Added insulation will increase heat loss
Added insulation will decrease heat loss
Convective heat loss will be less than conductive heat loss
Heat flux will decrease
A. Added insulation will increase heat loss
Increase
Decrease
Remain unaffected
May increase/decrease depending on temperature and thickness of insulation
Parallel flow type
Counter flow type
Cross flow type
Regenerator type
One dimensional cases only
Two dimensional cases only
Three dimensional cases only
Regular surfaces having non-uniform temperature gradients
Watt/mK
Watt/m²K²
Watt/m²K4
Watt/mK²
k/h₀
2k/h₀
h₀/k
h₀/2k
Conduction
Free convection
Forced convection
Radiation
K cal/kg m² °C
K cal m/hr m² °C
K cal/hr m² °C
K calm/hr °C
Less than those for gases
Less than those for liquids
More than those for liquids and gases
More or less same as for liquids and gases
Temperature
Thickness
Area
Time
Maximum
Minimum
Zero
None of these
Aluminium
Steel
Brass
Copper
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
Grashoff number and Reynold number
Grashoff number and Prandtl number
Prandtl number and Reynold number
Grashoff number, Prandtl number and Reynold number
Increases
Decreases
Remain constant
May increase or decrease depending on temperature
Same
Higher
More or less same
Very much lower
Direct mixing of hot and cold fluids
A complete separation between hot and cold fluids
Flow of hot and cold fluids alternately over a surface
Generation of heat again and again
Its temperature
Nature of the body
Kind and extent of its surface
All of the above
Zeroth law of thermodynamics
First law of thermodynamic
Second law of the thermodynamics
Kirchoff's law
Black radiation
Full radiation
Total radiation
All of these
Equal to one
Greater than one
Less than one
Equal to Nusselt number
Nature of body
Temperature of body
Type of surface of body
All of the above
Added insulation will increase heat loss
Added insulation will decrease heat loss
Convective heat loss will be less than conductive heat loss
Heat flux will decrease
S.H/(S.H + L.H)
(S.H + L.H) /S.H
(L.H - S.H)/S.H
S.H/(L.H - S.H)
Higher
Lower
Same
Depends upon the shape of body
0.1
0.23
0.42
0.51
Kirchhoff's law
Stefan's law
Wines law
Planck's law
m²/hr
m²/hr °C
kcal/m² hr
kcal/m. hr °C
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.
Increases
Decreases
Remain constant
May increase or decrease depending on temperature
Electric heater
Steam condenser
Boiler
Refrigerator condenser coils