R-744

A Look

I am a big fan of history and can never get enough of reading historical books or watching documentaries. If you don’t understand the past then how can you understand the present or even the future? While refrigerant history might not be as interesting as other historical topics it is still good to understand it. R-744 can be traced back all the way back to the nineteenth century. In fact it was one of the very first refrigerants to ever be developed and used across the world. Experiments in refrigeration began in the late seventeen-hundreds and began to pick up speed in the eighteen-hundreds. It was in 1850 that Carbon Dioxide was first proposed as a refrigerant by Alexander Twinning. In 1869 one of the very first ice machines invented used Carbon Dioxide. Then in 1897 the first Carbon Dioxide refrigerator was introduced. More and more inventions and innovations followed.

In the late 1800’s and the early 1900’s there were a few mainstream refrigerants that we saw. These were your natural and hydrocarbon refrigerants such as Ammonia, Propane, Isobutane, and Carbon Dioxide. At this time Carbon Dioxide was found in all kinds of applications ranging from display cabinets, cold storage areas, market places, home/commercial kitchens, movie theaters, hospitals, trains, and even on cargo transport ships. The other natural refrigerants weren’t used as widely as Carbon Dioxide due to their safety concerns.

It seemed that R-744 was going to reign supreme as the main refrigerant in the world. This held true until the 1930’s. It was then that a partnership was formed between General Motors and DuPont. This partnership was made with one goal in mind: To create a cheap, safety, and reliable refrigerant. While Carbon Dioxide was safe it had it’s own problems. Just like we mentioned in our Pros and Cons section R-744 systems had numerous failures due to the extreme pressure that they operated under. The technology just wasn’t there to prevent these failures either so these air conditioners and refrigerators would bey very expensive to maintain.

After some time the General Motors & DuPont partnership came out with a new artificial class of refrigerants known as CFCs and HCFCs. Some of the refrigerants in this new classification were R-12 and R-22. These new refrigerants checked all of the boxes. They were safe. They were cheap. They were reliable. There was no more constant failure due to high operating pressures. At first, the adoption of these refrigerants was slow but that was only because of the manufacturing speed of the product. It was in the 1950’s that an innovation was done that greatly increased the speed of manufacturing CFC and HCFC refrigerants.

Once the supply could be met the demand skyrocketed. It wasn’t long until CFC and HCFC refrigerants were found all over the world in various applications. They could be your home air conditioner, your automobile, your refrigerator, or your local grocery store. They were everywhere. In the 1960’s there were a few more CFC/HCFC refrigerants invented, including R-502, that led to even more explosive growth.

With the growth and dominance of these new refrigerants it seemed that R-744 had taken a backseat. It was cast aside when the newer refrigerants came to market due to the high pressure that it operated at. There was no reason to use this expensive refrigerant anymore due to the mass production and reliability of R-12, R-22, and R-502. At least for a while, R-744 had reached it’s peak. It was in the 1980’s that things began to change.

The Ozone

It was in the 1980’s that a problem was discovered. Two American scientists, Mario Molina and Shepwood Rowland, from a California university were the first to notice Chlorine’s effect on the atmosphere. (Remember now folks, all of these CFCs and HCFCs contain Chlorine.)

These two scientists found that when a CFC refrigerant was exposed to ultra-violet irradiation that the Chlorine atom would detach itself from the CFC molecules. The remaining residue is oxidized resulting in the creation of a Chlorine oxidized molecule and a new residue. The Chlorine atom and Chlorine oxidized molecule move their way up to the stratosphere. Within the stratosphere there is a layer called the Ozone layer. This Ozone layer protects the Earth from ultra-violet rays and irradiation. What these scientists found out is that all of this Chlorine from CFC and HCFC refrigerants was working it’s way to the stratosphere. When it reached the stratosphere the Chlorine began to attack and weaken the Ozone layer.

Over decades of using CFCs and HCFC refrierants Chlorine began to accumulate in the stratosphere and overtime a hole began to form in the Ozone layer. Now, I say hole but this wasn’t a hole per-say. Instead, there was a weakening of strength in the layer. So, while there was not a hole the thickness of the Ozone was decreasing and decreasing rapidly thanks to the CFC and HCFC refrigerants.

The Ozone prevents harmful UVB wavelengths of ultra-violet light from passing through the Earth’s atmosphere. Without it, or with a weakened version of it, a variety of bad things could happen. Some of these include a much higher increased chance of Skin Cancer, more severe sunburns, more chances of cataracts, and a whole host of other problems.

After discovering the weakening of the Ozone layer nations banded together in what is seen as one of the greatest and most effective treaty’s every made. In 1986-1987 the Montreal Protocol was created and signed by over one-hundred nations across the world. This Protocol was an international treaty designed to protect the Ozone layer and to completely phase out the chemicals responsible for the weakening of the Ozone. The treaty went into effect in 1989.

Soon after that date marked the beginning of the end for CFC and HCFC refrigerants across the globe. The industrialized countries, like America, began to phase out the refrigerants first. R-12 was phased out in the early 1990’s along with all of the rest of the CFC refrigerants. The HCFC refrigerants such as R-22 or even R-502 were given a bit more time. Heck, R-22’s true phase out didn’t even begin until 2010.

Out with the old and in with the new, so they say. The refrigerants that were proposed to replace CFCs and HCFCs were known as HFCs, or Hydroflurocarbons. These refrigerants contained no Chlorine so there was no chance of them hurting the Ozone layer. Some of these refrigerants include popular refrigerants today known as R-134a, R-404A, and R-410A. But, now these refrigerants are under fire for their increase to Global Warming.

R-744 Present & Future

As I mentioned above HFCs were seen as the world’s savior from the Ozone depleting refrigerants. But, HFCs had their own problem. Instead of the Ozone this time it was Global Warming. These HFC refrigerants such as R-134a, R-404A, R-410A are known as ‘Super Pollutants,’ or ‘Greenhouse Gases.’ In order to measure their impact on the environment each of these refrigerants were given a Global Warming Potential number. The higher the number the more damage the refrigerant causes to the world. As a zero based scale for this measurement our old friend R-744 was used. Carbon Dioxide has a GWP of one. In comparison, R-404A has a GWP of three-thousand nine-hundred and twenty-two. Obviously, there is a large difference here.

I’m writing this article in 2019 and over the past ten years or so there has been a worldwide push to phase down and in some cases phase out HFC refrigerants completely. In order to phase out HFC refrigerants we have to have a replacement refrigerant. In some cases companies and countries have turned to a new classification of refrigerants known as HFOs. These HFO refrigerants are again synthetic products created by Honeywell & Chemours (Formerly DuPont). The problem with HFOs though is that they still have Global Warming Potential. Yes, not as high as HFCs… but the numbers are still there. Along with the GWP risk they also have a slight flammability risk. To me, I do not see HFOs being sustainable. I imagine the world will decide to phase them out in another ten or twenty years.

So, what is the solution you may ask? It’s R-744! Well, R-744 and other natural refrigerants. Technology has changed significantly since the last time R-744 was used widely. It’s been almost one-hundred years since we saw the mainstream use of Carbon Dioxide and now with nearly a century behind us the technology has significantly reduced the chance of component failures due to high operating pressures. We are now able to create efficient and stable R-744 systems without a large risk of failure.

While the cost of implementing R-744 systems is still quite higher then a traditional HFC system the costs have been coming down. This holds especially true in recent years as the push to innovate R-744 systems increases substantially with the phasing down of HFCs. While we are not there yet the costs are quickly shrinking the gap between HFCs and R-744.

There are many companies pushing forward with R-744 systems. Most of these are on smaller systems such as vending machines, but we all need to take baby steps. One company in particular, Coca-Cola, has installed hundreds of CO2 vending machines across the country. Along with Coca-Cola there are other grocery store chains out there using cascade R-744 systems mixed with other refrigerants such as Ammonia or lower GWP HFCs. We are even beginning to see R-744 uses in automobiles with the innovations that Daimler has made. As we completely phase down HFCs over the next ten years we will see more and more usage of R-744. It’s time has come again!

Conclusion

Sometimes history can be funny. If you have ever heard the saying, ‘Learn history or else you’ll be doomed to repeat it.’ It looks like we will be repeating history again. When refrigeration started Carbon Dioxide was one of the first refrigerants used and now again in the 21st century we are seeing R-744 come to prominence again. We’ve come full circle. For more information on R-744 please check out our R-744 Refrigerant Fact & Info Sheet by clicking here.

Thanks for reading,

Alec Johnson

RefrigerantHQ

A Look

As we all know, there is no perfect refrigerant. Each one has its own individual upsides and downsides. It could have a great efficiency but also end up being very flammable. Or, it could be non-flammable and non-toxic but have very high Global Warming Potential. The point I’m making here is that there isn’t a perfect one out there and there may never be. In this section we’re going to take a brief look at the various Pros and Cons of using R-744 as a refrigerant. I pulled this information from all over the web, but one site in particular stuck out to me. This article from Emerson has an entire page dedicated to R-744 Pros and Cons. It can be found by clicking here and then scrolling to page twelve.

Let’s take a look at the Pros and Cons of R-744:

Pros

  • R-744 is seen as the ‘perfect’ natural refrigerant as it is climate neutral and there is not a flammability or toxicity risk.  It is rated as an A1 from ASHRAE. While it is non-toxic there is still risk if a leak occurs in an enclosed area as R-744 will displace the oxygen in the room and could cause asphyxiation. It is always best to have a leak detector with you so that you can detect the problem early before anything major occurs.
  • Overall, R-744 is more energy efficient and has better heat exchange then a standard HFC based system. While it may not be as efficient as Ammonia this gap between the two refrigerants is shrunk as the evaporator temperature drops. Carbon Dioxide also has a low compression pressure ratio which can improve volumetric efficiency. In some cases CO2’s volumetric efficiency is four to twelve times better then Ammonia. (Source – under Pressure & Temperature.)
  • I mentioned this earlier, but the biggest selling point of R-744 is that it is climate neutral. It has no Ozone Depletion Potential and it’s Global Warming Potential is one. In fact, R-744 is the zero basis for the whole GWP scale. This is a huge Pro as if there is one thing that business owners are looking for it is stability and consistency. R-744 is never going away due to it being so climate friendly.
  • One Pro to R-744 operating at such a high pressure and being such a dense gas is that the overall size of the parts and components is smaller and the overall charge required for a refrigerant cycle is lessened. In some cases the compressor can be up to ten times smaller than an ammonia compressor. As far as refrigerant charges, one example I read from manufacturing.net stated that to cool a two-hundred thousand square foot warehouse you would need forty-thousand pounds of Ammonia but with CO2 you would need less than seven-thousand pounds.
  • Carbon Dioxide is readily available and the price for this refrigerant is much less then HFC refrigerants that we see today. This is a welcome relief from the instability of prices on HFCs and HCFC refrigerants that we all know about.

