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Posts from the ‘CO2 as a Refrigerant’ Category

Mobile CO2 Booster Transcritical Training Unit Launches North American Tour

Liborio Mendola Liborio Mendola | Product Planner
Emerson Commercial & Residential Solutions

Emerson’s new CO2 Booster training unit is preparing to make several stops across the U.S. and Canada in 2019. Learn more about what this hands-on experience will offer attendees.

Adoption of the natural refrigerant CO2 (R-744) in commercial and industrial refrigeration applications is on the rise in North America and around the globe. With 0 ozone depletion potential (ODP) and a global warming potential (GWP) of 1, CO2 is considered the environmental standard by which other refrigerants are measured. But with its high operating pressures and unique performance characteristics, industry stakeholders have many questions about how to design, operate and service a CO2 system. That’s why Emerson is pleased to introduce its new, mobile CO2 Booster training unit.

The CO2 training unit is designed to give contractors, manufacturers, wholesalers and end users a hands-on experience and learn what it’s like to work on a CO2 refrigeration system. Launched in Canada in September, the unit has already visited locations in Quebec and trained more than 50 contractors. In early 2019, the unit will travel to the U.S. and make several stops, starting with an appearance in the Atlanta area timed to correspond with the conclusion of the AHR Expo. The current schedule is as follows:

  • January 16–17: Atlanta, Ga.
  • January 30–31: Orlando, Fla.
  • February 13–14: Rancho Cordova, Calif.
  • February 27–28: Elmsford, N.Y.
  • March 20–21: Cudahy, Wis.
  • April 10–11: Brantford, Ont.

Each stop will feature a two-day training session designed to accommodate 20 attendees and cover a wide range of CO2-related topics, including:

  • Subcritical vs. transcritical modes of operation
  • Overview of CO2 system architectures
  • Safe handling, maintenance and charging
  • Startup and shutdown sequences

Become familiar with CO2 and refrigeration system components

The open 360° view of the training unit allows attendees to familiarize themselves with the refrigerant and the components which make up a CO2 system. To demonstrate the volatility of CO2, the unit includes a phase change cell that shows how the refrigerant reacts to pressure changes. Starting in its liquid state, R-744 is subject to increasing pressures and begins its transition into a vapor state, then to a supercritical fluid, until it ultimately becomes a transparent gas. Then, as pressure is dropped within the cell, attendees can see the reverse of this transition as CO2 returns to a liquid state and then forms into a solid piece of dry ice.

The CO2 Booster training unit utilizes a full Emerson system that includes: low- and medium-temperature compressors, electronic controls, protectors, variable-frequency drives and transcritically rated electronic expansion valves. For ease of use, the unit is designed to improve the visibility of all components and dial gauges to demonstrate pressures and temperatures of certain elements.

The transportation container is designed for simplified transport and protection against the rigors of over-the-road travel. This container is also equipped with Emerson’s Cargo Solutions that allow live tracking of the unit’s location, ambient temperature and other conditions through Emerson’s Oversight app.

Registration for scheduled two day sessions is now open. The cost is $700 per person and includes all course materials, breakfast and lunch.

If you’re interested in learning more about CO2, be sure to reserve your spot (Class Title: CO2 Refrigeration) at an upcoming training session.

Emerson Study Compares CO2 and Hydrocarbon Energy Efficiency in Europe

The study found that those opting for integral R-290 systems could potentially achieve up to €51,000 savings per store on maintenance, energy consumption and refurbishment. The study also points to the ongoing evolution of natural refrigerant technologies and highlights the differences between CO2 and hydrocarbon refrigeration strategies.

Read more

Blog 10: The Convergence of Ammonia/CO2 Technologies

AndrePatenaude_Blog_Image Andre Patenaude | Director Food Retail, Growth Strategy

Emerson Commercial & Residential Solutions

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In my previous blog, I explained why CO2 and ammonia (aka NH3) refrigerant technologies are crossing over into each other’s traditional market spaces, i.e., CO2 making its way into industrial settings and low-charge ammonia systems in use in commercial applications.

