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Copeland™ Scroll Booster Architecture Balances Sustainability, Serviceability and Flexibility

Andre Patenaude | Director – Solutions Integration,

Emerson’s Commercial and Residential Solution’s Business

As refrigerant regulations continue to progress rapidly, commercial refrigeration stakeholders are looking for refrigeration solutions capable of balancing their sustainability, serviceability and equipment lifecycle goals. Emerson recently completed the development of a new distributed system architecture called Copeland scroll booster. It is designed specifically to help food retailers achieve these goals while providing the flexibility to accommodate a wide range of low- (LT) and medium-temperature (MT) applications.

When searching for viable and sustainable commercial refrigeration strategies, stakeholders often find themselves weighing the pros and cons of many different system types. Systems that use alternative refrigerants with a global warming potential (GWP) below 150 typically introduce increased service complexities and lifecycle costs. Other systems may not quite achieve sustainability targets but offer serviceability improvements. And when you consider the ever-expanding diversity of system designs needed to address modern commercial refrigeration requirements, system selection becomes even more complex.

Much of the work taking place at Emerson’s The Helix Innovation Center is focused on solving this industry-wide challenge, and the Copeland scroll booster architecture is a key outcome of these efforts.

Leveraging a new refrigerant alternative

Regulatory mandates are driving significant changes within commercial refrigeration system designs to minimize environmental impacts. Many operators are seeking alternatives to traditional centralized direct expansion (DX) refrigeration systems, which utilize large charges of high-GWP hydrofluorocarbon (HFC) refrigerants and are prone to leaks. This has led to an increasing variety of distributed refrigeration approaches — which offer smaller refrigerant charges, lower-GWP refrigerants and wider application flexibility.

Although natural refrigerants CO2 (R-744) and propane (R-290) have the lowest possible GWP ratings, they also come with high operating pressure (R-744) and flammability (R-290), introducing operational complexities and design limitations that many food retailers may not be prepared to address. Newer refrigerant blends — such as the A1 hydrofluoroolefin (HFO) refrigerant R-513A — deliver excellent performance characteristics, much lower GWP than HFCs and zero flammability. Offering the lowest possible GWP (573) among non-flammable refrigerants, R-513A has low-pressure characteristics that provide a familiar operating envelope and require no special training, certification or safety mitigation measures.

Mechanics of Copeland scroll booster

The Copeland scroll booster system is designed to use R-513A for both LT and MT refrigeration loads. Its distributed architecture offers an efficient and environmentally friendly alternative to large centralized systems. System configurations can scale from small, low-charge condensing units to larger distributed racks charged with several hundred pounds of refrigerant.

This innovative technology overcomes the typical challenges of operating a low-temperature system, including requiring compressor cooling via liquid injection and lowering compressor lifespan due to high compression ratios and discharge temperatures. This straightforward architecture leverages the advantages of R-513A’s low-pressure, high-efficiency and key system components to significantly lower discharge temperatures and compression ratios.

This flexible architecture is comprised of one or more MT scroll compressors coupled with one or more LT scroll compressors, where MT compressors can either be placed in a condensing unit or within a typical rack configuration. Condensers may be located remotely or integrated into the system and placed indoors or outdoors. To help reduce refrigerant charge, piping and associated costs, the LT scroll compressors can be placed near the LT evaporators, i.e., directly on top of or beside the case or remotely near the load.

The “booster” design strategy provides significant performance improvements by discharging (or boosting) the LT compressor directly into the nearest MT compressor’s suction line. The lower discharge temperatures of the LT scroll compressor minimize the suction gas temperature of the MT unit and allow the MT compressors to operate within their design limits without the need for additional cooling. The net result is an overall system efficiency gain while greatly minimizing the mechanical loads on the LT compressors.

Simplifying operational complexities

The innovative use of a low-pressure, low-GWP refrigerant within a simple, distributed architecture that’s based on familiar operating principles fills an urgent need within the larger food retail market. The Copeland scroll booster system helps operators to meet their sustainability goals without introducing unnecessary serviceability complexities. Offering the design flexibility to service store formats of varying sizes, its benefits check many key boxes on the list of modern supermarket refrigeration priorities:

  • Lower-GWP, A1 refrigerant (i.e., R-513A)
  • Reduced refrigerant charge
  • Lower leak rates due to lower-pressure system
  • Lower utility costs
  • System familiarity with technicians and end users
  • Low total cost of ownership (TCO) from lower annual energy consumption and lifecycle climate performance (LCCP)
  • Secure remote facility monitoring capabilities

Proof of concept and future evolution

Emerson has conducted successful trials of this technology in various applications and climates. This year, a distributed scroll booster system was installed at Gem City Market, a new small-format supermarket built in Dayton, Ohio. The project involved collaboration among the surrounding Dayton community, city officials and commercial refrigeration industry leaders — including Hussmann and Chemours — who donated their respective expertise and resources to the project. In the future, when even lower-GWP refrigerants (such as A2Ls) are approved for use by applicable codes and standards, a distributed scroll booster system can be adapted for use with these ultra-low refrigerant alternatives (less than 150 GWP).

