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Blog 2: Regulatory climate leads to inventive uses of natural refrigerants

AndrePatenaude_Blog_Image Andre Patenaude | Director, CO2 Business Development

Emerson Commercial & Residential Solutions

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Today, more supermarkets, restaurants and convenience stores are re-evaluating natural refrigerants to comply with environmental regulations and achieve sustainability objectives. As refrigeration technology continues to improve, equipment manufacturers are working closely with these forward-thinking companies to develop innovative solutions. These efforts have resulted in several creative natural refrigerant applications that expand upon their traditional uses in commercial refrigeration.

For example, the idea of using ammonia (NH3 or refrigerant name R-717) in food retail is relatively unheard of — until recently. In 2015, the Piggly Wiggly supermarket company opened a new 36,000-square-foot store in Columbus, Ga., that utilizes an NH3/CO2 cascade system manufactured by Heatcraft Worldwide Refrigeration. The all-natural refrigerant system uses an ultra-low charge of ammonia (53 pounds) located on the facility’s roof — away from occupied spaces and virtually eliminating any safety concerns. The innovative system earned the retailer the highest certification level (platinum) from the EPA’s GreenChill Partnership, making it only one of 10 supermarkets in the U.S. to receive the award. It’s also the fourth supermarket in the U.S. to use this NH3/CO2 cascade architecture.

In cold storage applications, where ammonia has been the preferred refrigerant for decades, companies are increasingly looking to carbon dioxide (CO2) to proactively lower ammonia charges and avoid regulatory entanglements. So, as older ammonia systems near replacement, many operators are evaluating the best option to expand their facility’s low-temperature capabilities. They’re accomplishing this by adopting NH3/CO2 cascade systems that not only utilize very low charges of ammonia, but also keep the R-717 circuit out of occupied spaces.

Propane is also making comeback, so much so that Target recently announced their intentions to use only propane in their self-contained units. Many other retailers have followed suit, implementing R-290 units as part of their refrigeration portfolios. It’s an indication that the mainstream perceptions about the viability of R-290 are shifting. Its lower charge limits make R-290 a logical fit for Target’s smaller, stand-alone refrigerated display cases and coolers. All of this is part of the retailer’s pledge to become a sustainability leader in the food retail space.

From strictly environmental or performance perspectives, these new natural refrigerant systems are tough to beat. Of course, there are other important considerations when selecting a commercial refrigeration system — such as safety and maintenance requirements — where natural refrigerants pose unique challenges. But these newer systems are proof of how operators are making the decision to go natural and deal with these challenges. Target, for example, gave its contractor network advanced notice to seek the necessary training before deploying its self-contained, R-290 units.

Often, these new systems are also delivering energy-efficiency improvements. And in many self-contained R-290 units being installed across the country, they are also meeting the DOE’s mandate for energy efficiency. So, for true future-proof refrigeration systems, natural refrigerants are currently the best option available to meet both EPA and DOE regulatory requirements.

Read the full Accelerate America article [pg.16].

 

Blog 1: Why natural refrigerants are playing a larger role in commercial refrigeration

AndrePatenaude_Blog_Image Andre Patenaude | Director, CO2 Business Development

Emerson Commercial & Residential Solutions

 

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In an era driven by historic regulatory activity and the necessity to deploy sustainable refrigeration system architectures, more businesses are looking at systems based on natural refrigerants to help them achieve these goals. Unlike the synthetic hydrocarbon (HFC) refrigerants that have commonly been used in refrigeration applications — such as R-404A, R-507A and HFC-134a — ammonia (NH3 or refrigerant name R-717), propane (refrigerant name R-290) and carbon dioxide (CO2 or refrigerant name R-744) are three naturally occurring refrigerants that pose very little threat to the environment.

The direct environmental impacts of refrigerants are measured by two key factors: global warming potential (GWP) and ozone depletion potential (ODP) — while their indirect impacts are measured by energy efficiency. While new synthetic refrigerants are being developed that offer lower GWP and no threat to the ozone layer, many of them are either largely untested or have yet to be deemed as acceptable substitutes by global environmental regulations, such as those set forth by the U.S. Environmental Protection Agency (EPA). In contrast, natural refrigerants are not only the benchmark for ultra-low GWP and ODP, they’re also acceptable for use in most refrigeration applications (subject to use conditions).

Let’s start by looking at the historic usage and performance characteristics of these natural refrigerants.

Ammonia
With its superior thermodynamic properties, R-717 was a logical first choice for early refrigeration systems. Classified as a B2L, its toxicity and mild flammability require the careful adherence to safe application procedures. The introduction of lower-risk, synthetic chlorofluorocarbon (CFC) refrigerants in the mid-twentieth century turned the refrigeration industry away from R-717. Even so, ammonia’s suitability in low-temperature applications has made it a mainstay in industrial, process cooling, cold storage and ice rink applications to this day.

