Hydrothermal performance of microchannel heat sink: The effect of channel design

Effect of the fluid flow fragmentation on the hydrothermal performance enhancement of a serpentine mini-channel heat sink

Copper aluminium oxide (Cu–Al2O3) films were synthesized on Al substrates through RF magnetron sputtering using the layer stacking technique and annealed under N2 environment at 350, 450, and 550 °C for 6 h. The structural properties of the films were investigated by using X-ray Diffraction while the thermal and optical performance of 4 W white LED attached on Cu–Al2O3 coated substrate and bare Al substrate was tested by using T3Ster system and spectrometer respectively. The thermal resistance was evaluated from the cumulative structural functions through software and exhibited low junction to ambient thermal resistance value, Rth (5.06 K/W) for the sample Cu–Al2O3 annealed at 450 °C among the tested samples. The driving current was also influenced the thermal resistance as observed from the cumulative structure functions. The observed value of substrate to ambient thermal resistance, R
 th s-a
 (3.92 K/W) was low for Cu–Al2O3 sample (annealed at 450 °C) compared to other tested samples at 500 mA. Consequently, noticeable reduction in junction temperature, T
 j
 (4.59 °C) was also noted for the same sample used as thermal interface material. Similarly, Cu–Al2O3 sample (annealed at 450 °C) was also displayed better optical performance in terms of lux and color correlated temperature among the other samples. No significant changes were noticed on the color rendering index and dominant wavelength, λ. Therefore, Cu–Al2O3 can be considered as an alternative thermal interface material for high power LEDs application.

Influence of annealed Cu–Al 2 O 3 thin film on the performance of high power LED: thermal and optical analysis

An extended meniscus of a ferrofluid solution on a silicon surface is subjected to axisymmetric, non-uniform magnetic field resulting in significant forward movement of the thin liquid film. Image analyzing interferometry is used for accurate measurement of the film thickness profile, which in turn, is used to determine the instantaneous slope and the curvature of the moving film. The recorded video, depicting the motion of the film in the Lagrangian frame of reference, is analyzed frame by frame, eliciting accurate information about the velocity and acceleration of the film at any instant of time. The application of the magnetic field has resulted in unique changes of the film profile in terms of significant non-uniform increase in the local film curvature. This was further analyzed by developing a model, taking into account the effect of changes in the magnetic and shape-dependent interfacial force fields.

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Kang Sungbum

Papers

レーザとディジタルモアレ縞画像処理技術(フリンジプロジェクション)を用いた反り測定の可能性とその複数の測定結果についての比較