Industrial Refrigeration: Ammonia and CO2 Systems

The turn of the New Year signaled the most recent step of the R22 refrigerant phase-out in the United States.

As a reminder, here’s the timeline according to the EPA final rule:

• On January 1, 2018, R22 production dropped 30 percent from the 2017 supply to 9 million pounds
• On January 1, 2019, production will drop 55 percent from the 2018 supply to 4 million pounds
• On January 1, 2020, R22 will be phased out completely with no new or imported R22 allowed in the U.S.

Since the supply just dropped at the beginning of this year, that means R22 prices (and repair prices) are increasing yet again.

If your refrigeration system uses R22, or any other refrigerant with a high Global Warming Potential (GWP), you have some decisions to make — and the clock is ticking.

Here are your options:

Do Nothing (For Now)

You can choose to delay any action on this matter, but you would simply be delaying the inevitable. If your equipment breaks down after 2020, you will be forced to replace your system. If your equipment breaks down before 2020, you will have to pay a high price for a repair or end up replacing your system anyway. (Remember, there are other equipment owners in the same boat, all scrambling to get their systems serviced at the same time.) For many owners, it is much better to plan for downtime rather than be forced to deal with it when their system suddenly stops working.

Retrofit Your Older System To Use Another Refrigerant

It may be possible to use an alternate synthetic refrigerant in your current system, but this is only a short-term solution. The acceptable direct replacement options involve refrigerants with GWPs thousands of times higher than that of Carbon Dioxide (CO₂). Ammonia (NH₃), by contrast, has a GWP of zero.

If you choose to switch to another synthetic, you must factor in the downtime your facility will endure in order to:

• Drain/reclaim your current system of all its refrigerant and oil
• Perform a nitrogen charge to clean out the system
• Drop in new refrigerant

Bear in mind that this won’t be an option for all systems, so you’ll need an inspection to determine if this is even possible at your facility. For many owners, the period of downtime is such a burden that the only reasonable choice is to upgrade to a foresighted solution like ammonia or CO₂.

A final option is to cross your fingers and hope someone will invent a new direct substitute with an acceptably low GWP. Without evidence of such a possibility, I like to recommend energy efficient, long-term solutions that minimize a system’s impact on our environment.

Upgrade Your System Proactively

If possible, the ideal, long-term solution is to perform a full system replacement and switch to natural refrigerants such as ammonia (NH₃) or carbon dioxide (CO₂). Other low-GWP replacement options exist (e.g., propane or butane), but are incompatible with industrial facilities due to the large volumes that would be required.

Ammonia refrigeration vs. CO₂ refrigeration

Like with anything, there are pros and cons to both of these options, so let’s look at some considerations if you choose to pull the trigger on a full system upgrade.

• Type of facility/occupancy — While ammonia systems are generally safe, they are a slightly higher-risk option compared to CO₂ systems. Some owners prefer using ammonia in facilities with less personnel (e.g., warehouses) and opt for CO₂ and/or cascade systems in facilities with greater occupancy. That said, both options are widely used and safe overall.

• Temperatures in the facility — CO₂ performs better at lower temperatures, so it’s often selected for facilities with a lot of low-temp freezers. On the other hand, for other temperature ranges (e.g., facilities with mostly 40-degree coolers), ammonia systems are generally the efficient and cost-effective option.

• Upfront cost — CO₂ operates at higher pressures, so that can make the equipment more expensive, especially for the more complex cascade systems; however, smaller bore CO₂ piping — and subsequently a reduced insulation cost — can make up much of this cost difference.

• Environmental impact — Generally speaking, both ammonia and CO₂ refrigerants have relatively low environmental impact. Both are highly energy-efficient when optimized for a system. While cooler systems will generally perform better with NH₃, ammonia is typically taken from natural gas, so there are some environmental costs from the associated natural gas extraction (this is largely a one-time impact). Since CO₂ is a byproduct from other industries, it’s typically abundant and requires little environmental trade-off to source. This wide availability also has a favorable impact on its cost.

Packaged Refrigeration

Low-charge packaged refrigeration is a safe, innovative solution that uses ammonia or CO₂ and a secondary refrigerant (such as glycol). This allows facilities to reap the benefits of these refrigerants’ excellent thermodynamic properties while minimizing the refrigerant charge and risk as the ammonia is isolated to one area and only the secondary refrigerant is circulated throughout the facility.

This new type of system is “packaged” or “modular,” with refrigeration equipment built off-site, mounted on a structural steel base (or skid), and delivered to your plant as a self-contained, “plug-and-play” system. Because it uses secondary refrigerants, which confines ammonia to the machine room and only uses about one pound of ammonia per ton of refrigeration, the charge is minimized.

Packaged refrigeration is just one more option when it comes to upgrading your R22 system.

About Stellar

Stellar is a fully integrated firm focused on planning, design, pre-construction, construction, refrigeration, mechanical & utility, building envelope, and total operations & maintenance services worldwide. Visit the company's blog at www.stellarfoodforthought.net or learn about its projects at stellar.net.