Refrigerant Transition Gains Momentum

Andre Patenaude | Director – Solutions Integration,

Emerson’s Commercial and Residential Solution’s Business

For over a decade, environmental advocates around the globe have recognized the need for the commercial refrigeration industry to make the transition from hydrofluorocarbon (HFC) refrigerants to lower-global warming potential (GWP) alternatives. An HFC phase-down is well underway in many countries and regions, and today conditions are favorable for these efforts to increase within the U.S. I recently contributed to an ACHR The NEWS article where we discussed how recent developments may accelerate this refrigerant transition.

Recent regulatory developments in the U.S. have increased the likelihood the HFC phase-down will become a higher priority for equipment manufacturers, contractors, and food retailers. Among the greatest contributing factors include:

  • The inclusion of HFC phase-down legislation in the recent Omnibus and COVID relief bill
  • A new presidential administration with a greater commitment to environmental stewardship
  • Continued regulatory activities taking place at the state levels

All eyes on California

For several years, the California Air Resources Board (CARB) has been proposing regulations targeting HFC emissions reductions in commercial refrigeration equipment used within grocery stores. In 2019, CARB banned the use of R-404A in new or retrofit centralized systems. Last December, CARB finalized those regulations and established an enforcement date, beginning January 1, 2022. Details of the rulemaking impact new (or remodeled) and existing facilities:

  • A limit of 150 GWP for new or fully remodeled facilities in California that utilize commercial refrigeration equipment containing more than 50 pounds of refrigerant.
  • Existing food retail facilities with refrigeration systems charged with more than 50 pounds must collectively meet a 1,400 weighted average GWP or 55 percent greenhouse gas potential (GHGp) reduction relative to a 2019 baseline by 2030.

As a result (in California, at least), natural refrigerant-based systems — such as CO2 transcritical boosters — are often considered leading options for compliance in new facilities.

California’s new regulations, along with new developments in federal refrigerant regulations, will present opportunities for manufacturers who already developed lower-GWP solutions. To support these efforts, Emerson has been qualifying its compressor lines to use a variety of lower-GWP refrigerants for more than a decade. Also, we are developing full-system strategies — such as CO2-based technologies and our distributed scroll booster architecture — that leverage new refrigerant alternatives and enable the implementation of lower-GWP systems. In addition, for retailers in California, we developed smart tools to help them evaluate their store fleets and calculate how they can achieve CARB compliance.

Elsewhere, a growing coalition of states — the U.S. Climate Alliance — has vowed to follow California’s lead. These member states are also continuing to develop their own legislation to enforce HFC phase-down commitments.

New federal legislation could provide industry-wide consistency

While state-level regulations have pushed forward, the status of refrigerant rulemaking at the federal level has been stagnant for several years — particularly after a 2017 court ruling determining the Environmental Protection Agency (EPA) did not have the authority to regulate HFCs under the Clean Air Act. But with the recent passage of the American Innovation and Manufacturing Act of 2020 (AIM Act) as part of the Omnibus and COVID relief bill, that may all soon change. The AIM Act restores the EPA’s authority to phase down the consumption and production of HFC refrigerants and establish sector-based limits.

As importantly, the new federal mandate will hopefully simplify the growing complexity of managing a multitude of state-led HFC phase-down initiatives. Ultimately, a federally-led refrigerant compliance program would provide much-needed guidance to the industry and remove the burden facing individual states. In addition, the industry could even see the adoption of new rulemaking from the EPA’s Significant New Alternatives Policy (SNAP) program.

This uptick in regulatory activity will likely result in a busy period for HVACR contractors and food retailers around the country — particularly those in California who will be preparing for the CARB regulations to take effect next year. Emerson is committed to helping commercial refrigeration stakeholders in the U.S. and throughout the world achieve their refrigeration goals and make the transition to lower-GWP refrigerant alternatives.

