Isothermal high pressure flow calorimeter

Abstract

An isothermal flow calorimeter suitable for measuring heats of reaction and heats of mixing at high pressure is described. With the calorimeter endothermic or exothermic processes can be studied from 0 to 70 °C and from 1 to 400 atm. Energy effects from 0.15 to 30 J/min are measured with a precision of ±0.4% at a constant temperature through the use of an automatic controlled variable heater and a constant cooling Peltier device. A complete heat-of-mixing curve can be generated from a single run. The calorimeter was tested by measuring the heats of neutralization of HClO4–NaOH and HClO4–TRIS and the heat of mixing of n-hexane-cyclohexane, and was found to produce data in very good agreement with published literature values.

Excess enthalpies of (toluene+methanol or heptane or methylcyclohexane) and of (heptane+methylcyclohexane) at the temperatures 255.4 K and 310.9 K and the pressure 13.8 MPa

“…The flow calorimeter and the experimental procedure have been described. (2)(3)(4) Water and a mixture of equal masses of water and ethan-1,2-diol were used as bath fluids for the experiments at T=310.9 K and 255.4 K, respectively. The temperature was read from a Hart model-1006 platinum resistance thermometer calibrated against a Rosemount thermometer (ITS-68).…”

Excess enthalpies of (carbon dioxide + propylene carbonate orN-methyl-ε-caprolactam or 1-formyl piperidine) at the temperatures 298.15 K and 308.15 K and pressures from 7.5 MPa to 12.5 MPa

“…The apparatus and solvent-delivery system are very similar in design to those described by Christensen and coworkers. (6,7) The water bath of the calorimeter (volume: 55 dm 3 ) provided temperature control of 20.0006 K. Fluids studied were injected into the flow cell by means of two Isco 260D high-pressure pumps operated in a steady-state (fixed-composition) mode. The total volumetric flow rate was 0.007 cm 3 ·s −1 or 0.010 cm 3 ·s −1 depending on the magnitude of the measured signal.…”

Calorimetric Properties of Hydrothermal Solutions

“…After the pioneering work of Monk and Wadsö (1968) and Picker with co-authors (Picker et al, 1969(Picker et al, , 1971Picker, 1974) on fl ow calorimetry at room temperature, already in the years 1975-77 fl ow mixing calorimeters were developed for measurements at elevated temperatures (up to 70-150 °C) at the University of Delaware, USA (Messikomer and Wood, 1975), at Brigham Young University, Provo, USA (Christensen et al, 1976) and at the University of Bristol, UK (Wormald, 1977).…”