Heat Transfer Advancement From Horizontal Cylinder Using Passive Shroud−Chimney Configuration: Experimental and Numerical Analysis

In a prior study, the novel shroud−chimney configuration (SCC) (semicircular shrouds and expended chimney) has been numerically demonstrated to passively augment natural convection heat transfer from a horizontal cylinder. However, to implement such a configuration for practical utilizations, the heat flow properties must be experimentally observed and understood. In this work, a controlled experiment is carried out to validate the impact of SCC on heat transfer from a horizontal cylinder subjected to a constant measured heat flux at its inner surface. Circumferential temperature measurements at the cylinder surface, shrouds, and ambient are achieved using thermocouples. The emissivity of the cylinder is measured and utilized to estimate radiation heat loss from the cylinder surface. All presented cases are numerically simulated for validation. The measured and numerically predicted cylinder surface temperatures are within 2% agreement. Moreover, the experimentally and numerically estimated Nusselt numbers agree to within 4%, which verifies the developed correlations for enhanced convection. Finally, a parametric study is presented to show the optimum range of design parameters for the best SCC performance. A newly defined term “effective flow rate” is quantified and correlated to the optimum location of the shroud relative to the cylinder. Several SCC design correlations resulted from the analysis.