Merck
  • Home
  • Search Results
  • Determining the composition of ammonia/water mixtures using short-wave near-infrared spectroscopy.

Determining the composition of ammonia/water mixtures using short-wave near-infrared spectroscopy.

Talanta (2015-11-26)
M Isabel Barba, Daniel Salavera, M Soledad Larrechi, Alberto Coronas
ABSTRACT

This paper proposes a methodology based on short-wave near-infrared spectroscopy to determine the ammonia content of ammonia/water mixtures with ammonia mass fraction in the range 0.35-0.65. Establishing this methodology meant modeling the relationship between the pressure bar (15-25)bar, temperature (20-50)°C and composition of the ammonia-water in the mixture (0.35-0.65 in ammonia mass fraction) with absorbance at 1033nm. The experiments were designed to optimize experimental work. A 2(3) factorial design+3 center points was used to establish and analyze the significance of the variables in the absorbance using analysis of variance (ANOVA). A linear model for absorbance was obtained using the least squares method. The trueness of the results versus the values obtained was assessed using a reference method; density measurement was chosen for this study. The accuracy of the results in terms of root-mean-square deviation (RMSD) was 3.7%. The methodology proposed represents a fast alternative for the "in-situ" measurement of the ammonia composition of ammonia-water mixtures in absorption refrigeration systems.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Ammonia, anhydrous, ≥99.98%
Sigma-Aldrich
Ammonia solution, 0.4 M in THF
Sigma-Aldrich
Ammonia solution, 4 M in methanol
Sigma-Aldrich
Ammonia-14N, 99.99 atom % 14N
Sigma-Aldrich
Ammonia solution, 2.0 M in isopropanol
Sigma-Aldrich
Ammonia solution, 2.0 M in methanol
Sigma-Aldrich
Ammonia solution, 7 N in methanol
Sigma-Aldrich
Ammonia solution, 0.4 M in dioxane