: Forced, natural and mixed convection.

3. Which of the following is an example of forced convection?
a) Chilling effect of cold wind on a warm body
b) Cooling of billets in the atmosphere
c) Heat exchange on cold and warm pipes
d) Flow of water in condenser tubes

Answer: d
Explanation: In forced convection, the flow of fluid is caused by a pump, fan or by atmospheric winds.

4. Which of the following is an example of steady state heat transfer?
a) Boilers and turbines
b) Chilling effect of cold wind on a warm body
c) Electric bulb cools down by the surrounding atmosphere
d) Cooling of I.C engine

Answer: c
Explanation: System is a perfect black body

5. Thermal conductivity is maximum for which substance
a) Silver
b) Ice
c) Aluminum
d) Diamond

Answer: d
Explanation: Thermal conductivity of diamond is 2300 W/m K.

6. The literature of heat transfer generally recognizes distinct modes of heat transfer. How many modes are there?
a) One
b) Two
c) Three
d) Four

Answer: c
Explanation: There are three modes of heat transfer i.e. radiation, convection and conduction.

7. Heat transfer takes place in liquids and gases is essentially due to
a) Convection
b) Conduction
c) Radiation
d) Conduction as well as convection

Answer: a
Explanation: Convection is a process by which thermal energy is transferred between solid and fluid flowing through it.

8. The rate equation used to describe the mechanism of convection is called Newton’s law of cooling. So rate of heat flow by convection doesn’t depend on
a) Convective heat transfer coefficient
b) Time
c) Temperature potential difference
d) Surface area through which heat flows

Answer: b
Explanation: It is directly proportional to all of above except time.

9. The famous Fourier series is named after
a) Diller and Ryan
b) J.B. Joseph Fourier
c) Stefan- Boltzmann
d) Wein’s

Answer: b
Explanation: He gave this theory in 1824.

10. Convective heat transfer coefficient doesn’t depend on
a) Surface area
b) Space
c) Time
d) Orientation of solid surface

Answer: a
Explanation: It is denoted by h and is dependent on space, time, geometry, orientation of solid surface.