A regenerator is located in the working fluid path between the hot side and the cold side of the engine. As the hot fluid passes through the regenerator, on its way to the cold side, it leaves behind much of its unused heat energy. Typically this energy was held in a filler of wire mesh, made of metals able to withstand very high temperatures and a corrosive environment. On the way back from the cold side to the hot side, it recovers some of this energy and reuses it. In this way, waste heat rejected from the engine is held to a minimum.
In the past, regenerator efficiency was sharply limited by the high operating temperatures of the engine. Materials chosen for use had to be able to withstand these temperatures, and could not be optimized for thermodynamic performance. In the case of our engine, we do not face these limitations.
Our entire regenerator core is encapsulated in a thermoplastic insulator. This vastly reduces energy lost to the surroundings. A solid core of thermoplastic material is also run down the center of the regenerator, filling what would otherwise be excessive dead volume. The regenerator mesh disks themselves are made of very fine copper wire. This very effectively transfers and holds energy.
Unwanted energy conduction down the length of the regenerator, from disk to disk, is sharply limited by the periodic inclusion of a plastic disk. This causes the unwanted flow of energy to be greatly impeded. Also included periodically are aluminum disks with a specific hole pattern, placed to redistribute the flow of working fluid evenly.
Use of all of these materials and optimization techniques is only possible because of the low pressures and temperatures used in our engine. This makes our regenerator far more effective thermodynamically than any used in previous designs.