Numerical Simulation of Nanofluid Suspensions in a Geothermal Heat Exchanger

Energies

卷:11

Wei-Tao Wu¹  Zhi-Hua Chen²  Hongbin Yan³  Xiao-Hui Sun⁴  Mehrdad Massoudi⁵ 

[1] Technology, Nanjing 210094, China;

[2] Key Laboratory of Transient Physics, Nanjing University of Science &

[3] School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China;

[4] School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China;

[5] U.S. Department of Energy, National Energy Technology Laboratory (NETL), Pittsburgh, PA 15236-0940, USA;

关键词: nanofluids;    geothermal heat exchanger;    suspension stability;    pulsed flow;    nanoparticle accumulation;   

DOI  :  10.3390/en11040919

来源: DOAJ

【 摘 要 】

It has been shown that using nanofluids as heat carrier fluids enhances the conductive and convective heat transfer of geothermal heat exchangers. In this paper, we study the stability of nanofluids in a geothermal exchanger by numerically simulating nanoparticle sedimentation during a shut-down process. The nanofluid suspension is modeled as a non-linear complex fluid; the nanoparticle migration is modeled by a particle flux model, which includes the effects of Brownian motion, gravity, turbulent eddy diffusivity, etc. The numerical results indicate that when the fluid is static, the nanoparticle accumulation appears to be near the bottom borehole after many hours of sedimentation. The accumulated particles can be removed by the fluid flow at a relatively high velocity. These observations indicate good suspension stability of the nanofluids, ensuring the operational reliability of the heat exchanger. The numerical results also indicate that a pulsed flow and optimized geometry of the bottom borehole can potentially improve the suspension stability of the nanofluids further.

【 授权许可】

Unknown