Abstract: An expendable refrigeration system is disclosed for use with an insulated storage compartment. The system utilizes a concept of the liquid coolant storage reservoir being kept at a cold temperature and withdrawing heat from a storage compartment. The pressurized uninsulated liquid carbon dioxide storage reservoir is within the storage compartment and has a vent from a gaseous space in the liquid storage reservoir. A pressure relief valve is installed in the vent adapted to maintain a substantially constant pressure within the liquid storage reservoir, such that the temperature of the liquid carbon dioxide within the storage reservoir is controlled and is below the desired temperature within the insulated storage compartment.