


































Energy and Earth Science 
Vol. 3, No. 1, 2020 

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ISSN 2578-1359 (Print)   ISSN 2578-1367 (Online) 

59 
 

Original Paper 

Effect of Nano-Silica on The Thermo-Physical Properties of the 

Thermal Eutectic (Na0.6K0.4)NO3 System 

H. I. ElSaeedy
1
, A. A. S. Al Ahmari

2
, K. F. Abd El-Rahman

3*
 & S. Taha

4
 

1
 Department of Physics, Faculty of Science for Girls, King Khalid University, P. O. Box 9004, Abha, 

Saudi Arabia 

2
 Department of Physics, College of Arts and Sciences, King Khalid University, P. O. Box 900, 

Mahayel Asir, Saudi Arabia 

3
 Department of Physics, Faculty of Education, Ain Shams University, Cairo, Egypt 

4
 Department of Physics, Faculty of Science, Fayoum University, Fayoum, Egypt 

*
 K. F. Abd El-Rahman, elrahman100@gmail.com 

 

Received: March 28, 2020        Accepted: April 9, 2020        Online Published: May 26, 2020 

doi:10.22158/ees.v3n1p59             URL: http://dx.doi.org/10.22158/ees.v3n1p59 

 

Abstract 

Here, we investigate the effect of adding nano-silica particles on the thermo-physical properties of the 

(Na0.6K0.4)NO3 based thermal energy storage systems. Five different systems tagged as M00, M01, M02, 

M03 and M04, with different nano-silica percentage of 0, 1, 2, 3, and 4 wt%, respectively, were prepared. 

Various experimental techniques were employed to study the thermo-physical properties of the systems 

during (solid-solid) phase P1, (solid-liquid) phase P2 and (liquid-solid) phase P3, and to clarify the 

effect of nano-silica on the thermal energy storage efficiency during both charging and discharging 

processes. According to the Differential Scanning Calorimeter (DSC) thermal analysis, it was found 

that the system M02 whose nano-silica addition rate of 2 wt%, has the most favorable thermal 

characteristics (i.e., highest specific heat and lowest enthalpy change). Moreover, the addition of 2 

wt% represents the optimum distribution of nano-silica inside the principal base system M00. This leads 

to an improvement in the porosity of the system due to the degree of homogeneity caused by the 

thermophoresis effect distribution, the high surface area of the nano-silica with the activity of the M00 

matrix alongside the degree of the alkalinity of nano-silica. Besides, the electric conductivity 

measurements showed that the 2wt% percentage is the optimum one for thermal energy storage 

systems.  

Keywords 

phase change material, thermal storage, nano silica, calorimetry 



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1. Introduction 

Thermal energy storage systems can be classified into sensible heat storage, latent heat storage and 

thermo-chemical heat storage. Latent heat storage systems use the Phase Change Materials (PCMs) as 

thermal energy storage media, where the thermal energy is stored or released during the material phase 

change transition processes. Phase Change Materials (PCM) have been widely used for the thermal 

storage systems due to their capability of storing and releasing large amounts of energy within a small 

PCM volume, a moderate temperature variation and prolong the charging and discharging period. 

Additionally, significant attention has been given to using salts as a phase change storage media (using 

encapsulation and otherwise) (Goswami et al., 1990, pp. 257-262; Xu et al., 2015, pp. 286-307; 

Gaosheng et al., 2018, pp. 1771-1786; Hassan et al., 2019, pp. 491-523). Moreover, several mixtures of 

alkali nitrates and nitrites have been used as a heat transfer medium because of its low cost and good 

compatibility with common structural materials (Borul et al., 1954, pp. 233-238). The NaNO3-KNO3 

system is one of the most extensively investigated binary inorganic salt systems (Voskresenskaya et al., 

2017, pp. 431-437; Silverman et al., 1977, pp. 1-26; Kamimoto et al., 1981, pp. 319-331; Kearney et al., 

2003, pp. 170-176; Zhang et al., 2003, pp. 441-446; Berg et al., 2004, pp. 2224-2229; Villada1 et al., 

