A rigid tank A of volume 0.6 cubic meters contains 3kg of water at 120 degrees celcius and rigid tankd B is 0.4 cubic meters with water at 600kPa, 200 degrees celcius. They are connected to a piston/cylinder initially empty with closed valves. The pressure in the cylinder should be 800kPa to float the piston. Now the valves are slowly opened and heat is transferred so that the water reaches a uniform state at 250 degrees celcius with the valves open. What is the heat transfer in the process?