Enhanced Evaporative Surface for Two-Phase Mounting Plates

This paper describes an enhancement to a grooved, evaporative surface for two-phase mounting plates. These equipment mounting plates could be used in two-phase thermal control systems such as that on the proposed Space Station.

An aluminum plate is machined with fine, rectangular grooves (39 grooves/cm). This grooved surface is then enhanced by an inexpensive process called Ivadizing™ (equipment for this process is patented by McDonnell Douglas). During Ivadizing, aluminum is vapor deposited onto the surface, forming a slightly porous coating on the land area between the grooves. The resulting surface has a much larger evaporative heat transfer coefficient and capillary pumping ability than that with plain, rectangular grooves.

We have used Ivadizing to enhance a mounting plate evaporative surface. Tests of this plate with R-11 showed improvement in evaporative heat transfer coefficient by a factor of 4. Analytic studies show that this enhanced surface should have at least three times the capillary pumping capacity of the rectangular grooved surface.