Abstract: This invention provides an isothermal turbocompressor and a combined turbo-compressor-condenser-expander arrangement, which includes heat-transferring blades that are mounted on, or surround, individual conduits to promote air exchange and heat transfer. In operation, the open framework rotates in free air to promote heat exchange. This optimizes contact with free air during rotation. The assembly includes a first plurality of spokes extending radially outwardly from a first central hub to an outer perimeter with first radial conduits that transport refrigerant under centrifugal force and compression from the hub to the outer perimeter. The first radial conduits include heat exchanging blades. A second plurality of spokes extend radially outwardly from a second central hub at an axial spacing from the first central hub. This second plurality of spokes each includes a second thermally-insulated conduit that transports refrigerant from the outer perimeter to the second central hub.