A Low Cost Compressor for Spacecraft Cryocoolers

The objective of the proposed project is to reduce by more than an order of magnitude the cost of reliable and contemination-free hermetically sealed compressors for long life Stirling and Pulse Tube Cryocoolers for spacecraft. State-of-the art compressors use unlubricated flexure bearings and non-contact seals to eliminate contamination and wear, approaches requiring expensive high precision manufacturing and assembly. They use linear motors which are expensive and heavy and require accurate non-contact position sensing and complex and sophisticated electronic controls to manage displacement and vibration cancellation. The inexpensive compressor proposed for Stirling and Pulse Tube cycle spacecraft cryocoolers makes use of design approaches and manufacturing technology proven by decades of mass produced industrial and commercial products. The diaphragm compressor provides nearly isothermal gas compression processes well suited to Stirling and Pulse Tube cycle thermodynamics. In Phase I the compressor design process will be developed and documented, a typical implementation will be analyzed, and a responsive machine design geometry will be synthesized. Fluid inventory management, lubrication effectiveness, seal leakage, windage losses, and vibration will be assessed to demonstrate feasibility of the concept for satisfying demanding spacecraft requirements. Manufacturing costs will be estimated and a final report prepared detailing all Phase I findings.