Study of free-convective heat exchange of air-coolable finned tube bundles intensified by exhaust shaft

Abstract

The results of experimental studies of free-convective heat transfer of single-, double- and four-row bundles of finned tubes without and with an exhaust shaft are presented. It is shown that the inter-tube spacing significantly affects the energy efficiency of the bundle. The optimum inter-tube spacing is 61 mm for single-row, about 70 mm for double-row, and over 70 mm for four-row bundles. With increase of the number of rows in the bundle the specific capacity of the bundle increases, but the rate of its increase decreases. The specific heat capacity of a single-row bundle with an inter-tube spacing of 58 mm is higher than with an inter-tube spacing of 64 mm. The specific heat capacity of two- and four-row bundles is less at low exhaust shaft heights, but it is more when the relative shaft height is more than 0.14 and 0.26, respectively. The heat transfer of the bundles can be increased (more than threefold) using optimal ratio of the outlet section of the shaft and the flow capacity of the tube.