A heat pipe is a heat transfer device that efficiently transfers heat between two mechanical interfaces.
- A hot interface
- A heatpipe which comprises:
- A sealed pipe which is typically manufactured out of copper, aluminum or stainless steel
- A working fluid that partially fills the heatpipe before it is vacuumed sealed.
- A wick structure which facilitates a capillary action inside the pipe
- A cooling interface (condenser) where the transferred heat cools on the heatsink surfaces
Heat pipes are often compared to Vapor Chambers, and while they share some similarities, they are quite different. Heat pipes remotely conduct the heat from one end to the other in a linear structure whereas vapor chambers evenly spread the dissipated heat.
Comparison Table: Vapor Chamber vs Heat Pipe
|Application||Dissipates heat directly on the device to be cooled||Moves heat dissipation to another part of the system|
|Form Factor||Top and bottom stamped plates which can take the form of the electronics to be cooled||Small diameter conductive tube (3mm to 10mm)|
|Shapes||Complex shapes due to the stamping process||Round, flattened or formed in any direction.|
|Size||Small (1mm to 5mm thick). Can be formed to the size of the electronics to be cooled||3mm to 10mm diemeter pipe which can be flattened into oval shapes and can be 500mm long||Mounting To Heat Source||Placement directly on the electronics to be cooled via through holes for attachment||Mostly, indirect contact unless the interface plate machine flat to the profile of the device to be cooled.|
|Heat Source||Direct contact with the heat source, mounting pressure up to 90psi||A base plate makes contact with heat source but heatsink can be remotely positioned ( >150mm) from the heat source connected by the heat pipe.|
|Qmax||T(Thickness)=5mm > 400W, T=3mm > 200W, t=1mm > 60W||∅5 > 20W, ∅6 > 40W, ∅8 >60W|
Per the diagram, during the Heatpipe' operation, the 'heat input' transfers thermal energy to the evaporator side of the Heatpipe. This heat converts the (working) liquid in the sealed chamber into a 'vapor' which is denoted by the red arrows (vapor flow).
The vapor then cools, via the wick, on the surfaces of the 'condenser section' where the heat will be removed by either convection cooling, forced air convection cooling or liquid cooling.
Once the vapor cools to a liquid, it will return to the evaporator via capillary action and this depicted by the blue arrows (liquid flow).
The cycle repeats continuously making the Heatpipe a highly efficient thermal management device especially where there is a need to move the transferred heat further away from the heat source.
Heatpipe Dissipation Guide
|Press thickness||Dia 2.0mm (W)||Dia 3.0mm (W)||Dia 4.0mm (W)||Dia 5.0mm (W)||Dia 6.0mm (W)||Dia 8.0mm (W)|
|t = 0.6||2.3||2.5||3.0||3.5|
|t = 0.7||3.0||5.0||5.0|
|t = 0.8||4.0||6.0||6.0||10.0|
|t = 1.0||3.0||5.0||5.0||7.0||8.0||12.0|
|t = 1.2||5.0||7.0||10.0||15.0||17.0|
|t = 1.5||7.0||7.0||7.0||12.0||17.0||23.0|
|t = 2.0||5.0||8.5||10.0||15.0||23.0||27.0|
|t = 2.5||10.0||12.0||18.0||31.0||40.0|
|t = 3.0||10.0||15.0||22.0||36.0||48.0|
|t = 3.5||17.0||23.0||38.0||50.0|
|t = 4.0||20.0||27.0||40.0||55.0|
|t = 5.0||30.0||45.0||60.0|
|t = 2.0||48.0||70.0|
|t = 2.0||80.0|
Samples Of Our Heat Pipe Capabilities
The table below depicts the performance characteristics of a variety of working fluids. However, the three most commonly used working fluid in the vast majority of vapor chambers are:
- Water: operating temperature ranges from 30°C to 200°C (readily available and environmentally friendly)
- Methanol: operating temperature range is slightly lower and narrower than water at 10°C to 130°C
- Ammonia: operating temperature ranges from -60°C to 100°C (manufacturing cost is higher due to the toxic nature of ammonia)
|Working Fluid||Melting Point (°C)||Boiling Pt (°C)||Useful Range (°C)|
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