As regulatory compliance concerns and sustainability objectives drive end users toward natural refrigerants, original equipment manufacturers (OEMs) are responding with new innovations that draw from traditional CO2 and ammonia architectures.

Let’s look at some innovations that are indicative of this convergence.

NH3/CO2 cascade — Ammonia in commercial refrigeration

Owners of large (+100-ton) commercial HFC systems are now considering implementing smaller, lower-charge NH3/CO2 cascade systems. In turn, some industrial OEMs are expanding their product portfolios to target the emerging niche for natural, energy-efficient systems in commercial refrigeration. These NH3/CO2 cascade systems are designed to operate with very low charges of ammonia (100 pounds or less) on the high side of the refrigeration cycle (in a remote location, e.g., the roof) to chill the CO2 sent out to the cases in a store.

CO2 transcritical booster — CO2 in industrial refrigeration

CO2 offers a documentation-free refrigeration alternative to long-time operators of large-charge ammonia systems. Commercial OEMs with CO2 expertise are answering the call for CO2 transcritical booster systems, which have proved viable in cooler regions. This system utilizes several compressors in parallel to meet the desired cooling requirement. CO2 blast freezers are also effective in low temperatures, especially below -40 °F.

Smaller-platform applications for ammonia

Both commercial and industrial operators with smaller facilities have a variety of low-charge ammonia options from which to choose to meet their cooling requirements and sustainability goals:

  • NH3 low-charge centralized — this remote, distributed architecture is designed to reduce the liquid line length and subsequent refrigerant charge.
  • NH3 direct expansion — available in distributed or remote varieties, this system requires the circulation of much less refrigerant.
  • NH3 chiller with pumped CO2 secondary — ammonia chills CO2 (volatile brine), which is then pumped into the refrigerated areas.
  • NH3 chiller with pumped CO2 secondary, plus CO2 cascade — combines an NH3 chiller that provides the medium-temperature load via a CO2 secondary design, plus a CO2 cascade system for the low-temperature side.

This convergence also proves that operators of commercial and industrial facilities have more in common than they realize. Both are trying to balance capital expenditures, total cost of ownership and sustainability objectives in their selection of refrigeration systems. So, the blurring of lines between CO2 and ammonia technologies in these markets is ultimately beneficial to all involved.

Read the full Accelerate America article on the convergence of ammonia and CO2 technologies [pg.16].

Blog 9: Why CO2 and Ammonia Are Trading Places

AndrePatenaude_Blog_Image Andre Patenaude | Director Food Retail, Growth Strategy

Emerson Commercial & Residential Solutions

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CO2 and ammonia (aka NH3) are two natural refrigerants that have historically played predictable roles in refrigeration. Ammonia has long been considered a workhorse in low-temperature, industrial refrigeration. More recently, CO2 has emerged as a leading alternative to hydrofluorocarbon (HFC) refrigerants, especially in commercial applications. Just as we became accustomed to their familiar roles, manufacturers are developing new refrigeration technologies that blur the lines between these traditional applications.

Driven by sustainability objectives and regulatory compliance, these natural refrigerant technologies are converging into competing market spaces — where CO2 is becoming a viable option in industrial applications and low-charge ammonia systems are making inroads into commercial applications.

CO2 has the global HFC phase-down to thank for gaining a foothold in commercial refrigeration. With near-zero global warming potential (GWP), it is one of the few ultra-low GWP refrigerants to be listed as acceptable by the Environmental Protection Agency’s Significant New Alternatives Policy. CO2 also has minimal safety or toxicity barriers to adoption with respect to building and fire codes.

On the other hand, ammonia has been the subject of increasing regulatory activity to address its potential toxicity concerns. The Occupational Safety and Health Administration (OSHA) requires operators to provide documentation for systems charged with at least 10,000 pounds of ammonia.

Operators of these large-charge systems, which are typically found in industrial applications, must be prepared for rigorous inspections enforced by OSHA’s National Emphasis Program (NEP) on process safety management industries.

