Energy Storage Science and Technology ›› 2020, Vol. 9 ›› Issue (6): 1775-1783.doi: 10.19799/j.cnki.2095-4239.2020-0133

• Energy Storage Materials and Devices • Previous Articles     Next Articles

Stability of the thermal performances of molten salt-based nanofluid

Zhao LI1(), Baorang LI2(), Liu CUI1, Xiaoze DU3()   

  1. 1.Key Laboratory of Power Station Energy Transfer Conversion and System (North China Electric Power University), Ministry of Education
    2.School of Energy Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
    3.School of Energy and Power Engineering, Lanzhou University of Technology, Lanzhou 730050, Gansu, China
  • Received:2019-04-02 Revised:2020-04-23 Online:2020-11-05 Published:2020-10-28
  • Contact: Baorang LI,Xiaoze DU E-mail:zhaoli@ncepu.edu.cn;libr@ ncepu.edu.cn;duxz@ ncepu.edu.cn

Abstract:

The performance of a molten salt-based nanofluid can be significantly enhanced, but its thermal stability caused by the nanoparticle cluster remains a main defect for practical application. This study prepared a solar salt-based SiO2 nanofluid with 1% mass fraction via a two-step method. To study the stability of the molten salt-based nanofluid, a long-term high-temperature (LTHT) condition is set, and the reduction of the specific heat capacity (SHC) enhancement and micro-morphology is adopted to make a comprehensive stability assessment. The experimental results show an SHC enhancement; however, the SHC is significantly decreased, and the SiO2 nanoparticle amount in the samples is reduced after the LTHT condition. In other words, the sample prepared by the two-step method is a poor-stability nanofluid. The investigation on the method improving the stability of the molten salt-based nanofluid is based on the preparation methods and the nanoparticle material selection. The high-temperature melting method is used to prepare the same nanofluid. The results show that the SHC enhancement is similar to that of the sample prepared by the two-step method; however, the SHC enhancement after the LTHT condition is slightly reduced with the nanoparticle amount increase. This result implies that the stability of the molten salt-based nanofluid can be improved to some extent using the high-temperature melting method. Hybrid nanofluids with total mass fraction of 1% (i.e., Al2O3-SiO2, TiO2-SiO2, and CuO-SiO2 nanofluids) are also investigated herein based on the high-temperature melting method. The results show that the attenuation rate of the SHC enhancement reduces to 6.1% after 100 h under the LTHT condition for the Al2O3-SiO2 hybrid nanofluid, indicating that the stability is further improved. On the contrary, the stability of the TiO2-SiO2 and CuO-SiO2 hybrid nanofluids is worse because no SHC enhancement occurs after the LTHT condition. The results are greatly significant for improving the stability of the molten salt-based nanofluid and enhancing its practicality.

Key words: molten salt, nanofluid, stability, specific heat capacity, preparation method, hybrid nanoparticle

CLC Number: