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This is a continuation of the Process Intensifier - Optimization with CFD: Part 1 paper. Residence Time DistributionResidence time is computed using Lagrangian analysis particle tracking procedures within the resultant flow state. The tracers are assumed to be neutrally buoyant and convected along by the flow. That is, that the tracers do not influence the flow field. This class of analysis by definition applies to discrete particles and not continuous flow characteristics. Two classes of analysis are done in this fashion, which include extracting particle path information along with a variant on Poincare analysis looking at plane intersections for the determination of residence time. The plane intersections provide this residence time by recording the time, position, velocity, and a number of other variables as a particle intersects a specified plane. The standard interpretation of Poincare planes is that they are applied in mixing tanks to collapse time out of the analysis. Data extracted from plane intersections can be subsequently studied by a variety of statistical means looking at min, max, average, median, and a variety of other statistical measures. Residence time statistics are handled from the injection point to a vertical plane at 35 inches (900 mm) down stream from the impellers. In the case of the radial impellers, the injection point is exactly below the lower impeller. In the case of the HGA the injection point is from that pipe between the criss-cross flow straighteners and the impeller shaft, which is 4 inches (100 mm) upstream of the shaft. For the LTA, the injection point is 35 inches (900 mm) up stream, either at the center of the pipe or split into two feed locations at the respective heights of the axial impellers. 1250 tracer particles were used in each CFD experiment of Table 6. LTR, HGR, and HGA had two injection ports. For these 625 tracer particles were used through each port. LTA had a singular port and so all 1250 tracer particles went through that port. The LTA - Split Injection case had two injection ports at the respective height of the impellers. Figures 19 - 20 show the results graphically. The time scales of Figures 19-20 are logarithmic so that more detail can be given to the shorter times.
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