Pandemic Creates Lasting Impact on Food Retailers and Commercial Refrigeration

Andre Patenaude | Director – Solutions Integration,

Emerson’s Commercial and Residential Solution’s Business

The year 2020 was an inflection point for the food retail industry. While many restaurants closed for in-person dining due to the COVID-19 pandemic, supermarkets and other food retailers were considered essential businesses and remained open. But for those responsible for these operations, this meant quickly adapting to new fulfillment scenarios, as many shoppers sought online grocery-ordering options such as curbside pickup and/or home delivery. I recently contributed to an ACHR The NEWS article where we discussed how the events of 2020 changed the food retail landscape and will continue to impact the commercial refrigeration industry in 2021 and beyond.

Online Retail Drives Refrigeration Decisions

As vaccine distribution increases and the COVID-19 pandemic hopefully recedes, the impacts of the pandemic will be felt well into the future. From a food retail perspective, the acceleration of e-commerce adoption appears to have permanently altered consumers’ buying behaviors and shifted the retail landscape.

According to a 2020 study by grocery e-commerce specialist Mercatus and research firm Incisiv, the growth rate of online grocery retail is expected to make up 21.5% of all grocery sales by 2025, representing a more than 60% increase compared pre-pandemic projections. As consumers continue to embrace both click-and-collect and home delivery options, many leading food retailers are rethinking their refrigeration strategies and expanding their fulfillment capabilities to meet both near-term and long-term projections.

The sheer volume of e-commerce sales took many food retailers by surprise in 2020 and has led them to take steps to shore up their online order fulfillment infrastructures. These include investments in additional refrigeration equipment and cold storage space — whether for in-house, click-and-collect operations, micro-fulfillment centers (MFCs) or even dark stores.

In addition, many retailers are evaluating their existing systems to determine if there’s available capacity to potentially tap into. Where there is not, distributed strategies such as stand-alone condensing units or self-contained cold storage are ideal solutions for creating additional refrigeration capacity. Of course, any new system designs or major retrofits will require more thorough consideration with respect to how these systems would align with retailers’ long-term sustainability goals.

It’s also important for contractors to continue playing a key role in helping retailers to make these decisions. They must be prepared with the knowledge and expertise in order to advise retailers on all the available short- and long-term refrigeration strategies — from self-contained propane cases to full CO2 systems to more distributed equipment architectures.

Cold Chain Data Tracking, Monitoring and Control

Another likely permanent impact will be the increased collective focus on cold chain tracking, monitoring and data analytics. Vaccine distribution challenges have highlighted the importance of monitoring product temperatures during transit – similar to the cold chain journey for food.

The adoption of temperature tracking, monitoring and control technologies used for the vaccines will likely accelerate the integration of these tools within the food cold chain — from farm to fork. This presents an opportunity to improve the working relationships, cooperation and technologies among producers, shippers and retailers to create an unbroken chain of temperature certainty throughout the food cold chain.

With supermarkets becoming one-stop shops for essential consumer needs — from freshly prepared and perishable foods to dry goods, pharmaceuticals and mini health care clinics — retailers have a variety of data streams strictly related to temperatures that they need to manage and monitor in order to preserve food quality and safety, as well as ensure proper vaccine storage. They also need to continuously track and monitor the performance of essential equipment and systems such as refrigeration, HVAC and lighting.

Fortunately, technological improvements and increased adoption of the internet of things (IoT) are giving supermarkets the abilities to capture, access, interpret and analyze data to deliver higher-value facility management solutions. Emerson’s Lumity™ supervisory control platform is designed to aggregate these data streams into consolidated views and provide insights to help retailers simplify their increasing facility management challenges.

From the perspectives of cold chain management, power management, equipment performance and preventative maintenance, we’re helping supermarket operators to bring all these aspects together within one cloud and one view — with robust data analytics to provide insights into each of these critical areas.

Explore the Advantages of Lowering Refrigerant Charges

Andre Patenaude | Director – Solutions Integration,

Emerson’s Commercial and Residential Solution’s Business

The need to reduce refrigerant charges in commercial refrigeration systems is often the focus of environmental regulations and sustainability initiatives shared by many supermarket retailers and operators. The reason is simple: lowering refrigerant charges reduces the potential for leaks and their associated environmental impacts. But there are also more pragmatic operational motivations for lowering refrigerant charges — from improving refrigeration system energy efficiency, performance and reliability to avoiding equipment replacement costs. In part two of a recent RSES Journal article series, I examine some of the leading strategies for reducing the refrigerant charges in existing refrigeration systems.

