Skip to content

Posts from the ‘Cold Chain’ Category

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.

Natural Refrigerant Cooling Trends for 2021

Andre Patenaude | Director – Solutions Integration,

Emerson’s Commercial and Residential Solution’s Business

I was recently interviewed by Accelerate America to discuss cooling trends for 2021, particularly with respect to the natural refrigerant and sustainable cooling marketplace. The Emerson to Continue Pushing NatRefs article (pages 20-22) also gave our organization an opportunity to discuss some of the specific plans we’re making to support our ongoing commitment to sustainable refrigeration technologies.

There’s little doubt that the installation of natural refrigerant-based systems will continue to increase this year, especially in California, where retailers will be preparing to meet 2022 California Air Resources Board (CARB) regulations. Elsewhere, we can also expect many retailers to continue with trials of natural refrigerant systems as potential strategies for meeting their sustainability targets. Whether it is a transcritical CO2 booster system or micro-distributed, R-290 integrated display cases, these architectures give retailers viable options for utilizing refrigerants with the lowest available global warming potential (GWP).

New investments and refrigeration solutions

For our part, Emerson will continue to invest heavily in research and development (R&D), which includes completing the construction of a new transcritical CO2 test lab at our main campus in Sidney, Ohio. This will be our second dedicated CO2 R&D facility, complementing our current CO2 test lab located at The Helix Innovation Center in Dayton, Ohio. These labs are designed to accelerate product development, collaborate with OEM partners and end-user customers, and help deliver simplified CO2 solutions for the industry.

We are also continuing the development of compression technologies, controls and valves for CO2 in commercial refrigeration, including a new rack supervisor CO2 and facility management controller for transcritical CO2 booster systems. These solutions are built with native applications that help to manage not only all of the standard system operational requirements, but also address high ambient strategies while providing enhanced integration with our CO2 case controls. We are also investing in the development of industrial CO2 compressors, including a new heat pump CO2 compressor.

In addition, we will continue to expand our R-290 based compression technologies, valving and electronic controls, including:

  • Copeland™ low-profile scroll portfolio of fixed- and variable-speed technologies that covers a capacity range from ¾ to 4 HP
  • Copeland variable-speed hermetic reciprocating compressor line that utilizes R-290 in fractional horsepower ranges from ⅛ to ⅞ HP

These R-290 solutions will deliver game-changing efficiency and performance improvements for commercial refrigeration reach-in OEMs as well as environmental life sciences, medical and pharmaceutical applications.

The critical role of digital controls

When dealing with CO2-based systems — and even to some degree, R-290 — digital controls are essential for providing basic refrigeration system management and optimizing energy efficiencies. These controls also contribute to a data stream that operators can leverage in analytics software to detect trends, automate decision making, and drive system performance.

Through the combination of our controls and compressor platforms, we are helping retailers to integrate their entire heating, refrigeration and air conditioning systems. For example, our E2 facility management controller, new CO2 rack supervisor controller and CO2 compressors — which include parallel compressor applications rated to operate at higher suction pressures — are capable of handling not only refrigeration requirements but also incorporating air conditioning systems.

COVID-19 impacts on retrofits and remodels

As the result of the increased food retail sales volumes, previously planned retrofit and remodel projects — either to improve energy efficiencies or transition to lower-GWP refrigerants — may continue to be temporarily placed on hold. The majority of remodeling efforts taking place during these high-volume periods are to provide mission-critical system improvements.

One such mission-critical area where retailers are investing in new refrigeration technologies is in support of emerging e-commerce fulfillment capabilities. While this may also divert attention away from planned retrofits, we expect to continue helping our end-user customers deploy new refrigeration equipment to augment their current systems to meet click-and-collect fulfillment requirements.

 

 

Factors Which Drive Innovations Toward the Next Generation of Refrigeration System Design

Katrina Krites | Marketing and Business Development

Manager, Food Retail

Emerson’s Commercial and Residential Solutions Business

The coronavirus pandemic has increased the retail food industry’s collective focus on food quality, safety and sanitation in supermarkets while driving consumer adoption of click-and-collect. At the same time, industry regulations impact retailer behaviors. These factors have brought more attention upon refrigeration systems. In a recent Progressive Grocer article (pages 76–80), I explored how refrigeration products, monitoring and sensing devices can support these initiatives.

