Terminology

1) Entropy:

     Entropy is defined as the quantitative measure of disorder or randomness in a system.

     Example:

 

2) Enthalpy:

    It is the sum of the internal energy added to the product of the pressure and volume of the system.

    It is denoted as H.

 

3) Sensible heat:

    Change in temperature without phase transformation.

 

4) Latent heat:

      Change of phase of a substance at a constant temperature.

      Latent heat for Ice to Water = 80 kCal/kg.

      Latent heat for Vapour to Water = 560 kCal/kg.

5) Thermal Conductivity:

    It is the amount of heat conducted by a substance per unit time, per unit kg, per unit the temperature difference of material.

K = BTU/hr

Q = UA Δ T, Q = Cp ΔT

                                      

_fi = thermal conductance of inside of the wall.

f₀ = thermal conductance of outside of the wall.

A = thermal conductance of air inside the material.