Top Quality Heat Pipes Manufactured By Maniks Heat Pipe-Thermal Energy Exchanger Manufactured by | Page 3

generation in the heat pipe, but this can be completely avoided by proper cleaning and assembly
procedures
Can heat pipes work against gravity?
Yes, this occurs whenever the evaporator is located above the condenser. In these applications
the working fluid must be pumped against gravity back to the evaporator. This occurs through
wick structures that pump working fluid through capillary pressure developed in the porous
wick. The finer the pore radius of a wick structure, the higher against gravity the heat pipe can
operate.
What materials can be used to construct a heat pipe?
The heat pipe wall or shell material selection is driven by compatibility of the working fluid. The
heat pipe working fluid is selected based on the operating temperature range of the application.
After a working fluid is selected, the heat pipe wall or shell material is selected based on its
chemical compatibility with the working fluid to prevent corrosion or chemical reaction between
the fluid and the heat pipe wall or shell material. A chemical compatibility problem between the
working fluid and wall material within a heat pipe can create a chemical reaction that produces a
non-condensable gas. Non-condensable gases within a heat pipe can cause operational failure.
What fluids are used in heat pipes?
Heat pipe working fluids range from helium and nitrogen for cryogenic heat pipe applications, to
liquid metals like sodium and potassium for high-temperature heat dissipation. Some of the more
common heat pipe fluids used for electronics cooling operations is ammonia, water, acetone and
methanol.
Can heat pipes freeze?
Yes, heat pipe working fluids, including water, maintain their normal freezing point. Heat pipes
will not operate until the temperature rises above the freezing temperature of the fluid. Properly
designed heat pipes, however, will not be damaged by freezing or thawing of the working fluid.
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