No. R744 operates on pressures up to ten times higher than R134a. Although it has been used for some time in stationary equipment, developing R744 systems for automotive applications has been a significant engineering challenge, with unique components and system layouts required for this refrigerant.
In heating mode, the performance of R744 HP system is much better than R134a HP system. The R744 HP system with or without battery cooling/heating shows a similar cooling/heating capacity, the COP of the system becomes larger if there is a demand for battery heating in cold weather.
Possible alternatives to R-134a
Attention is increasingly focused on low-GWP refrigerants that are hydrofluoroolefins (HFO). R-1234yf in particular is often seen as a possible alternative to R-134a. The GWP value of R-1234yf is 4, which means it has a very low global warming potential.
The GWP for R-134a refrigerant is 1,430, making it 1,430 times more harmful than carbon dioxide when released into the atmosphere. There are three refrigerants that can be used to replace R-134a: R-1234yf, R-152a, and R-744.
R744 (CO2) is refrigerant grade CO2, used as a replacement for R134a and R404A in ultra-low, low and medium-temperature refrigeration applications.
At this point, the use of R744 as a refrigerant began to decline as more and more businesses turned to synthetic gases instead. Years later, it became clear that these new refrigerants were depleting the ozone layer. HFC refrigerants were developed to replace them, which are still used today.
R744 is the refrigerant name for carbon dioxide, which first appeared in high-end cars from German brands including Mercedes-Benz and Volkswagen Group on the European market. CO2 requires operating pressures up to ten times higher than R134a.
A High-Performing Alternative to R-134a
Opteon™ XL10 (R-1234yf) refrigerant is a non-ozone depleting (ODP) hydrofluoroolefin (HFO) option that meets the industry's growing demands for sustainable, safe, and effective solutions.
Refrigerant R513A - Drop-In Alternative for R134a. R513A was developed as a replacement refrigerant for R134a. R513A is a modern, non-flammable refrigerant designed to replace R134a in a wide range of applications. It provides a sustainable solution for both new systems and retrofits.
The chemical stabilities of copper, steel, and aluminum have been tested and confirmed as acceptable for use with Freon™ 134a and lubricants. Acceptable plastics and elastomers have been found for use with existing CFC refrigerants.
Some notable substitutes for R134a [10] in AAC based on the preceding studies are R1234yf [[11], [12], [13], [14]], R1234z (E) [[15], [16], [17]], R152a [[18], [19], [20]], R290 [21,22], R744 [[23], [24], [25]], R430A [26,27], and R444A [28], etc.
In the United States, vehicles produced after 2021 no longer contain R-134A in the air conditioning system. In other parts of the world, including the United States, there are restrictions around using 1,1,1,2-tetrafluoroethane. Specifically, in California, retailers can deny selling customers canned R-134a.
With the scientific approach to reduce the global warming potential (GWP) of the refrigerant R-134A (i.e. 1430), the refrigerant R-513A with GWP of 631 is the drop-in replacement.
R744 (CO2) is refrigerant grade CO2, used as a replacement for R134a and R404A in ultra-low, low and medium-temperature refrigeration applications.
Still, the answer is an emphatic, “No.” Not only would a retrofit of this type negate the environmental benefits of R-1234yf, but it would also be a violation of Federal Law under Section 203 of the Clean Air Act: “tampering” with a vehicle's emissions control device.
The short answer is that the Global Warming Potential (GWP) of HFC-134a is significant and there are replacement gases available that have less environmental impact. The EU has banned most uses of HFC-134a.
GWP is expressed as a factor of carbon dioxide where its GWP is equal to 1. The GWP for R-134a refrigerant is 1,430, making it 1,430 times more harmful than carbon dioxide when released into the atmosphere. There are three refrigerants that can be used to replace R-134a: R-1234yf, R-152a, and R-744.
A Next-Generation R-134a Refrigerant Alternative
Opteon™ XP10 (R-513A) refrigerant is a non-ozone depleting potential (ODP), low global warming potential (GWP) hydrofluoroolefin (HFO) based replacement for R-134a.
You're wondering if you can mix different refrigerants for your air conditioning system. The short-long-only answer is no, never. There are many reasons why it's impractical, illegal, and not economical for a homeowner to mix refrigerant types.
While the production of new R12 is banned, it is not illegal to sell or use R12. In fact, many of the cylinders and cans of Freon R12 sold for decades throughout the United States are still around today.
Substitution of R134 with R744 working in a transcritical cycle. Optimization of the transcritical cycle exergetic performances. The exergetic performances of R134a are better than that of R744 (from +20 to +44%).
However, R-744 is unlikely to be used as a refrigerant in some applications because of its high working pressure. This creates challenges in the design and operation of refrigeration systems and can increase costs.
CO2 (R744)
Exempt from the Section 608 venting prohibition, meaning it is legal to knowingly release this refrigerant to the environment; however, CO2 is not exempt from the Section 609 requirements such as use of certified refrigerant handling equipment.