Both industrial refrigeration and air-conditioning are based on the same mechanism: the cooling of a substance. The refrigerating system made up of a compressor, evaporator, fan, condenser and expansion device, is the heart of both systems. Despite this, there are substantial differences between the systems, the components used, the design methods and the structures they are used in, such as to merit separate treatment.
Refrigeration is the process by which the temperature of fluids or bodies in general is decreased. In particular, it is used for the temporary storage and processing of perishable goods by the forced lowering of the temperature. If the temperature falls below freezing point, the process is no longer strictly called refrigeration, however this term can be loosely applied to include all processes that reach temperatures down to -60°C.

Food conservation involves various procedures, only one of which is refrigeration, which differ according to the duration:

• Refrigeration if the food is to be stored for a short time (0°C / +7°C).
• Freezing, deep-freezing, freeze drying if the food is to be stored for long periods.

For deep-freezing, the product must reach-18°C in less than 4 hours, while for freezing the product can reach -18°C in more than 4 hours. During freeze drying, the product is dried by the evaporation of its water content.

In the food industry, refrigeration is one of the more delicate and complex applications, as the food requires treatment at different temperatures according to the phase of processing. Refrigeration slows down the proliferation of bacteria in food: the technique used in practice is based on the extremely rapid and intense action of the cooling effect, which allows the organoleptic properties of the food to be preserved intact, thus extending the conservation time.
The systems designed and installed for both industrial and retail applications are based on standard procedures and techniques. The refrigeration system is just part of a more complex installation that allows the evaporator to define the ideal level of heat exchange and consequently the ideal storage of the food.

The main refrigeration units used for the conservation of food are:

• Cold rooms
• Maturing rooms
• Cabinets
• Display cases

The storage time of most food items is increased by storing them at low temperatures. The main foods that require conservation at low temperature are: meat, fish, fruit and vegetables. Some foods, such as meat, fish and bread, can also be stored by freezing (temperatures between -20°C and -30°C), without undergoing substantial variations.
In some cases, refrigeration may also represent one of the phases in the food production process.
The main foods that include refrigeration in their production process are: cheeses, drinks (beer, wine and frozen juices), bread and instant coffee.