Given data:
Calculate:
Solution:
By using steam table for superheated steam (at state 1): at and
By using steam table (for dry saturated steam): at
The internal energy per kg of superheated steam,
But, the change of internal energy
Finding unknown :
Internal energy of wet steam after expansion,
Finding unknown, :
Specific enthalpy of wet steam,
Finding unknown, :
Specific enthalpy of wet steam,
Therefore,
Hence, change of internal energy,
But, change of internal energy for 1.5 kg steam is,
Negative sign indicates decrease in internal energy.