Two long parallel surfaces each of emissivity 0.7 are maintained at different temperatures and accordingly have radiation heat exchange between them. It is desired to reduce 75% of the radiant heat transfer by inserting thin parallel shields of emissivity 1 on both sides. The number of shields should be

Heat and Mass Transfer
Two long parallel surfaces each of emissivity 0.7 are maintained at different temperatures and accordingly have radiation heat exchange between them. It is desired to reduce 75% of the radiant heat transfer by inserting thin parallel shields of emissivity 1 on both sides. The number of shields should be

One

Four

Two

Three

One

Four

Two

Three

ANSWER DOWNLOAD EXAMIANS APP

Heat and Mass Transfer
According to Prevost theory of heat exchange

Heat transfer in most of the cases takes place by combination of conduction, convection and radiation

It is impossible to transfer heat from low temperature source to t high temperature source

All bodies above absolute zero emit radiation

Heat transfer by radiation requires no medium

Heat transfer in most of the cases takes place by combination of conduction, convection and radiation

It is impossible to transfer heat from low temperature source to t high temperature source

All bodies above absolute zero emit radiation

Heat transfer by radiation requires no medium

ANSWER DOWNLOAD EXAMIANS APP

Heat and Mass Transfer
Radiation is the process of heat transfer in which heat flows from a ________, in a straight line, without affecting the intervening medium.

Smaller body to larger body

Cold body to hot body

Hot body to cold body

Larger body to smaller body

Smaller body to larger body

Cold body to hot body

Hot body to cold body

Larger body to smaller body

ANSWER DOWNLOAD EXAMIANS APP

Heat and Mass Transfer
Emissivity of a white polished body in comparison to a black body is

Lower

Same

Higher

Depends upon the shape of body

Lower

Same

Higher

Depends upon the shape of body

ANSWER DOWNLOAD EXAMIANS APP

Heat and Mass Transfer
The critical thickness of insulation for a sphere is

k/h₀

h₀/k

h₀/2k

2k/h₀

k/h₀

h₀/k

h₀/2k

2k/h₀

ANSWER DOWNLOAD EXAMIANS APP

Heat and Mass Transfer
The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles due to difference of density caused by temperature of the particle is known as

Forced convection

Radiation

Free convection

Conduction

Forced convection

Radiation

Free convection

Conduction

ANSWER DOWNLOAD EXAMIANS APP

Heat and Mass Transfer

Heat and Mass Transfer According to Prevost theory of heat exchange

Heat and Mass Transfer Radiation is the process of heat transfer in which heat flows from a ________, in a straight line, without affecting the intervening medium.

Heat and Mass Transfer Emissivity of a white polished body in comparison to a black body is

Heat and Mass Transfer The critical thickness of insulation for a sphere is

Heat and Mass Transfer The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles due to difference of density caused by temperature of the particle is known as

Heat and Mass Transfer
According to Prevost theory of heat exchange

Heat and Mass Transfer
Radiation is the process of heat transfer in which heat flows from a ________, in a straight line, without affecting the intervening medium.

Heat and Mass Transfer
Emissivity of a white polished body in comparison to a black body is

Heat and Mass Transfer
The critical thickness of insulation for a sphere is

Heat and Mass Transfer
The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles due to difference of density caused by temperature of the particle is known as