2014, pp. 622-625; Lin et al., 2018, pp. 685-708). The PCM’s low thermal energy storage efficiency 

remains, however, a big challenge for researchers. The PCM’s thermal performance is positively 

correlated with three different parameters, the thermal conductivity coefficient, area for heat transfer, 

and the heat transfer temperature difference. Accordingly, the thermal performance can be enhanced by; 

enhancing the thermal conductivity, extending the heat transfer area, and improving the uniformity of 

heat transfer processes (Tao et al., 2018, pp. 245-259). The thermal conductivity can be enhanced by 

using additives with high thermal conductivity coefficient. The high thermal conductivity carbon-based, 

metal- fillers, porous materials, and nano-particles are commonly used as additives to enhance the 

thermal conductivity of the PCM (Lin et al., 2018, pp. 2730-2742). Using of the metal-based porous 

material, such as metal foam enhances heat transfer by reducing the cell size leading to the large 

contact surface area. In this case, the scattered air within the pores expands significantly to cause the 

ejection restriction of the phase transformation for the PCM during the actual operation at elevated 

temperatures (Wu et al., 2011, pp. 1371-1380). Using metal fillers led to a reduced discharging time 

and significant weight and cost to the thermal storage systems as well (Farid et al., 2004, pp. 

1597-1615). In addition, corrosion could appear when using salts as PCM (Joel, 2008; Dorete et al., 

2012, pp. 13-25; Grant, 2002, pp. 1-34). Also the addition of graphite to the binary thermal storage 

system leads to enhance the thermal conductivity coefficient and reduced the total latent heat (Xiao et 

al., 2015, pp. 272-284; Berg et al., 2004, pp. 2224-2229; Xiao et al., 2014, pp. 52-58; Zhao et al., 2014, 

pp. 272-277; Lopez et al., 2010, pp. 1586-1593). For nano-enhanced PCM material, the thermal 

conductivity depends not only upon the nano particle’s concentration, the particle size and shape, but 

also on the base PCM material (Chieruzzi et al., 2013, pp. 448-456; Dudda et al., 2013, pp. 37-42; 

Leong et al., 2019, pp. 18-31; Jeyaseelan et al., 2019, pp. 235-242). In contrast to previous studies, 



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which addressed the impact of nano-particle on the thermal performance of PCM thermal storage 

material, the current study is devoted to investigate the effect of nano silica on both the thermal and the 

physical properties of the binary molten salt 0.6NaNO3-0.4KNO3. Phase Change Materials (PCMs) 

based on latent heat energy storage techniques over a nearly isothermal temperature range using 

Paraffin Wax Nano composite Based on Carbon-Coated Aluminum Nano particles have been regarded 

(Chen et al., 2017, pp. 12603-12609). The thermal stability of paraffin wax was improved by the shape 

stabilization with 10 wt% of carbon nano tubes (Fredi et al., 2017, pp. 405-420). They mentioned that 

the modified paraffin wax is a promising strategy to meet the highly efficient thermal management 

system for electric vehicles. 

 

2. Method 

The binary salt was prepared by mixing 60% of NaNO3 with 40% of KNO3 by weight, in its solid form; 

these salts nitrates are ultra-pure from Aldrich Company. The mixture heated up to 350  to achieve a 

complete melting for this mixture; the system was then cooled at room temperature. This system 

represents the eutectic system (Na0.6K0.4)NO3, and denoted in this work as M00 system. The solid binary 

salt was then milled to powder, and the nano-silica was dispersed into four concentrations: 1, 2, 3 and 4 

wt% in the solid binary nitrate (Na0.6K0.4)NO3 system separately to get M0x (x=1, 2, 3, and 4%wt.) 

systems. The binary system and the nano-silica particles were dispersed in 20 ml of distilled water by 

ultrasonic mixing for 2 hours using MXBAOHENG Ultrasonic Homogenizer FS-T Series with nominal 

frequency of 20 kHz. The solutions were stirred by the strong ultrasonic homogeneous instrument for 2 

hours, afterwards, the water solutions were heated at 150  on a hot plate to fully remove the water for 

at least 1 hour (Shin et al., 2011, pp. 1064-1070). 

By grinding the dried composites, samples were obtained, after the operation process for all samples, 

they were immediately used for thermal, electrical, structure and electron macroscopic analysis, to 

identify the effect of the nano-silica on the thermo-physical properties for the (Na0.6K0.4)NO3, which is 

representing the thermal storage media.  

 

3. Result 

3.1 DSC Measurements 

The DSC thermo grams measurements for M00 and M0x (x=1, 2, 3, 4 wt%) systems have been carried 

out during heating and cooling. The DSC measurements were performed by using SHIMADZU 

DSC-60 plus series equipment. Figure 1 shows the thermo-grams for the base matrix (M00) as 

representative example. The figure indicates to the existence of three peaks. The first broad peak 

located at ≈125 Co , is mainly due to the solid-solid phase transition (P1). This phase is related to the 

change in the specific heat (sensible heat storage) and the transition from the displacive type modified 

by orientation switching (Bauer et al., 2010, pp. 272-278; Al Sharhani, 2016; Hatakeyama et al., 1989, 

pp. 327-335). 



