MCQs of Conduction (Heat Transfer - 3151909)

Heat Transfer (3151909) MCQs

MCQs of Conduction

Showing 31 to 36 out of 36 Questions

31.

A wall of thickness 0.6 m has a normal area of 1.5 $m^{2}$ and is made up of a material of thermal of conductivity 0.4 W/mK. If the temperatures on the two sides are could be ....................K/W

(a)	0.2
(b)	0.6
(c)	1.0
(d)	1.8

32.

Heat is conducted through a 10 cm thick wall at the rate of 30 w/m² when the temperature difference across the wall is 10 $°$ C. What is the thermal conductivity of the wall material?

(a)	0.03
(b)	0.3
(c)	3.0
(d)	30.0

33.

A composite slab has two layers of different materials having thermal conductivities $k_{1}$ and $k_{2}$ If each layer has the same thickness, the equivalent thermal conductivity of slab would be

(a)	$\frac{k_{1} k_{2}}{k_{1} + k_{2}}$
(b)	$\frac{k_{1} k_{2}}{2 (k_{1} + k_{2})}$
(c)	$\frac{2 k_{1}}{k_{1} + k_{2}}$
(d)	$\frac{2 k_{1} k_{2}}{k_{1} + k_{2}}$

34.

A composite wall of a furnace has two layers of equal thickness having thermal conductivities in the ratio 3:2 What is the ratio of temperature drop across the two layers?

(a)	2 : 3
(b)	3 : 2
(c)	1 : 2
(d)	$\log_{e} 2 : \log_{e} 3$

35.

What is the heat loss per hour across a wall 4 m high, 10 m long, and 115 mm thick, if the inside wall temperature is 30 $°$ C and outside ambient temperature is 10 $°$ C? The thermal conductivity of the brick wall is 1.15 W/mK, heat transfer coefficient for the inside wall is 2.5 $W / m^{2} K$ and that for the outside wall is 4 $W / m^{2} K$

(a)	3635 kJ
(b)	3750 kJ
(c)	3840 kJ
(d)	3920 kJ

36.

With an increase in the thickness of insulation around a circular pipe, heat loss to surroundings due to

(a)	convection increases while that due to conduction decreases
(b)	convection decreases while that due to conduction increases
(c)	convection and conduction decreases
(d)	convection and conduction increases

Showing 31 to 36 out of 36 Questions