The Nestlé operations in Beauvais,France, produce a variety of frozen foods and ice cream. The production plant, and the warehouse used to store products prior to shipment must be maintained at temperatures between -20º and -30º C. A substantial amount of refrigeration is
necessary to maintain such temperatures in the 80 000 m3 warehouse.

This refrigeration was achieved using halon, an ozone depleting substance. As a result of Nestlé’s global phaseout programme, and also of international agreements to stop production and use of these substances, the Company began looking for suitable alternatives.

The early solution at many Nestlé factories was to revert to the use of ammonia as a refrigerant. Ammonia systems are technologically proven and operate efficiently in food manufacturing. However, these systems require certain safety precautions, particularly in large installations.

The solution found by Nestlé’s engineers in Beauvais was to use two substances. Because of its excellent properties as a refrigerant, a very small amount of ammonia was used as the primary refrigerant in an isolated system.

This system then cools a secondary material, CO2, which is used in the extensive network of coolers throughout the warehouse. This type of two-phase refrigeration allows the use of a minimal amount of ammonia and isolates it from the process areas, thus greatly reducing the risk of an accident. Using CO2 in the production areas is better, as it non-toxic, non-flammable and has little impact, should a leak occur from the closed system.

Further details regarding this issue can be found in the document: CO2 freezer story

Read more about Refrigerants.