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CO2 as a Refrigerant — Comparison of R744 with Other Refrigerants

This is post number six of a series, and compares CO2 to both traditional and new refrigerants.

R744 vs. Other Refrigerants

Table 1 shows a simple comparison of R744 with other types of refrigerants, including those that are currently commonly used and those that are currently being evaluated for future use. It uses a simple “traffic light” system and employs the common HFCs, such as R404A and R134a as a baseline.

This provides a simple introduction to the options — the situation varies globally, especially in the availability of refrigerants, components and expertise.

For retail applications a well-designed and installed R407A/F system generally has better efficiency than R744 systems. However, the overall environmental performance of R744 systems is better, primarily because of the low GWP in the event of leakage.

Table 1: Comparison of R744 with other refrigerants

Table 1: Comparison of R744 with other refrigerants

Blog post seven in this series will weigh the advantages and disadvantages of R744.

Andre Patenaude
Director – CO2 Business Development, Emerson Climate Technologies

Visit our website for additional information on CO2 Solutions from Emerson. 
Excerpt from original document; Commercial CO2 Refrigeration Systems, Guide for Subcritical and Transcritical CO2 Applications.

To read all posts in our series on CO2 as a Refrigerant, click on the links below:

  1. Series Introduction
  2. Criteria for Choosing Refrigerants
  3. Properties of R744
  4. Introduction to Trancritical Operation
  5. Five Potential Hazards of R744
  6. Comparison of R744 with Other Refrigerants
  7. R744 Advantages / Disadvantages
  8. Introduction to R744 Systems
  9. Introduction to Retail Transcritical Systems
  10. Retail Booster Systems
  11. Introduction to Retail Cascade Systems
  12. Introduction to Secondary Systems
  13. Selecting the Best System


6 Comments Post a comment
  1. Mark Buller BEng, Instructor, BCIT #

    It is interesting to see the fig. 1 diagram which seems to indicate, in order of usefullness (ie. red bars), that HC and R717 have the best usefulness when it comes to the criteria shown in the chart. More “green and yellow” lights would lead one to believe that these would be the best types of refrigerants to use not withstanding the flamability and toxicity challenges of the refrigerants with the most “green and yellow” lights.
    Given that the above comments are not the only criteria that are use in selecting a system and the refrigerant that is to be used, education for the professionals in the trade is and should be ongoing.

    July 22, 2015
    • Andre Patenaude #

      Mark, good observation. At a quick glance some might make that assumption, however selecting the right refrigerant for your market, application and to align with your company’s sustainability goals is not a simple decision. As you pointed out education is key!

      July 24, 2015
  2. Kapil singhal #


    You have captured HFOs as similar to HFCs from environmental impact. My view it should be green due to low GWP


    July 24, 2015
    • Andre Patenaude #

      Excellent point. Yes pure HFOs would have a better environmental impact from a weighted GWP point of view, however since we haven’t had a chance to calorimeter test many of them yet we are not 100% sure of their environmental impact due to indirect source such as energy efficiency.

      July 24, 2015
  3. Thanks for sharing good knowledge and information, this is very useful and understandable .. because we have been looking for this information for a long time. I am very thankful to your post.

    October 10, 2018
    • emersonadmin #

      Hi Jan!

      Thanks for the great feedback! 🙂 We try to always provide informational and knowledgeable information that will help our viewers.

      October 10, 2018

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