Propane
Propane is a hydrocarbon that was also identified in the early days of refrigeration as an extremely effective refrigerant. Offering high-capacity, energy-efficient performance and a very low GWP (3), its A3 classification (flammable) led to concerns about its safety. And as synthetic refrigerants became available, R-290 was overlooked in favor of its CFC and HFC counterparts. However, since the 2000s, R-290 has been regaining global popularity as a lower-GWP, effective alternative to R-404A and HFC-134a — especially in a wide range of low-charge, reach-in displays.

Carbon dioxide
CO2 is non-flammable and non-toxic and has proved to be a very effective natural alternative to HFCs in both low- and medium-temperature applications. CO2-based refrigeration systems have been successfully deployed in commercial and industrial applications in Europe for nearly two decades. Because of its low critical point and high operating pressure (around 1,500 psig or 103 bar), CO2 refrigeration strategies — such as cascade, secondary and transcritical booster — must be designed to account for its unique characteristics. In light of current environmental regulations, the popularity of these systems has increased significantly in North America in recent years.

Read the full Accelerate America article [pg.16].

More Food Retailers Opt for Natural Refrigerant Systems

AndrePatenaude_Blog_Image Andre Patenaude | Director, CO2 Business Development

Emerson Commercial & Residential Solutions

This blog summarizes an article from our most recent E360 Outlook, entitled Natural Selection.” Click here to read it in its entirety.

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One of the most complex decisions food retailers have today is selecting which refrigerant will serve as the basis of future refrigeration platforms. While there are very few refrigerants that can deliver regulatory compliance and align with corporate sustainability goals, three natural options are at the top of this short list: carbon dioxide (CO2 or refrigerant name R-744); the hydrocarbon propane (refrigerant name R-290); and ammonia (NH3 or refrigerant name R-717).

In recent decades, as synthetic chlorofluorocarbon (CFC) and hydrofluorocarbon (HFC) refrigerants were found to have either ozone depletion potential (ODP) or global warming potential (GWP), natural refrigerants have made their way back into the commercial refrigeration conversation — even being listed by the Environmental Protection Agency (EPA) as acceptable for use in most commercial refrigeration applications (subject to use conditions).

Make no mistake: these refrigerants are by no means perfect — each has its own caveats — but in terms of thermodynamic properties, operational efficiencies and eco-friendliness, natural refrigerants are often referred to as “future proof”.

Innovative installations

As modern refrigeration technologies continue to improve, equipment manufacturers are working closely with early adopters to develop innovative solutions. This has resulted in several creative natural refrigeration applications that belie their traditional uses — like ammonia being used in supermarket systems and CO2 playing a larger role in industrial process cooling.

Ammonia trials in food retail
In September 2015, the Piggly Wiggly supermarket company opened a new 36,000 square-foot store in Columbus, Ga., that utilizes an NH3/CO2 cascade system manufactured by Heatcraft Worldwide Refrigeration. The all-natural refrigerant system uses an ultra-low charge of ammonia (53 pounds) located away from occupied spaces (on the facility’s roof).

CO2 adoption in industrial cooling
In cold storage applications, where ammonia has been the preferred refrigerant for decades, companies are also seeking to lower ammonia charges. As older ammonia systems near replacement, many operators are determining the best option to expand their facility’s low-temperature capabilities. They’re accomplishing this by adopting NH3/CO2 cascade systems that not only utilize very low charges of ammonia, but also keep the R-717 circuit out of occupied spaces.

Propane in food retail
When major retailers like Target publicly announce their intentions to use only propane in their self-contained units, it’s an indication that the perceptions about the mainstream viability of R-290 are shifting. The smaller charge limits make R-290 a logical fit for Target’s smaller, stand-alone refrigerated display cases and coolers.

While efforts are needed to mitigate their associated risks and ensure their safe use, natural refrigerants represent true sustainable alternatives that do not sacrifice performance. As regulatory bodies and industry organizations work to refine these standards, natural refrigerants will continue to play a key role in the future of commercial and industrial refrigeration

Seven Keys to Servicing CO2 Systems

AndrePatenaude_Blog_Image Andre Patenaude | Director, CO2 Business Development

Emerson Commercial & Residential Solutions

This blog summarizes an article from our most recent E360 Outlook, entitled Keys to Servicing CO2 Systems.” Click here to read it in its entirety.

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From a service technician’s perspective, CO2 has unique performance characteristics and operating peculiarities that dictate system design and impact maintenance requirements. Following are seven key considerations to be aware of when servicing CO2 systems.

