CO₂ as a Refrigerant — Series Introduction

CO2 offers refrigeration with low global warming impact, but with new application and handling considerations

This is post number 1 of a series.

Commercial refrigeration has been in the environmental spotlight for more than a decade, especially as leakage studies have revealed the true effects of hydrofluorocarbon (HFC) emissions. Considerable reductions in emissions are possible, but implementing them is having a major impact on the refrigeration industry. In response, many new refrigerant options and system architectures have appeared — both on paper and in practice — creating tricky choices for decision-makers in commercial refrigeration.

The significant environmental advantages of R744 (CO₂) have guaranteed its position as a leading option for future refrigeration systems. It has demonstrated favorable results in different system configurations over many years, particularly in Europe, Australia and Canada. Initially high investment costs are now on a downward trend, while innovations in component technology and application methods continue to reveal potential performance gains. These results have ensured that CO₂ will be a long-term option in the foreseeable future.

This post is the first in a series that will introduce CO₂ as a refrigerant. The blog series will summarize the properties of R744 and examine how well it meets traditional and emerging needs for refrigerants. The series will also covers some of the reasons why CO₂ refrigeration systems differ from conventional systems, notably the design considerations created by the need for transcritical operation under certain conditions. Other topics concerning R744 will also be examined, including the general aspects of R744 systems; more detailed information about the design of R744 cascade, transcritical booster and secondary systems; and key points about their commissioning, operation and service.

In the next post, I will discuss the basics and considerations in criteria for choosing refrigerants. Multiple factors need to be carefully considered and we’ll take a look at how well R744 meets key criteria.