CH4 is liquified at a steady state. The liquefaction system is adiabatic. 1 kg/s of CH4 at 300 K and 100 bar (state 1) enters the heat exchanger. Upon cooling, this high-pressure gas is throttled at 1 bar forming a vapor- liquid mixture. Liquified CH4 exits the system as saturated liquid at 1 bar (state 2). The vapor stream is recycled back through the heat exchanger (dashed line in the figure below) and exits the system at 290 K, 1 bar (state 3). For your convenience, the enthalpy of CH4 (saturated liquid, 1 bar) is 284.73 kJ kg-1 and the entropy of CH4 (saturated liquid, 1 bar) is 4.922 kJ kg-1 K-1.

(a) Write a mass and energy balance for the system

(b) What is the mass flow rate of liquified CH4 (state 2)?

(c) What is the mass flow rate of recycled CH4 vapor (state 3)?

(d) Is this process reversible? Support your response with calculations.

(e) How does the mass flow rate of liquified CH4 change if the pressure of high-pressure CH4 at state 1 decreases? Conditions of state 3 and state 3 remain unchanged. Explain in 2-3 sentences using expressions obtained while solving the previous questions.