A thermodynamic framework to identify apposite refrigerant former for hydrate-based applications.

Area of Science:

• Materials Science
• Chemical Engineering
• Thermodynamics

Background:

• Clathrate compounds possess high latent heat storage capacity and natural salt rejection, making them suitable for energy load management and desalination.
• Water-based refrigerant hydrates operate under mild conditions, offering energy savings and operational simplicity.
• Scattered experimental data hinders direct comparison of hydrate formers, necessitating robust thermodynamic modeling.

Purpose of the Study:

• To address the deficit in phase assessment for clathrate hydrates.
• To identify the most suitable hydrate former among R13, R14, R22, R23, R125, R134a, and R152a for energy load management and desalination.
• To quantify model predictions using percent average absolute relative deviations (% AARD).

Main Methods:

• Utilized the van der Waals and Platteeuw model for phase assessment of clathrate hydrates.
• Quantified model predictions with % AARD, achieving 1.75% in pure phases and 2.68% in aqueous electrolytic phases (NaCl, KCl, CaCl2, MgCl2).
• Estimated model predictions at specific temperature/salinity conditions (281 K/0 wt% and 284 K/3.5 wt%).

Main Results:

• The van der Waals and Platteeuw model demonstrated high accuracy in predicting hydrate phase behavior.
• R152a was identified as the most appropriate hydrate former based on thermodynamic modeling.
• Qualitative assessments of vapor pressure, compressibility, and dissociation enthalpy supported the selection of R152a.

Conclusions:

• R152a is the optimal refrigerant hydrate former for both energy load management and desalination applications.
• Thermodynamic modeling, specifically the van der Waals and Platteeuw approach, effectively streamlines and predicts clathrate hydrate behavior.
• The study provides a validated method for selecting suitable hydrate formers, overcoming limitations of scattered experimental data.