Cons

While R-744 is the ‘perfect’ natural refrigerant in theory there are a lot of downsides.

  • The biggest one is for Carbon Dioxide to be used as a refrigerant it has to run under extremely high pressure. As an example, R-744 operates at ten times higher pressure then R-134a. Because of this extremely high pressure everything has to be custom built for an R-744 system so that it can withstand the high operating pressure. This includes the pipes, components, and everything else that goes along with the machine. If lesser components are used then you pose risk of constant failure due to the pressure.
  • If you wish to use R-744 as a stand alone refrigerant not in a cascade system then you will have to be running it as what’s known as a transcritical system. This is because R-744’s critical temperature point is only eighty-eight degrees Fahrenheit. There are many cases where the ambient temperature could be between eighty to one-hundred degrees. If your critical point for R-744 is only at eighty-eight degrees then how can you expect to remove the heat? (You can read more on the topic of transcritical refrigeration by clicking here.)
  • Suffice to say, a transcritical system and a high operating pressure system means two things.
    • The first is that there is increased expense for these systems. Not only do you have to pay for high pressure rated materials and parts but you also have to pay for a transcritical system. This setup is different then your standard subcritical system. The good news here is that with each year that passes technology improves and the cost of these higher pressure parts goes down.
    • The second is the increased complexity. The higher the complexity means less available qualified technicians. It may be a struggle to find qualified R-744 technicians, at least here in the United States. Each year though this is getting better as more and more businesses are adopting R-744 systems.
  • I mentioned efficiency in our Pros section earlier. The reason I mention it again is that the efficiency of R-744 is highly dependent on the type of system it’s being used in and the surrounding climate. I mean, think about it for a moment. We could have a subcritical cascade system for a supermarket in Miami. Or, we could have a transcritical ice rink in British Columbia. In each example we’re using R-744 but we now have two entirely different systems as well as two entirely different climates. Because of these variety of systems and applications it is difficult to measure one single efficiency measurement.

Conclusion

As you can see from the above synopsis, there is no perfect refrigerant. It all depends on what you are looking for in your refrigerant, what application you will be using it for, and even what part of the world you are in. For more information on R-744 please check out our R-744 Refrigerant Fact & Info Sheet by clicking here.

Thanks for reading,

Alec Johnson

RefrigerantHQ

A Look

R-744, or Carbon Dioxide, is quickly becoming one of the most popular refrigerants in the world. As the usage of this refrigerant grows I can’t help but laugh as we have now come full circle. You see, if you go back one-hundred years Carbon Dioxide was one of the main refrigerants used but its usage declined in the 1930’s with the invention of synthetic refrigerants such as CFCs and HCFCs.

These new synthetic refrigerants were safe, cheap, and reliable. Because of this they took over the marketplace. It wasn’t until it was found that CFC/HCFC refrigerants actively harm the environment that we began to see more R-744 applications appears. In this article we’re going to take a look the various R-744 applications that can be found in the world today:

R-744 Applications

Let me first start out by saying that R-744 is a very unique refrigerant, more so then others.  R-744 is a natural refrigerant. But, unlike other natural refrigerants, there is not a safety concern. With hydrocarbons you have the flammability risk, with Ammonia you have the toxicity risk, but with CO2 the safety risk is minimal. Along with it being a safe natural refrigerant it also is very versatile. It is mainly used in a transcritical refrigeration system but it can also be used in subcritical systems when done through a cascade. On top of that R-744 can be used as a secondary fluid refrigeration system. (For more information on transcritical systems please click here to be taken to a recently written article on the topic.)

Between these different types of refrigeration there are a wide a range of applications such as vending machines, supermarket refrigerators/freezers, industrial refrigeration, refrigerated transport, automotive air conditioning, heat pumps, and even in sports arenas for ice rinks. In this section we are going to take a look at each of these applications:

Vending Machines

One of the first targets in the global HFC phase down was R-404A. As you know, 404A was used in a variety of applications including vending machines. In the early 2010’s there was a push from a variety of companies, including Coca-Cola, to switch their vending machines away from 404A and over to R-744 Carbon Dioxide. Now, as I write this article CO2 vending machines are found all over the United States. One of the initial struggles of these systems was finding qualified technicians as these vending machines operate as a transcritical system rather then subcritical. The good news is that as the years go by and the amount of these transcritical machines grow then the technicians will become more seasoned and experienced with working on these kinds of systems.

Supermarket Refrigerators/Freezers

The grocery store refrigerators and freezer market didn’t switch over as fast as vending machines but there is significant progress being made. While R-744 isn’t necessarily the preferred refrigerant to use in these applications there are some companies moving forward. Depending on the application supermarkets will either use a stand alone plug-in unit that is very similar to a vending machine or they will use one system that connects to all of the various refrigerators and freezers.

When it comes to using R-744 the type of application will determine if the unit will be a subcritical cascade or a transcritical system. If we look at a stand alone refrigerator/freezer then we would be dealing with a standard transcritical system. This would operate very similar to how vending machines do. On the other hand, if we look at some of the larger systems that are all connected then we would be looking at a cascade system. A cascade system uses two or more refrigerants. In the example of R-744 we would find R-744 on the low temperature side of the cycle. By having R-744 isolated to the low end of the system we can prevent the refrigerant from going past the critical point and keep it subcritical. The other refrigerant used for the high side of the system can vary. It could be Ammonia, Propane/Isobutane, or even an HFC or HFO refrigerant.

Industrial Refrigeration

The term industrial refrigeration can be quite vague and can encompass a variety of applications from chillers, to chilled warehouses, to heat extraction, and so much more. In the past, before R-22 was phased out it was one of the top refrigerants used in these larger scale operations. When R-22 was phased out some companies switched over to the HFC R-404A/R-134a only to find that these refrigerants were going to be phased out soon as well.

In Europe, in Canada, and in other countries R-717 or Ammonia is one of the top picks when it comes to industrial refrigeration such as meat packing plants. Ammonia is chosen as it is highly regarded as the most energy efficient refrigerant out there. The downside, of course, is that Ammonia is toxic and can also be slightly flammable. Whenever you see a story in the new stating that a plant had to be evacuated due to a refrigerant leak the chances are that it is Ammonia is quite high. There are many instances of this occurring here in the United States and in most cases everyone is fine. We just have to ensure that the proper precautions are followed.

While R-744 may not be as efficient as Ammonia it has another thing going for it. It’s not toxic. That being said though it appears that the use of R-744 plants and chillers is still quite rare. I spent some time looking around online trying to find stories on R-744 plant usage but wasn’t able to find anything. It seems that Ammonia still has a strong hold on the industry but as technologies change and as HFCs become completely phased out we may begin to see more active R-744 industrial applications. If you know of some active R-744 plant applications please reach out to me and let me know.

Refrigerated Transport

When I hear the words refrigerated transport I instantly think of trucking. That’s most likely because I came from the trucking industry. I remember going through pallets of R-404A for our carrier refrigerated trucks. In the case of R-744 though the refrigerated transport we are discussing is naval transport or refrigerated shipping containers. It’s not just produce or meat being refrigerated on cargo ships though. No, in some cases cruise liners have installed CO2 systems to cool their larger refrigerators and freezers. Again, I looked around for any mention of R-744 being used in refrigerated cargo transport on trucks but saw no mention of it. This may still be down the road.

Automotive Air Conditioning

This one is definitely unique. If we rewind about ten years ago there were two refrigerants to choose from for automotive air conditioning. The first was the ever popular HFC R-134a. I am sure most of you are familiar with this refrigerant. You can buy cans of it at your local O’Reillys. At this time though a new refrigerant was introduced to the automotive sector. This refrigerant known as R-1234yf, was an HFO refrigerant invented between a partnership of DuPont and Honeywell. YF was to be the refrigerant of the future. It would replace R-134a and it would be used in every car from now on.

Most of the world was on board except for Germany. The German automakers had tested with YF and found that it was flammable. In one instance during a simulated collision the lines ruptured and spilled the refrigerant onto the hot engine block. The refrigerant ignited and caused a fire. This one test scared the German automakers, especially Daimler, away from using YF. While the rest of the world pushed forward with YF Daimler set off on their own to create the first automotive R-744 application.

Years later they achieved their goals and we now have German made cars using CO2 as their refrigerant. There is now no risk of flammability with their cars and they are still being environmentally friendly. I love hearing this story again and again as it’s a prime example of forging your own way and still coming out on top.

Heat Pumps

Japan has put forth a lot of focus on R-744 heat pumps. CO2 heat pumps can produce a much higher temperature output then a traditional HFC heat pump system. This is thanks in part due to the transcritical process. These heat pumps can heat water all the way up to one-hundred and ninety-four degrees Fahrenheit. (Source) The adaption of CO2 based heat pumps is moving forward, but it has been slowed due to the extremely high operating pressures and the breakage of components. (The same story we have seen in other CO2 applications.) In the future we will most likely begin to see CO2 heat pumps in mini-split air conditioner systems. Perhaps, down the road, we may even see them in traditional split air conditioning systems.

Ice Rinks

From my experience a typical ice rink uses either Ammonia, R-22, or an HFC such as R-134a or R-404A. What refrigerant is used seems to depend on what country you are in. Outside of America the standard refrigerant has been Ammonia. As we discussed earlier in this article Ammonia is widely seen as the most efficient refrigerant. When dealing with such a large application like an ice rink efficiency is a must. The downside of course, is the toxicity. The toxicity is especially important when it comes to a public area like ice rinks. It’s not just technicians or employees who are at risk but you also have the general public.

