WHIRLING FLOW PROMOTING TYPE BOILING HEAT TRANSFER TUBE

摘要

PURPOSE: To promote heat transfer while suppressing pressure loss into a low value and miniaturize a power supply source for driving fluid in a heat transfer tube by a method wherein the projecting height of a structure for promoting whirling flow in a section orthogonal to the axis of the tube is reduced toward the downflow direction of the fluid. ;CONSTITUTION: An opening 4 is provided on a whirling flow promoting plate 2 in the area II of gas and liquid two-phase flow in the downstream side of a boiling starting position ZB. The configuration of the opening 4 is determined so that the width (d) in the diametral direction of the opening 4 is increased gradually toward the downstream direction of the tube. The flow is provided with rotation by the promoting plate 2 in the area I of the single phase flow of liquid whereby convection heat transfer rate is improved. When the flow arrives at the boiling starting position ZB, nuclear boiling is generated on the wall of the heat transfer tube 1 whereby the flow becomes gas and liquid two-phase flow in the downstream of the same. The liquid is supplied to the wall of the heat transfer tube 1 at all times by gas and liquid separating effect whereby the generation of dry patch, in which the film of the liquid on the wall of the tube is broken locally, can be prevented and the nuclear boiling heat transfer, having a high heat transfer rate, can be maintained. The mixing ratio of gas is increased in the downstream of the area II and a pressure loss is also increased, however, the width (d) of the opening 4 is increased toward the downstream of the same and, therefore, the pressure loss can be reduced.;COPYRIGHT: (C)1993,JPO&Japio