5 kg of steam contained within a piston - cylinder assembly undergoes an expansion from state 1 , where the specific Internal energy ( the internal energy per unit mass ) is u , = 2709.9 kl / kg , to state 2 , where u₂ = 2659.6 kJ / kg . During the process , there is a heat transfer of energy to the steam with a magnitude of 80 kJ . Also , a paddle wheel transfers energy to the steam by work in the amount of 18.5 kl . There is no significant change in the kinetic or potential energy of the steam . Determine the amount of energy transfer by work in ki from steam to the piston during the process