Impacting food quality and safety

A grocer’s approach to refrigeration is a fundamental part of creating ideal shopping experiences for consumers. Starting with the configuration of the display cases, merchandising strategies are designed to present food in the most appealing ways. Many cases are now equipped with enhanced controls that turn on lights when a shopper approaches. By leveraging case controls and the internet of things (IoT) technologies, retailers can more effectively keep perishable foods within ideal temperature ranges, thus positively impacting food quality and safety while maximizing shelf life.

Continued improvements in data analytics and cloud-based, IoT technologies are enabling connectivity among equipment and devices, which will allow retailers to achieve much greater holistic controls of not only their refrigeration assets, but also other key facility systems, such as HVAC and lighting. These are areas in which Emerson has invested significant resources and will continue to do so in the future.

Closely related to that are the abilities to monitor and track the temperatures and locations of perishable foods throughout various steps along the cold chain journey.

Acceleration of click-and-collect

If what we’ve seen in 2020 is any indication, the supermarket industry can expect the continued adoption of online fulfillment options. This change in consumer shopping preferences will continue to drive innovations in the next generation of refrigeration system design.

With the growing popularity of click-and-collect, retailers are adding capacity specifically for these cold-storage purposes. With variable-capacity modulation capabilities that can adapt to changing load variations, the Copeland™ digital X-Line series provides refrigeration flexibility and reliability in click-and-collect applications. In addition, its onboard controls can be networked into a supermarket’s building management system (BMS) for complete refrigeration control and monitoring.

Our facility management controls (E2) and enterprise software (Connect+) also help retailers to remotely monitor their refrigeration assets, optimize system performance, and provide data-driven, proactive alerts of potential equipment issues.

The role of regulations

The regulation of refrigerants continues to be a source of great uncertainty for our industry. For several years, regulations have targeted the phase-down of hydrofluorocarbon (HFC) refrigerants to reduce carbon emissions and their potential contribution to climate change. Many retailers face global, national and state regulatory mandates that ban the use of refrigerants with high global warming potential (GWP) and call for the deployment of energy-efficient refrigeration equipment. As a result, the industry is undergoing a shift toward alternative refrigerants with lower GWP levels and no ozone depletion potential (ODP).

All of this has helped to bring low-GWP refrigeration solutions into the spotlight, and Emerson supports a wide range of options for retailers along the sustainability continuum.

Whether it’s natural refrigerants like CO2 or propane, or lower-GWP synthetic A1 or A2L blends, Emerson equipment is designed to cover the full spectrum of refrigerant preferences in various types of architectures. It’s important to remember that there is no one-size-fits-all solution for this refrigerant transition; food retailers are employing a wide range of strategies, depending on their unique regulatory and sustainability mandates.

Many operators simply may not immediately require a drastic reduction in refrigerant GWP and instead are seeking a more gradual transition toward their future sustainability goals. We are helping these retailers to develop equipment strategies that will allow them to transition to lower-GWP refrigerants today, while giving them a pathway for achieving reduced GWP levels in the future.

Energy regulations are also in play, and Emerson is committed to helping the industry meet Department of Energy (DOE) efficiency targets for commercial refrigeration equipment. For example, our recent launch of the Copeland digital X-Line series is designed to meet the DOE’s annual walk-in energy factor (AWEF) efficiency standards for walk-in coolers. These products can also help operators in the state of California to comply with the California Air Resources Board (CARB) requirements for small-format grocery and convenience stores. The X-Line series utilizes low-GWP R-448A and is designed to service a limited number of medium- or low-temperature refrigeration fixtures — making it ideal for small, urban store formats or large supermarkets seeking to add refrigeration loads outside of their existing direct expansion (DX) systems.

Innovation throughout the cold chain

Leveraging the power of IoT, operational data and the software that can extract insights and value from this information will also play much larger roles in future supermarket refrigeration strategies. To that end, continued efforts to achieve connectivity throughout the various links of the cold chain will allow supermarkets to gain much greater control of food quality and safety well before it reaches the shelves of grocery stores.

