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

作者：Rattner Alexander S; Garimella Srinivas^*

来源：International Journal of Refrigeration, 2016, 62: 39-59.

DOI：10.1016/j.ijrefrig.2015.09.009

• Absorption
• Ammonia-water
• Thermodynamic properties
• Zeotropic mixtures

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 r and Simulink r. 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 mu s, depending on the provided input properties. Additionally, a segmented, transient, ammonia-water absorber model is developed in Simulinko 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.

• 出版日期2016-2