Numerical study on flow field in inlet plenum of a pebble-bed modular reactor

Flow distribution and pressure drop analysis in the inlet plenum of a pebble-bed modular reactor (PBMR) have been performed numerically. Three-dimensional Navier–Stokes equations have been solved in conjunction with the k– model as a turbulence closure. Non-uniformity in the flow distribution is assessed for the reference case, and parametric studies have been performed for rising channels diameter, Reynolds number, angle between the rising channels, angle between the inlet ports, and aspect ratio of the plenum cross-section. Also, two different shapes of the inlet plenum, namely, rectangular and oval shapes, have been analyzed. The relative flow mal-distribution parameter variation shows that the flow distribution in rising channels for the reference case is strongly non-uniform. As the rising channels diameter is decreased, the flow uniformity as well as the pressure drop is found to increase. The flow distribution in the rising channels is independent of Reynolds number. Increase in the angle between the inlet ports and aspect ratio is found to increase the uniformity in flow distribution.