1.5 kg of steam originally at a pressure of 1 MN/m² and temperature 225°C is expanded until the pressure becomes 0.28 MN/m². The dryness fraction of steam is 0.9. Determine the change in internal energy.
a) 2704 kJ
b) 2163 kJ
c) 1892 kJ
d) 3247 kJ