Influence of chimney width on the natural convection cooling of a vertical finned plate

We investigated natural convection heat transfer for a finned plate inside a chimney for application in reactor cavity cooling systems (RCCSs). To achieve a large Rayleigh number, the mass transfer rates were measured rather than the heat transfer rates, exploiting the analogy between heat and mass transfer systems. Experiments were carried out with systematically varied fin heights, fin spacings, chimney heights, and chimney widths, and for large Rayleigh numbers (of up to 2.91 × 107). The experimental results were consistent with the existing correlations, which were based on numerical models. Larger heat transfer rates were observed for larger fin heights and smaller fin spacings due to the increased heat transfer area. As the distance between walls and the fin tip increased, the heat transfer rate decreased, until the chimney effect was no longer observed, where the plume circulated within the duct. An empirical correlation was derived using the test results. The study concludes that the optimizations of chimney parameters as well as fin parameters are required for RCCS applications.