Cooling unit

A cooling unit for storing temperature-sensitive goods at a desired cooling temperature, said cooling unit comprising

• a cooling compartment for storing the temperature-sensitive goods,
• an insulation separating the cooling compartment from an ambient space,
• a multi-stage cascade refrigeration system adapted to cool down the cooling compartment to the desired cooling temperature and/or maintain the desired cooling temperature in the cooling compartment, said multi-stage cascade refrigeration system comprising at least a high-temperature refrigeration cycle and a low-temperature refrigeration cycle,
• wherein said low-temperature refrigeration cycle comprises a low-temperature evaporator arranged to absorb heat from the cooling compartment, and whereas the high-temperature refrigeration cycle comprises a high-temperature condenser arranged to reject heat to the ambient space,
• wherein a high-temperature evaporator of the high-temperature refrigeration cycle is thermally coupled to a low-temperature condenser of the low-temperature refrigeration cycle in order to form an intercooler of said high-temperature refrigeration cycle and said low-temperature refrigeration cycle,
• wherein a heat exchanger selected from the group consisting of said high-temperature evaporator and said low-temperature condenser is thermally coupled to the insulation, wherein the heat exchanger is thermally coupled to the insulation by means of a heat collector, wherein said heat collector is either arranged inside the insulation or in contact with a surface of the insulation, wherein a thermally active surface of the heat collector is larger than a thermally active surface of the heat exchanger, and wherein the thermally active surface of the heat collector is at least twice as large as the thermally active surface of the heat exchanger.