Here in America we are always hesitant to use the more ‘dangerous’ refrigerants such as Ammonia or Hydrocarbons. Because of this hesitation we instead went the route of R-22 for our ice rinks and hockey arenas. Now though, with R-22’s phase out coming to a close in 2020 ice rink owners are looking for alternative refrigerants. Sure, there are HFC and now even HFO alternatives that can be used in these applications but each of these alternatives still have a higher then neutral Global Warming Potential (GWP). The problem with these refrigerants is that they will not stand the test of time when it comes to climate impact and phase outs.

If I was an arena owner or manager I would only seriously be considering two options. The first is Ammonia like I discussed earlier. This comes with it’s own risks but you get the low cost and energy savings. The alternative is R-744 Carbon Dioxide. R-744 has it’s own Pros and Cons which I’ll get into in our next section, but the big selling point is that you get a climate neutral refrigerant that is safe to the public in case a leak occurs. While R-744 systems aren’t widely found in the world today, they are growing. An article I was reading from 2016 had this quote, ”

“Today the number of CO2 ice rinks is growing rapidly. There are now 25-30 CO2 ice rinks in the world,” he says. 20-25 of these CO2 ice rinks are in North America, 20 of which are in Canada (mostly in Quebec) and three in Alaska, according to EKA.” – Source

Conclusion

As you can see Carbon Dioxide refrigerant is quickly being adapted across various applications here in the United States and across the world. While R-744 does have it’s downsides such as high pressure and more complex systems we have now become to overcome these challenges with new technology and adaptions. Out of all of the refrigerants that are available today I specifically advocate for R-744. This is for two reasons. The first is that it will never be phased out as it is what I like to call ‘Climate Neutral.’ Secondly, Carbon Dioxide is safe. It is non-toxic and non-flammable. These two factors alone make for a great refrigerant.

For more information on R-744 please check out our R-744 Refrigerant Fact & Info Sheet by clicking here.

Thanks for reading,

Alec Johnson

RefrigerantHQ

facts

R-744 Carbon Dioxide is one of the oldest refrigerants in the world. Its first usage can be traced all the way back to the nineteenth century. Before the popularity of CFC and HCFC refrigerants Carbon Dioxide was one of the most widely used refrigerants. Chances are if you went to a movie theatre in the 1920’s then you were experiencing an R-744 air conditioning system.

When R-12, R-22, and other HCFC/CFC refrigerants began to rise to prominence we began to see a large decline in R-744 usage. This was due to its extremely high operating pressures which caused numerous part failures. The newer artificial refrigerants were much easier to maintain. In today’s world, as we progress through the twenty-first century we have begun to see resurgence in R-744. This is due to the detrimental effects that CFC, HCFC, and HFC refrigerants have had on the environment. Carbon Dioxide on the other hand is climate neutral with zero Ozone Depletion and a Global Warming Potential of only one.

If you haven’t run into an R-744 system yet you soon will as its popularity grows with each passing year. In this article we’re going to take a deep dive and take a look at everything there is to know on R-744. If I miss something please let me know!

The Facts

Name:R-744
Name - Scientific:Carbon Dioxide
Name (2):744
Name (3):CO2
Name (4)R744
Classification:Natural Refrigerant
Chemistry:CO2
Status:Active & Growing
Future:Will Be Used All Over World in Various Applications
System Type:SubCritical (Cascade) & TransCritical
Application:Vehicle Air Conditioning & Transport Refrigeration
Application (2):Commercial Refrigerators & Freezers
Application (3):Commercial Vending Machines & Plug-Ins
Application (4):Industrial Refrigeration
Application (5):Ice Rinks
Replacement For:R-22, R-134a, R-404A, and other HFCs
Ozone Depletion Potential:0
Global Warming Potential:1
Global Warming Risk:Very Low
Toxicity Levels:A (No Toxicity Identified.)
Flammability Levels:Class 1 - No Flame Propagation
Lubricant Required:POE & PAG Oils
Boiling Point:−78 °C (-108.4 °F; 195.15 K)
Critical Temperature:31.04 °C or 87.87 °F
Critical Pressure:7,380 kpa
Triple Point:4.2 bar (60.9 psi) and -56.6 °C (-69.8 °F)
Temperature Glide:None
Molar Mass:44.009 g·mol−1
Density (2):1101 kg/m3 (liquid at saturation −37°C)
Melting Point:−56.6 °C; −69.8 °F; 216.6 K
Vapor Pressure:5.73 MPa (20 °C)
Heat Capacity:37.135 J/K mol
Manufacturers:Various Including: Honeywell, Chemours, Arkema, Mexichem, Chinese, etc.
Manufacturing Facilities:All Over Including: USA, Mexico, EU, China, and others.
Form:Gas
Color:Colorless gas
Odor:Low concentrations: none.
Odor(2):High concentrations: sharp; acidic
EPA Certification Required:No
Require Certification to Purchase?No
Cylinder Color:Unknown
Purchasing:CLICK FOR A QUOTE!

R-744 Pressure Chart

Knowing the pressure and the temperatures associated to the machine you are working on is essential to being able to diagnose any possible issues. Without knowing the temperatures you are more or less walking blind. These pressure checks give you the facts so that you can move onto the next step of your diagnosis. Instead of pasting a large table of information here I will instead direct you to our specific R-744 refrigerant temperature page. This can be found by clicking here.

R-744 Applications

Let me first start out by saying that R-744 is a very unique refrigerant, more so then others.  R-744 is a natural refrigerant. But, unlike other natural refrigerants, there is not a safety concern. With hydrocarbons you have the flammability risk, with Ammonia you have the toxicity risk, but with CO2 the safety risk is minimal. Along with it being a safe natural refrigerant it also is very versatile. It is mainly used in a transcritical refrigeration system but it can also be used in subcritical systems when done through a cascade. On top of that R-744 can be used as a secondary fluid refrigeration system. (For more information on transcritical systems please click here to be taken to a recently written article on the topic.)

Between these different types of refrigeration there are a wide a range of applications such as vending machines, supermarket refrigerators/freezers, industrial refrigeration, refrigerated transport, automotive air conditioning, heat pumps, and even in sports arenas for ice rinks. In this section we are going to take a look at each of these applications:

Vending Machines

One of the first targets in the global HFC phase down was R-404A. As you know, 404A was used in a variety of applications including vending machines. In the early 2010’s there was a push from a variety of companies, including Coca-Cola, to switch their vending machines away from 404A and over to R-744 Carbon Dioxide. Now, as I write this article CO2 vending machines are found all over the United States. One of the initial struggles of these systems was finding qualified technicians as these vending machines operate as a transcritical system rather then subcritical. The good news is that as the years go by and the amount of these transcritical machines grow then the technicians will become more seasoned and experienced with working on these kinds of systems.

Supermarket Refrigerators/Freezers

The grocery store refrigerators and freezer market didn’t switch over as fast as vending machines but there is significant progress being made. While R-744 isn’t necessarily the preferred refrigerant to use in these applications there are some companies moving forward. Depending on the application supermarkets will either use a stand alone plug-in unit that is very similar to a vending machine or they will use one system that connects to all of the various refrigerators and freezers.

When it comes to using R-744 the type of application will determine if the unit will be a subcritical cascade or a transcritical system. If we look at a stand alone refrigerator/freezer then we would be dealing with a standard transcritical system. This would operate very similar to how vending machines do. On the other hand, if we look at some of the larger systems that are all connected then we would be looking at a cascade system. A cascade system uses two or more refrigerants. In the example of R-744 we would find R-744 on the low temperature side of the cycle. By having R-744 isolated to the low end of the system we can prevent the refrigerant from going past the critical point and keep it subcritical. The other refrigerant used for the high side of the system can vary. It could be Ammonia, Propane/Isobutane, or even an HFC or HFO refrigerant.

Industrial Refrigeration

The term industrial refrigeration can be quite vague and can encompass a variety of applications from chillers, to chilled warehouses, to heat extraction, and so much more. In the past, before R-22 was phased out it was one of the top refrigerants used in these larger scale operations. When R-22 was phased out some companies switched over to the HFC R-404A/R-134a only to find that these refrigerants were going to be phased out soon as well.

In Europe, in Canada, and in other countries R-717 or Ammonia is one of the top picks when it comes to industrial refrigeration such as meat packing plants. Ammonia is chosen as it is highly regarded as the most energy efficient refrigerant out there. The downside, of course, is that Ammonia is toxic and can also be slightly flammable. Whenever you see a story in the new stating that a plant had to be evacuated due to a refrigerant leak the chances are that it is Ammonia is quite high. There are many instances of this occurring here in the United States and in most cases everyone is fine. We just have to ensure that the proper precautions are followed.

While R-744 may not be as efficient as Ammonia it has another thing going for it. It’s not toxic. That being said though it appears that the use of R-744 plants and chillers is still quite rare. I spent some time looking around online trying to find stories on R-744 plant usage but wasn’t able to find anything. It seems that Ammonia still has a strong hold on the industry but as technologies change and as HFCs become completely phased out we may begin to see more active R-744 industrial applications. If you know of some active R-744 plant applications please reach out to me and let me know.

Refrigerated Transport

When I hear the words refrigerated transport I instantly think of trucking. That’s most likely because I came from the trucking industry. I remember going through pallets of R-404A for our carrier refrigerated trucks. In the case of R-744 though the refrigerated transport we are discussing is naval transport or refrigerated shipping containers. It’s not just produce or meat being refrigerated on cargo ships though. No, in some cases cruise liners have installed CO2 systems to cool their larger refrigerators and freezers. Again, I looked around for any mention of R-744 being used in refrigerated cargo transport on trucks but saw no mention of it. This may still be down the road.

Automotive Air Conditioning

This one is definitely unique. If we rewind about ten years ago there were two refrigerants to choose from for automotive air conditioning. The first was the ever popular HFC R-134a. I am sure most of you are familiar with this refrigerant. You can buy cans of it at your local O’Reillys. At this time though a new refrigerant was introduced to the automotive sector. This refrigerant known as R-1234yf, was an HFO refrigerant invented between a partnership of DuPont and Honeywell. YF was to be the refrigerant of the future. It would replace R-134a and it would be used in every car from now on.

