Refrigeration systems can be a costly, but vital, component in the food market and with them comes a lot of questions. With the AIM Act looking to phase out refrigerants with high global warming potential as well as a consistent push to go to all natural refrigerants, our customers are now finding themselves wondering which route should I go? The truth is, there is not one set correct route to take as far as which refrigerant to use; that all depends on what each user is looking to do, what their priorities are, and how much of a heat load is ultimately on the system.
For example, if you have a grocery store with multiple refrigerated cases and walk-in coolers and freezers, a refrigeration rack system would most likely be best for you. This would still allow you to use either CO2 or an A2L refrigerant. The load of all the cases and walk-ins as well as piping route would ultimately determine how many pounds of refrigerant would be needed and could eliminate one of the options as there are charge limits within a single refrigeration system with some of the new A2L refrigerants. However, if you only have a couple of small cases or walk-ins, then individual condensing units paired with those cases or ceiling hung evaporators may be the preferred option. This will more than likely eliminate the possibility for CO2 to be used. Then a decision will have to be made on which of the new A2L refrigerants is best for this scenario.
Another component to consider is reheating. This is where you could use some of the heat captured in the refrigeration system to use as hot gas defrost for the refrigerated spaces or to heat up water prior to passing through a boiler which could reduce other utility usages as well since the load on those systems could reduce.
One of the “downsides” of CO2 is that it operates at a much higher pressure than our typical synthetic refrigerants do and is designed to operate in a trans critical state which has a part in a reduced overall efficiency of the refrigerant. If there is a significant amount of heating needed in a store or plant, the amount of time CO2 spends operating at that trans critical state can be reduced significantly and will ultimately allow for energy savings both in the efficiency of where that heat is being added as well as in the refrigeration system as a portion of the heat will be removed prior to the gas cooling stage of the refrigeration cycle.
One more thing to consider when designing a refrigeration system is future viability. While the current A1 refrigeration systems are still able to be serviced going forward, and same as the new A2L refrigeration systems, there will come a time at some point in the future when these systems will not be serviceable. At that point, a system with a natural refrigerant will most likely be the only way to go. While it is unclear at this point if the upfront as well as year over year costs of a CO2 system will be more, less, or equal to that of an A2L system, how “future proof” a customer is wanting to go is also something to consider. With the end goal, it appears; to have every refrigeration system using a natural refrigerant in the future it may be a worthy consideration to “take the leap” into CO2.
At Carlson & Stewart Refrigeration, Inc. we strive to design and install superior commercial and industrial refrigeration systems as well as help keep our clients make informed decisions to solve their needs now and into the future. For any questions on which refrigerant and system style may suite your operations needs the best, please contact Carlson & Stewart Refrigeration, Inc.