Understanding supercooling mechanism in sodium sulfate decahydrate phase-change material
[1];
[2];
[1];
[4];
[1];
[1];
[3]
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); University of Science and Technology Beijing, Beijing (China)
- Georgia Institute of Technology, Atlanta, GA (United States)
- Univ. of Tennessee, Knoxville, TN (United States)
Salt hydrate-based phase-change materials are considered promising for future heat storage applications in residential heating/cooling systems. Smooth phase transition from the liquid to solid phase and vice versa is essential for effective heat exchanger; however, supercooling in salt hydrates delays the onset of liquid–solid phase transition. We investigate the molecular level mechanism of supercooling in sodium sulfate decahydrate (SSD). SSD is a complex salt hydrate whose properties are governed by electrostatic forces that include pure Coulombic interactions as well as hydrogen bonds. Experimentally, we examine the importance of a nucleator in reducing supercooling temperatures. We investigated the effect of various mass concentrations of a borax nucleator on a decrease of supercooling temperatures. Molecular dynamics simulation techniques are used to obtain a basic understanding of supercooling in SSD. We observe that by introducing borax as a nucleator, there is a decrease in the supercooling temperature before nucleation. Our molecular dynamics simulations show that long-range electrostatics between sodium and sulfate ion pairs and that with polar water molecules is responsible for delayed nucleation in SSD that results in supercooling, and also, dynamics of charged molecules slows down. The lack of crystallization leads to amorphous structures in supercooled SSD.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE)
- Grant/Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1807290
- Alternate ID(s):
- OSTI ID: 1798537
- Journal Information:
- Journal of Applied Physics, Vol. 129, Issue 24; ISSN 0021-8979
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Nanoscale Stabilization Mechanism of Sodium Sulfate Decahydrate at Polyelectrolyte Interfaces
Effect of expanded graphite on the thermal conductivity of sodium sulfate decahydrate (Na2SO4·10H2O) phase change composites