Fourier's law of heat conduction is (where Q = Amount of heat flow through the body in unit time, A = Surface area of heat flow, taken at right angles to the direction of heat flow, dT = Temperature difference on the two faces of the body, dx = Thickness of the body, through which the heat flows, taken along the direction of heat flow, and k = Thermal conductivity of the body)

Heat and Mass Transfer
Fourier's law of heat conduction is (where Q = Amount of heat flow through the body in unit time, A = Surface area of heat flow, taken at right angles to the direction of heat flow, dT = Temperature difference on the two faces of the body, dx = Thickness of the body, through which the heat flows, taken along the direction of heat flow, and k = Thermal conductivity of the body)

k. (dx/dT)

(dx/dT)

(dT/dx)

k. (dT/dx)

k.

k. (dx/dT)

(dx/dT)

(dT/dx)

k. (dT/dx)

k.

ANSWER DOWNLOAD EXAMIANS APP

Heat and Mass Transfer
A designer chooses the values of fluid flow rates and specific heats in such a manner that the heat capacities of the two fluids are equal. A hot fluid enters the counter flow heat exchanger at 100°C and leaves at 60°C. A cold fluid enters the heat exchanger at 40°C. The mean temperature difference between the two fluids is

40°C

66.7°C

60°C

20°C

40°C

66.7°C

60°C

20°C

ANSWER DOWNLOAD EXAMIANS APP

Heat and Mass Transfer
The value of the wave length for maximum emissive power is given by

Wine’s law

Planck’s law

Stefan’s law

Kirchhoff’s law

Wine’s law

Planck’s law

Stefan’s law

Kirchhoff’s law

ANSWER DOWNLOAD EXAMIANS APP

Heat and Mass Transfer
The ratio of the energy absorbed by the body to total energy falling on it is called

Emissive power

Absorptivity

Emissivity

Absorptive power

Emissive power

Absorptivity

Emissivity

Absorptive power

ANSWER DOWNLOAD EXAMIANS APP

Heat and Mass Transfer
The radiation emitted by a black body is known as

Full radiation

All of these

Black radiation

Total radiation

Full radiation

All of these

Black radiation

Total radiation

ANSWER DOWNLOAD EXAMIANS APP

Heat and Mass Transfer
An electric cable of aluminium conductor (k = 240 W/mK) is to be insulated with rubber (k = 0.15 W/mK). The cable is to be located in air (h = 6 W/m²). The critical thickness of insulation will be

25 mm

40 mm

800 mm

160 mm

25 mm

40 mm

800 mm

160 mm

ANSWER DOWNLOAD EXAMIANS APP

Heat and Mass Transfer

Heat and Mass Transfer The value of the wave length for maximum emissive power is given by

Heat and Mass Transfer The ratio of the energy absorbed by the body to total energy falling on it is called

Heat and Mass Transfer The radiation emitted by a black body is known as

Heat and Mass Transfer An electric cable of aluminium conductor (k = 240 W/mK) is to be insulated with rubber (k = 0.15 W/mK). The cable is to be located in air (h = 6 W/m²). The critical thickness of insulation will be

Heat and Mass Transfer
The value of the wave length for maximum emissive power is given by

Heat and Mass Transfer
The ratio of the energy absorbed by the body to total energy falling on it is called

Heat and Mass Transfer
The radiation emitted by a black body is known as

Heat and Mass Transfer
An electric cable of aluminium conductor (k = 240 W/mK) is to be insulated with rubber (k = 0.15 W/mK). The cable is to be located in air (h = 6 W/m²). The critical thickness of insulation will be