Constant Conductance Heat Pipes

ACT delivers proven CCHP thermal control products.

ACT fabricates Constant Conductance Heat Pipes (CCHPs) to exact aerospace requirements. These devices are manufactured under ACT’s AS 9100-2009 and ISO 9001:2008 certified Quality System. The materials used for manufacturing (extrusions and working fluids) are certified and qualified to meet the demanding level of aerospace quality. Each aluminum extrusion is fully characterized to determine thermal capability and pressure containment capability as functions of operating temperature and fluid charge. The welding processes are performed by welders certified to AWS 17.1 Specification for Fusion Welding for Aerospace Applications.

ACT has specialized equipment required to manufacture CCHPs to achieve aerospace quality. This includes: multi-stage cleaning baths for chemically cleaning raw extrusions, triple distillation apparatus for working fluid purification, state-of-the-art helium mass spectrometer leak detector, dedicated charging, processing and non-condensable gas venting stations and specialized test setups for testing and characterization at various temperatures and elevations.

Aerospace Constant Conductance Heat Pipes

Examples of Aerospace Constant Conductance Heat Pipes

After the rigorous physical/chemical cleaning process, the heat pipes are further cleaned in-situ by operation at elevated temperatures with a high purity working fluid charge that is subsequently vented. A second high purity charge is loaded and the pipe is operated over a number of days with several checks for non-condensable gases at extremely low temperatures, where the slightest amount of non-condensable gas can be detected and removed before final hermetic sealing.

ACT has proprietary heat pipe models to simulate each design application and these models are used to assist with the selection of the right extrusion for each application. This software calculates the capillary limit and the associated thermal transport capability of the heat pipe taking into account the exact extruded groove geometry. The optimum fluid charge is determined for the specific application and the effect of excess fluid charge is determined for both 0-G and 1-G operations. The figure below compares the model predictions and test data on two specific CCHPs.

ACT’s CCHP Space Flight Hours:

Model Predictions for designing Aerospace Heat Pipes

Model Predictions for designing Aerospace Heat Pipes