Our Refrigerant Focus series delves into the history, properties, suitable applications, and pros and cons of some of today’s popular or otherwise noteworthy refrigerants. This installment will focus on R-744 (CO2).

Check out some of our refrigerant focus posts below.

• Refrigerant Focus #1: R-32
• Refrigerant Focus #2: R-410A
• Refrigerant Focus #3: R-1234ze
• Refrigerant Focus #4: R-407A
• Refrigerant Focus #5: R-290

Note: the following is a transcript of a podcast recorded on November 8, 2021. To listen, check out the SRC Podcast here or wherever you get your podcasts. 

Hello and welcome to another SRC podcast. On today's episode, we'll be talking about a new EPA rule regarding the phasedown of hydrofluorocarbons. We touched on this in our last recording, and since, there has been developments in terms of at that time, it was a proposed rule. It has now progressed to the point where it is a final rule. Since that development, we thought it'd be a good time to revisit this topic. Today, we're going to be talking about exactly what the implementation of that rule will look like, and then we'll also quickly review the contents of the rule. 

Note: the following is a transcript of a podcast recorded on July 14, 2021. To listen, check out the SRC Podcast here or wherever you get your podcasts. 

Hello and welcome to another SRC podcast. For this recording, we're going to be focusing on a proposed new rule from the EPA that's titled "Phasedown of Hydrofluorocarbons: Establishing the Allowance, Allocation, and Trading Program under the American Innovation and Manufacturing Act."

In a refrigeration circuit, the evaporator coil plays a critical role. Part of its responsibility is creating the controlled pressure drop necessary for the refrigerant to change phase, the bulk of which occurs via the system’s metering device, such as a thermostatic expansion valve (TXV).

In fin tube heat exchangers, the fluid (gas/water/glycol/refrigerant/etc.) circulating through the coil’s tubes is extremely important for the coil’s overall performance – it’s half the battle, along with airside heat transfer. The degree to which the fluid contacts the tube walls affects the coil’s performance and influences a system's overall efficiency – the more the fluid comes into contact with the tube wall, the better – and more economical – the heat transfer.

Around 2010, the first refrigeration systems operating on transcritical CO2 began cropping up in North American supermarkets. Since then, usage of transcritical CO2 systems has grown steadily and they’ve become viable options for places like supermarkets, food warehouses, and ice rinks, as more organizations move away from traditional HFC refrigerants. Natural refrigerant market accelerator Shecco estimates that transcritical CO2 systems grew from 140 in 2008 (all in Europe) to more than 35,000 systems worldwide today.

There are dozens of commercially available refrigerant options on the market today, including numerous refrigerant blends, which aim to replicate the effectiveness of former workhorses like R22, the production of which was made illegal as of January of this year. Two popular examples of refrigerants developed in the last 30 years or so that are used in the HVAC industry are R-410A and R-407C. These two refrigerants are often used for similar applications, but they have some marked differences that should be understood and considered when deciding between them.

This article has been updated. It is accurate as of 9/23/20.

For commercial operations that rely on effective heat transfer, external corrosion of heat exchanger components is a major concern. When left unchecked, corrosion can significantly reduce a coil's effectiveness, but sometimes it’s difficult to know which anti-corrosion option best meets your needs.