Most of the world was on board except for Germany. The German automakers had tested with YF and found that it was flammable. In one instance during a simulated collision the lines ruptured and spilled the refrigerant onto the hot engine block. The refrigerant ignited and caused a fire. This one test scared the German automakers, especially Daimler, away from using YF. While the rest of the world pushed forward with YF Daimler set off on their own to create the first automotive R-744 application.

Years later they achieved their goals and we now have German made cars using CO2 as their refrigerant. There is now no risk of flammability with their cars and they are still being environmentally friendly. I love hearing this story again and again as it’s a prime example of forging your own way and still coming out on top.

Heat Pumps

Japan has put forth a lot of focus on R-744 heat pumps. CO2 heat pumps can produce a much higher temperature output then a traditional HFC heat pump system. This is thanks in part due to the transcritical process. These heat pumps can heat water all the way up to one-hundred and ninety-four degrees Fahrenheit. (Source) The adaption of CO2 based heat pumps is moving forward, but it has been slowed due to the extremely high operating pressures and the breakage of components. (The same story we have seen in other CO2 applications.) In the future we will most likely begin to see CO2 heat pumps in mini-split air conditioner systems. Perhaps, down the road, we may even see them in traditional split air conditioning systems.

Ice Rinks

From my experience a typical ice rink uses either Ammonia, R-22, or an HFC such as R-134a or R-404A. What refrigerant is used seems to depend on what country you are in. Outside of America the standard refrigerant has been Ammonia. As we discussed earlier in this article Ammonia is widely seen as the most efficient refrigerant. When dealing with such a large application like an ice rink efficiency is a must. The downside of course, is the toxicity. The toxicity is especially important when it comes to a public area like ice rinks. It’s not just technicians or employees who are at risk but you also have the general public.

Here in America we are always hesitant to use the more ‘dangerous’ refrigerants such as Ammonia or Hydrocarbons. Because of this hesitation we instead went the route of R-22 for our ice rinks and hockey arenas. Now though, with R-22’s phase out coming to a close in 2020 ice rink owners are looking for alternative refrigerants. Sure, there are HFC and now even HFO alternatives that can be used in these applications but each of these alternatives still have a higher then neutral Global Warming Potential (GWP). The problem with these refrigerants is that they will not stand the test of time when it comes to climate impact and phase outs.

If I was an arena owner or manager I would only seriously be considering two options. The first is Ammonia like I discussed earlier. This comes with it’s own risks but you get the low cost and energy savings. The alternative is R-744 Carbon Dioxide. R-744 has it’s own Pros and Cons which I’ll get into in our next section, but the big selling point is that you get a climate neutral refrigerant that is safe to the public in case a leak occurs. While R-744 systems aren’t widely found in the world today, they are growing. An article I was reading from 2016 had this quote, ”

“Today the number of CO2 ice rinks is growing rapidly. There are now 25-30 CO2 ice rinks in the world,” he says. 20-25 of these CO2 ice rinks are in North America, 20 of which are in Canada (mostly in Quebec) and three in Alaska, according to EKA.” – Source

R-744 Pros & Cons

As we all know, there is no perfect refrigerant. Each one has its own individual upsides and downsides. It could have a great efficiency but also end up being very flammable. Or, it could be non-flammable and non-toxic but have very high Global Warming Potential. The point I’m making here is that there isn’t a perfect one out there and there may never be. In this section we’re going to take a brief look at the various Pros and Cons of using R-744 as a refrigerant. I pulled this information from all over the web, but one site in particular stuck out to me. This article from Emerson has an entire page dedicated to R-744 Pros and Cons. It can be found by clicking here and then scrolling to page twelve.

Let’s take a look at the Pros and Cons of R-744:

Pros

  • R-744 is seen as the ‘perfect’ natural refrigerant as it is climate neutral and there is not a flammability or toxicity risk.  It is rated as an A1 from ASHRAE. While it is non-toxic there is still risk if a leak occurs in an enclosed area as R-744 will displace the oxygen in the room and could cause asphyxiation. It is always best to have a leak detector with you so that you can detect the problem early before anything major occurs.
  • Overall, R-744 is more energy efficient and has better heat exchange then a standard HFC based system. While it may not be as efficient as Ammonia this gap between the two refrigerants is shrunk as the evaporator temperature drops. Carbon Dioxide also has a low compression pressure ratio which can improve volumetric efficiency. In some cases CO2’s volumetric efficiency is four to twelve times better then Ammonia. (Source – under Pressure & Temperature.)
  • I mentioned this earlier, but the biggest selling point of R-744 is that it is climate neutral. It has no Ozone Depletion Potential and it’s Global Warming Potential is one. In fact, R-744 is the zero basis for the whole GWP scale. This is a huge Pro as if there is one thing that business owners are looking for it is stability and consistency. R-744 is never going away due to it being so climate friendly.
  • One Pro to R-744 operating at such a high pressure and being such a dense gas is that the overall size of the parts and components is smaller and the overall charge required for a refrigerant cycle is lessened. In some cases the compressor can be up to ten times smaller than an ammonia compressor. As far as refrigerant charges, one example I read from manufacturing.net stated that to cool a two-hundred thousand square foot warehouse you would need forty-thousand pounds of Ammonia but with CO2 you would need less than seven-thousand pounds.
  • Carbon Dioxide is readily available and the price for this refrigerant is much less then HFC refrigerants that we see today. This is a welcome relief from the instability of prices on HFCs and HCFC refrigerants that we all know about.

Cons

While R-744 is the ‘perfect’ natural refrigerant in theory there are a lot of downsides.

  • The biggest one is for Carbon Dioxide to be used as a refrigerant it has to run under extremely high pressure. As an example, R-744 operates at ten times higher pressure then R-134a. Because of this extremely high pressure everything has to be custom built for an R-744 system so that it can withstand the high operating pressure. This includes the pipes, components, and everything else that goes along with the machine. If lesser components are used then you pose risk of constant failure due to the pressure.
  • If you wish to use R-744 as a stand alone refrigerant not in a cascade system then you will have to be running it as what’s known as a transcritical system. This is because R-744’s critical temperature point is only eighty-eight degrees Fahrenheit. There are many cases where the ambient temperature could be between eighty to one-hundred degrees. If your critical point for R-744 is only at eighty-eight degrees then how can you expect to remove the heat? (You can read more on the topic of transcritical refrigeration by clicking here.)
  • Suffice to say, a transcritical system and a high operating pressure system means two things.
    • The first is that there is increased expense for these systems. Not only do you have to pay for high pressure rated materials and parts but you also have to pay for a transcritical system. This setup is different then your standard subcritical system. The good news here is that with each year that passes technology improves and the cost of these higher pressure parts goes down.
    • The second is the increased complexity. The higher the complexity means less available qualified technicians. It may be a struggle to find qualified R-744 technicians, at least here in the United States. Each year though this is getting better as more and more businesses are adopting R-744 systems.
  • I mentioned efficiency in our Pros section earlier. The reason I mention it again is that the efficiency of R-744 is highly dependent on the type of system it’s being used in and the surrounding climate. I mean, think about it for a moment. We could have a subcritical cascade system for a supermarket in Miami. Or, we could have a transcritical ice rink in British Columbia. In each example we’re using R-744 but we now have two entirely different systems as well as two entirely different climates. Because of these variety of systems and applications it is difficult to measure one single efficiency measurement.

R-744 Past/Future

History

I am a big fan of history and can never get enough of reading historical books or watching documentaries. If you don’t understand the past then how can you understand the present or even the future? While refrigerant history might not be as interesting as other historical topics it is still good to understand it. R-744 can be traced back all the way back to the nineteenth century. In fact it was one of the very first refrigerants to ever be developed and used across the world. Experiments in refrigeration began in the late seventeen-hundreds and began to pick up speed in the eighteen-hundreds. It was in 1850 that Carbon Dioxide was first proposed as a refrigerant by Alexander Twinning. In 1869 one of the very first ice machines invented used Carbon Dioxide. Then in 1897 the first Carbon Dioxide refrigerator was introduced. More and more inventions and innovations followed.

In the late 1800’s and the early 1900’s there were a few mainstream refrigerants that we saw. These were your natural and hydrocarbon refrigerants such as Ammonia, Propane, Isobutane, and Carbon Dioxide. At this time Carbon Dioxide was found in all kinds of applications ranging from display cabinets, cold storage areas, market places, home/commercial kitchens, movie theaters, hospitals, trains, and even on cargo transport ships. The other natural refrigerants weren’t used as widely as Carbon Dioxide due to their safety concerns.

It seemed that R-744 was going to reign supreme as the main refrigerant in the world. This held true until the 1930’s. It was then that a partnership was formed between General Motors and DuPont. This partnership was made with one goal in mind: To create a cheap, safety, and reliable refrigerant. While Carbon Dioxide was safe it had it’s own problems. Just like we mentioned in our Pros and Cons section R-744 systems had numerous failures due to the extreme pressure that they operated under. The technology just wasn’t there to prevent these failures either so these air conditioners and refrigerators would bey very expensive to maintain.

After some time the General Motors & DuPont partnership came out with a new artificial class of refrigerants known as CFCs and HCFCs. Some of the refrigerants in this new classification were R-12 and R-22. These new refrigerants checked all of the boxes. They were safe. They were cheap. They were reliable. There was no more constant failure due to high operating pressures. At first, the adoption of these refrigerants was slow but that was only because of the manufacturing speed of the product. It was in the 1950’s that an innovation was done that greatly increased the speed of manufacturing CFC and HCFC refrigerants.

Once the supply could be met the demand skyrocketed. It wasn’t long until CFC and HCFC refrigerants were found all over the world in various applications. They could be your home air conditioner, your automobile, your refrigerator, or your local grocery store. They were everywhere. In the 1960’s there were a few more CFC/HCFC refrigerants invented, including R-502, that led to even more explosive growth.

With the growth and dominance of these new refrigerants it seemed that R-744 had taken a backseat. It was cast aside when the newer refrigerants came to market due to the high pressure that it operated at. There was no reason to use this expensive refrigerant anymore due to the mass production and reliability of R-12, R-22, and R-502. At least for a while, R-744 had reached it’s peak. It was in the 1980’s that things began to change.