Implement variable fan speed control

Most centralized direct expansion (DX) systems are designed for peak summer heat and use mechanical head pressure control valves to maintain fixed pressure in the condenser equivalent to 105 °F condensing. In cooler seasonal conditions, this approach creates a considerably oversized condenser, where a substantial portion of the condenser volume is being used to store liquid in order to build pressure up to 105 °F minimum condensing.

A potential fix to remedying this situation is to remove the mechanical head pressure control valve and install a variable-frequency drive (VFD) to control the condenser fan’s speed. Instead of operating with a minimum fixed head pressure, this strategy provides variable head pressure throughout the year. This allows the system to operate with less refrigerant by removing the need to have a “winter charge” to flood the condenser in low ambient conditions.

Note: For operators in northern climates with sustained periods of sub-zero temperatures (-20° F to -30° F), utilizing a flooded head pressure approach may be necessary to keep systems running during those periods.

If you discover that a condenser needs to be replaced, an additional charge reduction can be achieved from implementing a split-condenser design. The approach effectively helps to maintain system pressure by cutting the condenser surface area in half as ambient temperatures drop, creating a net reduction in condenser surface area, which further lowers the system charge. In summer months, when the condenser utilizes every inch of its surface area, excess liquid refrigerant can be stored in a large receiver tank designed to hold both the summer and winter charges. Consider also using a low-condensing approach in combination with an efficient liquid subcooling strategy to achieve additional charge reductions while maximizing system performance, energy efficiency and reliability.

Adopt a looped piping strategy

In conventional centralized DX systems, individual liquid refrigerant and return suction lines are fed from the refrigeration rack to each case in a supermarket — which requires a large refrigerant charge to support the full load of all cases. An alternative to this approach would be to adopt a looped piping strategy by running fewer large lines to designated sections of the store, from which smaller lines branch off to individual cases. For example, instead of running 30 long lines to individual cases, four to five line loops would support key store sections — with much smaller lines branched off these loops to feed the individual cases. In doing so, store operators can reduce piping, lower leak rates, and achieve a significant reduction in refrigerant charge.

Disconnect and re-distribute remote refrigeration loads

Another common centralized DX refrigeration challenge is to provide adequate refrigeration for cases that are located farthest from the machine room. Unless the system is operating perfectly, the liquid refrigerant traveling through those long liquid lines can develop flash gas bubbles by the time it reaches these distant cases. This results in a variety of issues, which can ultimately increase the amount of refrigerant needed and impact case temperatures.

One potential solution is to disconnect these remote cases from their suction group and install segments of distributed equipment to handle them individually. This reduces the refrigerant charge in the centralized DX system and allows it to operate more efficiently. The Copeland™ digital outdoor refrigeration unit, X-Line Series is ideal for servicing these remote cases or supporting new refrigeration requirements, such as walk-in coolers for click-and-collect fulfillment. In addition, the Copeland indoor modular solution provides flexible options for spot merchandizing cases, which could also be disconnected from a DX system.

Transition to distributed architectures

The prospect of large-scale leak events is always a possibility in large DX centralized systems, which can often be charged with up to 4,000 pounds of refrigerant. If even half of that charge were to be emitted in a catastrophic leak, operators would face potential environmental penalties and excessive refrigerant replacement costs. But this centralized approach is no longer the only option for large-supermarket refrigeration. In their place is an emerging variety of distributed architectures designed to lower refrigerant charges, deliver improved energy efficiencies, and operate using lower-GWP refrigerants.

Distributed architectures that utilize Copeland scroll compression technology can deliver significant system efficiencies, particularly when using a low-pressure refrigerant like R-513A. For example, Emerson’s distributed scroll booster architecture is designed to overcome common low-temperature system challenges and leverage R-513A’s low pressure and high efficiency to provide:

  • Lower discharge temperatures and compression ratios: 1.9:1 at -10 °F saturated suction temperature (SST) and 20 °F saturated discharge temperature (SDT)
  • Reduced compressor strain and related maintenance issues
  • Increased overall system efficiency and lifespan
  • Reduced stress on pipes and fittings, which lowers the potential for leaks

All the strategies discussed herein will not only help to lower your refrigerant charge but also deliver a variety of system efficiency and reliability benefits.

Strategies for Maximizing Refrigeration System Efficiencies

Andre Patenaude | Director – Solutions Integration,

Emerson’s Commercial and Residential Solution’s Business

For many supermarket operators, reducing energy spend in their refrigeration systems is a key sustainability objective. But as most refrigeration systems drift from their original commissioned states, they inevitably lose efficiencies over time. In a recent RSES Journal article, I explored some of the root causes of this all-too-common problem and presented proven strategies for maximizing refrigeration system efficiencies.

