+ 1970 News Releases (7.6 Mb PDF file) - NASA

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The device is basically a hollow tube containing a small amount
of fluid. The fluid will absorb heat until it reaches v_porization
temperature_ a temperature determined by the type of fluid and the
pressure inside the tube. The fluid vapor will then transfer heat
uniformly through the tube to a point where it can either be radiated
or made to do useful work.
Heat tuf0es can be formed into continuous loops and the loops
stacked to form the structure of a space vehicle. By controlling
the pressure or changing the fluid within the pipes, future astronauts
could provide the proper temperatures for any given area of the
vehicle with little or no concern about the vehicle_ attitude toward
the
sun.
Two heat pipes are supported above the Subsystem Test Bed in
Chamber A. The pipes are stainless steel_ about one-half inch in
diameter and are formed into a 15-foot-diameter loop. To assist
with absorption and radiation of thermal energy/ four-inch longitudinal
fins made of copper have been attached to each of the pipes. A
stainless steel wick inside the pipes is used to collect condensed
vapor and return it to the heat source by capillary action.
One of the pipes contains 300 cubic centimeters of v_ter and
is expected to reach an equ.ilibri_a temperature of about 76 degrees
Fahrenheit. The second pipe contains 300 cubic cent_m_eters of
methanol and will be used as a comparison for the pipe containing
water.
The heat pipes to be used in MSC tests are the larges_ of their
type ever built. They were desig_ed and fabricated by TRW Systems
Group of Redondo Beach_ California.
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