Aclosed rigid tank contains 1.5 kg of refrigerant, initially at p1 = 1.1 mpa and u1 = 277.25 kj/kg. the tank is fitted with a paddle wheel that transfers energy to the refrigerant at a constant rate of 0.1 kw. after 20 minutes of stirring, the refrigerant is at p2 = 0.85 mpa and u2 = 247.93 kj/kg. assume changes in kinetic and potential energy are negligible. a. determine work [kj] during the process (magnitude and direction) b. determine heat transfer [kj] during the process (magnitude and direction)