CO₂ as a Refrigerant – Blog Series Introduction

This is the first post of CO₂ as a Refrigerant, a blog series covering the fundamental considerations and characteristics of CO₂ as a refrigerant (R-744). CO₂ offers a proven, sustainable refrigeration strategy — with a global warming potential (GWP) of 1 and zero ozone depletion potential — but introduces new system design, application and handling considerations.

Commercial refrigeration has been under increasing environmental scrutiny for more than a decade, especially as studies have revealed the true effects of leaked hydrofluorocarbon (HFC) emissions. A global phasedown of HFC refrigerants is underway, and reducing leaks in the existing equipment installed base is a top priority for industry stakeholders. In response, manufacturers are introducing a variety of lower-GWP refrigerant options and system architectures — creating an ever-expanding range of choices for refrigeration equipment decision-makers.

The significant environmental advantages of R-744 have solidified its market position as a leading option for future refrigeration systems. Not only has R-744 demonstrated favorable results in different system configurations for more than two decades — particularly in Europe, Australia and Canada — but it is also experiencing increased popularity in the U.S. First and applied costs are now on a downward trend, while innovations in component technology and application methods continue to deliver real-world performance gains. These advancements and developments have helped to ensure that CO₂ will continue to be a viable option for 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 R-744 and examine how it meets traditional and emerging needs for refrigerants and equipment technologies. Throughout this series, I will also cover some of the reasons how and why CO₂ refrigeration systems differ from traditional HFC systems, notably the design considerations needed to adapt to supercritical operation under certain conditions. Additional topics and considerations for using R-744 will be explored, including the basics of R-744 systems; more detailed information about the design of CO₂ booster, single-stage and cascade systems; and key points about their commissioning, operation and servicing.

In the next CO₂ as a Refrigerant post, I will discuss the primary considerations and criteria for choosing refrigerants, examining multiple factors, and assessing R-744’s effectiveness at meeting key selection criteria.