Refrigerants – general information
Definition of a refrigerant
In refrigeration and HVAC systems, a refrigerant is a natural or synthetic working substance that performs a series of thermodynamic transformations and participates in heat transfer. It acts as a cooling medium in an evaporator by absorbing heat from another substance, such as air heated by stored products. Refrigerants exist both as pure, single-component substances and as mixtures of various components.
How do refrigerants work?
Refrigerants absorb heat from the cooled product or space at low temperature and pressure and release it at high temperature and pressure due to their appropriate physical and chemical properties. Since such heat transfer, according to the second law of thermodynamics, cannot occur on its own, external energy must be supplied to compress the refrigerant. For most refrigerants, the effect of heat absorption and rejection is a phase transition: evaporation and condensation, respectively. The latent heat of these phase transformations varies with the type and thermodynamic properties of the refrigerant. The higher the value of the latent heat of vaporization, the more energy can be taken away from the substance to be cooled.
Where refrigerants are used?
There are many examples of applications of refrigerants in everyday life. The most common are domestic refrigerators, freezers, air conditioning units, and heat pumps. One of the main application of refrigerants is in the food industry. Here we can distinguish commercial food storages of fruits, meat, vegetables, dairy products, and others. Refrigerants are also used in cooling devices of grocery stores such as cooling cabinets and counters. We can find them also in transportation industry, for example in the installation of car or plane air conditioning. Another examples of mobile refrigeration systems are trucks, ships, and trains, where refrigerants are used to keep low temperature of food and other temperature-sensitive products must be shipped in a long distance. Refrigerants are also used in the pharmaceutical, medical industries, and winter sports, for example in the cooling systems of ice rinks and ski jumps.
Properties of an ideal refrigerant
The refrigerant used in refrigeration systems is usually selected depending on the type of application. Unfortunately, there is no refrigerant that meets all the major requirements for every kind of systems. For example, the best refrigerant for low-temperature applications will not be as good for medium-temperature applications. Therefore, the working medium shall be selected consistently to best suit to the chosen application. The ideal refrigerant should have the parameters shown in the table.
GWP and ODP – what does it mean?
Many refrigerants, especially synthetic ones, have a negative effect on the environment and the atmosphere. To determine the environmental impact of a refrigerant, two indicators were introduced:
GWP – Global Warming Potential
It is a relative indicator of heat absorbed and trapped in the atmosphere by a certain mass of any greenhouse gas. According to the standard, the GWP value for a gas is a multiple of the heat that would be absorbed by the same mass of carbon dioxide CO2, for which the value is equal to 1. For example, the leakage of 1 tonne of R134a refrigerant (GWP=1430) is equivalent to the emission of 1430 tonnes of CO2.
ODP – Ozone Depletion Potential
It is a relative indicator of the effect of a given substance on ozone layer degradation, compared to the R-11 refrigerant for which the ODP value is set equal to 1. Specifically, ODP is defined as the ratio of global loss of ozone due to the given substance to the global loss of ozone due to CFC-11 of the same mass.
Natural refrigerants as one of the leading refrigeration industry trends
Thanks to the sustainable development of refrigeration technology, ecological awareness both of consumers and the industry, and the growing need to protect the environment, we observe the increase in the quantity of natural refrigerant condensing units operating on the market.
Area Cooling Solutions provides smart solutions for a green future. With our inverter iCOOL CO2 condensing units, we contribute to reducing the environmental impact.
