Heat Transfer Mcqs

Q:

A radiator in a domestic heating system operates at a surface temperature of 60 degree Celsius. Calculate the heat flux at the surface of the radiator if it behaves as a black body

A) 697.2 W/m² B) 786.9 W/m²
C) 324.7 W/m² D) 592.1 W/m²
 
Answer & Explanation Answer: A) 697.2 W/m²

Explanation: As, q = Q/A = 5.67 * 10-? (273+60)? = 697.2.

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261
Q:

Thermal conductivity is maximum for which substance

A) Silver B) Ice
C) Aluminum D) Diamond
 
Answer & Explanation Answer: D) Diamond

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

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235
Q:

How many types of convection process are there?

A) One B) Three
C) Four D) Two
 
Answer & Explanation Answer: B) Three

Explanation: Forced, natural and mixed convection.

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124
Q:

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) Surface area through which heat flows
C) Time D) Temperature potential difference
 
Answer & Explanation Answer: C) Time

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

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154
Q:

Convective heat transfer coefficient doesn’t depend on

A) Surface area B) Space
C) Time D) Orientation of solid surface
 
Answer & Explanation Answer: A) Surface area

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

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243
Q:

Unit of the rate of heat transfer is

A) Joule B) Newton
C) Pascal D) Watt
 
Answer & Explanation Answer: D) Watt

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

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238
Q:

An oil cooler in a high performance engine has an outside surface area 0.12 m² and a surface temperature of 65 degree Celsius. At any intermediate time air moves over the surface of the cooler at a temperature of 30 degree Celsius and gives rise to a surface coefficient equal to 45.4 W/ m² K. Find out the heat transfer rate?

A) 238.43 W B) 190.68 W
C) 543.67 W D) 675.98 W
 
Answer & Explanation Answer: B) 190.68 W

Explanation: Q = (T? – T?) A h = 0.12 (65-30) 45.4 = 190.68 W.

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155
Q:

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 & Explanation Answer: C) Three

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

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