Fast, stable computation of thermodynamic properties of ammonia-water mixtures

Alexander S. Rattner, Srinivas Garimella

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Software implementations of thermodynamic property routines for ammonia-water mixtures are developed for refrigeration and air-conditioning applications. Saturation correlations are employed to identify single-phase state points, yielding up to a 5-fold reduction in property evaluation time. A run-time database of previously evaluated state points is implemented to improve initial guesses for iterative property evaluation, reducing property evaluation time by 45% in a representative study. The property routines are implemented in a standalone program and as a compiled routine for use in MATLAB® and Simulink®. Both implementations perform property evaluations significantly faster than existing software packages. Program performance is measured on a 2.2 GHz machine, and average individual state point evaluation times were found to range from 50 to 930 μs, depending on the provided input properties. Additionally, a segmented, transient, ammonia-water absorber model is developed in Simulink® to assess the use of the property routines for practical engineering calculations. The proposed computational techniques can be applied to accelerate property evaluations for other mixtures.

Original languageEnglish (US)
Pages (from-to)39-59
Number of pages21
JournalInternational Journal of Refrigeration
Volume62
DOIs
StatePublished - Feb 2016

All Science Journal Classification (ASJC) codes

  • Building and Construction
  • Mechanical Engineering

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