Engineering :: Heat Transfer

@ : Home > Chemical Engineering > Heat Transfer

11.

Thermal conductivity is maximum for

A.	coke	B.	gasoline
C.	steel	D.	air

12.

Thermal conductivity is minimum for

A.	asphalt	B.	water
C.	petroleum coke	D.	air

13.

Heat transfer by conduction depends upon

A.	temperature difference and thermal conductivity only	B.	temperature difference and area only
C.	temperature difference and thickness only	D.	temperature difference thermal conductivity area and thickness

14.

Which one of the four factors would cause heat transfer rate by conduction to decrease if the value of that factor were increased?

A.	temperature difference	B.	thermal conductivity
C.	area	D.	thickness

15.

A sphere a cube and a thin circular plate all made of the same material and having the same mass are initially heated to a temperature 300?C. Which of these objects will cool slowest when left in air at room temperature ?

A.	sphere	B.	cube
C.	circular plate	D.	all will cool at the same rate

16.

The thermal conductivity of copper

A.	remains unaffected with change in temperature	B.	increases with increase in temperature
C.	decreases with increase in temperature	D.	is less than the thermal conductivity of aluminium at the same temperature

17.

In general the thermal conductivity of a non-homogeneous material

A.	decreases with increasing temperature	B.	decreases with increasing apparent bulk density
C.	increases both with increasing temperature and increasing apparent bulk density	D.	increases with increasing temperature but decreases with increasing apparent bulk density

18.

The thermal conductivity of engine oil (unused)

A.	is greater than the thermal conductivity of water at the same temperature	B.	remains unaffected with change in temperature
C.	decreases with increase in temperature	D.	increases with increase in temperature

19.

The thermal conductivity of a perfect heat insulator is

A.	zero	B.	infinity
C.	one	D.	between zero and infinity

20.

The conductance is

A.	directly proportional to the resistance to heat flow	B.	the reciprocal of the resistance to heat flow
C.	directly proportional to the thermal potential difference	D.	the reciprocal of the thermal potential difference