Both the fluids at inlet (of heat exchanger where hot fluid enters) are in their coldest state
Both the fluids at inlet are in their hottest state
Both the fluids at exit are in their hottest state
One fluid is in hottest state and other in coldest state at inlet
B. Both the fluids at inlet are in their hottest state
k/h₀
2k/h₀
h₀/k
h₀/2k
Their atoms collide frequently
Their atoms are relatively far apart
They contain free electrons
They have high density
Varies with temperature
Varies with the wave length of incident ray
Varies with both
Does not vary with temperature and wave length of the incident ray
Convection
Radiation
Conduction
Both convection and conduction
Black radiation
Full radiation
Total radiation
All of these
Below which a gas does not obey gas laws
Above which a gas may explode
Below which a gas is always liquefied
Above which a gas will never liquefied
0
0.5
0.75
1
Reynold's number
Grashoff's number
Reynold's number, Grashoff's number
Prandtl number, Grashoff's number
Velocity reduction method
Equal friction method
Static regains method
Dual or double method
Aluminium
Steel
Brass
Copper
A dimensionless parameter
Function of temperature
Used as mathematical model
A physical property of the material
The heat transfer in liquid and gases takes place according to convection.
The amount of heat flow through a body is dependent upon the material of the body.
The thermal conductivity of solid metals increases with rise in temperature
Logarithmic mean temperature difference is not equal to the arithmetic mean temperature difference.
k. A. (dT/dx)
k. A. (dx/dT)
k. (dT/dx)
k. (dx/dT)
K cal/kg m² °C
K cal m/hr m² °C
K cal/hr m² °C
K calm/hr °C
Conduction
Convection
Radiation
Conduction and convection
Absolute temperature
Square of the absolute temperature
Cube of the absolute temperature
Fourth power of the absolute temperature
20°C
40°C
60°C
66.7°C
Cold body to hot body
Hot body to cold body
Smaller body to larger body
Larger body to smaller body
The better insulation must be put inside
The better insulation must be put outside
One could place either insulation on either side
One should take into account the steam temperature before deciding as to which insulation is put where
Higher
Lower
Same
Depends upon the shape of body
RN = hl/k
RN = μ cp/k
RN = ρ V l /μ
RN = V²/t.cp
I.C. engine
Air preheaters
Heating of building in winter
None of the above
It is impossible to transfer heat from low temperature source to t high temperature source
Heat transfer by radiation requires no medium
All bodies above absolute zero emit radiation
Heat transfer in most of the cases takes place by combination of conduction, convection and radiation
A.Cmin/U
U/A.Cmin
A.U.Cmin
A.U/Cmin
In heat exchanger design as a safety factor
In case of Newtonian fluids
When a liquid exchanges heat with a gas
None of the above
Convection
Radiation
Forced convection
Free convection
Increases
Decreases
Remain constant
May increase or decrease depending on temperature
P = 0, x = 0 and a = 1
P=1, T = 0 and a = 0
P = 0, x = 1 and a = 0
X = 0, a + p = 1 Where a = absorptivity, p = reflectivity, x = transmissivity
P = 0, x = 0 and a = 1
P= 1, T = 0 and a = 0
P = 0, x = 1 and a = 0
X = 0, a + p = 0 Where a = absorptivity, p = reflectivity, X = transmissivity.
Absorptive power
Emissive power
Emissivity
None of these