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COBEM 2021
26th International Congress of Mechanical Engineering
IMPLEMENTATION AND DEVELOPING OF A ROUTINE TO DEFINE THE AMMONIA-WATER THERMODYNAMIC PROPERTIES BY USING GIBBS FREE ENERGY DEFINITION
Submission Author:
Beethoven Narváez-Romo , SP
Co-Authors:
Beethoven Narváez-Romo, Andres Acosta, José Roberto Simões Moreira
Presenter: Beethoven Narváez-Romo
doi://10.26678/ABCM.COBEM2021.COB2021-0835
Abstract
Computational study of ammonia-water absorption refrigeration cycles requires a proper assessment of thermodynamic properties of the working fluids in subcooled, saturated and superheated states, in order to characterize physical transformation processes that occurs in refrigeration cycle’s fluids. Some of the existing and most accurate thermodynamic libraries have been provided in commercial software such as Engineering Equation Solver (EES), and routines suitable for several programming languages handed over by International Association for the Properties of Water and Steam (IAPWS). On the one hand, EES uses an equation-of-state based on Gibbs free energy developed by Ibrahim and Klein (1993), but on the other hand IAPWS formulation implements Tillner-Roth and Friend (1998) correlations, which are based on Helmholtz free energy. However, IAPWS routines have a limited use due to the limited input parameters allowed (temperature, pressure, and density), and EES requires the acquisition of a license. Therefore, the current study aims to develop an open-source Python thermodynamic library for ammonia-water mixtures by using Ziegler and Trepp (1984) equation-of-state. First of all, a detailed derivation of each property is presented, secondly a comparison within the exposed equations-of-state is carried out, and finally numerical results are compared to experimental data available in open-literature. Such comparisons are performed within 0.2 and 50 bar and from 230 K up to 500 K. It is worth to mention that the implementation of any equation-of-state in a programming language such as python possibilities to approach whatever characterization process in which non-ideal fluid behavior occurs e.g, heat and mass transfer processes and transport phenomena.
Keywords
equation of state, Gibbs Free Energy, Helmholtz free energy, Ammonia-water, absorption refrigeration cycle
