4- Frictionless piston cylinder device contains 8 kg of steam at 500 kPa and 300°C. The steam now is cooled at a constant pressure until 70% of it condenses. Determine: (1) quality (x), (2) Au, Ah & Av, (3) the work

Define the system to be a container full of steam. If the steam condenses, did the system hae a positive or negative entropy change?

One kg of superheated steam is at 400 kPa and 400°C. Heat is added to raise the temperature to 500°C. Find the amount of heat needed (kJ) if: (a) The volume of the steam is kept constant during the heating. (b) The steam is allowed to expand during the heating (e.g., in a piston/cylinder system) such that the pressure is constant. Hint: The steam is not an ideal gas under these conditions.

Refrigerant-134a (R-134a) enters the expansion valve of a refrigeration system at 650 kPa with a quality of 20%. The pressure of R-134a at the outlet is 200 kPa. a)Determine the temperature of R-134a at the outlet in oC. Calculate the difference of internal energy between the outlet and inlet in kJ/kg