Modification of a C-80 Setaram calorimeter for measuring heat capacities of liquids at temperatures up to 548 K and pressures up to 20 MPa

• Published in: The Journal of chemical thermodynamics 1991, Vol.23 (11), p.1075-1083
• Main Authors: Coxam, J.-Y., Quint, J.R., Grolier, J.-P.E.
• Format: Article
• Language: English
• ISSN: 0021-9614; 1096-3626
• DOI: 10.1016/S0021-9614(05)80113-2

A method is presented for obtaining heat capacities at constant pressure in the temperature range 343 K to 548 K at pressures up to 20 MPa with an estimated accuracy of ±0.003 · C p . Special cells made of Hastelloy C have been designed for a Setaram C-80 calorimeter to work with liquids at high pressures and high temperatures. An experiment covering the whole temperature range ran automatically for 38 h at a given pressure. As test measurements the heat capacities of NaCl(aq) in the molality range 0.1 mol·kg −1 to 2 mol·kg −1 at temperatures up to 548 K and at the pressure 16.5 MPa are reported. Comparison with literature values (1–3) shows excellent agreement for molalities less than 1 mol·kg −1 and at temperatures up to 500 K. Our results appear to be higher by about 0.01· C p for molalities greater than 1 mol·kg −1 and at temperatures greater than 500 K.