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FlO. 17.24. Energy balance for Ihe Philips Stirling engine in the urtificial heart system (after

Wcstinghouse 1075).

Another feature of interest is the use of magneticcoupling for transmitting power from the engine shaft to the flywheel ard hence to the output shaft. Construction of the flywheel in two parts coupled magnetically permits the interposition of an impervious titanism membrane and the consequent hermetic sealing of the engine crank;ase. Interesting details of these innovative features will be found in the cuarterly progress report (Westinghouse 1976).

One particular difficulty of the Westinghousc/Philips system was the transfer of engine reject heat to the blood pump for dissipation in the blood. Early versions used a water cooling circiit energized by a bellows pump incorporated in the blood pump (Poucfcot et al. 1975). This was supplanted bv a flexible heat pipe describee bv Krasicki and Pierce (1977).

No mention of animal experiments was included in any of the references consulted. It may be these are projected for a later phase of the program when operational prototypes of t'le system have reached a reasonable level of development.

Complete details of the progress of the Wcstinghouse/Philips program are reported in the quarterly progress reports (up to No. 29 at mid-1977). These are not readily available and are somewhat tedious to search through, so the general reader may find more useful the annual summary papers published in the Intersociety Energy Conversion Engineering Conference.

closure

Outside the United States the only known artificial heart research involving Stirling engines is the Messerschmidt-Bulkow-Blohm program in West Germany reported by Frank et al. (1974) and by von Rcth et al. (1975). This is an early stage of development of a Bush-type free-piston thermocompressor engine similar to the Aerojet unit described above. 'Fhe status of the program is unknown.

The other work on Stirling engines summarized above is a small part of a large program on artificial hearts in progress in the United States.

Frequently, these Stirling engine programs are overlooked because the power levels are :to low and the subject so esoteric as to be outside the general interest. This assessment is mistaken. Four teams of exceedingly capable and innovative engineers have laboured for a decade al the absolute frontiers of technology in materials, control systems, heat transfer. fluid mechanics, thermodynamics, instrumentation, and experimental technique. There is much in their work that can be carried over into engines of larger size and power output, and close study of the annual contractor reports and papers in the open literature is recommended to all those professionally interested iri Stirling engines.

Solar Stirling Engine Basics Explained

Solar Stirling Engine Basics Explained

The solar Stirling engine is progressively becoming a viable alternative to solar panels for its higher efficiency. Stirling engines might be the best way to harvest the power provided by the sun. This is an easy-to-understand explanation of how Stirling engines work, the different types, and why they are more efficient than steam engines.

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