Question

Calculate the hfg and sfg of steam at 120oC from the Clapeyron equation, and compare them to the tabulated values.

Answer 1

The tabulated values at 120 C of hfg = 2202.1 kJ/Kg and sfg = 5.6

kJ/Kg.K

Step-by-step explanation:

According to Clapeyron Equation :

`h_(fg)=TV_(fg)\left ((\partial P)/(\partial T)  \right )_(sat)`

`=T(V_(g)-V_(f))_(120^(0))\left ( (\Delta P)/(\125^(0)-115^(0)) \right )`

Taking P2 at temperature 125 and P1 at 115 degree Celsius .

T = 120 + 273.15 = 393.15 K

P2 = 232.23 kPa and P1 = 169.18kPa

(these are experimental values given in the Data)

`= 393.15(0.88133 -0.001060\ m^(3)/Kg)(232.23-169.18 kPa)/(10)`

`h_(fg) = 2206.8 kJ/Kg`

`S_(fg)=(h_(fg))/(T)`

`(2206.8)/(393.15)`

= 5.6131 kJ/Kg.K

The tabulated values at 120 C of hfg = 2202.1 kJ/Kg and sfg = 5.6131

kJ/Kg.K