Thermal Property Measurement of Nanofluid Droplets with Temperature Gradients

Autor: Dong-Wook Oh
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Energies, Vol 13, Iss 1, p 244 (2020)
Druh dokumentu: article
ISSN: 1996-1073
DOI: 10.3390/en13010244
Popis: In this study, the 3ω method was used to determine the thermal conductivity of nanofluids (ethylene glycol containing multi-walled carbon nanotubes (MWCNTs)) with temperature gradients. The thermal modeling of the traditional 3ω method was modified to measure the spatial variation of thermal conductivity within a droplet of nanofluid. A direct current (DC) heater was used to generate a temperature gradient inside a sample fluid. A DC heating power of 14 mW was used to provide a temperature gradient of 5000 K/m inside the sample fluid. The thermal conductivity was monitored at hot- and cold-side 3ω heaters with a spacing of 0.3 mm. Regarding the measurement results for the hot and cold 3ω heaters, when the temperature gradient was applied, the maximum thermal conductivity difference was determined to be 3% of the original value. By assuming that the thermo-diffusion of MWCNTs was entirely responsible for this difference, the Soret coefficient of the MWCNTs in the ethylene glycol was calculated to be −0.749 K−1.
Databáze: Directory of Open Access Journals
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