A tank that volume is unknown is divided into two parts by a partition. One side of the tank contains 0.01 m3 of refrigerant R-134a that is a saturated liquid at 0.8 MPa, while the other side is evacuated. The partition is now removed, and the refrigerant fills the entire tank. If the final state of the refrigerant is 20°C and 400 kPa, determine the volume of the tank. Do you think this is a reversible or irreversible process?