The Ozone

It was in the 1980’s that a problem was discovered. Two American scientists, Mario Molina and Shepwood Rowland, from a California university were the first to notice Chlorine’s effect on the atmosphere. (Remember now folks, all of these CFCs and HCFCs contain Chlorine.)

These two scientists found that when a CFC refrigerant was exposed to ultra-violet irradiation that the Chlorine atom would detach itself from the CFC molecules. The remaining residue is oxidized resulting in the creation of a Chlorine oxidized molecule and a new residue. The Chlorine atom and Chlorine oxidized molecule move their way up to the stratosphere. Within the stratosphere there is a layer called the Ozone layer. This Ozone layer protects the Earth from ultra-violet rays and irradiation. What these scientists found out is that all of this Chlorine from CFC and HCFC refrigerants was working it’s way to the stratosphere. When it reached the stratosphere the Chlorine began to attack and weaken the Ozone layer.

Over decades of using CFCs and HCFC refrierants Chlorine began to accumulate in the stratosphere and overtime a hole began to form in the Ozone layer. Now, I say hole but this wasn’t a hole per-say. Instead, there was a weakening of strength in the layer. So, while there was not a hole the thickness of the Ozone was decreasing and decreasing rapidly thanks to the CFC and HCFC refrigerants.

The Ozone prevents harmful UVB wavelengths of ultra-violet light from passing through the Earth’s atmosphere. Without it, or with a weakened version of it, a variety of bad things could happen. Some of these include a much higher increased chance of Skin Cancer, more severe sunburns, more chances of cataracts, and a whole host of other problems.

After discovering the weakening of the Ozone layer nations banded together in what is seen as one of the greatest and most effective treaty’s every made. In 1986-1987 the Montreal Protocol was created and signed by over one-hundred nations across the world. This Protocol was an international treaty designed to protect the Ozone layer and to completely phase out the chemicals responsible for the weakening of the Ozone. The treaty went into effect in 1989.

Soon after that date marked the beginning of the end for CFC and HCFC refrigerants across the globe. The industrialized countries, like America, began to phase out the refrigerants first. R-12 was phased out in the early 1990’s along with all of the rest of the CFC refrigerants. The HCFC refrigerants such as R-22 or even R-502 were given a bit more time. Heck, R-22’s true phase out didn’t even begin until 2010.

Out with the old and in with the new, so they say. The refrigerants that were proposed to replace CFCs and HCFCs were known as HFCs, or Hydroflurocarbons. These refrigerants contained no Chlorine so there was no chance of them hurting the Ozone layer. Some of these refrigerants include popular refrigerants today known as R-134a, R-404A, and R-410A. But, now these refrigerants are under fire for their increase to Global Warming.

R-744 Present & Future

As I mentioned above HFCs were seen as the world’s savior from the Ozone depleting refrigerants. But, HFCs had their own problem. Instead of the Ozone this time it was Global Warming. These HFC refrigerants such as R-134a, R-404A, R-410A are known as ‘Super Pollutants,’ or ‘Greenhouse Gases.’ In order to measure their impact on the environment each of these refrigerants were given a Global Warming Potential number. The higher the number the more damage the refrigerant causes to the world. As a zero based scale for this measurement our old friend R-744 was used. Carbon Dioxide has a GWP of one. In comparison, R-404A has a GWP of three-thousand nine-hundred and twenty-two. Obviously, there is a large difference here.

I’m writing this article in 2019 and over the past ten years or so there has been a worldwide push to phase down and in some cases phase out HFC refrigerants completely. In order to phase out HFC refrigerants we have to have a replacement refrigerant. In some cases companies and countries have turned to a new classification of refrigerants known as HFOs. These HFO refrigerants are again synthetic products created by Honeywell & Chemours (Formerly DuPont). The problem with HFOs though is that they still have Global Warming Potential. Yes, not as high as HFCs… but the numbers are still there. Along with the GWP risk they also have a slight flammability risk. To me, I do not see HFOs being sustainable. I imagine the world will decide to phase them out in another ten or twenty years.

So, what is the solution you may ask? It’s R-744! Well, R-744 and other natural refrigerants. Technology has changed significantly since the last time R-744 was used widely. It’s been almost one-hundred years since we saw the mainstream use of Carbon Dioxide and now with nearly a century behind us the technology has significantly reduced the chance of component failures due to high operating pressures. We are now able to create efficient and stable R-744 systems without a large risk of failure.

While the cost of implementing R-744 systems is still quite higher then a traditional HFC system the costs have been coming down. This holds especially true in recent years as the push to innovate R-744 systems increases substantially with the phasing down of HFCs. While we are not there yet the costs are quickly shrinking the gap between HFCs and R-744.

There are many companies pushing forward with R-744 systems. Most of these are on smaller systems such as vending machines, but we all need to take baby steps. One company in particular, Coca-Cola, has installed hundreds of CO2 vending machines across the country. Along with Coca-Cola there are other grocery store chains out there using cascade R-744 systems mixed with other refrigerants such as Ammonia or lower GWP HFCs. We are even beginning to see R-744 uses in automobiles with the innovations that Daimler has made. As we completely phase down HFCs over the next ten years we will see more and more usage of R-744. It’s time has come again!

Conclusion

Well folks, after all of that I feel like we have covered our bases when it comes to R-744.  If you only take a few things away from this article let them be this. First, R-744 is a growing market across the world and you will begin to see more applications. It doesn’t matter what section of the industry you specialize in. R-744 is so adaptable that it’s only a matter of time before you come across it.

Secondly, since R-744 has no Ozone Depletion Potential and a Global Warming Potential of only one you can be safe in assuming that Carbon Dioxide will never be phased down our across the world. It is a natural refrigerant that has been used for over one-hundred years and it will continue to be used for another one-hundred years or more.

If you find that you’re still looking for more on R-744 then please check out our sources section below. This is where we pulled most of our data from and in some cases these websites can have a ton of information.

Thanks for reading,

Alec Johnson

RefrigerantHQ

Sources

RefrigerantHQ's Pressure Charts

Regardless of what system you are working on rather it is a home air conditioner, a vehicle’s air conditioner, a supermarket refrigeration system, or a large scale industrial application they all have one thing in common: Pressure.

Yes, as we all know one of the very first steps when it comes to diagnosing a refrigeration or air conditioning system is determining the various pressures that the system is operating at. Besides a simple visual inspection knowing the operating pressures of the machine is crucial. Having these facts along with the saturation point, the subcool, and the superheat  numbers for the refrigerant you are working on are essential when it comes to really understanding what is going wrong with your system.

After a visual inspection the very next step for the most seasoned technicians is pulling out their gauges and checking the pressure and temperature. It just becomes second nature after enough calls. I have heard stories of rookie techs calling some of the pros on their team for help on a system that they’re stuck on. It doesn’t matter what the situation is. It doesn’t matter if you’re in Miami or in Fargo. It will never fail that one of the first questions the pros ask the rookie is what your subcool is and what is your superheat? Having and understanding these numbers is instrumental to figuring out what to do next.

But, these numbers won’t do you any good if you don’t know what refrigerant you are dealing with and what the refrigerant’s boiling point is at each pressure level. This article aims at providing you with just that information.

R-744 Carbon Dioxide Pressure Chart

For those of us here in the United States coming across an R-744 Carbon Dioxide application may still be a rare occurrence. But, the world is changing and the popularity of this natural refrigerant is increasing. Along with the popularity the vast array of applications is increasing as well. You can find R-744 being used in vending machines, automobiles, supermarkets, and even in ice-skating rinks. The sheer versatility of R-744 and its climate friendliness is the reason we have seen such growth in its uses.

While we had mentioned earlier the concept of ‘subcool,’ it is important to note that in most cases R-744 applications do not have a subcool. This is because most R-744 systems operate as a transcritical system. Most refrigeration/air conditioning systems operate in what’s known as a subcritical process. This is your standard process that we are all used to. The difference with a R-744 application is that its operating temperatures can exceed the critical point temperature.  Carbon Dioxide’s critical temperature is just under eighty-eight degrees Fahrenheit. That eighty-eight degrees mark can easily be at or below the ambient temperature and when this occurs is when a transcritical system is required.

For more information on transcritical systems you can click here to be taken to our overview. The pressure and temperatures for R-744 can be found below:

°F°CPSIKPA
-68.8-5662.26429.3
-65.2-5469.13476.6
-61.6-5276.45527.1
-58.0-5084.25580.9
-54.4-4892.54638.0
-50.8-46101.33698.6
-47.2-44110.66763.0
-43.6-42120.53831.0
-40.0-40130.96902.9
-36.4-38141.98978.9
-32.8-36153.611059.1
-29.2-34165.871143.6
-25.6-32178.771232.6
-22.0-30192.341326.1
-18.4-28206.61424.5
-14.8-26221.561527.6
-11.2-24237.251635.8
-7.6-22253.691749.1
-4.0-20270.91867.8
-0.4-18288.911992.0
3.2-16307.752121.9
6.8-14327.412257.4
10.4-12347.962399.1
14.0-10369.372546.7
17.6-8391.72700.7
21.2-6414.982861.2
24.8-4439.213028.2
28.4-2464.423202.1
32.00490.653382.9
35.62517.943571.1
39.24546.293766.5
42.86575.753969.7
46.48606.364180.7
50.010638.134399.8
53.612671.124627.2
57.214705.354863.2
60.816740.885108.2
64.418777.755362.4
68.020816.035626.3
71.622855.765900.3
75.224897.036184.8
78.826939.956480.7

Conclusion

There you have it folks. I hope this article was helpful and if you find that something is inaccurate here in my chart please do not hesitate to reach out to me. I have sourced this the best I could but there is always going to be conflicting data.  I’ve seen it multiple times on various refrigerants. I’ll search for a refrigerant’s pressure chart and get various results all showing different pounds per square inch temperatures.

The aim with this article is to give you accurate information so again, if you see anything incorrect please let me know by contacting me here. On top of this post we are also working on a comprehensive refrigerant pressure/temperature listing. The goal is to have every refrigerant out there listed with a pressure/temperature chart that is easily available.

Thanks for reading,

Alec Johnson

RefrigerantHQ

Sources

A Look

I’ll be the first to admit that I know very little when it comes to a transcritical system. I have seen it mentioned numerous times and have also seen that it is starting to become a trend in certain newer environmentally friendly applications. In an effort to educate myself I’m going to take a look at transcritical systems and how they work in this article.

