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What IS a heatpipe?
A heat pipe is a closed-loop, cooling device wherein heat is transferred
from the "evaporator"-end to the "condenser"-end of a sealed tube using
the latent heat of vaporization as the principal means of energy transfer.
construction
A heat-pipe consists of three principal elements: 1) a sealed tube (typically copper),
2) a heat-transfer medium (such as water, ammonia, or methanol) enclosed under
partial vacuum within the tube, and 3) an internal 'wick' structure.
Capillary action within the wick transports the liquid medium to the evaporator end of the tube,
whereupon the liquid is vaporized by the addition of heat, and is transported by
vapor pressure to the condenser end, thus closing the loop.
history
Heat-pipes have been used commercially for decades as a means of 'passively' removing
excess heat from critical, confined areas and transporting it to a remote condenser.
Heat pipes are used in spacecraft, for instance, to remove power from internal
electronic components, and transport that power to radiators on the outside of the spacecraft.
They are also used in portable computers where large amounts of heat must be transported through
small apertures and openings.
Heat pipes have recently become very affordable, due to major advances in automated
manufacturing techniques, and are available in a variety of lengths and diameters.
capabilities
Due to the enormous latent heat of vaporization of some fluids, the capabilities of
heat pipes can be enormous, easily 10,000 times that of solid copper rods. In addition,
the "delta-T" or difference in temperature between a 100-Watt source and the condenser
can be as low as a few degrees while for a similar length and diameter of copper rod,
the delta-T would be over 250 degrees! This condition is typically only met when heat
exchange is limited primarily to conduction, as it is in the Ultra High Vacuum (UHV) region.
(Radiation and convection are the other means of thermodynamic exchange.)
The WattRod™ vacuum feed-through heat-pipe assembly has no moving parts except for an optional
condenser fan, and therefore has extremely long life. It provides a passive means of removing
large amounts of power (hundreds of Watts), inexpensively, simply, and effectively, without
compromising the cleanliness of the vacuum chamber.
The WattRod™ is constructed entirely out of Ultra-high Vacuum (UHV) compatible materials and
coatings to permit optimal operation within the UHV environment. Nickel-plated copper and
highly-polished aluminum clamp pieces help to minimize radiative coupling to the vacuum chamber walls.
The WattRod™ can therefore be operated at room temperature, even when the surroundings are at
very elevated temperatures.
Which vacuum feedthroughs are available?
The WattRod™ is available with either Kwik-Flange™ or Del-Seal™ vacuum flanges.
Standard flanges are NW-25 and 2-3/4" Del-Seal, but special flanges are available upon request.
What sizes are available?
Standard WattRod™ heatpipes are available in lengths from 12" to 18", providing from 7" to 13" extension inside vacuum.
Additional length and flexibility can be gained by connecting the heatpipes in series within the vacuum chamber.
The serial-extenders are available only by special order.
Standard pipe diameters are 5/8", but special orders will be accepted for 1/4", 3/8", and 1/2" diameter WattRods™.
Can they really operate at ANY angle?
Due to the special design of the WattRod™ heatpipe, it can be operated in virtually any orientation.
While it is possible to operate the WattRod™ with the heat-source above the condenser-end, efficiency is
severely limited, and only short runs (~6") are possible.
We therefore recommend that the WattRod™ be operated either horizontally, or with the evaporator-end below
the condensor-end.
Precautions:
The WattRod™ can withstand a wide range of operating temperatures, ranging from -50º C to +180º C.
Under no circumstances should the WattRod™ ever exceed 180º C, or the vapor pressure inside the tube will cause
the tube to burst (a seal will open near the condensor-end of the tube.)
Who are we?
koolpipes.com is an ALIAS Aerospace company - www.ALIASAerospace.com
We can be reached at:
support@koolpipes.com
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Koolpipes.com
1241 Adams Street, #1015
St. Helena, CA 94574
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Phone: (707) 280 - 5030
WattRod and koolpipes are trademarks of ALIAS Aerospace, Inc.
Copyright © 2001. All rights reserved.
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