Construction of the equation of a state octafluorocyclobutane in area superheated steam and supercritical parameters

On the basis of the spent experimental researches of density C4F8 and given other authors the new equation of a state is constructed. The equation provides calculation of thermodynamic properties in superheated steam area and supercritical parameters of a condition octafluorocyclobutane. By means of the received equation of a condition tables of thermodynamic properties are made at temperatures 20 … 450ºС and pressure to 10 MPa. Accuracy of the presented settlement data about density is estimated by authors no more than 0,3 %. The data can be used at calculation of cycles turbine-steam the installations using octafluorocyklobutane as a working substance

DOI:10.1068/htwu168 Thermodynamic properties of ozone-friendly substances: individual and combined refrigerants

Abstract. Experimental thermodynamic data of individual substances and some mixtures were selected for a statistical treatment. The substances selected are the ozone-layer-friendly cooling liquids (HFC-134a, HFC-152a, HC-290, HC-600a, etc, and their mixtures). As a result of the treatment the equations of state (EOS) were produced in the form of the Carnahan ^ Starling ^ De Santis (CSD) EOS. The same form of EOS was accepted for the blends including HFC-134a/HFC-152a, HC-600a/HFC-152a, HC-600a/HFC-134a, and HC-290/HC-600a. Software programs combined in a data base were produced in order to evaluate coefficients of EOS with experimental data, to calculate thermodynamic properties of cooling liquids, and to determine the characteristics of refrigerating cycles which use the liquids. The modelling of several types of cycle was carried out for pure substances and the mixtures. The characteristics of the cycles were compared with those of CFC-12. The results of the cycle modelling show that the blends HFC-134a/HFC-152a and HC-600a/HFC-152a have some advantages relative to HFC-134a. These blends can be used as effective alternative refrigerants.