| Strengths & Weaknesses
| Future Development
| Vendors |
The primary challenges faced by kinetic Stirling engines over the last two decades have been their long-term durability/reliability and their reputation (both real and perceived) for high cost.
Durability challenges have included:
- Shaft seals to separate the high pressure hydrogen space from the lubrication in the mechanical drive train
- Low-leakage piston rings and bearings for operation in the unlubricated working engine space
- Minimization of material stress and corrosion in the high temperature/high pressure heater head, which must operate at internal pressures of >2000 psi and 1300°F
- Blockage of fine-meshed heat matrices used in the regenerator assemblies with particles/fines generated through the rubbing action of piston rings
While these challenges have delayed the penetration of Stirling engine technology, manufacturers are now beginning to approach run-times that may be acceptable in some distributed power applications.