Abstract: A steam generator (1) is provided for a Rankine cycle, especially for a waste heat recovery device (37) of an internal combustion engine (36), and preferably in a motor vehicle. The steam generator includes: a heat exchanger channel (2), in which a heat exchanger (3) is arranged, and a bypass channel (4) for bypassing the heat exchanger channel (2). A heating fluid can flow through the heat exchanger channel (2) and bypass channel (4) during the operation of the steam generator (1). A medium to be evaporated can flow through the heat exchanger (3) during operation of the steam generator (1). A compact structural shape with high energy efficiency is achieved with the heat exchanger channel (2) enveloping the bypass channel (4).

Abstract: An evaporator (1) for a waste heat recovery device includes a plurality of evaporation devices (2) for the flow of a fluid. The evaporation devices (2) are arranged in a stack-line manner in a stacking direction (S). A plurality of rib structures (3) are designed and arranged for the flow of a gas through them, in a gas flow direction (G). Each evaporation device (2) has a pair of plates (4). The first and second evaporator plates (5, 6) are mutually complementary with one another and have a meandering evaporation channel (9) each on a respective inner side (7, 8). The inner sides (7, 8) of the first and second evaporator plate (5, 6) are in flat contact with one another in a mounted state outside the evaporation channel (9). Adjacent pairs of plates (4) are supported with their respective outer sides (16, 17) on the rib structure (3).