Apparatus for simultaneous determination of the densities and heat capacities of liquids and of liquids with dissolved gas under an extended range of pressure (0.1-100 MPa)

Abstract

This design note describes an experimental device, based on a Setaram C-80 calorimeter and an Anton Paar 512P densimeter, developed in order to measure densities and heat capacities at constant pressure of liquids and of liquids with gas dissolved. Pressure ranges from 0.1 to 70 MPa for the density measurement and from 0.1 to 100 MPa for the heat capacity determination, at temperatures from 303 to 473 K. The specific arrangement incorporated in the apparatus and the method of transfer of samples into the measurement vessels required for the study of these mixtures are also detailed. The functioning of this instrument was tested by measuring the heat capacity of liquid n-hexane, with calibration performed with water. Comparison with literature data obtained by an indirect method indicates that the deviation is less than 0.6%. The results of an investigation of a binary mixture, of n-decane and carbon dioxide, which has two phases under normal conditions, is also given.

Volumetric Behavior of Decane + Carbon Dioxide at High Pressures. Measurement and Calculation

“…The experimental arrangement (see Figure 1) and the preparation and transfer methods into the densimeter cell inherent to these mixtures have already been detailed. 5 Nevertheless, several important points should be noted. The work on mixtures containing dissolved gases (here, the carbon dioxide) required the separation of the pressurizing system, which is gas (nitrogen) and the sample.…”

“…For this purpose, a bypass line (13) was introduced into the pressurization system to fill the densimeter cell and the buffer volume was connected downstream with nitrogen at a pressure slightly below the mixture pressure. The starting up of the pneumatic pump (5) and the simultaneous opening of the upper valve of the separator (8) allow the buffer volume to be filled via the densimeter cell under isobaric conditions. Then, the three-way valve (9) closes off the circuit.…”

Heat capacity and Joule-Thomson coefficient of selected n -alkanes at 0.1 and 10 MPa in broad temperature ranges

“…Relative deviation between Cp values obtained in this work (Cp exp ) and those from literature (Cp lit ) for (a) n-hexane[Zaripov et al [56] (), Bessières et al[15] (), Cerdeiriña et al[55] (), González-Salgado et al[1] (), Zábranský et al[9] (), Span and Wagner[43] ()]; (b) n-octane [Banipal et al[16] (), Cerdeiriña et al[55] (), Růžička et al[6] (), Span and Wagner[43] (), Burgdorf et al [57] (), Coulier et al [62] ()]; (c) n-decane [Gates et al [59] ( ̵ ), Banipal et al [16] (), Páramo et al [2] (), Bessières et al [17] (), González-Salgado et al [1] (), Cerdeiriña et al [58] (), Schlinger and Sage [60] (─), Zábranský et al [9] (), Lemmon and Span [44] ()]; (d) n-dodecane [Cerdeiriña et al [55] (), Páramo et al [2] (), Bessières et al [4] (), Khasanshin et al [18] (), González-Salgado et al [1] (), Burgdorf et al [57] (), Salvetti et al [61] (), Zábranský et al [9] (), Lemmon and Huber [45] ()]; (e) n-tetradecane [González-Salgado et al [1] (), Khasanshin et al [19] (), Zábranský et al [9] ()] and (f) n-hexadecane [Banipal et al [16] (), Cerdeiriña et al [55] (), Petit and Minassian [14] (), Zábranský et al [9] ()]. Black symbols represent data at 0.1 MPa and grey symbols represent data at 10 MPa.…”

“…Moreover, data on Cp of these n-alkanes at high pressures is far from comprehensive. To the best of our knowledge, Cp data for n-hexane at high pressures was measured by Bessières et al [15] up to 100 MPa and temperatures up to 373.15 K, by González-Salgado et al [1] up to 60 MPa and 323.15 K and by Zaripov et al up to 147 MPa and 348.17 K. For n-octane, Banipal et al [16] published Cp values up to 10 MPa and 373.15 K. Regarding n-decane, Banipal et al [16] reported Cp values up to 10 MPa and 373.15 K, Bessières et al [17] up to 10 MPa and 372.27 K and González-Salgado et al [1] up to 60 MPa and 323.15 K. As for n-dodecane, Bessières et al [4] measured values up to 100 MPa and 373.15 K and González-Salgado et al [1] up to 60 MPa and 323.15 K, also Khasanshin et al [18] reported values of this property up to 140 MPa and 433.15 K obtained from heat capacity and density data at atmospheric pressure, as well as speed of sound data as a function of temperature and pressure. As regards n-tetradecane, high pressure data was previously published by González-Salgado et al [1] up to 60 MPa and 323.15 K and calculated from speed of sound data by Khasanshin et al [19] up to 140 MPa and 433.15 K. Finally, for n-hexadecane, Cp data at high pressures were previously reported by Banipal et al [16] up to 10 MPa and 373.15 K. These existing data show that an effort has been made to report accurate values of Cp of n-alkanes in broad temperature and pressure ranges, however it is also shown that there is still lack of accurate Cp data at high temperature and pressure conditions.…”

Heat capacities of aqueous solutions of sodium hydroxide and water ionization up to 300°C at 10MPa

“…To minimize these effects, the design of Bessieres et al (2000) was adopted. This design utilizes a pre-heater (C in Fig.…”