An insulated vertical piston–cylinder device initially contains 10kg of water, 5kg of which is in the vapor phase. Initially the pressure is 200 kPa inside the cylinder. A linear spring is connected to the piston therefore the pressure changes linearly with volume (P=m*V+b). Super heated steam at 0.5 MPa and constant temperature is allowed to enter the cylinder from a supply line until all the liquid in the cylinder has just vaporized and the pressure and volume in the cylinder have both doubled. Determine the final temperature, mass of the steam, boundary work, and specific enthalpy

R-134a is a refrigerant, which is used inside of refrigerators and air conditioners. You can buy canisters of this as a compressed liquid, which can be used to recharge a leaky air conditioner. The canister initially contains 0.539 kg of R-134a at room temperature (25 °C). For simplicity, let's assume that the R-134a is initially saturated liquid. You use this canister to recharge an air conditioner, until the canister has half of its original mass remaining. The canister is upright with the exit on the top of the canister, so the exit flow is saturated vapor. In order to maintain the temperature at 25 °C, how much heat must be supplied to the canister? Note that this is why compressed liquid/gas canisters feel cold when you use them – they require heat - input to maintain constant T.

A thermally insulated cylinder-piston assembly contains R-12 at 25°C and 90% titre. The volume, in this state, is 45 liters. The piston is allowed to move and the R-12 expands until it reaches a saturated vapor state. During this process, the R-12 performs 7.0 kJ work against the piston. Assuming that the process is adiabatic, determine the final specific internal energy of R-12 in this expansion process in kJ/kg.