19 research outputs found
ํ์ค์ ์ฌ๋ฆฌํ์ฃผ์ ๋นํ์ ๊ดํ ์ฐ๊ตฌ : ใ๋ ผ๋ฆฌ์ฐ๊ตฌใ๋ฅผ ์ค์ฌ์ผ๋ก
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ผ๋ฌธ(์์ฌ)--์์ธ๋ํ๊ต ๋ํ์ :์ฒ ํ๊ณผ ์์์ฒ ํ์ ๊ณต,2003.Maste
ํจํ ๋ ์ด์ ์กฐ์ฌ๋ฅผ ์ด์ฉํ ์๋ฃจ๋ฏธ๋, ์ฐํํฐํ๋ ๋๋ ธ์ ์ฒด์ ์ด์ ๋๋ ๋ฐ ๋ถ์ ์์ ์ฑ ๊ทน๋ํ
MasterNanofluid has been considered as working fluid of future because of high thermal properties such as thermal conductivity, thermal diffusivity and heat transfer coefficient. Nanofluid manufactured by adding various nanoparticles such as metallic and nonmetallic nanoparticles to various base fluids has high surface area. So it has tendency to agglomerate and become lumpy. In this study, femtosecond laser irradiation technique is used to enhance thermal conductivity and stability by controlling cluster of suspension and modifying size of nanoparticles. Alumina (Al2O3) and titanium oxide (TiO2) nanoparticles with different mean diameters are used. The thermal conductivity is measured by 3 omega method widely used in measuring the thermal conductivity of thin film and liquid with small volume. And the commercial device which is Zetasizser nano ZS90 (Malvern instrument Inc., London, UK) is used to measure zeta-potential and Hydrodynamic diameter. The experimental result shows substantially enhancement of thermal conductivity and stability when laser is irradiated to nanofluid. The value of thermal conductivity increased as size of particles decreased and zeta-potential increased until the optimal condition by laser fluences and number of pulses. And the long-term stability still stayed in range of good stable condition for 30 days. And the XPS analysis was conducted to analyze the effect of laser irradiation on TiO2 nanofluid