돌출-피라미드 표면의 열성능

Abstract

The recent miniaturization of electronic devices has increased the power densities of such systems. The increase in heat density might deteriorate the life and performance of electronic equipments if they are not managed properly. Power transmitters used for sonar systems are typical examples seriously influenced by the increasing heat density. Power transmitters for sonar systems are thermally-managed under forced convection conditions. Harsh spacial constraints are required for power transmitters. Hence, low-profile and high performance extended surfaces are needed to thermally control power transmitters. In this study, a novel protrusion-pyramid (PP) surface composing of protrusions and pyramids is proposed. The 3-D CFD thermal model and the test rig have been developed to explore the thermal performances of the PP surface. The 3-D CFD thermal modeling has been validated by comparing the measurement results and the numerical results. The comparison shows the discrepancy between the experimental result and the numerical result is within 10%. Eight case studies are conducted using various configurations of pyramids, dimples, protrusions, and cylindrical pins to explore the feasibility of the PP surface. The investigation has found that the PP surface may have better thermal performance compared with conventional surfaces. The validated thermal model has been used to investigate parametric influences on the performance of the PP surface under various parametric conditions including height, depth, and diameter of either protrusions or pyramids. The study reveals that the increase of the height and the depth of the PP could enhance the thermal performance although it should induce the higher pressure loss. The study also shows that the effect of the diameter on the thermal performance of the PP surface is moderate. The investigation has found that the performance factor considering thermal and hydraulic performances is higher at the region of Re ranging from 500-to 1500 than other Re regions. The highest value of the performance factor is determined to be1.28 at Re of 1800 and a diameter of 3.5mm.