A wetted-wall column of 2.0-cm inner diameter and 50-cm wetted length is used to oxygenate blood as a continuous, steady-state process, as shown in the figure below. Blood containing 1.0 gmole/m³of dissolved oxygen enters the top of the wetted-wall column at a volumetric flow rate of 300 cm3/min. Pure, 100% O₂gas at 1.0 atm and 25°C enters the bottom of the column at a volumetric gas flow rate of 600 cm³/min. A very simplified description for estimating the equilibrium solubility of O₂dissolved in blood is where p_Ais the partial pressure of O₂in the gas phase, H = 0.8 atm-m³/gmole for O₂in the blood plasma, k = 28 atm^€“1for the blood hemoglobin, and c_AL,max = 9.3 gmole O₂/m³ for the hemoglobin.

 

At 25°C, the kinematic viscosity of blood is 0.040 cm²/s and the density of blood is 1.025 g/cm³. You may assume that the diffusion coefficient of O₂ in blood approximates the diffusion coefficient of O₂ in liquid water, which is 2.0 × 10^€“5 cm²/s at 25°C.

a. What is the mass-transfer coefficient for O₂ into the flowing liquid film?
b. What is the concentration of dissolved oxygen in the liquid exiting the bottom of the column, c_AL,out?

Transcribed Image Text:

Liquid in (blood + dissolved O,) CALO = 1.0 mol/m3 Vo = 300 cm/min D = 2 cm Z = 50 cm - Liquid film D 100% O, flow in 1.0 atm, 25°C 600 cm/min gas Liquid out (blood + dissolved O2) CALout = ?