Due to the significant role in the destruction of the ozone layer, the previously widely used refrigerants (chlorofluorocarbon CFCs) were mostly replaced by hydrofluorocarbons and hydrochlorofluorocarbon refrigerants (HFCs and HCFCs). However, they have also recently come under regulation due to their high global warming potential (GWP). For example, the previously widely used R-134a refrigerant (CFC) has a GWP value of 1300, which means that kg of R-134a is equivalent to 1300 kg of CO2 when viewed its contribution to global warming. Based on this, the possibility of using other refrigerants with a low GWP value was studied. Two suitable candidates are propane and CO2. Using CO2 is potentially attractive because it is toxic and combustible. However, its use requires a higher value of the working pressure than HCFCs, which toughens the requirements for materials that are used as gaskets and seals.
Speaking about the cost of refrigerants, which are currently actively used in industry, namely HFCs, it is much higher in comparison with natural ones. Moreover, there is an increase in the cost of artificial refrigerants, which makes their use less appropriate.
Indicators of ozone-depleting potential and global warming potential under the current provisions of the Montreal Protocol is one of the keys, since these values govern the possibility of using refrigerants in the Russian Federation, which has assumed the obligations of this protocol. Thus, for a natural CO2 refrigerant, two of these indicators are equal: ODP = 0; GWP = 1. Natural refrigerants are also explosion-proof and are characterized by relative non-toxicity. However, it is worth noting that the operating pressures in systems where CO2 is used are higher than those of plants operating on HFCs and HCFCs. This fact requires a special approach to the design of these systems and special training of personnel who will maintain and operate these installations. This means that in order to change the pressure per unit of the measured value, it is necessary to change the temperature by a lower value, in contrast to artificial refrigerants. As a result, minor pressure losses are less pronounced and acceptable with respect to concerning CO2 than in other refrigerants.
|Affiliation of speaker||ITMO University|
|Publication||Impact Factor journals|