  1. Low critical point (subcritical vs. transcritical) — R-744 has a relatively low critical point (1,055 psig or 87.8 °F) that determines its modes of operation. Subcritical mode refers to systems operating in regions with colder climates and lower ambient temperatures where the refrigeration cycle takes place below 87.8 °F. Transcritical mode takes place above this point (also referred to as supercritical) such as in warmer regions or periods during the summer heat.
  2. Higher operating pressure — one of the common reservations when using CO2 is its relatively high operating pressure. But, it’s important to realize that high pressure only takes place in the beginning stages of the refrigeration cycle while the rest of the refrigeration cycle operates at pressures like that of a traditional R-410A high-side system. Stainless steel piping is typically used to handle these pressures, although high-pressure ferrous alloy copper piping has recently been introduced.
  3. High triple point (possibility of dry ice formation) — triple point is the point at which the three phases of CO2 coexist (60.4 psig or -69.8 °F). While the temperature seems low, the pressure is relatively high by refrigerant standards. As the pressure approaches that point in CO2 systems, the refrigerant will turn to dry ice (an unusable state that’s neither a vapor nor a liquid). This can occur during maintenance when a contractor mistakenly thinks the lines are clear, taps the system and discovers the formation of dry ice.
  4. System charging — the high triple point affects R-744’s charging procedures. After pulling a vacuum, the internal pressures of the system will be well below 60.4 psig. Since standard atmospheric pressure is 14.696 psig, the process cannot start with liquid charging. Instead, contractors must vapor-charge the system (roughly to around 145 psig), and then wait until the system has equalized with 145 psig of vapor before charging with liquid.
  5. Managing scheduled shutdowns and power outages — when a CO2 system shuts down for longer periods of time, pressures will build more quickly than in an HFC system. To preserve the system charge, the most reliable method is to install a generator with a standby condensing unit. When the power goes out, the generator powers a condensing unit that has a loop within the flash tank (i.e., receiver) designed to cool the volume of liquid within the tank and keep pressures down.
  6. Resumption of power — the electronic expansion valve (EEV) on every CO2 case utilizes a stepper motor or a pulse-width modulated type of valve. When the power goes out, the stepper motor is frozen in that exact position, leaving the system’s CO2 evaporators susceptible to flooding. R-744 naturally migrates quickly to these cold evaporators, and when the system resumes, this can cause considerable damage to compressors. To avoid this, liquid line solenoids placed upstream of the EEV, supercapacitors or battery backups are often used on case controls to force the valves closed during a power outage.
  7. Form a refrigerant plan — managing CO2 is different from what contractors may be accustomed to with traditional HFCs. Operators and contractors alike need to understand the local codes for storing R-744 cylinders (inside or outside the building), and develop an appropriate strategy.

Grocer’s New CO2 Refrigeration System Earns EPA GreenChill award

 AndrePatenaude_Blog_Image Andre Patenaude | Director, CO2 Business Development

Emerson Commercial & Residential Solutions

This blog summarizes a success story in our most recent E360 Outlook, entitled Natural Born Chillers.” Click here to read it in its entirety.

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Natural refrigerant adoption is on the rise in the U.S., and forward-thinking supermarket retailers are leading the charge. Driven by corporate sustainability objectives and the desire to achieve EPA and DOE regulatory compliance, some operators are turning to eco-friendly options like CO2 to reduce their carbon footprint. Such is the case with New Seasons Market, a northwestern U.S. grocer that was recently awarded the EPA’s GreenChill Platinum Certification in its newest store for installing a transcritical CO2 booster system.

In many ways, sustainability is in New Seasons’ DNA. They partner with local farmers, ranchers and producers to offer the best of the region, and sell homegrown, organic favorites along with traditional grocery store staples. With 20 locations in the states of Washington, Oregon and California, the chain’s recently launched 37,000-square-foot store in Mercer Island, Wash., was the first to earn this distinction from the EPA.

New Seasons partnered with its engineering firm to develop a natural refrigeration system that would meet the sustainability objectives for the new location. The system, which is based on the Hussmann Purity platform, features Emerson’s compression and system controls technology, including:

  • Transcritical CO2 rack — consists of six compressors — three of which are low-temperature Copeland Scroll Digital™ CO2 compressors — with digital capacity modulation to provide energy-efficient refrigeration for the entire store. The system is charged with 1,100 pounds of CO2 (R-744).
  • Roof-mounted gas cooler — a gas cooler utilizes energy-efficient, low-velocity, variable-frequency drive (VFD) fans to reduce overall energy usage.
  • Controls — An E2 RX refrigeration controller manages the system in conjunction with Emerson case controls in the store fixtures. These tools enable the ease of system setup while ensuring ongoing performance optimization, maintaining consistent temperatures throughout the store, minimizing product shrink and preserving food quality.

The EPA GreenChill Platinum Certification recognizes New Seasons’ efforts in revamping the store’s refrigeration system — an HFC system installed by the previous retailer at this location — to a CO2 architecture that reduced refrigerant emissions by at least 95 percent.

The success of the Mercer Island store has opened the door for additional CO2 systems. Their leadership is currently planning the construction of two new stores in 2018 that will also rely on transcritical CO2 booster system architectures.

This blog summarizes a success story in our most recent E360 Outlook, entitled Natural Born Chillers.” Click here to read it in its entirety.

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