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Figure 1. The DSC Thermo-Grams for M00 System 

 

While the second endothermic peak located at ≈234
o
C, is related to the melting point of the M0 system, 

i.e., the phase change from solid-liquid phase (P2). The third exothermic peak at ≈223
o
C represents the 

phase change from liquid-solid phase (P3), i.e., the solidification process. The same three peaks 

appeared with the thermograms measurements of the samples M0x (x=1, 2, 3, 4 %wt.). The variations in 

the thermal parameters, such as the enthalpy, transition point, and peak position have been studied for 

all samples. For example, the specific heat of the sample scan be determined from the relation 

(Hatakeyama et al., 1989, pp. 327-335): 

                                (1) 

Where  is the peak height of the sample,  is the height of the standard material from the zero line 

of the starting of the equipment (DSC),  is the mass of the standard material (Al2O3),  is the 

mass of the sample and  is the specific heat of the standard material. 

Also, the activation energy for all phases (P1, P2 and P3) at any system by using the modified Kissinger 

equation (Rysava, 1987, pp. 1015-1021): 

                      (2) 

Where different heights corresponding to different temperatures for each peak have been obtained. The 

extracted data were used to plot as ln(ΔQ) and1/T according to the equation and hence to get the 

activation energy.  

All the thermal kinetic parameters for the M0 system are shown in Figure2 (a and b) as representative 

example. It can be easily seen that the transition temperature does not nearly change in the all phases 

(P1, P2 and P3) with the increasing the concentration of the nano-silica in the M0x system. These results 

suggest that the nano-silica inside the M0x system having a uniform distribution and a homogeneous 

dispersion. This leads the SiO2 (nano-silica) takes part in the network structure as a network former 

(Chieruzzi et al., 2013, pp. 448-456).  

 



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The variations in entropy (ΔH), the peak height, the transient temperature (ΔT) and the transient time 

(Δt) with the concentration of the nano-silica for all phases (P1, P2 and P3) are mainly related to the 

distribution effect on the interaction potential of Na
+ 

and K
+
 ions around the (NO3)

-
 group in the M0x 

system (Taha et al., 1994, pp. 217-226). For the entropy (ΔH) and the peak height, it is clear from the 

figure that there is a minimum value corresponding to concentration value x≈2% of nano-silica. This 

means that the M0 system at that percentage become more stable than that at any other concentration of 

nano-silica, due to the stability of the thermodynamics function (Thirriwg, 2006, pp. 113-121).  

The minimum value of (ΔH) at this concentration (x≈2% of nano-silica) indicates that the system has a 

higher ordered and mechanical stability than other any concentration. 

0 1 2 3 4 5
0

20

40

60

80

100

120

140

P
e

a
k

 H
ig

h
t

0 1 2 3 4 5
8

10

12

14

16

18

20

22

24

26

P2

P2
T

ra
n

s
ie

n
t 

T
e
m

p
. 

(o
C

)

P1

0 1 2 3 4 5
0

20

40

60

80

100

120

140

T
ra

n
s

ie
n

t 
T

im
e

 (
s

e
c

)

Weight Oercentage

0 1 2 3 4 5

100

120

140

160

180

200

220

240

260

T
ra

n
s
it

io
n

 T
e
m

p
. 

(o
C

)

 

Figure 2. The Thermal Kinetic Parameters (Peak Height, Transient Temperature, Transient 

Time and Transition Temperature) for M0x System with Different Concentration of Nano Silica 

 

This is supported by the variation of the transient temperature (ΔT) and the transient time (Δt), where 

(ΔT) and (Δt) which does not nearly change in the concentration range 1%  x  for each phase 

(P1, P2 and P3). These results are mainly related to the introduction of the incompatible second 

components, like K
+
 ion in the NaNO3 structure or Na

+
 ion in the KNO3. The introduction of ions 

influenced the order kinetics in a significant way which is related to the equilibrium kinetics in the M0 

system (Ping et al., 2009, pp. 27-36). 



