A piston-cylinder assembly contains a two-phase liquid-vapor mixture of H2O at 200 lbf/in² with a quality of 80%. The mixture is heated and expands at constant pressure until a final temperature of 480°F is reached. Determine the work for the process, in BTU per lb of H2O present.
a) 224 BTU/lb
b) 256 BTU/lb
c) 288 BTU/lb
d) 320 BTU/lb