Determine the specific volume of refrigerant-134a at 1 MPa and 50°C, using (a) the ideal-gas equation of state and (b) the generalized compressibility chart. Compare the values obtained to the actual value of 0.021796 m3/kg and determine the error involved in each case.

( a ) The specific volume by ideal gas equation = 0.02632

% Error =  20.75 %

(b) The value of specific volume From the generalized compressibility chart = 0.0142

% Error =  - 34.85 %

Explanation:

Pressure = 1 M pa

Temperature = 50 °c = 323 K

Gas constant ( R ) for refrigerant = 81.49

(a). From ideal gas equation P V = m R T ---------- (1)

⇒ =

⇒ Here = Specific volume = v

⇒ v =  

Put all the values in the above formula we get

⇒ v = ×81.49

⇒ v = 0.02632

This is the specific volume by ideal gas equation.

Actual value = 0.021796

Error =  0.02632 - 0.021796 =   0.004524

% Error =   × 100

% Error =  20.75 %

(b). From the generalized compressibility chart the value of specific volume

  = v = 0.0142

The actual value = 0.021796

Error = 0.0142 - 0.021796 =  

% Error = × 100

% Error =  - 34.85 %

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