Development and investigation of a natural refrigerant for low-temperature applications

In the EU Regulation 517/2014 on fluorinated greenhouse gases, which has been in force since 1.1.2015, with the phase-down or reduction of the greenhouse-promoting refrigerants regulated. Due to the lack of suitable replacement refrigerants, there is currently no exemption for the area of cryogenic refrigeration with application temperatures (refrigerated goods) of less than -50°C. Apart from the fluorinated refrigerants used up to now, which have a high direct contribution to the greenhouse effect, there are currently only combustible alternatives such as ethane. The development of a new refrigerant with thermodynamically favorable properties that is safe to use was the focus of the project presented here. To this end, a mixture of nitrous oxide (N2O), also known as laughing gas, and carbon dioxide (CO2) was investigated for its suitability as a low-temperature refrigerant. This included, in addition to series of measurements on a test plant, corresponding investigations into the possible decomposition of the mixture as well as the material compatibility with the materials and operating materials normally found in a refrigeration plant, such as the refrigerating machine oil used to lubricate the compressor. 

Maurath T, Kauffeld M: Development and investigation of a natural refrigerant for cryogenic applications. In: Forschung Aktuell, ISSN 1613-4958 (2019), pp. 60-64 (Electronic publication: Research Aktuell 2019)