Passive Natural Convection Augmentation from Horizontal Cylinder Using a Novel Shroud-Chimney Configuration

A novel method to passively improve natural convection from a horizontal isothermal cylinder is proposed and numerically analyzed. The improvement is achieved by using a cylinder configured with semicircular shrouds and expended chimney. The numerical simulations indicate that adding the shroud-chimney configuration (SCC) to the cylinder promotes the convection heat transfer (up to 12%). New parameters describing the physics of the convection activities are introduced. The parameters are demonstrated to correlate well with the enhancement in the heat transfer coefficient when the SCC is used. Three correlations are proposed to optimize the design of SCC, and to evaluate the corresponding enhancement in the heat transfer. The proposed method is inexpensive, simple, and compact compared with other available configurations (e.g., using extended surfaces or confining long vertical walls). This makes the technology more practical for industrial applications.