Ternary nitric acid nano-molten salt heat transfer and storage medium, preparation method and application thereof

Abstract

Belonging to the technical field of heat storage and transfer, the invention provides a ternary nitric acid nano-molten salt heat transfer and storage medium, a preparation method and application thereof. The ternary nitric acid nano-molten salt heat transfer and storage medium contains a ternary nitric acid molten salt system formed by potassium nitrate, sodium nitrate and sodium nitrite. The ternary nitric acid nano-molten salt heat transfer and storage medium is characterized in that it also includes metal oxide nanoparticles and/or non-metal oxide nanoparticles. The nanoparticles are dispersed into the ternary nitric acid molten salt system to undergo compounding so as to form the ternary nitric acid nano-molten salt heat transfer and storage medium. The ternary nitric acid nano-molten salt involved in the invention has a low melting point, an upper limit use temperature up to 600DEG C, good thermal stability, and high heat conductivity, thus being very suitable for the heat storage and transfer system of industrial energy storage and solar-thermal power generation.

Description

technical field [0001] The invention belongs to the technical field of heat storage and transfer, and relates to a heat storage and heat transfer composite medium, in particular to a ternary nitric acid nanometer molten salt heat transfer and heat storage medium and its preparation method and application. Background technique [0002] In industrial energy storage and solar high-temperature heat storage technology, the heat storage and heat transfer media currently used mainly include air, water, heat transfer oil, molten salt, sodium and aluminum and other metals. Molten salt has become a potential heat transfer and heat storage medium in solar thermal power generation technology due to its wide operating temperature range, low vapor pressure, low viscosity, good stability, and low cost. A relatively mature heat transfer and heat storage medium. High-temperature molten salts mainly include nitrates, carbonates, sulfates, fluorides, chlorides, oxides, etc. [0003] Nitric a...

AI Technical Summary

Problems solved by technology

Ternary nitrate system (53% KNO 3 -7%NaNO 3 -40%NaNO 2 ) upper limit operating temperature is low, resulting in low heat engine efficiency and solar energy utilization efficiency of the power generation system, but the low melting point of ternary nitric acid molten salt is beneficial to reduce heat preservation energy consumption, which is very attractive. Adding the fourth component to the salt system, while maintaining a low melting point, increasing its upper limit operating temperature as much as possible is an important development direction for the development of heat transfer and storage media for solar thermal power generation

[0005] However, the addition of the fourth component in actual work often makes the upper limit working temperature of the whole system higher than that of the ordinary ternary nitrate system, and at the same time increases the lower limit working temperature, resulting in increased maintenance costs

Chinese patent application 00111406.9 discloses a LiNO 3 -KNO 3 -NaNO 3 -NaNO 2 system, its working temperature ranges from 250°C to 550°C. The upper limit working temperature of this system is higher than that of the ternary nitrate system, reaching 550°C, but the lower limit working temperature is also increased, resulting in increased maintenance costs when clouds are covered, and LiNO 3 The addition of it increases its corrosiveness and costs

[0006] U.S. Patent US007588694B1 discloses a LiNO 3 -KNO 3 -NaNO 3 -Ca (NO 3 ) 2 system, its melting point is lower than 100°C, and the upper limit use temperature is higher than 500°C, but LiNO 3 The addition of the molten salt increases the corrosion and cost of the molten salt system, and the thermal stability of calcium nitrate is poor, and it is easy to thermally decompose at high temperature to form calcium oxide and release gas

[0007] At present, there is no ternary nitrate system on the market that contains the fourth component and can ensure that the upper limit working temperature of the whole system is higher than that of the common ternary nitrate system, while also ensuring a lower lower limit working temperature

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