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A Shift in Industrial Refrigeration

AndrePatenaude_Blog_Image Andre Patenaude | Director, Food Retail Marketing & Growth Strategy, Cold Chain

Emerson Commercial & Residential Solutions

I discussed the large industrial refrigeration market and the use of natural refrigerants in the Accelerate America article entitled, “Exploiting CO2on pg. 16.

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For decades, ammonia (aka NH3 or R717) has been the backbone of many cold storage applications in the large industrial refrigeration market. More recently, the increasing popularity of CO2 (R744) in commercial applications has led refrigeration manufacturers to look for ways to incorporate this natural refrigerant in industrial systems. With the technology to combine the benefits of both refrigerants and facilitate this transition coming to fruition, a shift in the industry may be coming.

NH3 has excellent performance efficiency and ultra-low environmental impact, making it a near-perfect refrigerant. However, its toxicity causes hesitancy in use. Tightening regulations by the Occupational Safety and Health Administration (OSHA) has sought to improve the safety of NH3 systems, requiring operators to provide documentation for systems charged with at least 10,000 pounds of ammonia.

Enter NH3/CO2 cascade technology, a system architecture that has been successfully deployed in many commercial applications with HFCs on the high side, to leverage ammonia’s efficiency and limit the potential for toxic exposure to workers and product spoilage.

Transitioning to the large industrial market does cause several concerns that need to be addressed, such as:

  • Finding a way to deliver high-tonnage refrigeration capacity while keeping ammonia charges low
  • Ease documentation requirements
  • Lowering the potential for exposure
  • Complexities related to installation, commissioning, operation and servicing requirements
  • Potential heat exchanger leaks of CO2 and NH3 that can mix and create ammonium carbamate, resulting in system failure
  • Maintaining uptime during the transition from a legacy system to a new cascade system

Self-contained systems

Meeting high-tonnage, cold storage requirements while addressing the known operational challenges of ammonia and CO2 meant that manufacturers have had to expand upon the existing cascade architecture. Developing a self-contained system that integrates an entire NH3/CO2 cascade system into a modular refrigeration unit seemed to be the best solution.

Designed to be located on the rooftop or next to a building of a cold storage facility, this modular refrigeration unit combines CO2 and NH3 compression technologies and electronic controls in a cascade system that contains two independent CO2 and NH3 circuits with separate condensers and evaporators (including a shared cascade heat exchanger).

The self-contained, modular unit essentially serves as the system’s mechanical room, enabling installation and efficiencies typically not found in traditional systems. Existing facilities can even install this system while their legacy system is still running, positioning the unit at the desired rooftop location and connecting the ductwork in as little as a few days. Then, as soon as the facility manager is ready, he/she can simply shut down the old system and let the new system assume refrigeration duties.

The simplicity of this drop-in, plug-and-play design also lowers maintenance requirements while improving serviceability throughout the lifecycle.

Read the full article, Exploiting CO2 on pg. 16, to find out other ways the industry is working to address these concerns and how natural refrigerants are driving innovation.

 

The Big Green Chill – Progressive Grocer

AndrePatenaude_Blog_Image Andre Patenaude | Director, Food Retail Marketing & Growth Strategy, Cold Chain

Emerson Commercial & Residential Solutions

This blog summarizes an article from Progressive Grocer, entitled “The Big Green Chill.” Click here to read the article in its entirety.

Sustainability initiatives and energy-efficient practices are asserting themselves as top priorities in the minds of food retailers and foodservice professionals. Suppliers like Emerson have acknowledged this trend and have begun developing technologies and solutions that can assist with furthering these initiatives and help our customers work toward a more sustainable and environmentally-friendly future.

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Retailers can implement sustainability initiatives through the use of precise temperature and pressure controls, which allow for a true steady state of operation. These can help better enable the benefits of lowering condensing temperatures to improve the efficiency of the entire system when combined with an electronic expansion valve.

Because of an increase in competitivity in the foodservice, supermarket and transport industries, customers are seeking products and solutions which provide them assurance that operators are maintaining the highest quality of perishable food items from farm to fork.

Retailers can also utilize Emerson Copeland Scroll™ digital compressors to improve “green” operations. They have digital modulation capabilities that allow for infinite capacity adjustments within specific modulation ranges. This means that instead of having to cycle on and off to match capacity, these compressors are capable of adjusting their output to precisely match a load.

Emerson’s supervisory controls are other tools that retailers can use to manage major refrigeration, lighting and HVAC systems. Supervisory controls grant powerful energy-efficient temperature and condition management capabilities through a user-friendly, dashboard-style interface that puts critical information at the users’ fingertips.

Looking ahead, the growing adoption of newer control technologies and the upgrading of older refrigeration systems will continue into the future as two primary means of achieving sustainability and energy efficiency. The combination of new systems with enhanced digital controls will serve as a way of further realizing energy efficiencies and additional cost savings.

Along with energy-efficiency improvements, retailers are simultaneously evaluating other sustainable practices such as: the use of natural refrigerants, implementing refrigeration leak detection, deploying advanced demand-reduction methods, and exploring energy storage potential and considering how to incorporate natural refrigerants.

More retailers are likely to challenge their previous decisions in these areas and learn about entirely new architectures in store controls, refrigeration systems and HVAC units that are capable of meeting overall sustainability challenges.

For more information, read the full article here.

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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