There is often a domino effect that contributes to declining refrigeration efficiencies: setpoints are changed, mechanical subcooling strategies become ineffective, condensing pressures increase, and overall system energy consumption rises. At the same time, maintaining consistent case temperatures can become a constant struggle — often causing the reliability of these systems to suffer.

But this inefficient, unreliable state neither has to be your status quo, nor does it necessarily mean that it is time to replace your existing refrigeration system. In fact, there are a variety of tools and techniques for taking back control of your supermarket refrigeration system.

Shore up your liquid subcooling strategy

Refrigerant (liquid) subcooling results in denser liquid — which packs more BTUs per pound and maximizes system capacity and performance — and is a strategy utilized within many supermarket refrigeration systems. But because this approach is based on design parameters that account for the hottest anticipated day of the year, it can present challenges in other weather conditions. In some regions, this can represent more than 95 percent of the time

As ambient temperatures drop, the condenser operates more efficiently, thus decreasing the subcooling load requirements. The net effect is that the plate heat exchanger — which acts as an evaporator to cool the refrigerant — is oversized for most of the year. And as the system tries to adapt to changing weather conditions, the liquid quality output can become more erratic and cause flash gas in liquid lines, which can starve the evaporator.

To manage this load variability, system designers often use electronic evaporator pressure regulators (EPRs), which must be properly set to maintain ideal liquid-out temperatures. If not, these conditions can combine to create a perpetual state of fluctuation as the system “hunts” for the liquid quality for which it was designed, resulting in a myriad of system issues with the potential to negatively impact energy efficiency and reliability.

Install electronic expansion valves

Replacing a system’s mechanical expansion valves with electronic expansion valves (EEVs) is the key to helping operators overcome these subcooling challenges and restoring system efficiencies. EEVs are typically located at the inlet of the subcooler to control and modulate the refrigerant flow of the heat exchanger much more effectively, regardless of whether it is the hottest or coldest day of the year. As temperatures and liquid quality fluctuate, EEVs allow a system to run at maximum capacity and deliver the performance advantages for which it was originally designed:

  • Higher BTUs per pound of circulating refrigerant
  • Reduced liquid line size and charge reduction
  • Improved efficiency for energy savings

Note: for optimum control of a subcooling heat exchanger equipped with an EEV, consider using a variable-capacity compressor like the Copeland™ scroll digital compressor or adding a variable-frequency drive (VFD) to a Copeland Discus™ compressor to provide a balanced load approach.

Raise system suction pressures

The higher the system suction pressures are, the lower the associated compressor power consumption will be — particularly in lower-temperature refrigeration systems. For every 1 PSI increase in suction pressure, a compressor’s energy efficiency ratio (EER) is improved by approximately 2%.

Electronic evaporator pressure regulators (EPRs) are commonly used in centralized racks to maintain evaporator temperatures within various suction groups and optimize the suction pressure to its highest possible point based on case demand. To save additional energy, technicians may “float the suction pressure” by allowing it to rise slightly when the lowest temperature case is satisfied. This can only be achieved if the EPRs are properly set.

Low-condensing operation

Another way to offset the inefficiencies of a system designed for the hottest day of the year is to implement low-condensing operation (aka “floating the head pressure”). Instead of artificially keeping head pressures near 105 °F with the use of head pressure control valves, EEVs installed at cases allow systems to float head pressures down as the temperatures drop — typically maintaining temperatures at 10–20 °F above the ambient temperature.

On average, systems can achieve 15–20% EER improvements on compressor performance for every 10 °F decrease in head pressure. EEVs are designed to modulate with fluctuations in capacity and liquid quality to digest flash gas and control superheat. Using this technique, supermarket operators can reliably float system pressures to 70 °F or lower and achieve:

  • 15–20% EER improvements on compressor performance
  • Increased compressor capacity for faster pull-down rates
  • Lower pressure, which reduces system stress
  • Higher system reliability, which lowers total cost of ownership (TCO)

Give your system an efficiency boost

Emerson provides the tools, technologies and expertise to help operators implement efficient liquid subcooling and low-condensing pressure strategies. Our EX series EEVs feature a patented ceramic gate port design that can manage a wide range of liquid quality and condensing pressures — and deliver precise refrigerant control via variable-capacity modulation from 10–100%.

The companion EXD-SH1 or SH2 superheat controller regulates evaporator superheat to optimize system performance, regardless of ambient conditions. Its integrated display allows operators to check a variety of system conditions, such as superheat, percentage of valve opening, pressure and temperature values.

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