European Space Agency

High Performance Constant Conductance Heat Pipes (HPCCHP)


The objectives of @BUS High Performance Constant Conductance Heat Pipe project is to develop, design and test new high performance heat pipes (in the range 500 to 700 Wm) with a limited weight target and constant conductance performances.

The requested heat pipe will be a constant conductance heat pipe, made of AlMgSi0.5 or 6063 aluminium and using high purity ammoniac as working fluid.

Based on the known EHP & ALCATEL SPACE large heat pipe transport capability, the new high performance heat pipe shall perform a heat transport capability similar or superior to the performance of the large diameter profiles but with an important reduction of the linear mass, hence with a reduction in diameter.


The main requirements are the following:

  • Heat transport capability of 500 W.m at +75ºC with an objective up to 700 W.m,

  • Heat flux density of 7 W/cm²,

  • Heat transfer coefficient (vapour/interface) > 5000 W/m²ºC in [+20ºC, +85ºC],

  • Mass increase shall be limited to have a heat pipe mass less than 500 g/m.


With the improved transport capability and the reduced outer volume and weight, the HPCCHP will offer to the @Bus platform an improved weight to performance ratio. The result of this will be the possibility to increase the available equipment mass and volume onboard the platform.

The expected high heat transfer coefficients will minimise the delta of temperature between the dissipating elements and the cold source at the level of the radiators hence allow for higher power dissipation at iso. temperature.


The High Performance Heat Pipe is of constant conductance type with the envelope in aluminium alloy (6063 T6) and ammonia as working fluid, This heat pipe definition leads to a reliable configuration, well adapted to the requested operating temperature range.

The wick structure will be composed of longitudinal grooves. Axially grooved heat pipe is a flight proven design and the manufacturing is simple with extrusion techniques. EHP & ASPI benefits from a considerable flight heritage on these axially grooved heat pipes.


The HPCCHP project plan is based on two main phases divided in major tasks such as concepts trade-offs, detailed design and test plan definition for the phase 1 followed by the manufacturing, test and qualification program definition through the phase 2 activities

Two new improved designs will be developed and manufactured and then submitted to a concurrent testing phase to highlight the most promising solution for the @Bus platform application.

Current status

The trade-off phase is about to be finalised with the selection of four possible candidates to be further designed through the detailed design task.

Status date

Monday, November 19, 2007 - 16:10