After many years of oblivion of carbon dioxide, the interest to it from the side of developers of refrigeration equipment has recently increased noticeably, which is caused primarily by aggravated environmental problems. In recent years, many cascade installations for commercial and industrial low-temperature cooling (t₀ = - 50 °С) have been successfully put into operation. It should be kept in mind that in comparison with other refrigerants C0₂ has better thermophysical properties in this mode. This is chemically inert, fire and explosion-proof substance.

The comparative temperature conditions currently used for testing compressors according to standards ASHRAE 41.9, EN 12900 and G OST17008-85 do not correspond to the real operating conditions in domestic refrigerators. The standard ASHRAE is totally unacceptable for the assessment of characteristics of compressors operating on different refrigerants, The European standard is more acceptable, but the most objective comparison of compressors can be obtained only under temperature conditions actually existing in domestic refrigerators during most part of the year.

To evaluate the compressors working on zeotropic mixtures it is necessary to use the equivalent thermodynamic cycles that are considered in this article. If the compressor is designed for work in a two-compartment refrigerator its tests should be carried out according to a special cycle.

In 2001, the medium-capacity CO₂ screw compressor units with a cooling capacity of 750 kW for use as part of cascade refrigeration systems were presented at the IKK Hannover exhibition.
Today Grasso offers cascade refrigeration systems based on screw compressor units for CO₂/NH₃ with refrigerating capacity of 280 ... 2587 kW at boiling point in the lower branch of the cascade -45 °С.

R404A (FX70) refrigerant is a quasi-azeotropic mixture of R125/R143/R134a with a 44/52/4 component mass fraction ratio. Temperature glide is less than 0,5 °С. Environmental characteristics: ODP = 0, HGWP = 0.94. Initially (since 1993) R404A refrigerant has been used in the new equipment designed for low and middle boiling points.At present time R404A is used for retrofit of the systems operating on R502, and in the new equipment (instead of R22). R404A refrigerant is used in refrigerated containers for obtaining low temperatures, it is also promising for application in ship refrigerated transport.

Plate freezers are complex and expensive equipment, the purchase of which is a long-term investment. Its correct choice (performance, reliability, ease of operation, maintainability) determines the return on investment. To facilitate the consumer the difficult task of choosing the plate fast freezing equipment, we give a description of the principles of its operation and different options of technical design.

At present, the range of compressor equipment produced by Danfoss is clearly visible in two areas: Danfoss Household Compressors - compressors and compressor-condensing units for household and commercial applications and Danfoss Commercial Compressors - compressors and compressor-condensing units for commercial applications.

The experience of application of self-conditioning systems in modern multistory buildings is described. The layout of provision of unit blocks of central air conditioners with self- contained sources of refrigeration is presented. Characteristics of compressor units added to standard central air conditioners are given. The calculation of operating conditions of the air conditioner in the warm time period in Moscow is presented.

Frost freezing of frosty soils in the bases of refrigerators occurs in most cases as a result of dampening of thermal insulation in the floors, which is associated with a long period of operation and deterioration of its thermal and technical properties. The cause of freezing can be periodic and sometimes permanent shutdowns of floor heating systems, as well as changing the temperature mode of storage without the agreement of the design organization. All these options lead to negative consequences.

The production of chilled and frozen food products on an industrial basis offers broad prospects for organizing a balanced diet and improving the structure of the supply of high-quality foodstuffs. At the same time the widespread construction of wholesale and consumer markets, the development of trade functions of industrial and distribution refrigerators, vegetable depots and shopping centers require the observance of strict hygienic standards provided for by SanPiN 2.3.2.1078-01. In this document, hygienic standards for microbiological safety indicators for the first time include control of foodstuffs for the presence of Listeria monocytogenes, a pathogenic microorganism particularly dangerous for people (Listeria).
Considering the ability of Listeria to multiply in ready-to-eat food products when stored in refrigerators at low temperatures, which are traditionally used to suppress bacterial growth, the processing and food industries of various countries have to spend enormous resources to prevent production of contaminated products. The social and economic damage caused by this foodborne infection is also connected with the high mortality rate. In the United States, for example, annual damages from foodborne listeriosis range from $230 million to $313 million per year.