Involute Foil Regenerator

A method of making a regenerator through which fluid can flow for transferring thermal energy into and out of the fluid, the method comprising:

• a) forming an inner wall having a radially outwardly facing cylindrical surface;
• b) disposing an outer wall substantially coaxial with the inner wall and spaced radially outwardly therefrom, forming an annular gap between the inner wall and the outer wall, said outer wall having a radially inwardly facing cylindrical surface;
• c) mounting a plurality of foils in the annular gap extending along substantial involutes of the radially outwardly facing cylindrical surface, each foil having an inner edge at the radially outwardly facing cylindrical surface of the inner wall at substantially equal circumferentially spaced intervals and an outer edge spaced from the inner edge, the outer edge being circumferentially displaced from the inner edge and extending toward the radially inwardly facing cylindrical surface of the outer wall;
• wherein a plurality of longitudinal gaps, each longitudinal gap being formed between one of the foils and its respective next adjacent foil, extends from the inner wall to substantially the outer wall, the longitudinal gaps forming involute flow passages that extend substantially uninterrupted between the inner and outer walls.