Abstract: The invention relates to a heat-exchanger element for a freeze drier, which includes an outer pipe for the through-flow of freezing mixture, and an inner pipe, disposed within the outer pipe, for the through-flow of the gas to be dried, and which is characterized by a core pipe, located within the inner pipe, for through-passage of a fluid. The bore of the core pipe may be in communication at at least one end, and preferably at both ends, of the heat-exchanger element with the bore of the outer pipe. A feed pipe for the through-passage of a second fluid is preferably provided at the end of the core pipe. There may be provided between the end of the core pipe on the one hand and two fluid feed pipes on the other hand a valve means of which the core pipe can be placed in communication with one and/or the other feed pipe.