This book presents a concise, yet thorough, reference for all heat transfer coefficient correlations and data for all types of cylinders: vertical, horizontal, and inclined. This book covers all natural convection heat transfer laws for vertical and inclined cylinders and is an excellent resource for engineers working in the area of heat transfer engineering.
The influence of perforated cylindrical shrouds on the convective heat transfer to circular cylinders in transverse flow has been studied experimentally. Geometries studied were similar to those used in industrial platinum resistance thermometers. The influence of Reynolds number, ventilation factor (ratio of the open area to the total surface area of shroud), radius ratio (ratio of shroud's inside radius to bare cylinder's radius), and shroud orientation with respect to flow were studied. The experiments showed that perforated shrouds with ventilation factors in the range 0.1 to 0.4 and radius ratios in the range 1.1 to 2.1 could enhance the convective heat transfer to bare cylinders up to 50%. The maximum enhancement occurred for a radius ratio of 1.4 and ventilation factors between 0.2 and 0.3. It was found that shroud orientation influenced the heat transfer, with maximum heat transfer generally occurring when the shroud's holes were centered on either side of the stagnation line. However, the hole orientation effect is of second order compared to the influence of ventilation factor and radius ratio.
The work analyzes the natural convection of a fluid contained in an infinitely long horizontal cylinder at large Prandtl number and unit order Grashof number. The motion is generated by an imposed cosine wall temperature distribution which includes an arbitrary phase angle. This phase angle may be varied to allow for cases ranging from heating-from-the-side to heating-from-below to be investigated. From an asymptotic ordering of the governing energy and vorticity transport equations for large Prandtl number, it is shown that the core region, which contains the fluid surrounded completely by a boundary-layer flow along the cylinder wall, may assume either of two configurations. The choice of the core configuration is shown to depend upon the nature of the streamlines therein. Solutions obtained from linearized forms of the full governing equations agree with the core temperature and velocity fields which were observed experimentally for heating angles sufficiently away from the heating-from-the-side case. Also, the influence of various linearizations is studied. For heating angles near the heating-from-the-side case, a linearized form of the boundary layer equations is developed which allows the solutions to match with the second possible core configuration. The form of the results agrees generally with experimental evidence for heating-from-the-side. (Author).
