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Anode influence on the electroplating system was investigated when natural convection heat transfer in a packed bed is simulated by mass transfer based on the analogy. The cathode to anode area ratio (Ac/Aa) was varied from 1 to 50. For three different anode positions of top and bottom of test section and corner of acryl tank, the distance of anode...
Citations
The influence on heat transfer between two spheres in a packed bed was investigated with horizontal and vertical pitches using the copper sulfate‑sulfuric acid (CuSO4-H2SO4) electroplating system. The natural convective heat transfer of two spheres in an open pool was also analyzed for a comparative purpose. Both the bed diameter-to-sphere diameter ratios (D/d) and the bed height-to-sphere diameter ratios (H/d) were fixed at 10. The sphere diameter was 0.0158 m, which is consistent with Grd of 1.66 × 10⁵. All the possible geometric arrangements of the two spheres in a rhombohedral packing were simulated. In an open pool, the natural convection of the two heating spheres was influenced by initial velocity, preheating and stagnant flow effects. The heat transfers of the lower and upper spheres were either weakened due to the stagnant flow and preheating effects or improved due to the initial velocity effect. In a packed bed, similar tendency but weaker influences were observed due to the friction loss and separation of the plume by adjacent spheres. The visualization of local heat transfers of spheres performed by copper plating patterns, showed the breakup of thermal boundary layer of spheres in packed bed.
We measured the heat load to a reactor vessel with and without the in-vessel debris bed under an IVR-ERVC condition. Mass transfer methodology was adopted based on heat and mass transfer analogy to achieve high Ra′H of order ∼10¹⁵ with compact test rigs. We postulated the in-vessel debris bed has a flat top and particulate debris was simulated as an identical diameter spheres. We conducted experiments varying the height of the debris bed and the results showed that Nusselt numbers decreased in both uppermost and curved surfaces with the increasing bed height. Once the debris bed is formed, it acts as an obstacle to the natural convective flow, which reduces the buoyancy. The reduction of driving force results in the impaired heat transfer in both upward and downward heat transfers.
Influences of sphere diameter and bed height on the natural convective heat transfer of packed bed was investigated. Mass transfer experiments using the copper electroplating system were performed based on analogy between heat and mass transfers, which enabled the e.asy realization of all self-heating spheres. The sphere diameter (d) was varied from 0.004 to 0.010 m, which corresponds to Rad of 5.43 × 10⁶ to 8.48 × 10⁷. The bed height (H) was varied from H/d = 5 to 40. The Particle Image Velocimetry (PIV) measured very slow natural convection velocity of about 10⁻² m/s in the packed bed. Turbulent-like flows due to wake and vortex were generated by geometry of packed bed when d and H were large enough. It also revealed random characteristics in the velocity profiles formed by complex flow passages. The average heat transfer on packed bed decreased as the H increased, but the trend diminished with decreasing d.
