A flow calorimeter for the measurement of the isothermal Joule-Thomson coefficient of gases at elevated temperatures and pressures. Results for nitrogen at temperatures up to 473 K and pressures up to 10 MPa and for carbon dioxide at temperatures up to 500 K and pressures up to 5 MPa

• Published in: The Journal of chemical thermodynamics Vol. 27; no. 7; pp. 721 - 733
• Main Authors: Cuscó, L., McBain, S.E., Saville, G.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 1995; Elsevier
• Subjects: Calorimetry; Exact sciences and technology; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Physics; Thermal instruments, apparatus and techniques; Calorimeters; Carbon dioxide; Instrumentation; Joule Thomson coefficient; Nitrogen; Experimental study; Pressure; Isothermal processes; Temperature range 400-1000 K
• ISSN: 0021-9614; 1096-3626
• DOI: 10.1006/jcht.1995.0073

A new isothermal flow calorimeter for gases at high temperatures and pressures is described. The calorimeter employs a throttling-capillary tube to provide both the pressure drop and the heating element. Considerable care was taken to operate the calorimeter in an isothermal environment by use of a fluidized-bed thermostat. The instrument has been used to make measurements of the molar isothermal Joule-Thomson coefficient of N
2at temperatures in the range 295 K to 473 K and at pressures in the range of 1.0 MPa to 10.0 MPa and also of CO
2at temperatures in the range 300 K to 500 K and at pressures in the range 3.0 MPa to 5.0 MPa. The molar isothermal Joule-Thomson coefficient for N
2has been measured to ± 1 J·MPa
−1·mol
−1and that for CO
2to ± 4 J·MPa
−1·mol
−1}. Agreement is found with other available experimental results and with the predictions made by the IUPAC-approved equations of state.