Accuracy analysis in flow calorimetry

Accurate Thermodynamic Properties from the BACKONE Equation for the Processing of Natural Gas

“…The only exception were comparisons of the coefficients of performance (COPs) and the volumetric refrigeration capacities (VRCs) of the equimolar mixtures of propane with n -butane or isobutane. In that case, we made comparisons with results from the excess Helmholtz energy (EHE) approach of Lemmon, which is similar to the techniques of Tillner-Roth . Actually, many mixtures that have been described in the present paper with BACKONE have already been considered by Lemmon with EHE.…”

“…The excellent quality of BACK-ONE for this mixture has already been shown 7 by comparison with experimental data for VLE iso-therms, [81][82][83][84][85][86] densities in the homogeneous phases, 112 and isochoric heat capacities. 113 Figure 6 shows a new comparison between the BACKONE results and the measurements of Grini et al 114 for the isobaric enthalpy increments of methane + ethane for a temperature change from T 1 to T 2 . The measurements were made at three different isobars (1.0, 7.6, and 13.9 MPa), and for each isobar, a set of measurements was taken at several isotherms.…”

Enthalpy increment measurements on liquid ethane between the temperatures 146.0 K and 256.2 K, at pressures (≈1.6, 3.20, and 5.07) MPa

“…Calculation of the standard uncertainty of the measurements is presented elsewhere. (4) All measured data, except the mass flow rate ṁ are recorded directly on a PC. These data are transferred to a database and converted into SI units and corrected through calibration factors.…”

A new flow calorimeter for the measurement of the isobaric enthapy increment and the isenthalpic Joule–Thomson effect. Results for methane and (methane + ethane)

“…This is a typical value for isobaric heat sections in precise calorimeters. (14) The main part of that value (0.3 W) is caused by axial heat conduction through the tube walls, the rest (0.09 W) is due to heat dissipation generated in the power supply lines which connect the installed electrical heating with the current source outside the vacuum vessel. Expressed in terms of enthalpy difference, the measurement error due to unwanted heat transfer amounts to approximately 3.3 J·mol −1 (based on an average gas throughput of 0.12 mol·s −1 ).…”