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0 1 2 3 4 5
0

2

4

6

8

10

A
c
ti

v
a

ti
o

n
 E

n
e

rg
y

 (
e

V
)

0 1 2 3 4 5
0

5

10

15

20

25

P3

P2

S
p

e
c

if
ic

 H
e
a

t 
(J

/g
.o

C
)

P1

0 1 2 3 4 5
0

40

80

120

160

H
e
a
t 

E
n

th
a
lp

y

Weight Percentage

0 2 4
0

5

10

15

20

25

A
m

o
u

n
t 

o
f 

H
e
a
t 

(J
)

 

Figure 3. The Thermal Kinetic Parameters (Activation Energy, Specific Heat, Heat Enthalpy and 

Amount of Heat) for M0x System with Different Concentration of Nano Silica 

 

The changes in the activation energy (Eg), the specific heat (Cp) and the latent heat (ΔQ) for the 

different phases (P1, P2 and P3) in the M01 systems are mainly related to the thermal activation process 

in this system. These parameters are affected by the concentration percentage of nano-silica and the 

variation in the strength of Na
+
 and K

+
 ions bonds in the (Na0.6k0.4)NO3 (M0) system. This variation in 

the bonds strength plays an important role in the delocalization of charge carried inside the M0x system. 

The changes in the latent heat (ΔQ) and (Cp) for the phase (P1) are very small, because this phase has a 

rather low heat for the transformation process. However, in the two phases P2 and P3, the changes in 

ΔQ and Cp are greater than the phase P1, which is mainly related to the large volume variations during 

the transformation process. 

The value of the activation energy in phase (P3) is higher than the values obtained for the phase P2 and 

phase P1. This is because the ordered parameters in the phase P3 increase with decreasing the 

temperature of transformation (liquid-solid). However, the ordered parameters decrease with increasing 

the temperature in phase (P2) (solid-liquid) phase, i.e., higher disorder, so that the Eg in phase P3 is 

higher than P2 and P1 phases (Papon et al., 2002). 

 

 

 



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The effect of the nano-silica on the thermal properties for the thermal storage M0 system could be 

potentially due to the large distribution of the nano-silica per unit volume. This is because the 

nano-particl has a small diameter and could be more effective dispersed into the salt (Na0.6K0.4)NO3 and 

give better pores system and thermal characteristic, that is mainly related to the high specific surface 

energy in the M0 system associated with the high surface area of the nano- silica inside the M0 matrix 

(Chieruzzi et al., 2013, pp. 448-456). 

The obtained results confirmed that the rates of changes in the kinetic and thermo-physical parameters 

are mainly dependent on the concentration rate of nano-silica inside this system. The results confirmed 

that the optimum concentration for the thermal storage (Na0.6K0.4)NO3 system is x≈2% of nano-silica. 

3.2 Electrical and Thermal Conductivity Measurements 

One of the most popular of the nano-silica is mainly related to its good resistance of heat and electricity, 

so that it has tendency to agglomerate or cluster due to the dominant intermolecular Van der-Waals 

interaction between the particles. So that the electrical and thermal conductivity of the mixed samples 

with nano-silica particles mainly depend on the characterization of these nanoparticles and the uniform 

of dispersion of the nanoparticles in the matrix [Na0.6K0.4]NO3 (Ning et al., 2009, pp. 518-523). 

Figure 3 shows the variation of the electrical conductivity for the system M01 as a function of the 

temperature. The inset shows the variation of electrical conductivity with the concentration of nano 

silica at certain temperature (≈125
o
C). From this figure, we can see that the values of electrical 

conductivity increase with increase the nano-silica up to x=2%, and then it decreases with the increase 

of the nano-silica. This modification enhanced the electrical conduction mechanism inside the M01 

system (Chieruzzi et al., 2013, pp. 448-456). The increase in the electrical conductivity up to x=2%, 

may be related the mono dispersion of spherical nano-silica in the matrix M0 system. Besides that, the 

increase in the rate of the reorientation process inside the M0 matrix for the K
+
 and Na

+
 ion surrounding 

the NO3
-
 ion group by the effect of temperature on the M01 matrix. However, the decreasing in the 

electrical conductivity with the increasing of nano-silica after (x=2% wt), could be attributed to the 

reduction in the bond of mobility ions released by the distribution of nano-silica inside the M0 matrix. It 

could be also attributed to the effect of the alkalinity degree of nano-silica ratio for the M01 system. 

Also, the nano-silica has a lower relative density than M0 system, therefore for given mass replacement 

from nano-silica into the M0 system consequently leads to a lower pore volume, due to the size of the 

nano-silica particles. Beside that the nano-silica is not a good conductor for the electrical properties 

(Kumar, 2008, pp. 684-687). 

 



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110 115 120 125 130

0.00

0.02

0.04

0.06

0.08

0.10

1 2 3 4

0.00

0.01

0.02

0.03

0.04

0.05

c
o

n
d

u
c

ti
v

it
y

, 
(

.c
m

-1
)

nano silica %

 

 

0.2 %

0.4 %

0.1 %

E
le

c
tr

ic
a

l 
C

o
n

d
u

c
ti
v
it
y
 (


.c
m

-1
)

Temperature (
o
C)

0.3 %

 

Figure 4. The Variation of Electrical Conductivity with Temperature for Different Nano-Silica 

Concentrations in the Solid-Solid Phase 

 

The activation energies of the M0x crystal systems are calculated according to the well-known 

exponential relation (Rysava, 1987, pp. 1015-1021). 

