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강보선 ( B. S. Kang ),이신표 ( S. P. Lee ) 한국분무공학회 2014 한국액체미립화학회지 Vol.19 No.2
Nanofluids is that metallic or nonmetallic nanometer-sized particles are dispersed in liquid and they can be used in various fields to increase the heat transfer rate. This study conducted experiments to evaluate whether the cooling efficiency of nanofluids is better than that of water in spray cooling. A heated surface was designed and fabricated to make the temperature distribution be linear, which was confirmed by three thermocouple measurements under the heated surface. Spray cooling experiments were conducted using water, 0.2% wt. (weight), and 0.5% wt. Al2O3 nanofluids at the pressure of 0.2 MPa and 0.3 MPa. Based on the results, it is shown that the cooling efficiency of nanofluids is higher than that of water especially in the region of single phase heat transfer. As a result, we can expect that nanofluids can be used as efficient coolants in the cooling of electronic packages where the temperature of the heated surface is not high enough for boiling incipience.
강보선 ( B. S. Kang ),이신표 ( S. P. Lee ) 한국분무공학회 2014 한국액체미립화학회지 Vol.19 No.2
Nanofluids are that metallic or nonmetallic nanometer-sized particles are dispersed in liquid. They can be used in various fields to increase the heat transfer rate because the thermal conductivity of nanofluids can be increased significantly. Nanofluids may be used as a good alternative of coolants in spray cooling. This study conducted experiments to compare the characteristics of sprays between water and nanofluid sprays. The radial distributions of droplet velocities and diameters of water, 0.2% wt.(weight), and 0.5% wt. Al2O3 nanofluids at the pressure of 0.2 and 0.3 MPa were measured by laser doppler instruments. The radial distributions of droplet diameters and velocities at two axial positions with water and 0.2% wt. nanofluid sprays didn’t show much difference. A big difference, however, was observed between 0.5% wt. nanofluid and water sprays. With the increase of the mass of nano-particles, the average droplet diameters were increased and the average droplet velocities were decreased.