Solid-liquid equilibria for the dimethyl ether plus carbon dioxide binary system

A recently built experimental setup was employed for the estimation of the solid-liquid equilibria of alternative refrigerants systems. The behavior of dimethyl ether (DME) + carbon dioxide was measured down to temperatures of 131.6 K. To confirm the reliability of the apparatus, the triple point of the DME was measured. The triple point data measured revealed a good consistency with the literature. The results obtained for the mixtures were corrected by the Rossini method and interpreted by means of the Schröder equation. © 2010 Akadémiai Kiadó, Budapest, Hungary

Development and optimization of a method for analyzing biodiesel mixtures with non-aqueous reversed phase liquid chromatography

Biodiesel (a mixture of fatty acid esters) is normally analyzed using gas chromatography/flame ionization detection, as specified by the ASTM D6584 and EN14105 standards. This paper proposes a binary gradient method for analyzing biodiesel mixtures using non-aqueous reverse phase HPLC with a UV detector capable of overcoming the drawbacks of the gas chromatographic technique normally used. The new analytical method was developed by means of a statistical sensitivity analysis applied to the main parameters influencing the recording, using the full factorial design method combined with the Yates algorithm and the steepest ascent optimization procedure. The present study shows the influence of the main biodiesel mixture separation analysis parameters. The resulting tool proved valid for analyzing not only biodiesel but also any traces of unreacted oil

Second virial coefficients for dimethyl ether

Dimethyl ether (DME) is a clean and economical alternative fuel. In addition, it is also an ozone-friendly refrigerant. Burnett measurements were carried out at temperatures from (344 to 393) K and at pressures from (0.055 to 4.015) MPa. A total of 138 experimental points, taken along 15 isotherms and 12 different temperatures, were obtained. The apparatus was calibrated by helium. The derived second coefficients were compared with the selected correlations and with literature data

Solid-liquid equilibria for nitrous oxide+ fluoromethane and triple point measurements for refrigerants

To evaluate the Solid-Liquid Equilibria (SLE) of alternative refrigerants systems, an experimental set-up was employed. The behaviour of the nitrous oxide + fluoromethane (N2O + R41) binary system was measured down to temperatures of 126.5 K. The triple point temperature of carbon dioxide, nitrous oxide and of seven of the most widely applied alternative refrigerants, namely fluoromethane (R41), difluoromethane (R32), trifluoromethane (R23), pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), 1,1,1-trifluoroethane (R143a) and 1,1-difluoroethane (R152a), were also measured. All triple point data measured revealed a generally good consistency with the literature. The results obtained for the mixtures were corrected by the Rossini method and interpreted by means of the Schröder equation. © 2012 Old City Publishing, Inc

Alternative biofuels:PVTx measurements for DME + propane

This study presents the experimental results for the dimethyl ether (DME) ? propane system obtained using the Burnett method. The apparatus was calibrated using helium. PVTx measurements were taken for four isotherms (344, 354, 364, and 375 K), performing 16 Burnett expansions in pressures ranging from about 3,000 to 70 kPa. The second and third virial coefficients were derived from experimental results. The experimental uncertainty in the second and third virial coefficients was estimated to be within ±5 cm 3/mol and ±1,000 cm6/mol2,respectively

PVT properties of an alternative biofuel: dimethyl ether

Dimethyl ether is an important chemical material and it has many engineering applications. It is a clean and economical alternative fuel and an ozone-friendly refrigerant. In this work, its PVT properties have been object of study. In particular, the experimental work was performed both in the two-phase region and in the superheated vapor region phase by means of the isochoric method. The isochoric measurements were carried out at temperatures from 219 K to 363 K and at pressures from 22 kPa up to 1,740 kPa. A total of 159 points, both in the two phase (71 points) and in the superheated vapor region (88 points) were obtained. The present experimental PVT data contribute to the deeper knowledge of the behaviour of the fluid both in the superheated vapour and in the saturation pressure region and to the development of a new equation of state