The dependence of activation energy on the concentration of nano-silica is shown in Figure 4. It is clear 

from the figure that there is a minimum value at x=2% nano silica. The variation of activation energy is 

mainly related to the lattice thermal vibration and the formation of polarizabillity arising from the 

cationic Na
+
 and K

+
 ions around the (NO3)

-
 group (Taha, 1989, pp. 341-354).  

This process is mainly affected by the temperature of the system and the rate of concentration of 

nano-silica inside the M0 matrix system. The modification of activation energy (Eg) by the presence of 

nano silica can be attributed to the appearance of different polaronic and defect levels in the structure of 

the M01 system (Papon et al., 2002). 



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1 2 3 4

0.30

0.32

0.34

0.36

E
g
, 
(e

V
)

concentration

 

Figure 5. The Variation of Activation Energy Eg with Different Concentrations of Nano Silica in 

the Solid-Solid Phase 

 

The thermal conductivity (k) for theM0x systems was calculated from the analysis of the DSC 

thermo-gram curve for the phase P1 and during heating by using the following relation: 

                       (3) 

Where q is the heat flow, L is the thickness, A is the area, (Th-Tl) is the difference between high and 

low temperature.  

The variation of the thermal conductivity k of the M0 and M01 systems with the concentration of the 

nano-silica is shown in Figure 5. It is clear from the figure that thermal the conductivity decreases with 

the increasing of concentration of the nano-silica and then it reaches a nearly constant value starting at 

x=2% of nano silica. 



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0 1 2 3 4
0

2

4

6

8

10

12

T
h

e
rm

a
l 
c

o
n

d
u

c
ti

v
it

y
, 
k

 (
W

/c
m

.o
C

)

Concentration

 

Figure 6. The Variation of Thermal Conductivity with Different Concentration of Nano-Silica for 

M01 System in the Solid-Solid Phase 

 

This indicates that the presence of nano silica increases the thermal resistance to the thermal 

fluctuations process (Kumar, 2008, pp. 684-687).  

It can be said also that the stability of thermal conductivity starting at x=2%. This is because the 

decreasing for the thermal fluctuations leads to decrease in the free energy, i.e., the system become 

thermally stable (Kumar, 2008, pp. 684-687). 

 

4. Conclusion 

The additive nano-silica to the eutectic (Na0.6K0.4)NO3 system bring a new and good additional physical 

properties to the thermal storage materials, which reasonable to improve the thermal charge and 

discharge heat energy during the phase changes transformation process. It has been found that the 

optimum conditions for this additive are satisfied at 2% wt for nano-silica Nano-silicais characterizes 

by high mechanically stability and act as insulator for heat and electricity. The variation in the 

thermo-physical properties (Cp, ∆H, ∆Q, and peak height) for each phase (P1, P2 and P3) are mainly 

related to the effect of the nano-silica. It causes also an enhancement in the thermal properties, which is 

the aim from this work. The thermal analysis measurements indicated that nano-silica has no effect on 

the transition temperature (Tr), which is mainly related to the high stability of solid-solid phase (P1), 

due to the kinetic hindrance of the disphasic region (Na K) around the (NO3) group in the M0 system. 

The effect of the nano-silica on the thermal storage media (M0) matrix is mainly related to the reflected 

modification of the electronic structure of this material. This considerable variation can be attributed to 

the appearance of different polaronic and defect levels. It has been found that the system M02 whose 



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nano-silica addition rate of 2 wt%, has the most favorable thermal characteristics. This leads to an 

improvement in the porosity of the system due to the degree of homogeneity caused by the 

thermophoresis effect distribution. The distribution of the nano-silica in the M0 system (thermophoresis 

effect) makes changes in the porous ratio, due to the high specific area of the nano-silica. This change 

in the porous system leading to effect on the performance of heating and cooling cycle, beside the rate 

of melting and freezing for this system. 

 

References 

Al Sharhani, M. A. S. (2016). Temperature Dependence of Physical Properties of Some Thermal 

Storage Materials in Solid Phase (M.Sc thesis). King Khalied Univeristy, physics department, 

Faculty of science. 

