Sub-cooling system of a compression-refrigeration system

Method of refrigerating and maintaining at temperature an insulated enclosure comprising essentially two steps, i.e. a step of cooling to a specific desired temperature of said enclosure, and a step of maintaining said enclosure at said desired temperature, implementing an installation comprising:

• a refrigeration unit comprising a compressor driven by a heat engine, a refrigerant circulation circuit, a pressure reducing valve, a condenser and an evaporator and,
• a thermochemical type cooling system comprising a reservoir containing a liquefied gas capable, after evaporation, of being combined with a reactive product contained in a reactor, and which is composed of a mixture of a reactive salt and expanded natural graphite, the apparent density of the latter being between 100 and 120 kg/m3 and the proportion by mass of the salt in the reactive product being between 50% and 75%, said combination being accomplished according to an exothermic thermochemical reaction, the reaction product obtained being capable of being regenerated by heating while releasing said gas according to an inverse thermochemical reaction, wherein:
• during the cooling step, the refrigerant of the refrigeration unit is cooled by a thermochemical cooling system before it enters the evaporator,
• the reaction product is heated by means of the heat released by the heat engine.