1. An insulated cylinder/piston contains R-134a at 150 lbf /in.2, 120 F, with a volume of 3.5 ft3. The R-134a expands, moving the piston until the pressure in the cylinder has dropped to 15 lbf/in.2. It is claimed that the R-134a does 180 Btu of work against the piston during the process. Is that possible?
2. Heat transfer from a 70 F kitchen to a block of 3 lbm ice at 15 F melts it to liquid at 50 F. Find the entropy generation.