Bauer, T., Laing D., & Tamme, R. (2010). Overview of PCMs for concentrated solar power in the 

temperature range 200 to 350
o
C. Advances in science and Technology, 74, 272-278. 

https://doi.org/10.4028/www.scientific.net/AST.74.272 

Berg, R. W., & Kerridge, D. H. (2004). The NaNO3/KNO3 system: The position of the solidus and 

subsolidus. Dalton Transactions, 15, 2224-2229. https://doi.org/10.1039/b403260h 

Borul, S. I., & Bergman, A. G. (1954). Izv. SektoraFiz. Khim. Analiza Inst. Akad. Nauk. SSSR, 25, 

233-238. 

Chen, Y. M., Luo, W., Wang, J., & Huang, J. (2017). Enhanced Thermal Conductivity and Durability 

of a Paraffin Wax Nanocomposite Based on Carbon-Coated Aluminum Nanoparticles. J. Phys. 

Chem. C, 121(23), 12603-12609. https://doi.org/10.1021/acs.jpcc.7b02651 

Chieruzzi, M., Cerritelli, G. F., Miliozzi, A., & Kenny, J. M. (2013). Effect of nanoparticles on heat 

capacity of nanofluids based on molten salts as PCM for thermal energy storage. Nanoscale 

Research Letters, 8, 448-456. https://doi.org/10.1186/1556-276X-8-448 

Dorete, L., Wolf-Dieter, S., Rainer, T., Antje, W., & Stefan, Z. (2012). Advances in thermal 

energystorage development at the german aerospace center (DLR). Energy Storage Science and 

Technology, 1(1), 13-25.  

Dudda, B., & Shin, D. (20133). Effect of nanoparticles dispersion on specific heat capacity of binary 

nitrate salt ecutectic for cocentrated solar power applications. International Journal of Thermal 

Science, 69, 37-42. https://doi.org/10.1016/j.ijthermalsci.2013.02.003 

Farid, M. M., Khudhair, A. M., Razack, S. A. K., & Al-Hallaj, S. (2004). A review on phase change 

energy storage: Materials and applications. Energy Conversion and Management, 45, 1597-1615. 

https://doi.org/10.1016/j.enconman.2003.09.015 

Fredi, G., Dorigato, A., Fambri, L., & Pegoretti, A. (2017). Wax Confinement with Carbon Nanotubes 

for Phase Changing Epoxy Blends. Polymers, 9(9), 405-420. 

https://doi.org/10.3390/polym9090405 

 

https://doi.org/10.4028/www.scientific.net/AST.74.272
https://doi.org/10.1039/b403260h
https://doi.org/10.1021/acs.jpcc.7b02651
https://doi.org/10.1186/1556-276X-8-448
https://doi.org/10.1016/j.ijthermalsci.2013.02.003
https://doi.org/10.1016/j.enconman.2003.09.015
https://doi.org/10.3390/polym9090405


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Gaosheng, W., Gang, W., Chao, X., Xing, J., Lijing, X., Xiaoze, D., & Yongping, Y. (2018). Selection 

principles and thermophysical properties of high temperature phase change materials for thermal 

energy storage: A review. Renewable and Sustainable Energy Reviews, 81(2), 1771-1786.  

Goswami, D. Y., Jotshi, C. K., & Olszewski, M. (1990). Analysis of thermal energy storage in 

cylindrical PCM capsules embedded in a metal matrix, 25th Intersociety Energy Conversion 

Engineering Conference. IECEC Reno, NV, USA (August 12-17). 

Grant, D. J. W. (2002). Theory and origin of polymorphism. In H. G. Brittain, & D. Marcel (Eds., 2nd 

ed., pp. 1-34), Polymorphism in Pharmaceutical solids. New York.  

Hassan, N., Mariah, B., Francisco, J., Bolivar, O., Marllory, I. R., Xinhai, X., … Arunachala, M. K. 

(2019). Recent developments in phase change materials for energy storage applications: A review. 

International Journal of Heat and Mass Transfer, 129, 491-523. 

https://doi.org/10.1016/j.ijheatmasstransfer.2018.09.126 

Hatakeyama, T., & Kanetsuna, H. (1989). Thermal analysis of polymer samples by round robin method: 

part II factors affecting transition. Thermochimica Acta, 138(2), 327-335. 

https://doi.org/10.1016/0040-6031(89)87269-7 

Jeyaseelan, T. R., Azhagesan, N., & Pethurajan, V. (2019). Thermal characterization of NaNO3/KNO3 

with different concentrations of Al2O3 and TiO2 nanoparticles. Journal of Thermal Analysis and 

Calorimetry, 136, 235-242. https://doi.org/10.1007/s10973-018-7980-6 

Joel, B. (2008). Polymorphism in molecular crystal. UK: Oxford University Press  

Kamimoto, M. (1981). Thermodynamic properties of 50 mole% NaNO3-50% KNO3 (HTS2). 

