Calorimetric Techniques for Measuring Heat of Mixing

The calorimetric techniques for measuring heats of mixing two fluids can be classified into their mode of measurement and their principle of heat detection. The isothermal displacement calorimetry will refer to a static mode and flow calorimetry, to a dynamic mode . The principles of heat detection in the following examples will be power compensation or heat flux determination. 

In order to make it possible the determination of enthalpies of solution of gases in organic liquid solvents, Battino and Marsh [70] set up a modified burette arrangement. This modified technique proved to be effective for the particular systems where small gas solubilities are observed. However the technique was impractical in the case of CO2 dissolution in aqueous solution of amine. This was mainly due to high solubility of carbon dioxide and consequently, large volumes of injected gas. Then Carson 

Kim and Svendsen [18] at Norwegian University of Science and Technology choose a similar technique for measuring heat of mixing of CO2 in amine solutions. The main difference with Carson et al. modified calorimeter [19] results in a larger range of experimental temperatures (253-473 K) and pressures (up to 10 MPa) that can be investigated. Their experimental procedure (Fig. 14.3) consists as previously in multiple successive injections of CO2 up to reach a CO2 pressure in the gas reservoir tank close to pressure in the calorimeter vessel. 

This dynamic technique used by Oscarson and co-workers [21] at Brigham Young University (USA) to study CO2 capture studies was developed in same University by Christensen and coworkers [71]. The principle of isothermal compensation calorimeter is based on the measurement of an external heat power used to maintain a reaction vessel at constant temperature during mixing. In flow mode the fluids flow to the 

This dynamic technique was initially developed by Mathonat and coworkers at University of Clermont-Ferrand (France). It is a flow technique where the heat of mixing is measured in a mixing cell located inside a Calvet type calorimeter (Fig. 14.5a). The Calvet sensors are a thermopiles constituted of thermocouples surrounding the mixing cell and measuring the heat power exchanged with a thermostated calorimetric block. The mixing cell represented in Fig. 14.5b consists of an hastelloy tube 

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