Tubular Heat-pipes
These are the simplest and most popular type of Heat-pipe and are used
in most applications to transfer heat energy from one point to another.
They can also be used as heat spreaders to isothermalise components
where a uniform temperature is desired. Although Heat-pipes are
predominantly used in cooling applications, they can also be used very
effectively in heating applications, this negates having multiple
electrical heating elements, and simplifies cabling, design and
installation
Annular Heat-pipes
These
are Heat-pipes with an axial concentric hole through the middle. These
may be used in a variety of situations where high heat transfer is
required together with mechanical access,
examples include; as a flow channel for gas or liquid, for cabling or
thermocouple access, as a push rod mechanism location sleeve.
Larger diameter Heat-pipe rollers have also been produced similarly
with open bore for use as rotary thermal spreaders and having internal
air cooling.
Baffle Heat-pipes
Baffled Heat-pipes are used in water cooled applications i.e. core
cooling applications used commonly in plastic injection moulding tools.
The Heat-pipes are installed into manifolds and transfer heat from the
heat source to the cooling water. The baffle plates direct water along
the Heat-pipe cooling length to give an increased cooling area contact.
Bent Tubular Heat-pipes
Common
application requirements require Heat-pipes to be bent to fit a route
in a particular installation, possibly involving complex 3-D
architecture. By using special internal wick structures, CRS
Engineering is able to produce Heat-pipes which can be formed to shape
by customers upon installation. Where exact bending is required, or
where tight bending radii are involved, it is essential that CRS
Engineering carry out this process during manufacture.
Flexible Tubular Heat-pipes
A
limited degree of flexibility is possible with most standard range
Heat-pipes, as a function of their length and diameter. Often this may
be sufficient to accommodate small dimensional tolerance differences
encountered during assembly and installation with other components.
Truly flexible Heat-pipes incorporate an intermediate convoluted
bellows section providing excellent flexibility and anti-vibration
characteristics.
High Performance Heat-pipe Heat Sinks
Integral
Heat-pipe heat sinks built with cooling fin assemblies provide one of
the most effective means of providing efficient cooling for power
electronics components. The forced air cooled assembly shown opposite
achives an oustanding thermal performance.
Performance: Rth = 0.09°C/W.
i.e with 100 W heat dissipation the input heat block temperature is only 9°C higher than the ambient cooling air temperature!
Diode Heat-pipes
Diode Heat-pipes have a high thermal conduction in one direction and a
low thermal condution in the opposite direction. They are typically
used in aerospace applications where it is possible for heat sink
temperatures to exceed the Heat-pipe evaporator temperature due to
solar radiation. Usually an array of diode Heat-pipes are used together
to dissipate heat to a number of alternative heat sinks so that heat
sinking facilities are constantly maintained.
Variable Conductance Heat-pipes
VCHP
Heat-pipes provide a means for automatic temperature control. By
regulation of the Heat-pipe thermal conductivity it is possible to
maintain the evaporator section at near constant temperature with
around only 5 °C fluctuation. VCHP’s are specifically pre-set to
operated over a specific temperature range of varying ambient
condidions and variable heat input loading. Where very precise control
is required they can be also integrated with electronic control
achieving temperature stabilization of better than 1°C with minimal
electrical power comsuption for the controlling circuit.
