The Effect of the Pipe Cross-Sectional Shape on the Longitudinal Heat Transfer in Oscillatory Flows in Pipe Bundles

The enhancement of longitudinal heat transfer by means of fluid pulsation in pipe bundles has been investigated. Bundles of circular, triangular, square and hexagonal pipes are considered. Heat transfer characterisitics of each pipe and the gross performance as pipe bundles including the heat conductance in pipe walls are discussed. The distribution of the longitudinal heat transfer intensity across the pipe section reveals the existance of a region where heat is transferred toward the high temperature end when the pulsation frequency is high. Although the gaps between three circular pipes deteriorate the heat transfer characteristics by fluid in a circular pipe bundle, when acrylic pipes are assumed, the gross performance is the best with a circular pipe bundle, because the area ratio occupied by pipe wall in a cross-section, where the low thermal conductance deteriorates the performance, is least when the pipes are circular.