Heat exchanger for temperature control of a substrate for cultivating horticultural products, substrate drawer, and rack

A rack for carrying a substrate for cultivating horticultural products, wherein the rack is provided with a heat exchanger for temperature control of the substrate, the heat exchanger having a structure comprising a heat exchange surface arranged for heating or cooling the substrate, wherein the structure forms a carrier plate with a carrier surface for supporting the substrate, wherein the heat exchange surface forms the carrier surface, wherein one or more mounts suspend the heat exchanger at or along its edges to the rack, and wherein the structure of the heat exchanger is self-supporting for supporting the substrate at least between the one or more mounts without additional support elements below the heat exchanger, such that a bottom surface of the structure opposite the heat exchange surface faces an ambient environment, wherein the structure comprises an extendible section, configured to extend or shorten laterally in a plane of the carrier plate between the mounts for compensating thermally induced contraction or expansion of the heat exchanger, respectively, wherein the structure forms an impervious barrier, arranged for preventing passage of substrate material through the structure.