To mitigate safety and compliance concerns, a trend is emerging that favors lower-charge ammonia systems and moving the NH3 portion out of occupied spaces. This is enabling these systems to be deployed not only in industrial settings, but also in commercial applications. Likewise, adaptations of common CO2 architectures are making their way into what have historically been ammonia-based, industrial applications.

Regardless of potential installation caveats or market segment, many end users are primarily motivated by the desire to leave a smaller carbon footprint. Natural refrigerants like CO2 and ammonia are helping them meet this objective through the deployment of low-GWP, energy-efficient systems.

That’s why both commercial and industrial operators are turning to original equipment manufacturers (OEMs) to explore the potential of these natural refrigerant options. In turn, OEMs are responding with new innovations and system technologies that borrow from traditional architectures and cross over into competing market spaces.

In my next blog, I’ll look at some innovations that are indicative of this convergence.

Read the full Accelerate America article on the roles of CO2 and ammonia [pg.16].

Blog 8: CO2 System Architectures: Opportunities in Food Retail

AndrePatenaude_Blog_Image Andre Patenaude | Director Food Retail, Growth Strategy

Emerson Commercial & Residential Solutions

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Food retailers seeking to make the move to CO2 refrigeration have two primary system types from which to choose: CO2 transcritical booster and cascade systems. A closer look at each option may help you decide which is a better fit for your operations.

CO2 transcritical booster

A complete R-744 system, CO2 transcritical booster utilizes direct expansion (DX) for low- and medium-temperature suction groups. This system is called transcritical because it is designed to operate at pressures above CO2’s critical pressure (1,500 psig). Heat produced from low-temperature case compressors is rejected into the medium-temperature suction group’s compressors. The medium-temperature compressors are the workhorses of the system and must be sized to handle:

  • The total heat of rejection of low-temperature loads
  • 100 percent of the medium-temperature load
  • The flash tank bypass load

Only one condenser or gas cooler is needed for all low- and medium-temperature cases. CO2 pumped technology — where CO2 is used as a secondary fluid — is also available on both low- and medium-temperature stages.

CO2 cascade

CO2 cascade systems utilize two distinct refrigeration circuits: a CO2 circuit for the low-temperature suction group, and an HFC-based circuit (such as HFC-134a) for the medium-temperature needs. It’s called cascade because the heat produced from the low-temperature circuit is discharged into the suction stage of the medium-temperature circuit via an intermediate heat exchanger. Medium-temperature compressors send gas to an air-cooled condenser on the roof. Like a standard refrigerant, CO2 is maintained below its critical point (or subcritical mode) of 88 °F.

For an all-natural cascade alternative, some retailers have even experimented with using NH3 (ammonia) as the medium-temperature refrigerant. These low-charge ammonia circuits are typically housed on the facility roof, far removed from the store’s occupied spaces.

Evolution of electronics

Unlike traditional HFC systems, CO2 system architectures introduce the requirement for additional electronic components, including: case controllers, pressure transducers, temperature sensors and electronic expansion valves. While these components may contribute to increased system costs, they’re necessary for optimizing the refrigerant quality and pressures to the cases. From an end user and servicing perspective, these case controllers provide quick access to precise temperature controls and ongoing, optimized energy efficiencies.

The benefits of going green

For those U.S. retailers who have experimented with CO2 refrigeration, the benefits are obvious. New Seasons is a Northwestern grocer whose first CO2 system earned a GreenChill Platinum Certification award for green refrigeration. Their CO2 transcritical booster system delivered the following improvements:

  • Up to 30 percent lower total equivalent warming impacts (TEWI)
  • 95 percent fewer refrigerant emissions
  • Smaller refrigeration footprint

The retailer is currently planning additional CO2 installations.

  1. http://www.atmo.org/presentations/files/5907fb91732731493695377MIjnG.pdf, pg. 3

Read the full Accelerate America article on CO2 system architectures [pg.16].

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