 

 

Grow Your Bottom Line With Sustainable Refrigeration Retrofits

Katrina Krites | Marketing and Business Development

Manager, Food Retail

Emerson’s Commercial and Residential Solutions Business

Across the food retail market, supermarket operators are re-evaluating their legacy refrigeration architectures. A dynamic mix of regulatory mandates, sustainability goals and the emergence of e-commerce fulfillment models are dictating changes in the status quo of refrigeration. We recently published an article in the RSES Journal that discussed refrigeration retrofit strategies that allow retailers to meet their sustainability objectives while improving their bottom lines.

When considering refrigeration retrofits, food retailers must remember that sustainability is a two-sided coin. While reducing leaks of global warming potential (GWP) refrigerants is important for lowering direct emissions of greenhouse gases (GHGs), many supermarket operators often overlook the potential for indirect GHG emissions caused by poor system energy efficiencies.

The Environmental Protection Agency (EPA) estimates that supermarkets are the most electricity-intensive of all commercial buildings. Commercial refrigeration systems account for 40–60% of supermarket energy consumption and are by far the greatest contributor to indirect GHG emissions. Combined, direct and indirect emissions make up the true measure of sustainability, or a system’s total equivalent warming impact (TEWI).

Reduce direct emissions with lower-GWP refrigerants

The transition from high-GWP refrigerants and those with ozone depletion potential (ODP) is inevitable. Common legacy refrigerant options such as the HFC R-404A will be phased down while hydrochlorofluorocarbons (HCFCs) such as R-22 are being phased out. But this does not necessarily mean operators should immediately transition to an alternative refrigerant or embark on a complete refrigeration rebuild.

Lower-GWP A1 refrigerants, such as the hydrofluoroolefin (HFO) blend R-448A/R-449A, are available that allow end-users to retrofit their existing system, reduce GWP from direct emissions by up to 60%, and still maintain a familiar operational footprint similar to the one they have today.

For those operators currently using R-22, the transition to R-448A/R-449A is relatively straightforward and requires very few substantive architecture changes. The transition from R-404A to R-448A/R-449A is slightly more involved but can still be accomplished without significant architectural changes. R-448A/R-449A produces compressor discharge temperatures that run approximately 10–12% higher than R-404A. This may require additional compressor cooling mitigation such as head cooling fans, demand cooling modules, or a liquid or vapor injected scroll compressor. Consult your compressor OEM’s guidelines for specific retrofit procedures.

Improve system energy efficiencies

Any system retrofit or upgrade comes at a cost, so food retailers must ensure their investment delivers long-term viability and returns to their bottom line. This is where reducing indirect emissions by improving energy efficiencies plays such an important role. The U.S. Department of Energy (DOE) estimates that every dollar saved in electricity is equivalent to increasing sales by $59.

While it makes sense to undertake energy-efficiency measures in conjunction with a refrigerant transition, energy optimization best practices can — and should — be performed periodically on all systems. Before considering any retrofit options, start by performing a system assessment to determine your current performance metrics — which in many cases will deviate significantly from the system’s original commissioned baseline.

The next logical step in the energy optimization process is to enable a variable-capacity modulation strategy by either upgrading to a digitally modulated compressor or adding a variable-frequency drive (VFD) to a fixed-capacity compressor. Variable-capacity modulation provides significant system improvements, not just to energy efficiency but also to overall refrigeration system performance, reliability and lifespan. Benefits include:

  • Precise matching of capacity to changing refrigeration loads
  • Tight control over suction manifold pressures, allowing increased setpoint and energy savings
  • Improved case temperature precision
  • Reduced compressor cycling (on/off)

In digital compressor retrofit scenarios, we’ve demonstrated that replacing an underperforming, fixed-capacity compressor with a variable-capacity compressor can result in an additional 4% energy savings — even before activating digital modulation capabilities. And once digital modulation is activated, operators can expect an additional 12% energy savings.

Whether you’re trying to reduce your direct emissions with lower-GWP refrigerants or seeking to improve energy efficiencies and lower your indirect emissions, Emerson has compression technologies and sustainable refrigeration solutions to help you meet your specific objectives. The Copeland™ digital semi-hermetic and Copeland™ digital scroll compressors provide opportunities to transition to lower-GWP refrigerants and enable variable-capacity modulation to drive energy efficiencies.

%d bloggers like this: