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Effect of nanoparticles on heat capacity of nanofluids based on molten salts as PCM for thermal energy storage.

Chieruzzi M, Cerritelli GF, Miliozzi A, Kenny JM - Nanoscale Res Lett (2013)

Bottom Line: In particular, this research shows that the addition of silica-alumina nanoparticles has a significant potential for enhancing the thermal storage characteristics of the NaNO3-KNO3 binary salt.These results deviated from the predictions of the theoretical model used.SEM suggests a greater interaction between these nanoparticles and the salt.

View Article: PubMed Central - HTML - PubMed

Affiliation: Civil and Environmental Engineering Department, UdR INSTM, University of Perugia, Strada di Pentima, 4, 05100 Terni, Italy. manila.chieruzzi@unipg.it.

ABSTRACT
In this study, different nanofluids with phase change behavior were developed by mixing a molten salt base fluid (selected as phase change material) with nanoparticles using the direct-synthesis method. The thermal properties of the nanofluids obtained were investigated. These nanofluids can be used in concentrating solar plants with a reduction of storage material if an improvement in the specific heat is achieved. The base salt mixture was a NaNO3-KNO3 (60:40 ratio) binary salt. The nanoparticles used were silica (SiO2), alumina (Al2O3), titania (TiO2), and a mix of silica-alumina (SiO2-Al2O3). Three weight fractions were evaluated: 0.5, 1.0, and 1.5 wt.%. Each nanofluid was prepared in water solution, sonicated, and evaporated. Measurements on thermophysical properties were performed by differential scanning calorimetry analysis and the dispersion of the nanoparticles was analyzed by scanning electron microscopy (SEM). The results obtained show that the addition of 1.0 wt.% of nanoparticles to the base salt increases the specific heat of 15% to 57% in the solid phase and of 1% to 22% in the liquid phase. In particular, this research shows that the addition of silica-alumina nanoparticles has a significant potential for enhancing the thermal storage characteristics of the NaNO3-KNO3 binary salt. These results deviated from the predictions of the theoretical model used. SEM suggests a greater interaction between these nanoparticles and the salt.

No MeSH data available.


Related in: MedlinePlus

Heat flow versus temperature for NaNO3-KNO3 binary salt mixture and nanofluids (0.5 wt.% of oxide nanoparticles).
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Figure 1: Heat flow versus temperature for NaNO3-KNO3 binary salt mixture and nanofluids (0.5 wt.% of oxide nanoparticles).

Mentions: Figures 1, 2, and 3 show the DSC thermograms of the NaNO3-KNO3 salt mixture and the nanofluids with different nanoparticles and concentrations. As it can be seen, the different nanoparticles induce a change in the shape of the heat flow curve of the base salt. To evaluate the effect of the nanoparticles on the phase-change curve, the heat of fusion, the melting point, and the onset temperatures of all samples were obtained from DSC measurements and reported in Table 1. The onset temperature was taken as the intersection point of the baseline before transition and the inflectional tangent while the melting points were calculated taking into account the fact that the peaks are not symmetric. In particular, the area under the curve was divided into two equal parts and the corresponding temperature taken as melting point. The temperatures were reported in Table 1.


Effect of nanoparticles on heat capacity of nanofluids based on molten salts as PCM for thermal energy storage.

Chieruzzi M, Cerritelli GF, Miliozzi A, Kenny JM - Nanoscale Res Lett (2013)

Heat flow versus temperature for NaNO3-KNO3 binary salt mixture and nanofluids (0.5 wt.% of oxide nanoparticles).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4231368&req=5

Figure 1: Heat flow versus temperature for NaNO3-KNO3 binary salt mixture and nanofluids (0.5 wt.% of oxide nanoparticles).
Mentions: Figures 1, 2, and 3 show the DSC thermograms of the NaNO3-KNO3 salt mixture and the nanofluids with different nanoparticles and concentrations. As it can be seen, the different nanoparticles induce a change in the shape of the heat flow curve of the base salt. To evaluate the effect of the nanoparticles on the phase-change curve, the heat of fusion, the melting point, and the onset temperatures of all samples were obtained from DSC measurements and reported in Table 1. The onset temperature was taken as the intersection point of the baseline before transition and the inflectional tangent while the melting points were calculated taking into account the fact that the peaks are not symmetric. In particular, the area under the curve was divided into two equal parts and the corresponding temperature taken as melting point. The temperatures were reported in Table 1.

Bottom Line: In particular, this research shows that the addition of silica-alumina nanoparticles has a significant potential for enhancing the thermal storage characteristics of the NaNO3-KNO3 binary salt.These results deviated from the predictions of the theoretical model used.SEM suggests a greater interaction between these nanoparticles and the salt.

View Article: PubMed Central - HTML - PubMed

Affiliation: Civil and Environmental Engineering Department, UdR INSTM, University of Perugia, Strada di Pentima, 4, 05100 Terni, Italy. manila.chieruzzi@unipg.it.

ABSTRACT
In this study, different nanofluids with phase change behavior were developed by mixing a molten salt base fluid (selected as phase change material) with nanoparticles using the direct-synthesis method. The thermal properties of the nanofluids obtained were investigated. These nanofluids can be used in concentrating solar plants with a reduction of storage material if an improvement in the specific heat is achieved. The base salt mixture was a NaNO3-KNO3 (60:40 ratio) binary salt. The nanoparticles used were silica (SiO2), alumina (Al2O3), titania (TiO2), and a mix of silica-alumina (SiO2-Al2O3). Three weight fractions were evaluated: 0.5, 1.0, and 1.5 wt.%. Each nanofluid was prepared in water solution, sonicated, and evaporated. Measurements on thermophysical properties were performed by differential scanning calorimetry analysis and the dispersion of the nanoparticles was analyzed by scanning electron microscopy (SEM). The results obtained show that the addition of 1.0 wt.% of nanoparticles to the base salt increases the specific heat of 15% to 57% in the solid phase and of 1% to 22% in the liquid phase. In particular, this research shows that the addition of silica-alumina nanoparticles has a significant potential for enhancing the thermal storage characteristics of the NaNO3-KNO3 binary salt. These results deviated from the predictions of the theoretical model used. SEM suggests a greater interaction between these nanoparticles and the salt.

No MeSH data available.


Related in: MedlinePlus