Ideal Gas Model

• For many gases, the ideal gas assumption is valid and the relationship can be simplified by using the ideal gas equation of state:
  
  
• For an ideal gas, it has been mentioned that the specific internal energy is a function of temperature only,
  
  
• Accordingly, specific enthalpy is a function of temperature only, since
  
  
• Physically, a gas can be considered ideal only when the inter-molar forces are weak.

This usually happens in low pressure and high temperature ranges.

(8.13)

(8.14)

•  Specific heat ratio

(8.15)

(8.16)

or,

(8.17)

or,

(8.18)

• In some cases, the temperature dependence of the specific heat can be written in polynomial form.
  
  
• Otherwise, ideal gas tables are also available. They are easier to use compared to the thermodynamic tables since temperature is the only parameter.