The invention relates to a device, comprising at least one flow chamber (20′) having an inlet opening and an outlet opening, said flow chamber being provided for the flow of a medium therethrough. The flow chamber (20′) is arranged in a single-piece block element (2) and is at least partly delimited by a diathermal wall in order to effect absorption or release of thermal energy through the wall by means of the medium. The at least one flow chamber (20′) is formed in the block element (2) from a plurality of first channels (22) spaced apart from each other, which extend straight and parallel to each other, and a plurality of second channels (23) spaced apart from each other, which extend straight and parallel to each other, the first and the second channels (22, 23) each having two ends and being closed at least at one (27) of the two ends. The second channels (23) are arranged at an angle to the first channels (22), the first channels and the second channels thus crossing. Support pillars (21) having a parallelogram-shaped cross-section are present within each flow chamber (20′) between the crossing points of two adjacent first channels (22) and two adjacent second channels (23). A turbulent flow of the medium can be produced very effectively in the device according to the invention.