The sodium nitrate–urea binary mixture as a phase change material for medium temperature thermal energy storage. Part I: Determination of the phase diagram and main thermal properties

2016 ◽  
Vol 157 ◽  
pp. 1065-1075 ◽  
Author(s):  
G. Diarce ◽  
E. Corro-Martínez ◽  
L. Quant ◽  
Á. Campos–Celador ◽  
A. García–Romero
Keyword(s):  
Phase Diagram ◽  
Thermal Properties ◽  
Energy Storage ◽  
Binary Mixture ◽  
Thermal Energy ◽  
Sodium Nitrate ◽  
Thermal Energy Storage ◽  
Medium Temperature ◽  
Change Material

scholarly journals Demonstration of Phase Change Thermal Energy Storage in Zinc Oxide Microencapsulated Sodium Nitrate

2021 ◽  
Vol 11 (13) ◽  
pp. 6234
Author(s):  
Ciprian Neagoe ◽  
Ioan Albert Tudor ◽  
Cristina Florentina Ciobota ◽  
Cristian Bogdanescu ◽  
Paul Stanciu ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Thermal Properties ◽  
High Temperature ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Sodium Nitrate ◽  
Thermal Energy Storage ◽  
Metal Corrosion ◽  
Scanning Calorimetry

Microencapsulation of sodium nitrate (NaNO3) as phase change material for high temperature thermal energy storage aims to reduce costs related to metal corrosion in storage tanks. The goal of this work was to test in a prototype thermal energy storage tank (16.7 L internal volume) the thermal properties of NaNO3 microencapsulated in zinc oxide shells, and estimate the potential of NaNO3–ZnO microcapsules for thermal storage applications. A fast and scalable microencapsulation procedure was developed, a flow calorimetry method was adapted, and a template document created to perform tank thermal transfer simulation by the finite element method (FEM) was set in Microsoft Excel. Differential scanning calorimetry (DSC) and transient plane source (TPS) methods were used to measure, in small samples, the temperature dependency of melting/solidification heat, specific heat, and thermal conductivity of the NaNO3–ZnO microcapsules. Scanning electron microscopy (SEM) and chemical analysis demonstrated the stability of microcapsules over multiple tank charge–discharge cycles. The energy stored as latent heat is available for a temperature interval from 303 to 285 °C, corresponding to onset–offset for NaNO3 solidification. Charge–self-discharge experiments on the pilot tank showed that the amount of thermal energy stored in this interval largely corresponds to the NaNO3 content of the microcapsules; the high temperature energy density of microcapsules is estimated in the range from 145 to 179 MJ/m3. Comparison between real tank experiments and FEM simulations demonstrated that DSC and TPS laboratory measurements on microcapsule thermal properties may reliably be used to design applications for thermal energy storage.

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