AT-96-17-3 -- Improved Property Data Correlations of Absorption Fluids for Computer Simulation of Heat Pump Cycles PDF

Substantial amounts of data have been generated over the years on the thermodynamic and transport properties of absorption fluids, based on measurements conducted both in laboratory equipment and in working heat pump systems. In recent years, efforts have been under way to extend the range of available data to higher temperatures and pressures to facilitate implementation of advanced, multistage cycles. The data have been presented in the literature in various forms, including tables, equations of state based on thermodynamic models and empirical equations for different ranges. The growing need for computer simulations of absorption systems has prompted the correlation of property data. The objective of the present study has been to compile the most recent available information on common absorption fluids and present it in a form suitable for computer calculations. Considering the fact that modelling a complex cycle may involve a large number of iterations by the simulation program, easy evaluation of the required properties is of utmost importance. In correlating the data, an effort has been made to reduce to a minimum any iterative calculations. Property data correlations have been developed for the fluids most commonly used in absorption systems - water, lithium bromide (LiBr)-water, and water-ammonia. The correlations are based on physical equations of state, relying on thermodynamic models. Correlations are given for vapour-liquid equilibrium (PTX), liquid and vapour enthalpy, liquid density, and vapour entropy. The correlations have been implemented in a computer code for simulation of absorption systems and were found to be both accurate and convenient for calculations.

KEYWORDS: year 1996, calculating, properties, water, lithium bromide, absorbents, mixtures, computers, heat pumps, cyclic, thermodynamics, heat content, boiling point, temperature, absorption heat pumps, heat transfer fluids