Thermochimica Acta, 49(2), 319-331. https://doi.org/10.1016/0040-6031(81)80184-0 

Kearney, D., Herrmann, U., Nava, P., Kelly, B., Mahoney, R., Pacheco, J., … Price, H. (2003). 

Assessment of molten salt heat transfer fluid in a parabolic trough solar field. J. Sol. Energy Eng., 

125(2), 170-176. https://doi.org/10.1115/1.1565087 

Kumar, G. G., Senthilarasu, S., Lee. D. N., Kim, A. R., Kim, P., Nahm, K. S., … Elizabeth, R. N., 

(2008). Synthesis and characterization of aligned SiO2 nanosphere arrays: Spray method. 

Synthetic Metals, 158(17-18), 684-687. https://doi.org/10.1016/j.synthmet.2008.04.031 

Leong, K. Y., Abdul Rahman, M. R., & Gurunathan, B. A. (2019). Nano-enhanced phase change 

materials: A review of thermo-physical properties, applications and challenges. Journal of Energy 

Storage, 21, 18-31. https://doi.org/10.1016/j.est.2018.11.008 

Lin, Y., Alva, G., & Fang, G. (2018). Review on thermal performances and applications of thermal 

energy storage systems with inorganic phase change materials. Energy, 165, 685-708. 

https://doi.org/10.1016/j.energy.2018.09.128 

Lin, Y., Jia, Y., Alva, G., & Fang, G. (2018). Review on thermal conductivity enhancement, thermal 

properties and applications of phase change materials in thermal energy storage. Renewable and 

Sustainable Energy Reviews, 82, 2730-2742. https://doi.org/10.1016/j.rser.2017.10.002 

 

https://doi.org/10.1016/j.ijheatmasstransfer.2018.09.126
https://doi.org/10.1016/0040-6031%2889%2987269-7
https://doi.org/10.1007/s10973-018-7980-6
https://doi.org/10.1016/0040-6031%2881%2980184-0
https://doi.org/10.1115/1.1565087
http://dx.doi.org/10.1016/j.synthmet.2008.04.031
https://doi.org/10.1016/j.synthmet.2008.04.031
https://doi.org/10.1016/j.est.2018.11.008
https://doi.org/10.1016/j.energy.2018.09.128
https://doi.org/10.1016/j.rser.2017.10.002


www.scholink.org/ojs/index.php/ees                      Energy and Earth Science                     Vol. 3, No. 1, 2020 

71 
Published by SCHOLINK INC. 

Lopez, J., Acem, Z., & Del Barrio, E. P. (2010). KNO3/NaNO3—Graphite materials for thermal energy 

storage at high temperature: Part II. Phase transition properties. Applied Thermal engineering, 

30(13), 1586-1593. https://doi.org/10.1016/j.applthermaleng.2010.03.014 

Ning, N., Calro, F., Van Duin, A. C. T., & Wales, D. J. (2009). Spontaneous self-assembly of silica 

nanogases in inorganic framework materials. J. phys. Chem. C., 113(2), 518-523. 

https://doi.org/10.1021/jp804528z 

Papon, P., Lcblond, J., & Meijer, P. E. H. (2002). The physics of phase Transitions. Springer verlag 

berlin Heidelberg Germany. https://doi.org/10.1007/978-3-662-04989-1 

Ping, W., Harrowell P., Byrne N., & Angell C. A. (2009). Composition dependence of the solid state 

transitions in NaNO3/KNO3 mixtures. Thermochimica Acta., 486(1), 27-36. 

https://doi.org/10.1016/j.tca.2008.12.017 

Rysava, N., Spasov, T., & Tich, L. (1987). Isothermal DSC method for evaluation of the kinetics of 

crystallization in the Ge-Sb-S glassy systems. Journal of Thermal Analysis, 32, 1015-1021. 

https://doi.org/10.1007/BF01905157 

Shin, D., & Banerjec, D. (2011). Enhancement of specific heat capacity of high-temperature 

silica-nanofluids synthesized in alkali chloride salt ecutectics for solar thermal energy storage 

applications, Int. J. Heat Mass. Tran., 54(5), 1064-1070. 

https://doi.org/10.1016/j.ijheatmasstransfer.2010.11.017 

Silverman, M. D., & Engel, J. R. (1977). Survey of Technology for Storage of Thermal Energy in Heat 

Transfer Salt (pp. 1-26). US Dep. Commer, ORNL/TM-5682. 

