Experimental research of the thermophysical properties of ternary mixed carbonate molten salts

doi:10.19799/j.cnki.2095-4239.2021.0126

Abstract

Abstract:

The thermophysical properties of three different proportions of high-temperature mixed carbonate molten salts were studied to meet the requirements of high-temperature heat transfer and storage in a supercritical carbon dioxide solar thermal power generation system. The results show that the melting points of the mixed carbonate molten salts are 388.7 ℃, 337.9 ℃, and 391.3 ℃; initial crystallization points occur at 454.9 ℃, 639.7 ℃, and 535.4 ℃; and decomposition temperatures of the first and third salts are 916.2 ℃ and 920.4 ℃, respectively. The initial crystallization point of the second mixed carbonate molten salt is high, and its melting latent heat is small. Therefore, the first and third mixed carbonate molten salts are selected to measure specific heat, thermal conductivity, and viscosity. It is found that the specific heat of the first and third salts initially decrease and then increase with increasing temperature within the experimental range. The average thermal conductivity of the first mixed carbonate molten salt is 1.024 W·(m·K)^-1, which is 2.29 times of that of the third salt; the viscosity of these salts gradually decreases with increasing temperature. The minimum viscosity values of the first and third mixed carbonate molten salts are 6.62 and 5.28 mPa·s, respectively.

Key words: solar energy, carbonate molten salt, thermal energy storage, thermophysical properties

CLC Number:

TK 02

Yuting WU, Subudao MING, Cancan ZHANG, Yuanwei LU. Experimental research of the thermophysical properties of ternary mixed carbonate molten salts[J]. Energy Storage Science and Technology, 2021, 10(4): 1292-1296.

Figures/Tables 7

Table 1

Experiment instruments"

仪器名称	测量范围	精度
WH-71 型电热恒温干燥箱	30～250 ℃	$± 0.1 ? ℃$
Naberthem 马弗炉	30～2000 ℃	$± 1 ? ℃$
STA 409 PC同步热分析仪	30～1800 ℃	$D S C < 1 ?? μ W$
LFA 457 激光导热仪	0.1～2000 W/(m·K)	$± 3 %$
熔盐黏度仪	1.6～16 mPa·s	$< ± 0.2 ?? m P a · s$
WH-71 型电热恒温干燥箱	30～250 ℃	$± 0.1 ?? ℃$

Table 1

Fig. 1

Fig. 2

Table 2

Fig. 3

Fig. 4

Fig. 5

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序号	1号	2号	3号
熔融峰起点/℃	388.7	337.9	391.3
初晶点/℃	454.9	639.7	535.4
熔化潜热J/g	203.9	56.11	160.9
分解温度/℃	916.2	—	920.4

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