Abstract: A recuperative or restorative spiral heat exchanger with separating walls spirally extending between fluid streams of medium having an exploitable temperature gradient. Each two adjacent separating walls enclose between themselves a flow duct for one of the two streams of medium and the spiral space between two flow ducts forms the path of flow for the other stream of medium. The spiral is provided in the form of a multiple or multi-channel spiral by arranging a plurality of flow ducts. In particular, the spiral heat exchanger consists of two multiple spirals with opposed directions of current.