Vapor Locking as a Limitation to the Stability of Composite Conductors Cooled By Boiling Helium

Abstract

Recently Wilson and Walters [¹] suggested that it seemed “worthwhile to investigate stagnant two-phase cooling.” Their suggestion was based on the assumption that “gas is free to vent but no new liquid enters the zone during the pulse.” Subsequent experiments by Iwasa et al [²] showed that in narrow channels the gas did not vent freely but expelled liquid instead. Were new liquid not to enter and were no gas to vent at all, the helium would then have only about one-seventh the energy-absorbing capacity as supposed by Wilson and Walters (because of the sevenfold volume expansion upon vaporization). Once the channel is filled with vapor, for all practical purposes, heat transfer stops. If recovery is to occur, it must occur before this happens.

Work supported by U. S. Energy Research and Development Administration under contract with Union Carbide Corporation.