PURPOSE: To raise the efficiency by positioning the Perkins tube of an evaporation part outward in radial direction from the Perkins tube of a condensation part, and making working fluid occupy a great part of the evaporation part, leaving the minimum space where the steam from fluid shifts, in the above heat exchanger such as a washing drier or the like.

CONSTITUTION: A Perkins tube 36 is positioned so that an evaporation part 28 may be outward in radial direction from a condensation part 30. Then, it is arranged so that the working fluid 66 filled therein may concentrate on the evaporation part 28 by the centrifugal force accompanying the rotation of the rotary heat exchanger, and that 50% to 100% of the capacity of the working fluid 66 may fill up the evaporation part 28. On the other hand, it is arranged so that the condensation part 30 may be filled up with the one of 0% to 22% of the working fluid, and that the remainder may be filled with the gas arising from fluid. Then, the connection between the Perkins tubes 36 of both sections 28 and 30 is made of a tilt coupling tube 96 which forms the minimum space to allow the shifting of the gasified working fluid 66.