We are all familiar with subcritical refrigeration process. This is the same process that is used in most every air conditioner or refrigerator across the world. It consists of four specific processes known as evaporation, compression, condensation, and expansion. A subcritical system has ALL of it’s processes occur below the refrigerant’s critical temperature.

When parts of the cycle process take place at pressures above the critical point and other parts below the critical pressure the cycle process is referred to as transcritical cycle. Transcritical systems are found when using R-744 Carbon Dioxide refrigerant. This is due to R-744 having an extremely low critical temperature of thirty-one degrees Celsius. As a comparison, R-134a has a critical temperature of one-hundred and one degrees.

There are many cases where the ambient temperature could be between twenty-five to thirty degrees Celsius. If your critical point for R-744 is only at thirty degrees then how can you expect to remove the heat?

Difference of Subcritical & Transcritical

The key difference with transcritical systems is that the heat rejection process is different. There is in fact no condensation. This is due to the low critical temperature of certain refrigerants. In transcritical systems the heat rejection takes place at temperatures above the refrigerant’s critical temperature.

When a refrigerant reaches a temperature above it’s critical point it is no longer known as a gas or a liquid but instead known as a fluid. This fluid condition is also known as a gas condition or state. So, when rejecting heat with a transcritical system it is known as ‘gas cooling.’ Therefore the heat exchanger in an transcritical system is known as a ‘gas cooler.’

Besides the difference in heat rejection though the rest of the refrigerant cycle remains the same. We will go into the transcritical process in our next section:

The Process

A transcritical process begins with the compressor just like it does with a subcritical system. The difference here though is that as the compressor compresses the vapor refrigerant the temperature rises and rises until it reaches past the refrigerant’s critical temperature. This is where the state change differs. Instead of a liquid we get a state in between liquid and vapor known as fluid.

The next step in the process is the rejection of the heat gained from compressing the vapor. The heat exchanger, or gas cooler, expels the heat all the while having the temperature staying above the critical point. During this process you will also have the temperature vary between the point it left to the compressor to when it goes to the expansion valve.

Next, as you know, is the expansion process. At the time the refrigerant comes into the expansion vale it is above the critical temperature and in a fluid state. When leaving the expansion valve the refrigerant is no longer above the critical temperature and it is a mixture state of liquid and vapor.

Lastly, we are at the evaporator. In the evaporator the refrigerant comes in as a liquid at a constant pressure. Obviously, during the evaporation cycle we change states again to vapor that is slightly superheated. The vapor then makes it’s way to the compressor to start the process over again.

One thing to note that with a transcritical system superheat and subcooling temperature aren’t as important. While they can still be helpful, most folks only look at evaporating and condensing temperatures. In fact, with a transcritical system there is no condensation process and therefore no subcooling.

Questions

Are There CO2 Systems That Aren’t Transcritical?

  • Yes, most often these are found in what’s known as cascade systems. These systems contain two types of refrigerants. In these examples the CO2 refrigerant is used during the low temperature stage of the refrigerant cycle. This ensures that the refrigerant does not rise above the critical temperature.

Are there other popular transcritical refrigerants?

  • From what I have researched CO2/R-744 is the only transcritical systems used today. I also went through a list of all refrigerants and their critical temperature and only found a few that were very low. R-744 was the only common one that I found that is used today. If you know otherwise, please reach out and let me know.
    • One reader reached out to me and informed me that in some cases R-410A can be used in a transcritical system. That is because 410A’s critical temperature is only one-hundred and sixty-two degrees Fahrenheit. If you are in a warmer climate, in the summer, and the sun is beating down on a rooftop condenser then temperatures could very well come close tot hat one-hundred and sixty degrees mark.

How often do we use transcritical systems?

  • With constantly improving technology and the push to move the worlds towards greener refrigerants we are seeing a substantial rise in transcritical systems across the globe. Most of these new systems are found in Europe and other countries but the United States is making inroads as well. We’re always just a bit behind Europe though…

Are transcritical systems more expensive?

  • Yes, they are when compared to traditional HFC systems. This is especially true here in the United States as there aren’t as many technicians who are familiar with the technology and the parts aren’t as readily available. In the US these systems are nearly twice as expensive but in the EU they are only around thirty percent more.
  • The good news here is that CO2 systems are slightly more efficient then HFC systems and the cost of R-744 refrigerant is significantly cheaper then HFC refrigerants.

Why Should I Choose a Transcritical CO2 System?

  • Yes these R-744 systems are more expensive but you get peace of mind with a transcritical CO2 system. They are never going to be phased out like a R-404A application will be. CO2 has a negligible environmental impact and will be around for decades to come. It is a safe investment in the future of your business.

Conclusion

Well folks I learned quite a bit during writing this article. I had to dig through some articles to educate myself. All of my sources articles can be found below. If you have further interest in learning about transcritical systems then I highly recommend the first two sources from ACHRNews & Danfoss. These articles are great and go in-depth on the transcritical process as well as including diagrams and illustrations to help drive the points home.

Thanks for reading,

Alec Johnson

RefrigerantHQ

Sources

Well folks, as most of you know today is Earth Day. Personally, I don’t do anything to celebrate it besides walking around my property and enjoying the view. I just cleared an area by our pond this weekend and now I’ve got a nice quiet place to relax after a day’s work.

As I was reading the news today I saw a plethora of Earth Day stores. One that stuck out to me though was that the Environmental Investigation Agency (EIA) announced that they had launched a website in honor of Earth Day. This website aims at identifying retailers within the United States who have begun to use natural refrigerants instead of HFCs. The goal here is to have the companies who have started moving forward with natural refrigerants to be recognized for leading the pack.

Before we get to the website, let’s take a look at who the Environmental Investigation Agency (IEA) is. I have not heard of them before, and when I haven’t heard of something I like to research it. EIA is a non-profit organization that was founded back in 1984 out of the United Kingdom. Today they have offices in London and in Washington DC and focus on environmental crime and abuse across the globe. Their main website can be found by clicking here. They work on wide variety of things from endangered animals and poaching all the way over to climate change and refrigerants.

The new HFC website that EIA created can be found by clicking here. At first glance when looking at this website and the map that shows you where the natural refrigerant supermarkets are within the United States I couldn’t help but laugh. Nearly every location is in California or New York. This was expected as California usually leads the way in environmental progress, but still it was quite funny to see that the closest one to me is about one-thousand miles away (I’m in Kansas City).

Regardless of how far away they are progress is progress. According to IEA there are five main companies that have been pushing their locations to move away from HFCs and switch over to natural refrigerants. These companies are: Target, Aldi, Ahold Delhaize, Whole Foods Market, and Sprouts. Each of these companies has their own innovative ways of applying these alternative refrigerants. These range from:

  • Transcritical CO2 systems
  • Cascade or indirect systems using a combination of two low-GWP refrigerants
  • Micro-distributed systems using hydrocarbon condensing units on a chilled water or glycol loop
  • Stand-alone display cases using hydrocarbons

I won’t get into the details of what every company has done over the past few years to make this listing, but instead give you a quick highlight from each company. If you wish to read more on the subject feel free to visit our ‘Sources’ section at the bottom of this article to continue reading.

Aldi has been one of the leaders here in the United States. This isn’t surprising in the slightest as they are a European based company and have European ideals. (Europe is always ahead of us when it comes to environmental changes.) According to IEA Aldi has over two-hundred stores with transcritical R-744 systems with plans to add another one-hundred by the end of 2019. Along with that they have launched R-290 propane self-contained refrigerators/freezers and they have transitioned their warehouses over to R-717 ammonia based systems.

Target is another big driver of change. So far they have over one-thousand stores using self-contained hydrocarbon refrigerators/freezers (R-290 and R-600a). They have also begun experimenting with CO2 applications. They are piloting a transcritical R-744 application in two stores and they have also begun using CO2 cascade systems in their larger stores. Also, just like Aldi, they are using ammonia R-717 in their food distribution warehouses.

The other stores haven’t done as much as Aldi and Target, but they are still making strides to cleaner refrigerants. Whole Foods, now owned by Amazon, has begun distributing propane stand-alone refrigerators/freezers across their entire store network. They have also been piloting a transcritical CO2 system in their Brooklyn, New York store. The company Ahold USA was the very first store ever in the United States to begin using a transcritical CO2 system. Lastly, Sprouts was the first grocery store in the United States to use a R-744 ejection refrigeration system.

Conclusion

Along with these companies being environmentally friendly and being recognized by such agencies such as the IEA they also get the added benefit of increased energy efficiency. More often than not natural refrigerants are far more efficient than your standard HFC refrigerant. Ammonia, for example, is the most efficient refrigerant out there. All of this efficiency means decreased monthly energy bills for these stores and companies. So, while there may be a larger expense up front with a natural system the business owner will make it back month to month with lower operating expenses. They also get the peace of mind knowing that natural refrigerants will never be phased out by the Environmental Protection Agency as they have no, or extremely little, impact on the climate and the Ozone layer.

While looking at the map of all of stores using natural refrigerants was comical, we do all have to start somewhere. I’m willing to bet though that the map isn’t covering every store in the country. There’s a Whole Foods and an Aldi not far from me and I bet one of those stores are using a propane based refrigerator. With each year that passes the chance of running into these systems increases. If you haven’t already familiarized yourself with them I would recommend looking into it soon.

What is interesting though was after reading this I saw very little mention of HFO refrigerants from Honeywell and Chemours. Are the HFO refrigerants being eclipsed by natural refrigerants?  Will we begin to see the mass conversion away from R-404A before HFOs can be fully rolled out? Time will tell.

Thanks for reading,

Alec Johnson

RefrigerantHQ

Sources

Here in the United States most of our ice rinks rather they be hockey stadiums or a kids ice-skating park were and are mostly powered by the common HCFC R-22 refrigerant. As you all know R-22 was phased down back in 2010 and is in the process of being phased out entirely. The question on the owners minds of these complexes is with what refrigerant should they replace their older R-22 systems with? Is there a preferred one out there?

