High-pressure fluid-phase equilibria: Experimental methods and systems investigated (2000-2004)

Solar-powered absorption chillers: A comprehensive and critical review

The viscosity and density of four pure liquid compounds (dimethyl carbonate, diethyl carbonate, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether) were measured at several temperatures between 283.15 and 353.15 K. The density measurements were performed up to 60 MPa with an uncertainty of 1×10−4g·cm−3. The viscosity at atmospheric pressure was measured with an Ubbelohde-type glass capillary tube viscometer with an uncertainty of ±1%. At pressures up to 100 MPa the viscosity was determined with a falling ball viscometer with an uncertainty of ±2%. The density (410 experimental values) and viscosity data (184 experimental values) were fitted to several correlation equations.

High-Pressure Measurements of the Viscosity and Density of Two Polyethers and Two Dialkyl Carbonates

In this work, we propose a new predictive entropy-scaling approach for Newtonian shear viscosities based on group contributions. The approach is based on Rosenfeld’s original work [Rosenfeld, Y. Phys. Rev. A 1977, 15, 2545−2549]. The entropy scaling is formulated as third order polynomial in terms of the residual entropy as calculated from a group-contribution perturbed-chain polar statistical associating fluid theory (PCP-SAFT) equation of state. In this study, we analyze the course of entropy scaling parameters within homologous series and suggest suitable mixing rules for the parameters of functional groups. The viscosity of nonpolar, of polar, and of self-associating (hydrogen bonding) components are considered. In total, 22 functional groups are parametrized to viscosity data of 110 pure substances, from 12 different chemical families. The mean absolute relative deviations (MADs) to experimental viscosity data are typically around 5%. For three chemical families, namely, branched alkanes, 1-alcohols,...

Group Contribution Method for Viscosities Based on Entropy Scaling Using the Perturbed-Chain Polar Statistical Associating Fluid Theory

The use of ammonia-based working fluids for absorption prevails in a wide range of applications due to the low freezing temperature of the refrigerant and the absence of crystallization as well as the lack of problems under vacuum conditions. This paper presents a comprehensive overview on the use of ammonia-based absorption chillers and heat pumps. The thermodynamic and physical properties of pure ammonia and binary and ternary ammonia mixtures are presented in correlation formulas. Developments and applications in subfreezing refrigeration, heating/domestic hot water, renewable energy utilization, waste heat recovery, thermal energy storage and miniaturization of absorption systems are presented and summarized. In subfreezing refrigeration, the evaporation temperatures for single-stage absorption lie mainly between −30 °C and −5 °C, and they can reach as low as −70 °C in advanced absorption systems. Air-source and ground-source absorption heat pumps are suggested for heating/domestic hot water applications in cold regions. For renewable energy uses, ammonia-based solar absorption applications with various working fluids are quite popular, whereas geothermal and biomass energy systems are less studied. In thermal energy storage, ammonia-based working fluids are not advantageous for storage capacity or cycle efficiency, but they prevail for subfreezing energy storage. Additionally, ammonia-based fluids are also attractive options for the miniaturization of absorption systems due to the absence of crystallization.

An overview of ammonia-based absorption chillers and heat pumps

Liquid densities and heat capacities at 1 MPa, and kinematic viscosities at atmospheric pressure of monoethylene glycol diethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol dibutyl ether, and dipropylene glycol dimethyl ether were measured in the temperature range (283.15 to 423.15) K. For each substance, experimental data were correlated with temperature using empirical polynomial equations. The experimental data of kinematic viscosity and heat capacity were used to evaluate the predictive capability of some estimation methods of the literature.

Liquid Densities, Kinematic Viscosities, and Heat Capacities of Some Alkylene Glycol Dialkyl Ethers

The density, dynamic viscosity, and heat capacity of ammonia + lithium nitrate and ammonia + lithium nitrate + water mixtures were measured between (293.15 and 353.15) K at 1.8 MPa, using a vibrating-tube densimeter, a piston-style viscosimeter, and a heat flux Calvet-type calorimeter, respectively. The measured data were correlated as a function of temperature and composition using simple polynomial equations. Kinematic viscosity data of binary and ternary mixtures were also determined.

Densities, Viscosities, and Heat Capacities of Ammonia + Lithium Nitrate and Ammonia + Lithium Nitrate + Water Solutions between (293.15 and 353.15) K

Densities and viscosities of the binary mixtures of interest for absorption refrigeration systems and heat pumps

Research on new working fluid pairs for use in absorption refrigeration systems and heat transformers continues. Densities, kinematic viscosities, and excess molar enthalpies have been determined for methanol + polyethylene glycol 250 dimethyl ether at 303.15 K over the entire range of composition and at atmospheric pressure. Experimental viscosities were correlated by the McAllister, Stephan, Soliman, and Marshall correlations.

Xavier Esteve

Papers

Liquid Densities, Kinematic Viscosities, and Heat Capacities of Some Alkylene Glycol Dialkyl Ethers

Densities, Viscosities, and Heat Capacities of Ammonia + Lithium Nitrate and Ammonia + Lithium Nitrate + Water Solutions between (293.15 and 353.15) K

Densities and viscosities of the binary mixtures of interest for absorption refrigeration systems and heat pumps

Densities, viscosities, and enthalpies of mixing of the binary system methanol + polyethylene glycol 250 dimethyl ether at 303.15 K

Performance analysis of a triple-effect absorption cooling cycle using aqueous (lithium, potassium, sodium) nitrate solution as a working pair