Abstract: A heat exchanger has a stack of thermally conductive plate elements, each having a wave-shaped cross sectional profile. The plate elements are connected in a fluid-tight manner along abutting wave profile regions to form first and second channel structures which are separated from each other in a fluid-tight manner. The wave profiles of the plate elements comprise at least two types of waves of different width: a first type of wave defines the channels of the first channel structure, and a second type of wave defines the channels of the second channel structure. The channels of the first channel structure have a larger passage cross section than the channels of the second channel structure.

Abstract: An evaporator unit in the form of a plate construction has evaporation spaces and heat transfer medium spaces respectively arranged between successive plates. The plates have an essentially circular construction and have recesses for forming inflow and outflow lines for the medium to be evaporated and for a heat transfer medium which extend perpendicularly to the plates. The inflow line for the medium to be evaporated is arranged in the area of the center of the circular plates. The outflow lines for the evaporated medium and for the heat transfer medium are arranged in the circumferential area of the circular plates. For the heat transfer medium, several inflow lines can be provided at a radial distance from the center of the circular plates between the inflow line and the outflow lines for the medium to be evaporated.