The well-mixed bubbler tank shown in the figure below is used to prepare carbonated water needed for the production of soft drinks. The tank volume is 2.0 m³, and the tank diameter is 1.0 m. The process operates at steady state. Pure water containing no CO₂ is continuously added to the tank, and carbonated water containing dissolved CO₂ continually exits the tank. Pure carbon dioxide gas at 2.0 atm is bubbled into a tank at a rate of 4.0m³ gas per minute. At these conditions, the “gas holdup” inside the tank is 0.05 m³  gas/m³ liquid, and the average bubble diameter delivered by the fine bubble sparger is 2.0 mm. The CO₂ gas not absorbed by the water exits the tank. The process temperature is kept constant at 293 K. The process is liquid film controlling since only pure CO₂ is present in the gas phase. The Henry’s law constant for dissolution of CO₂ in water is 29.6 atm m³/kgmole at 293 K. The inlet water flow rate of 0.45m³ per minute (25 kgmole H₂O/min) contains no dissolved CO₂.
a. What is the liquid film mass-transfer coefficient associated with the bubbling of CO₂ gas into water?
b. Is the inlet flow rate of CO₂ gas sufficient to ensure that the CO₂ dissolution is mass-transfer limited?
c. What is the outlet concentration of dissolved CO₂? 

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Fresh water CAL0 = 0 0.45 m³/min CO₂ out 100% CO₂ gas 2.0 atm V=2.0 m³ 0 0 0 0 0 0 0 0 0 0 Gas sparger (2.0 mm bubbles) 100% CO₂ gas *2.0 atm, 293 K 4.0 m³/min CAL