Characterization of Sodium Nitrate as Phase Change Material

Abstract

In this article the results of material investigations of sodium nitrate (NaNO 3 ) with a melting temperature of 306 • C as a phase change material (PCM) are presented. The thermal stability was examined by kinetic experiments and longduration oven tests. In these experiments the nitrite formation was monitored. Although some nitrite formation in the melt was detected, results show that the thermal stability of NaNO 3 is sufficient for PCM applications. Various measurements of thermophysical properties of NaNO 3 are reported. These properties include the thermal diffusivity by the laser-flash, the thermal conductivity by the transient hot wire, and the heat capacity by the differential scanning calorimeter method. The current measurements and literature values are compared. In this article comprehensive temperature-dependent thermophysical values of the density, heat capacity, thermal diffusivity, and thermal conductivity in the liquid and solid phases are reported.

Experimental analysis of the performance of optimized fin structures in a latent heat energy storage test rig

“…Both comparisons show good qualitative correlation at all three measurement locations. The model uses material data analysed in [8]. The model is based on a finite element method applied to the transient heat conduction equation not considering effects due to natural convection.…”

Inorganic Salt Hydrate for Thermal Energy Storage

“…Table 3 presented a variety of salt solutions with large enthalpy values that can apply to low temperature fields. NH 4 Cl, NaCl, KCl and NH 4 Br etc are mainly additional salt that can add to other PCMs to decrease melting point according to their abilities to weaken the hydrogen bond among water molecule [84,85]. An investigation of PCM panels with NH 4 Cl and water placing against internal wall in a refrigeration during 24 h for 2 weeks was carried out by Gin [86].…”

Transient Numerical Simulation of the Melting and Solidification Behavior of NaNO3 Using a Wire Matrix for Enhancing the Heat Transfer

“…In the literature, different data for the melting temperature of the sodium nitrate are available. In the present work a constant melting temperature of T = 579.15 K was used for NaNO 3 , which is based on the references [37,38]. The heat of fusion with L = 176.256 kJ/kg is taken from [38].…”

“…The heat of fusion with L = 176.256 kJ/kg is taken from [38]. It can be seen in the references [37,38], which have made a comparison with a higher number of published data, that the gradient of the specific heat capacity in the liquid region of NaNO 3 is approximately constant. In the solid region of the sodium nitrate, the specific heat capacity shows a slight upward trend starting from the environment temperature up to the melting temperature.…”

“…However, the local maximum of the specific heat capacity is not within the temperature region of the numerical simulation. Therefore, the specific heat capacity for the solid as well as liquid NaNO 3 was modeled within the present study with the constant value of c p = 1635 J/kgK (this is the value of the liquid NaNO 3 ) based on the references [37,38].…”