Over in the European Union they have been a big fan of R-717 (Ammonia.) in their ice rinks. Ammonia has been used since the 1930s as a refrigerant. It is actually referred to as one of the most efficient refrigerants out there as it has a low boiling point and it is highly energy efficient. On top of that you have no Ozone depletion risk and zero Global Warming Potential. It all sounds too good to be true, right? Here’s the catch folks, R-717 is classified as a B2L refrigerant on toxicity and flammability. The ‘B’ means that it is toxic if inhaled and the ‘2L’ means that it is slightly flammable.

If an Ammonia leak does occur it has to be taken very seriously. There was an incident towards the end of last year up in British Columbia that resulted in three fatalities due to the toxicity of the Ammonia leaking into the building. During the leak the event center had to be evacuated along with any neighboring businesses or homes. I wrote an article about this tragic event which can be found by clicking here. This example right here is why the US has been skiddish about adopting R-717 and the end all be all replacement for R-22. Originally, R-22 was chosen for ice rinks here in the US due to it’s low toxicity. If a person breathed in R-22 there would be no ill effects. So, what other options are out there besides R-22 and R-717? There are some Ammonia advocates here in the US but since this incident occurred just north of our border the skepticism on R-717 has only increased.

CO2 to the rescue?

Most of you who have been following the industry over the past couple years know exactly where I am going. It seems that everything is either moving towards the new HFO refrigerant line from Chemours/Honeywell or they are moving to R-744 (Carbon Dioxide.) I don’t care if you look at vending machines, refrigerated units in supermarkets, or even in ice rinks. CO2/R-744 is showing up everywhere. CO2, like Ammonia, has no Ozone depletion and has a GWP of one. Here’s the best part though it’s rated as a A1 in toxicity and flammability. That means it is NOT toxic or flammable. The downside of CO2 is that it operates at a MUCH higher pressure then other refrigerants on the market. This higher pressure can cause components to fail prematurely.

When I was going through my research tonight I found an article from a local news station out of Alaska. The article took place in Wasilla, a small town north of Anchorage. The town only has a population of about eight-thousand people. (My kind of town!) Their ice rink is one of their larger attractions, but it is over thirty years old and is dealing with an antiquated R-22 system. We all know how much the price of R-22 has gone up these days. Can you imagine recharging a one-thousand pound system? The cost would be astronomical. Imagine having to try and absorb that expense into your P&L for the year.

Luckily for the town of Wasilla there was a twenty-two million bond that was passed by the voters back in October of 2016. Three million dollars of that twenty-two will be going towards removing the old R-22 system on this ice rink and replacing it with a new R-744 CO2 system. On top of that massive expense the complex will also be closed for Spring and Summer while the construction is completed. The goal of completion is set for Labor Day.

This is such a laborious and expensive process as there is just no easy way to retrofit or replace an aging R-22 ice rink system. These installations are massive and when working with a completely different refrigerant such as R-22 nearly everything will have to be replaced. Remember now that CO2 operates at a MUCH higher pressure than R-22. Most of the components will have to be reinforced in order to accommodate this increase in pressure.

Conclusion

Are our only choices today R-744 and R-717? Is there going to be an HFO alternative out there that we can expect? Through my research tonight I wasn’t able to find an HFO refrigerant that could be used for these ice rink applications. I may have overlooked them but I have a feeling that the ice rink market is very niche within the refrigerant industry and Honeywell and Chemours are more focused on the R-404A or R-410A replacements. If any of you know of any please let me know.

I fear that these pricey conversions and retrofits over to these new systems could put a lot of ice rinks out of business. I already know of one in my area that has closed within the past couple years. Just think about that three million dollar number we spoke of earlier. That’s just one complex. That is one hell of an expense. What can these owners do? Do they keep holding out on their dying R-22 systems hoping and praying that they don’t have a leak or a failure? Or, do they bite the bullet and hope they can afford the cost of the new system? That’s not even mentioning the downtime the business would face while the new system is installed. Every day their doors are closed is money being lost.

I’m all for switching to newer refrigerants but like with anything there are going to be winners and losers here.

Thanks for reading,

Alec Johnson

RefrigerantHQ

Sources

While all of the other car manufacturers around the world are scurrying towards the latest and newest fad of HFO refrigerants Daimler is stepping away from the pack and creating their own alternative refrigerant method for automotive air conditioning. If we look at the automotive market today we can see one primary refrigerant known as R-134a. 134a is an HFC refrigerant and is known for it’s extremely high Global Warming Potential number of one-thousand four-hundred and thirty times that of Carbon Dioxide. That means that any of this R-134a that is released or vented into the atmosphere actively contributes to Global Warming at a rate a thousand times more than Carbon Dioxide.

The rush was on to develop a new alternative refrigerant. Honeywell and Chemours offered a solution. They offered the new Hydrofluoroolefin refrigerant known as 1234yf. This yf refrigerant is non Ozone depleting and also has a minimal GWP of four. Automotive companies jumped at this new refrigerant as a solution to their problems. However, there was one company, Daimler, that was not in favor of this new refrigerant. Their reasoning was that this new refrigerant went up a scale on the refrigerant flammability rating. 134a was rated as a 1, or non-flammable. 1234yf was rated as a 2L, or mildly flammable. To remove their doubts about this new refrigerant Daimler did numerous test scenarios to see how the refrigerant would react when the tank was ruptured and the refrigerant made contact with the hot parts of the engine. The test did not end well, in fact the refrigerant ignited causing a fire under the hood of the vehicle. There is a video of this that can be found by clicking here.

After this test result was released the rest of the world tried to replicate it, but no one was able to. After time the governments and companies dismissed the video and test as a fluke and stated that it was not reproduce-able. Since then the world has moved forward with 1234yf. In fact in the European Union 134a was banned entirely on new models. There is a similar ban coming to the United States in the year 2020. (2021 model years.) Throughout all of these changes Daimler fought and fought against companies and even against the European Union.

They wanted to continue using R-134a as they deemed 1234yf as unsafe. I won’t get into all of the details here but there was a large back and forth between Daimler, Germany, and the European Union. After years of debate and arguing Daimler eventually agreed to use 1234yf in all of it’s model ranges starting in 2017. To get around the safety issues that they saw with 1234yf Daimler developed their own innovations including a patented system to keep the fluid and hot engine components separated even in the event of an accident.

The Rise of R-744

Remember how I said that all Daimler 2017 models would be using 1234yf? Well, there is an exception to that. The S-Class and the E-Class models will not be using 1234yf and will not be using R-134a. No, folks. They will be using the first R-744 Carbon Dioxide automotive application. What is so amazing about this is that Daimler started working towards their own alternative clean refrigerant in January of 2014 and then just three short years later they already had models rolling out of the shop with it installed and ready to go. Talk about German efficiency.

This was no easy feat either. As most of you know CO2 operates at a much higher pressure then other refrigerants. CO2 was actually one of the first mainstream refrigerants to be used across the United States but it’s popularity waned due to the high rate of part failure and also due to the invention of CFC and HCFC refrigerants like R-12 and R-22. In order for Daimler to properly use CO2 for their cars they had to redesign nearly all of the components to accommodate the higher operating pressure. To give an idea of the pressure difference, CO2 operates around ten times the pressure of a regular system. So, that meant that they had to create a new compressor, evaporator, and condenser. That’s not even factoring in the new seals, hoses, o-rings, and everything else that was involved. Frankly, folks I’m astonished at how they accomplished this. It makes me want to go out and by a Daimler vehicle… if only I could afford one.

Usually, when a company makes this kind of invention and progress on new technology they like to hold on to it and patent it so that they keep the competition’s hands off of it. Not Daimler. Nope. They have allowed other companies access to the designs and equipment used so that other OEs can more easily design their own CO2 systems. That is a stand up move by Daimler and really shows that they care about the safety of the drivers as well as the environment.

 

Conclusion

Now, you may remember from earlier that I said Daimler was using 1234yf refrigerant on most of their models in 2017. This was not their choice but they gave in after a long and hard fought battle. Well the good news here is that this yf usage from Damiler is only temporary. It was only because of the time crunch that they were under. On January 1st, 2017 R-134a was no longer acceptable in new vehicle models in the European Union. So, Daimler was practically forced to use 1234yf on their models. Their ultimate plan is to transition all of their vehicle models over to the new R-744 application but at this time they are just not quite ready yet. Don’t worry though I’m sure it will only take them a couple more years.

Regardless, I am just amazed at the speed and innovation that Daimler has done when faced with a new refrigerant that they felt was not safe for public use. Instead of towing the line like the rest of the OEMs in the world they decided to set themselves apart and make their own system. That alone speaks to the quality of Daimler.

Thanks for reading,

Alec Johnson

RefrigeantHQ

Sources

The grocery store chain Aldi has announced their intention to switch all of their stores in the United Kingdom to CO2 refrigerant. (Also known as R-744.) Their goal is by the end of the year 2018, just over twelve months from now, that one-hundred of their stores will be fully converted over to R-744. This is a twenty million Euro investment for the German based company. That’s equal to about twenty-three and a half million dollars. This is just the start for their conversion as Aldi has over seven-hundred stores in the United Kingdom and plans to open up another three-hundred over the next couple years. All of these stores will be using CO2 as their main refrigerant source.

There are two main reasons Aldi has made this decision. The first is to become compliant with the European Union F-Gas regulations that come into effect in 2030. (For more information on the EU’s F-Gas Regulation please click here.) Like most other countries around the world the European Union has agreed to phase-out HFC refrigerants entirely. These refrigerants include R-404A, R-410A, and R-134a. (There are others, but these are the most popular.) The plan is to cut the availability of HFC refrigerants by seventy-nine percent between the years 2015 and 2030. Only companies with approved EU quotas will be able to supply, manufacture, or import HFC refrigerants. A full schedule of the phase-out can be seen in the picture below:
F-Gas HFC Phaseout

The second reason Aldi made this decision was for it’s impact on the environment. Sure, you can say that the environment was their primary reason but they are a business and they weighed the pros/cons and the cost involved in switching now or switching later when they got closer to the 2030 deadline. Switching now made more financial sense. By switching over to CO2, or R-744, Aldi will be reducing their gas carbon emissions down by ninety-nine percent and will see an annual decrease of over fifteen-million in Global Warming Potential. CO2 refrigerant has a GWP of 1. That is a HUGE difference when comparing it to the commonly used R-404A refrigerant which has a GWP of 3,922! You can begin to see why governments have been pushing to phase these HFC refrigerants out.

