Refrigeration apparatus comprising: - an external housing cabinet; - an inner storage cabinet housed in said external housing cabinet and having a first compartment intended to be cooled at a first temperature, and a second compartment intended to be cooled at a second temperature lower than said first temperature, said first and second compartments (13, 14) having respective accesses for loading/unloading a product to be cooled, and being separated from one another by a partition wall, said inner storage cabinet being provided with at least one duct that allows the passage of air from said first compartment to said second compartment; - at least one air passage allowing the passage of air from said second compartment to said first compartment; - at least one fan arranged to generate a forced air flow circulating from said first compartment to said second compartment through said at least one duct, and from said second compartment to said first compartment through said at least one air passage; - at least one evaporator arranged to cool down said forced air flow before its emission into said second compartment, or when it is flowing into said second compartment; wherein said first and second compartments (13, 14) and said partition wall being defined by a single-piece plastic liner, and said first compartment has at least one first aperture that acts as an intake mouth of said at least one duct and said second compartment has at least one second aperture that acts as an outflow mouth of said at least one duct, said at least one duct comprising at least one connector element applied to the inner storage cabinet so as to fluidly connect said first and second apertures (23A,23B) one another, characterized by at least one door associated with said external housing cabinet for closing the accesses of said first and second compartments (13, 14) and said at least one air passage comprises a gap between said partition wall and said door. - an external housing cabinet; - an inner storage cabinet housed in said external housing cabinet and having a first compartment intended to be cooled at a first temperature, and a second compartment intended to be cooled at a second temperature lower than said first temperature, said first and second compartments (13, 14) having respective accesses for loading/unloading a product to be cooled, and being separated from one another by a partition wall, said inner storage cabinet being provided with at least one duct that allows the passage of air from said first compartment to said second compartment; - at least one air passage allowing the passage of air from said second compartment to said first compartment; - at least one fan arranged to generate a forced air flow circulating from said first compartment to said second compartment through said at least one duct, and from said second compartment to said first compartment through said at least one air passage; - at least one evaporator arranged to cool down said forced air flow before its emission into said second compartment, or when it is flowing into said second compartment; wherein said first and second compartments (13, 14) and said partition wall being defined by a single-piece plastic liner, and said first compartment has at least one first aperture that acts as an intake mouth of said at least one duct and said second compartment has at least one second aperture that acts as an outflow mouth of said at least one duct, said at least one duct comprising at least one connector element applied to the inner storage cabinet so as to fluidly connect said first and second apertures (23A,23B) one another, characterized by at least one door associated with said external housing cabinet for closing the accesses of said first and second compartments (13, 14) and said at least one air passage comprises a gap between said partition wall and said door. said first and second compartments (13, 14) and said partition wall being defined by a single-piece plastic liner, and said first compartment has at least one first aperture that acts as an intake mouth of said at least one duct and said second compartment has at least one second aperture that acts as an outflow mouth of said at least one duct, said at least one duct comprising at least one connector element applied to the inner storage cabinet so as to fluidly connect said first and second apertures (23A,23B) one another, characterized by at least one door associated with said external housing cabinet for closing the accesses of said first and second compartments (13, 14) and said at least one air passage comprises a gap between said partition wall and said door.