The invention relates to a connection unit having a multi-channel heat exchanger with high-pressure channels and low-pressure channels and a connection element with a high-pressure reservoir and a low-pressure reservoir, both with a connection for connection. The axial end of the multi-channel heat exchanger is limited by a termination element that has axial passage holes for the high-pressure flow to the high-pressure reservoir. At the axial end of the multi-channel heat exchanger, in the region of the low-pressure reservoir, longitudinal slots are formed through which the low-pressure flow flows from the low-pressure channel to the low-pressure reservoir.