Experimental setup for obtaining VLE and heat of absorption data

“The experimental setup for obtaining VLE and heat of absorption data is schematically shown in Figure 2. This is precisely the same equipment used by Kim et al. (44,45) The core of the setup is the calorimeter CPA122 fabricated by ChemiSens AB.”


“Figure 2. Schematic view of the calorimeter CPA122 setup.”

“Initially, vacuum is made into the stirred-cell reactor so that the solvent can be easily inserted through differential pressure (i.e., “sucked” into the cell). A certain measured amount of lean solvent, typically around 1.2 L, is fed to the reactor (2 L) through an upper inlet. This inlet is coupled with a valve, and closing this valve seals the reactor with the solvent therein. Once sealed, the reactor is vacuumed two to three times so that only the solvent and its equilibrium vapor remain inside the stirred cell. Enough time under vacuum conditions is given so that one can verify that the system is airtight. A temperature setpoint is chosen, and the stirrer is set to rotate at about 500 rpm. In the meantime, during the experiment, CO2 5.0 is stored in a pair of cylinders (4.55 liters total) submerged in a water bath so as to keep their temperature constant. Pressure and temperature are measured at each moment, and the number of moles of CO2 stored in the cylinders can be calculated by means of the Peng–Robinson equation of state (EOS). When injecting CO2 into the reactor, this EOS is employed to calculate the mass of CO2 before and after the gas leaves the cylinders so that one can find precisely how much CO2 has been injected. Simultaneously, and differently from the setup employed in our previous publication, (32) this setup includes a mass-flow controller (MFC) through which one has a second evaluation of how much CO2 is injected at each moment.”

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