Standard heat pipes products are also sometimes known as Constant Conductance Heat Pipes (CCHPs), but this is a term more commonly used in the Spacecraft Thermal Control industry, most often referring to Aluminum-Ammonia CCHPs.
As shown in the above video, a heat pipe works through heat that is transferred by the evaporation and condensation of a working fluid:
- Heat transfer to the evaporator vaporizes liquid within the wick.
- Vapor pressure drives fluid to the condenser
- Heat transfer from the condenser condenses vapor at the wick.
- The liquid returns to the evaporator by capillary forces generated in the wick
The typical bend radius is recommended to maintain greater than 3 times the O.D. of the heat pipe; see Figure 1. Below, two examples of copper water heat pipes used to cool discrete components are showing in Figure 2 . The heat pipes can be bent as necessary between the heat source and sink.
The benefits of a standard heat pipe include:
- High Thermal Conductivity (10,000 to 100,000 W/m K)
- Low Cost
- Shock/Vibration tolerant
There are several limitations that must be taken into consideration with designing a thermal solution that uses standard heat pipes:
- Heat Pipe Entrainment
- Thermosyphon Flooding
Characteristics and considerations for standard heat pipes:
- Most heat pipes are not structural components
- Heat is transported from discrete sources
- Heat flows in both directions
- Diode heat pipes only allow the transfer of heat from the evaporator to the condenser
- Power is only limited by the source and sink conditions
ACT’s heat pipe calculator can be used to estimate the performance of standard copper-water heat pipes.