Fusion Science and Technology / Volume 47 / Number 3 / April 2005 / Pages 610-615
Technical Paper / Fusion Energy - Inertial Fusion Technology
An experimental and numerical investigation has been conducted to examine the effectiveness of gas/liquid mist as a means of cooling the Electra hibachi structure. The aim is to quantify the effect of various operating and design parameters, viz. gas/liquid combination, gas velocity, liquid mass fraction, liquid atomization nozzle design (i.e. spray geometry, cone angle, and droplet size distribution), and heat flux on mist cooling effectiveness. The data are used to validate a mechanistic model which can be used to predict the hibachi foil's response under prototypical pulsed operating conditions.
A fully-instrumented experimental test facility has been designed and constructed. The facility includes three electrically-heated test sections, including a channel with prototypical Electra hibachi dimensions. Water is used as the mist liquid, with air, or helium, as the carrier gas. Three mist generating nozzles with significantly different spray characteristics are used. Values of the local heat transfer coefficient along the channel surface are measured for a wide range of operating conditions. The data indicate that mist cooling can increase the heat transfer coefficients by nearly an order of magnitude compared to forced convection using only the carrier gas. Comparison has been made between the data and predictions of a mechanistic three-dimensional computer program for transient two-phase flow in the channel coupled with heat conduction in the surrounding structure; excellent agreement has been obtained. The results indicate that gas/liquid mist can effectively cool the Electra hibachi structure within the design constraints imposed on circulating power requirements.