Abstract: A multi-tier refrigeration tunnel of modular construction, with lateral doors, in which fans are disposed between each tier, in which they are driven by shafts extending from ceiling to floor of the tunnel, and in which the shafts are driven by top mounted fan motors. A multi tier refrigeration tunnel, not of modular construction and without lateral doors, in which fans are disposed between each tier, in which the fans are driven by shafts extending from the floor of the tunnel and from the ceiling of the tunnel, in which the shafts are driven by top mounted and bottom mounted fan motors. A multi tier refrigeration tunnel, and by extension also a single tier refrigeration tunnel, in which two products of different required processing times can be processed simultaneously. A multi tier refrigeration tunnel, preferably without lateral doors but not necessarily, in which fans are disposed above the upper tier and in which fans are disposed next to, and to the side of, the lower tiers.