Taha, S., & Tosson, M. (1994). The effect of temperature and phase state on the infrared spectrum of 

Ba(NO3)2. Thermochemica Acta, 236, 217-226. https://doi.org/10.1016/0040-6031(94)80270-X 

Taha, S., Abou-Sehly, A. M., Attia, G., & El-Sharkawy, A. A. (1991). Measurements of 

thermo-physical properties of KNO3. Thermochemica Acta, 181, 167-171. 

https://doi.org/10.1016/0040-6031(91)80421-E 

Taha, S., EL-Kabbany, F., & Tosson, M. (1989). Detailed IR study of the phase transition in the system 

AgNO3-Fe(NO3)3. Annalen der physic, 501(5), 341-354. 

https://doi.org/10.1002/andp.19895010504 

Tao, Y. B., & He, Y. L. (2018). A review of phase change material and performance enhancement 

method for latent heat storage system. Renewable and Sustainable Energy Reviews, 93, 245-259. 

https://doi.org/10.1016/j.rser.2018.05.028 

Thirriwg, W. (2006). Paths of Discovery. Pontifical Academy of sciences, Vatican City. Acta, 18, 

113-121. 

Villada1, C., Bolívar, F., Jaramillo, F., Castaño1, J. G., & Echeverría, F. (2014). Thermal evaluation of 

molten salts for solar thermal energy storage. Renewable Energies and Power Quality journal, 12, 

622-625. https://doi.org/10.24084/repqj12.431 

 

https://doi.org/10.1016/j.applthermaleng.2010.03.014
https://doi.org/10.1021/jp804528z
https://doi.org/10.1007/978-3-662-04989-1
https://doi.org/10.1016/j.tca.2008.12.017
https://doi.org/10.1007/BF01905157
https://doi.org/10.1016/j.ijheatmasstransfer.2010.11.017
https://doi.org/10.1016/0040-6031%2894%2980270-X
https://doi.org/10.1016/0040-6031%2891%2980421-E
https://doi.org/10.1002/andp.19895010504
https://doi.org/10.1016/j.rser.2018.05.028
https://doi.org/10.24084/repqj12.431


www.scholink.org/ojs/index.php/ees                      Energy and Earth Science                     Vol. 3, No. 1, 2020 

72 
Published by SCHOLINK INC. 

Voskresenskaya, N. K. (1970). Handbook of Solid-Liquid Equilibria in Systems of Anhydrous 

Inorganic Salts. In Jerusalem (pp. 431-437). Kete Press. 

Wu, Z. G., & Zhao, C. Y. (2011). Experimental investigations of porous materials in high temperature 

thermal energy storage systems. Solar Energy, 85(7), 1371-1380. 

https://doi.org/10.1016/j.solener.2011.03.021 

Xiao, J., Huang, J., Zhu, P., Wang, C. H., & Li, X. (2014). Preparation, characterization and thermal 

properties of binary nitrate salts/expanded graphite as a composite phase change material. 

Thermochimica Acta, 587, 52-58. https://doi.org/10.1016/j.tca.2014.04.021 

Xiao, X., Zhang, P., & Li, M. (2015). Experimental and numerical study of heat transfer performance 

of nitrate/expanded graphite composite PCM for solar energy storage. Energy Conversion and 

Management, 105, 272-284. https://doi.org/10.1016/j.enconman.2015.07.074 

Xu, B., Li, P. W., & Cholik, C. (2015). Application of phase change materials for thermal energy 

storage in concentrated solar thermal power plants: A review to recent developments. Applied 

Energy, 160, 286-307. https://doi.org/10.1016/j.apenergy.2015.09.016 

Zhang, X., Tian, J., Xu, K., & Gao, Y. (2003). Thermodynamic Evaluation of Phase Equilibria in 

NaNO3-KNO3 System. Journal of Phase Equilibria, 24(5), 441-446. 

https://doi.org/10.1361/105497103770330091 

Zhao, Y. J., Wang, R. Z., Wang, L. W., & Yu, N. (2014). Development of highly conductive 

KNO3/NaNO3 composite for TES (thermal energy storage). Energy, 70, 272-277. 

https://doi.org/10.1016/j.energy.2014.03.127 

 

https://doi.org/10.1016/j.solener.2011.03.021
https://doi.org/10.1016/j.tca.2014.04.021
https://doi.org/10.1016/j.enconman.2015.07.074
https://doi.org/10.1016/j.apenergy.2015.09.016
https://doi.org/10.1361/105497103770330091
https://doi.org/10.1016/j.energy.2014.03.127

