Absorption refrigerating machine

Thermally driven cold-vapour machine that absorbs the refrigerant vapours emitted by a liquid or solid; the vapours are driven out again by supplying heat at higher energy level.

Air-conditioning refrigeration system

Refrigerating machine used as part of an air-conditioning system to cool and dehumidify (as needed) the air.


Mixtures of refrigerants, selected to give particularly desireable, or to avoid particularly undesireable properties.

Cascade refrigerating plant

Refrigeration system consisting of two cycles, which usually use different refrigerants.

Chill Refrigeration

Refrigeration for storage conditions above 0°C.

Chlorinated hydrocarbons

see Halogenated hydrocarbons

Chlorofluorocarbons (CFCs)

CFCs are relatively non-toxic. They are used as propellants in spray cans, as refrigerants and as solvents in dry-cleaning. CFCs are very stable and non-combustible. CFCs destroy the protective ozone layer in the stratosphere. The culprits are chlorine atoms contained in the CFCs, which are released through photolysis. This leads to increased UV radiation on Earth, which among other things results in an increased incidence of skin cancer and crop failures. Compared with the climate effects of carbon dioxide, CFCs have a global warming potential that is 3,000 to 8,000 times higher. Between 1950 and 1980 approx. 11.5 million tons of R11 and R12 alone were produced. Germany has banned CFCs and halon since 1991 (CFC-Halon-Verbots-Verordnung). This ban and other climate-protection measures will not have any effect in the short term, as CFCs take roughly 15 years to reach the stratosphere and do their damage there. HCFCs, FCs and HFCs, which are currently used as substitutes, also have a greatly increased global heat potential.

Cold air machine

Mechanically driven refrigerating machine that operates on the cold gas principle. It uses air as a refrigerant. Usually, an expansion engine is used to expand the compressed refrigerant producing mechanical power.

Cold chain

The virtually uninterrupted refrigeration of a product between the time of its manufacture and its consumption, including transport and storage.

Cold gas process

Process in which the refrigerant remains in a gaseous state during the entire work cycle.

Cold vapour machine

Refrigerating machine that operates on the cold vapour process principle.

Cold vapour process

Thermodynamic process in which the refrigerant goes through at least one change between liquid and gaseous states.

Comfort air conditioning

Air-conditioning in residential, work and recreational spaces, using man-made refrigeration with the aim of creating comfortable conditions in the room.

Compression refrigerating machine

Cold vapour machine with a mechanical compressor (positive displacement or centrifugal compressor).


Coefficient of Performance / Relationship between refrigerating capacity (output) and power input, index used to rate the efficiency of a refrigeration system.


Refrigeration at storage conditions between approx. -18 and -30°C.

Evaporation temperature

Temperature at which a refrigerant evaporates, thereby drawing heat from its surroundings.


Thermodynamic quantity that represents the technically useful part of energy.

Final energy

Energy available at the place of consumption.

Greenhouse gases

Gases in Earth's atmosphere that impede the radiation of heat from the Earth's surface into space.


Global Warming Potential / Greenhouse potential (CO2 equivalent) Global Warming Potential (GWP) The greenhouse effect arises from the ability of substances in Earth's atmosphere to reflect the heat radiated by the Earth back onto our planet. The direct greenhouse potential (GWP) of a compound is expressed as its' CO2 equivalent (GWP of a CO2 molecule = 1; 100-year time frame). Ammonia (NH3) 0 Carbon dioxide (CO2) 1 Hydrocarbons (propane C3H8, butane C4H10) 3 Water (H2O) 0 Chlorofluorocarbons (CFC) 3.800–8.100 Hydrochlorofluorocarbons (H-CFC) 90–1.800 Fluorocarbons (FCs) 6.500–11.700 Hydrofluorocarbons (HFCs) 140–3.800

Halogenated hydrocarbons

Collective term for hydrocarbon compounds containing halogens such as chlorine, fluorine or bromine: CFC, H-CFC, FCs and HFCs. The chlorinated hydrocarbons in particular are risky. Highly toxic chemicals may escape during their production. Halogens are stable, endanger the environment, have negative effects on the ozone layer and climate and accumulate in human fatty tissue and in mothers' milk. Halogens are also suspected of being carcinogenic. Halogens are used as solvents, propellants, refrigerants and pesticides.


Halogens is the term used to describe the chemical elements fluorine, chlorine, bromine, iodine and astatine. Halogens are essential for people (fluorine, chlorine and iodine), but are also toxic and corrosive to varying degrees. In elemental or loosely bound states, they are used as disinfectants. Halogens react especially violently with hydrogen. Dissolved in water, these compounds form strong acids.


Hydrocarbons, in organic chemistry, are chemical compounds composed of carbon and hydrogen.

Industrial air conditioning

In production processes, atmospheric conditioning using technology-induced refrigeration, where maintaining certain atmospheric conditions is crucial to the production process.

Liquid chiller

Refrigerating machine for cooling a liquid (secondary refrigerant).

Low temperature technology

A branch of refrigeration (or cryotechnology) that deals with the generation of temperatures below approx. -120°C.

Natural refrigerants

Natural refrigerants occur in nature's material cycles without human intervention. These materials include ammonia, carbon dioxide, natural hydrocarbons, water and oxygen.


Ozone Depletion Potential / Ozone Destruction Potential more

Primary energy

Energy content of energy sources not yet subjected to modification/transformation.


Substance that circulates in a refrigerating machine, taking in heat (flow) at low temperatures and releasing it again at higher temperatures.

Refrigerating capacity

Heat (flow) removed from the environment by the refrigerant.

Required power input

Power required by a refrigerating machine to produce a given refrigerating capacity.

Secondary refrigerant

Liquid used to transport heat between the items or spaces to be chilled and the refrigerating machine.

Synthetic refrigerants

Synthetic refrigerants are man-made substances. They include CFCs, H-CFCs, HFCs and FCs.


Total Equivalent Warming Impact: Method for calculating the total impact (direct and indirect) of a refrigeration system on the greenhouse effect.

Total cooling requirement

The total cooling requirement of a group or several groups of refrigerant applications.

Total energy requirement

Total electrical, mechanical or thermal end energy required to drive a refrigerating machine.

Transport refrigeration

One field of refrigeration; deals with the cooling of goods during transport.