CO2 R-744 Refrigerant

R-744 refrigerant is becoming increasingly popular across the world. It’s ironic really as CO2 was one of the first widely used refrigerants in the world. Let’s go back one-hundred years. Chances are if you went to a movie theater on a hot summer day in the 1920s that the movie theater would have been cooled by CO2. You’d step in from the heat and feel the cool and relaxing air and then watch yourself a Charlie Chaplin film.

The problem with CO2 back then, and today, is that it requires an extremely high pressure to operate in a refrigeration cycle. This high pressure caused units and parts to break repeatedly. It was during the depression when a new cheaper alternative refrigerant was discovered. The CFC R-12. The moment R-12 was discovered it took off and was soon found in every application across the globe. Next came R-22, and so on and so on.

So, we went from CO2 > CFCs > HCFCs > HFCs > and now back to CO2. We’ve come full circle folks. The difference here is that with today’s technology, new parts, and equipment the extremely high pressure of CO2 is no longer a problem. We have stronger, tougher, and better tools and parts to compensate for this pressure. Now the big concern is danger to the earth and the climate. R-744 is one of the most logical answers here.

Conclusion

Like it or not folks natural refrigerants, like CO2, are going to be part of our future. HFCs are going away and the HCFCs are pretty much gone already. We have two choices. We are either going all in on the new HFO refrigerants or we are going back in time to the days of Natural Refrigerants such as CO2 or Ammonia. Which do you prefer?

If and when you do come across a CO2 unit just think of yourself as honoring the past. You’re honoring the memories of your grandparents and maybe even their parents. The people who pioneered this technology we are now using today.

Thanks for reading,

Alec Johnson

RefrigerantHQ

Sources

Germany Automakers Rebelling Against 1234YF

Well folks it looks like the automotive refrigerant market is going to be split into two. Today, most everybody is still using R-134a as the main refrigerant for automotive applications. If you have been working on newer cars you may have seen some vehicles with the HFO 1234YF systems. R-134a is being phased out across the world due to it’s high global warming potential of over 1,000. In the European Union R-134a was banned in the year of 2011. All new cars manufactured in Europe have to be using a refrigerant with a Global Warming Potential of less than 150.

The European Union chose the HFO 1234YF as it’s primary replacement and it’s not just Europe that is switching over to the HFO. General Motors announced that all of it’s vehicles will be switching over to 1234YF with a goal date of 2018. Chrysler announced that they would be switching over as well. Not to mention various other foreign manufactures. It seems like HoneyWell, DuPont, and the all of the major manufacturers are pushing for 1234YF. After all, it is a viable alternative to the harmful 134a being used today… or is it?

Germany Automakers Warn Against 1234YF

Remember how I said almost every automotive manufacturer is switching over to 1234YF? Well, I did say almost. The German manufacturers Daimler and now Volkswagen have declared that they will NOT be using 1234YF in any of their vehicles. Their reasoning stems from some tests that Daimler did in 2012 testing the safety of 1234YF. In two-thirds of the tests that Daimler conducted the 1234YF refrigerant ignited when the compressor ruptured and the refrigerant gas hit the hot engine. This test is designed to simulate a head on collision. When Daimler did the same tests with R-134a the refrigerant did not ignite. You can read more about this by clicking on this link to Daimler’s website. On top of the flammability Daimler also found that the refrigerant can emit toxic hydrogen fluoride gas when it burns. So, your car will be on fire and you’ll be choking to death. Good times…

After these tests were completed the German Transit Authority did it’s own tests but they were not able to replicate the results that Daimler had. On top of that the European Union did additional tests as well as DuPont and Honeywell. All tests came back negative. Daimler didn’t care about these other tests and claimed that they will NOT be using 1234YF in any of their vehicles. Instead, Daimler went forward on designing a CO2, or R-744, refrigerant system for their vehicles. On top of Daimler switching to CO2 it was announced this week that Volkswagen will be transitioning over to CO2 instead of 1234YF. The official article is in German, so I’ll post a small article from The Cooling Post about the announcement.

The Split

Well, with Daimler, Volkswagen, Porsche, Audi, and BMW all switching over to CO2 and the rest of the world using 1234YF we now have a split in the automotive air conditioning market. So, if you’re a mechanic and occasionally work on German cars you are now going to have to know your way around 134a systems, 1234YF systems, and CO2 systems. Obviously, this is inconvenient for everybody, but I can’t really complain as the German automakers firmly believe that they are making the right decision here. If I saw the tests that they had I would probably be pushing for CO2 as well. At the same time though, there have been hundreds of other tests that showed the refrigerant works fine. Are the German companies being stubborn, or is there legitimate concern?

Conclusion

The automotive air conditioning market is in a state of flux right now. 134a is banned in the European Union but still active in the US. The EU has switched over to 1234YF except for Germany who has switched to CO2. The USA is still majorly using 134a and slowly moving over to 1234YF. Asian markets are moving to 1234YF as well. The tide is with 1234YF but who knows what will happen. All it takes is one or tow bad accidents with 1234YF to prove Germany was right.

Thanks for reading,

Alec Johnson

Owner.

 

 

CO2 Refrigeration Systems

CO2 The Natural Refrigerant Gaining Popularity… Again.

Well ladies and gentlemen it seems that we have come full circle in the past hundred years on refrigerants. We started with CO2 and now we’re circling right back to it. Every time I’m writing one of these articles about phasing out refrigerants I can’t help but chuckle. It seems that whenever we get close to the ‘perfect’ refrigerant something is found wrong with it. Either it depletes the Ozone, it has a high global warming potential, or it’s too flammable.

CO2 History

R-744 refrigerant, or CO2, was one of the first refrigerants invented and widely used in the late 1800s and early 1900s. We were using CO2 even before R-12 Refrigerant was invented. The idea of using CO2 as a refrigerant dates back to the 1850s and the first legitimate patent on CO2 was all the way back in 1867 Thaddeus S.C. Lowe. 

The idea was picked up again in Germany in the 1890s when Franz Windhausen of Germany designed the first carbon dioxide compressor and his design was purchased by J&E Hall of Great Britain. Here it began to see widespread use on cargo ships throughout Europe.  In America CO2 saw widespread use as well in ice machines, ships, and entertainment venues. Even the first movie theaters in the 1920s were cooled with CO2 refrigerants.

R-744 was eventually phased out due to two main reasons:

  • The Great Depression played a big part in the phase out of R-744. Refrigeration became a luxury that a lot of people just could not afford and the demand crashed.
  • R-744 is notoriously high pressure. Unfortunately, the technology in the early 20th century just wasn’t there  to keep the CO2 equipment running smoothly. The new R-12 Refrigerant was the easier choice as it did not have the high pressure complications that CO2 did.

CO2 is Coming Back!

I’ve been watching the refrigeration industry over the past year and I am definitely seeing the trend of CO2 making a resurgence. The reason we’re seeing this is mainly due to the phase outs of refrigerants in the late 20th century and the early 21st century.

First we phased out the CFCs and HCFCs due to their ODP, or Ozone Depletion Potential. These were phased across the world in accordance to the Montreal Protocol and the world transitioned over to HFC refrigerants such as R-404A, R-410A, and R-134a.

Well now it’s been found that HFC refrigerants have an extremely high Global Warming Potential. So, now that we’ve spent all this time switching everybody over to the HFCs there is now a push to phase out the HFCs. The question is what is going to replace the HFCs?

There are many companies and experts suggesting various refrigerants and alternatives and one of those alternatives happens to be CO2.

Benefits  and Drawbacks of CO2

CO2 offers a variety of benefits when comparing it to the refrigerants that are in use today:

  • No Ozone depletion potential.
  • Global Warming Potential is 1. (R-134a is over 1,000)
  • Non-Toxic
  • Non-Flammable
  • Far more efficient than other refrigerants.
    • Save everybody some money on their energy bills!

Now, I am not an expert here but the only drawback that I can see on CO2 systems is that is a very high pressure refrigerant. Back in the day this caused a lot of parts to fail and fail often. However, I believe in the 21st century that we have the technology to utilize CO2 and to do it safely. Keep in mind that you will need specially designed systems to handle CO2.

So, Who’s Using CO2 Now?

I’ve found quite a few articles on recent CO2 usage and I even found a website specifically dedicated to CO2 that can be found here http://r744.com.

I won’t go into detail about EVERY company that is using CO2 but here are some examples:

  • CO2 is used during the transportation/storage of ice cream and as most of you may know ‘Dry Ice,’ is CO2 in solid form.
  • Coca-Cola announced a few years ago that they would be discontinuing all usage of HFCs in their vending machines and would be transitioning over R-744.
    • Article can be found here.
    • Now, Coca-Cola fell short of their announced goal as you can read here, but as of today they have over 1.4 million CO2 vending machines on the market. This number is only expected to grow and other companies have begun to follow suit.
  • I found this article the other day detailing the first CO2 ice skating rink in Alaska. Ice skating rinks using CO2 is common place in Canada and is expected to spread in other parts of Alaska.
    • Article is here.
      • Now, I have to say this… but why does an ice rink in Alaska need cooled? It’s freaking Alaska!
  • Large supermarkets and grocers have begun to switch to CO2. I found a great article from ACHRNews on this.

I can keep listing examples, but I feel that this gives a taste of what’s to come with CO2.

CO2 versus HFOs?

Besides CO2 one of the other alternative refrigerants that is coming to market are the HFOs produced by DuPont and Honeywell. I won’t get too deep into this but I have a feeling that as time goes on we’re going to see a ‘war’ between CO2 and it’s HFO counterparts. Are we going to be using 1234YF in our automobiles five years from now or will we be using CO2? How about for our super markets? Even residential?  At this point it’s too early to tell what’s going to happen but it is exciting to see the innovation that is coming to the market.

Conclusion

As I stated in the beginning of this post it feels like we’ve gone in full circle…. and maybe that was how it was supposed to go. With this industry it feels like it’s impossible to predict anything. Regardless, CO2 is coming back and you best be ready!

Thanks for reading,

Alec Johnson

Owner.