p-T-x Measurements for 1,1,1,2-Tetrafluoroethane (R134a) + N,N –dimethylacetamide (DMA), and N-methyl-2-pyrrolidone (NMP)

International audienceThe present study concerns p-T-x phase equilibria measurements involving two working fluid pairs (Refrigerant + Organic solvent) , namely 1,1,1,2-tetrafluoroethane (R134a) + N,N – dimethylacetamide (DMA) and , 1,1,1,2-tetrafluoroethane + N-methyl-2-pyrrolidone (NMP), using the static-analytic method at temperatures varying between 303 and 353 K. The experimentally measured data were successfully correlated using the Peng – Robinson equation of state (PR-EoS) in combination with Huron-Vidal mixing rule, and the non-random two liquid activity coefficient model (NRTL), contrarily to the predictive Soave-Redlich-Kwong (PSRK) group contribution equation of state which failed to reproduce accurately enough such data

Isothermal Vapor-Liquid Equilibrium Data of 1,1,1,2-Tetrafluoroethane (R134a) + Dimethylformamide (DMF) Working Fluids for an Absorption Heat Transformer

International audienceVapor-liquid equilibrium data of 1,1,1,2-tetrafluoroethane (R134a) + dimethylformamide (DMF) were measured in the temperature range from (303.30 to 353.24) K by the static analytic method. The results are of interest to test the possibility of using R134a as a refrigerant in combination with an organic absorbent, that is, DMF, in an absorption heat transformer. The experimental data are correlated using the Peng-Robinson equation of state in combination with the Mathias-Copeman alpha function, MHV1 mixing rules, and the non-random two liquid (NRTL) activity coefficient model. We have compared our experimental results to predictions obtained using the predictive Soave-Redlich-Kwong (PSRK) group contribution equation of state

p-T-x Measurements for Some Working Fluids for an Absorption Heat Transformer: 1,1,1,2-Tetrafluoroethane (R134a) + Dimethylether Diethylene Glycol (DMEDEG) and Dimethylether Triethylene Glycol (DMETrEG)

International audienceThe solubilities of 1,1,1,2-tetrafluoroethane (R134a), CF3CH2F, + dimethylether diethylene glycol (DMEDEG), CH3O(CH2CH2O)2CH3, and R134a + dimethylether triethylene glycol (DMETrEG) binary systems were measured, using the “static-analytic” method at temperatures between (303 and 353) K. This work was an opportunity to test the use of R134a as a refrigerant in combination with an organic absorbent, like DMEDEG and DMETrEG, in an absorption heat transformer (AHT), also known as a type II absorption heat pump or a reversed absorption heat pump. The experimental data were correlated using the Peng-Robinson equation of state (PR-EoS) in combination with Mathias-Copeman R function, Huron-Vidal mixing rules, and the nonrandom two-liquid (NRTL) activity coefficient model. The experimental results were compared to the predicted values obtained using the predictive Soave-Redlich-Kwong group contribution equation of state (PSRK-EoS)

Experimental and predicted excess molar enthalpies of some working pairs for absorption cycles

International audiencein this work, the measured excess molar enthalpies of absorption heat pump working pairs (refrigerant + absorbent), viz. water + rnono-, di- and tri-ethylene glycol, water + glycerol, and ethanol + di- and tri-ethylene glycol mixtures are presented at 298.15 K and ambient pressure using a Setaram Calvet C80 calorimeter. The experimental results are represented and correlated by a Redlich-Kister type equation. Modeling of the excess enthalpies has been performed using the UNIFAC molecular group-contribution method, and UNIQUAC Gibbs energy model. In addition, the data and results are used to predict the Gibbs energy of all binary systems. This allows a preliminary evaluation of the suitability of the binary systems as heat pump working pairs. (C) 2009 Elsevier B.V. All rights reserved