Heat exchanger

Abstract

A heat exchanger has upper and lower plenums which communicate with each other via heat transfer tubes. A downwardly-extending tube used to introduce secondary sodium coolant into the lower plenum extends among the heat transfer tubes and is fastened to the lower tube plate to communicate with the lower plenum. The downwardly-extending tube is stretched through the lower plenum in the axial direction thereof to contact at its lower end a bottom surface of the heat exchanger body. A plurality of openings are provided in a wall of the portion of the downwardly-extending tube which is in the lower plenum. Primary sodium coolant of a high temperature flows into the heat exchanger body from the portion thereof which is below an upper tube plate, and flows out of the heat exchanger body from the portion thereof which is above the lower tube plate. Secondary sodium coolant of a low temperature flows downward through the downwardly-extending tube to be ejected in the horizontal direction from the above-mentioned openings into the lower plenum to flow in parallel currents therein to enter each of the heat transfer tubes and advance upward. The secondary sodium coolant heated in the heat transfer tubes is ejected into the upper plenum.