Fundamental study of development of high temperature plate-fin heat exchanger

This study aims at making an original proposal to install twisted tapes in plate-fin heat exchanger channels for making uniform the outlet temperature of heated gas or for decreasing thermal stresses. First, in order to clarify flow and temperature performances by the insertion of twisted tapes up to 650°C, experiments are made using two kinds of channels with aspect ratios 1 and 2. Second, numerical calculations are made to obtain the optimum pitch ratio distributions of the tape to have a uniform heated gas temperature profile. Experiments on the temperature fields are made using a heat exchanger and the validity of the theoretical prediction is confirmed. Third, by use of the other heat exchanger of brazen construction, the change of thermal stresses by the insertion of tapes is measured. It is shown by the experiments that the maximum stress appears near the piping connecting part of the cover plate, and this is decreased nearly 1/3 by the insertion of twisted optimum tapes.