Heat pumps move heat from a source to a higher temperature heat sink. This invention enables spontaneous source-to-sink heat transfer. Spontaneous heat transfer is accomplished by conducting heat from the source through rotating disks to a portion of the generally warmer sink flow that is cooled to a temperature below that of the source by the Bernoulli effect. The nozzled flow required for Bernoulli cooling is provided by the corotating disk pairs. The distance between the opposing surfaces of the disk pair decreases with distance from the rotation axis, forming a nozzle. The heat-sink flow through the nozzle is maintained by centrifugal force caused by the circular motion of the gas near the disk surfaces. Embodiments of the invention differ in the paths followed by the source and sink fluid flows, by the number of disk pairs and by the state (gas or liquid.) of the heat source.