Abstract: An apparatus for preserving and transporting fresh or frozen products, particularly for thermally insulated containers, includes at least one heat accumulator associated with a respective inner wall of a container. The apparatus further includes a plurality of longitudinally extended heat accumulation modules, each one having an enclosure that delimits a cavity adapted to contain a heat accumulation liquid. The cavity accommodates a heat exchanger that can be supplied with a heat transfer fluid. The heat accumulation modules are mutually connected mechanically and thermally, and in that the enclosure has a first wall that faces the inner face of the container and has a substantially flat surface. The modules also include a second wall opposite the first wall and being directed towards the internal compartment of the container, having an at least partially ribbed surface.