shelves and condenser form a cavity 210 which contains a vaporizable and condensable substance the capture shelves are extended into the blades of the compressor rotor by holes or passages 208 that penetrate into the blade body substantially parallel to the axis of rotation so that the cooling effects of the fluid are also extended into the blades the condenser can be cooled by any of a number of means such as air drawn from the compression system at a lower level of pressure than that delivered by the compressor under discussion or a liquid cooling system or any other that provides a suitable temperature and cooling capacity for removal of the heat transferred from the compressor blades the view of fig6 is cross sectional taken along a centerline passing through the axis of rotation and midway through the thickness of one of the compressor blades the capture shelves of the return flow cascade evaporative cooling system are arranged with circular symmetry about the axis of rotation on the opposite surface of the wall of the disc that carries the compressor blades as in the above referenced u s patents and aforesaid patent application all the liquid from the condenser which is near the axis of rotation enters the innermost shelf first some of it evaporates thence to cool the part of the compressor rotor adjacent that shelf while the remainder spills or is channeled into the next outward shelf this coolant cascade repeats so that the fluid supplies all the shelves the vapor produced in the shelves passes inward through a cavity formed by a cover disc to a condenser region near the axis of rotation condensing on the inner surface of the condenser the fluid is then.