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Refrigeration Basics: Understanding Refrigerants With Glide

         Don Gillis | Lead Technical Trainer

          Emerson’s Educational Services

Welcome to our new series of blogs intended to help not just beginning service technicians, but anyone who wants to learn more about the basics of refrigeration. I plan to share insights, best practices and other information from our Emerson training program as well as from our commercial and residential solutions experts. In addition, we’ve created companion videos about each topic that you can cross-reference while accessing other related information at Education.Emerson.com.

In this series, I’ll touch on topics ranging from how condensers, compressors and evaporators work, to superheating and subcooling, to the refrigeration cycle, vapor injection and basic refrigeration system troubleshooting. In this blog, I explain the key environmental considerations of refrigerants, how to account for refrigerant glide, and how the dew point impacts climate control equipment performance.

What’s the difference between ODP and GWP?

A refrigerant’s environmental characteristics are determined largely by two factors: 1) its impact on the Earth’s ozone layer, or ozone depletion potential (ODP); and 2) its potential to produce greenhouse gas emissions, or global warming potential (GWP). Chlorine-containing ODP refrigerants have been banned for use, while high-GWP hydrofluorocarbon (HFC) refrigerants are currently the target of global regulations (i.e., the HFC phasedown). Today, refrigerant manufacturers are introducing a variety of lower-GWP refrigerant alternatives to help commercial and residential customers achieve a full spectrum of sustainability goals.

In the United States, federal and state regulations are accelerating the phasedown of the use of high-GWP refrigerants. Meanwhile, corporate sustainability objectives also are driving more companies to re-evaluate their choices of refrigerants and refrigeration systems.

What is refrigerant glide?

Refrigerants are often comprised of a blend of two or more constituents. These individual components’ different saturation temperatures can impact the refrigerant’s performance characteristics. Working with refrigerants with glide requires understanding the boiling point of each of its constituents:

  • Bubble point, or lowest condensing temperature of a constituent
  • Mean condensing temperature
  • Dew point, or the highest condensing temperature of a constituent

The difference between the boiling points of the first and last constituents is referred to as glide. Essentially, the least volatile component condenses first, and each additional component of a refrigerant blend will start and end at different boiling points. The total temperature glide of a refrigerant blend is defined as the temperature difference between the saturated vapor temperature and the saturated liquid temperature at a constant pressure. An alternate definition is the temperature difference between the starting and ending temperatures of a refrigerant phase change within a system at a constant pressure.

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.

Introducing Copeland™ Variable Speed Reciprocating Hermetic Compressors for Refrigeration

Derek Langenkamp | Product Manager, Hermetic Reciprocating

Emerson’s Commercial and Residential Solution’s Business

Making equipment design changes to meet increasing energy efficiency standards is nothing new for original equipment manufacturers (OEMs) in the commercial refrigeration space. For quite some time, the medium- and low-temperature, stand-alone coolers and freezers commonly used in restaurants, convenience stores (C-stores) and small-format food retailers have been key targets of the Department of Energy’s (DOE) energy efficiency mandates. Because highly efficient compression technologies are among the few design options left to help OEMs meet these targets, Emerson is pleased to announce its Copeland variable speed reciprocating hermetic compressor line designed specifically for this purpose. For full details, you can read our latest E360 Product Spotlight.

While our industry expects that the DOE will soon be proposing its next phase-down in energy reductions for these applications — which are likely to take effect in 2024 — the need for highly reliable, energy-efficient compressors extends well beyond commercial refrigeration. In fact, OEMs in the environmental life sciences, medical and pharmaceutical industries can also benefit from the high efficiency and reliable performance of the Copeland variable speed reciprocating hermetic compressor line. In addition, many OEMs are also seeking a competitive edge by offering equipment that achieves ENERGY STAR® certification. The range of applications across these industries includes:

  • Medium- and low-temperature stand-alone refrigerators and freezers, including ultra-low temperature (ULT) freezers
  • Island cases
  • Display cases
  • Ice machines
  • Food prep tables
  • Medical equipment
  • Process chillers

Superior energy efficiency and refrigeration performance

Copeland variable speed reciprocating hermetic compressors are designed to deliver significant efficiency and performance improvements for commercial refrigeration reach-in OEMs. This low-profile, variable speed solution is comprised of two components:

  1. Copeland variable speed reciprocating hermetic compressor — available in ranges from ⅛ to ⅞ HP; featuring a brushless permanent magnet (BPM) motor vs. a standard induction motor
  2. Variable speed (VS) drive with a smart controller — includes serial, frequency and drop-in modes; drop-in mode serves as the system controller

Standalone, reach-in freezer optimized and tested with Emerson components and controls, under EPA-approved test lab for the ENERGY STAR® program per ASHRAE 72 and DOE energy testing requirements showed:

  • System efficiency increased by 13% by replacing fixed speed compressor with variable speed solution
  • Compressor cycling reduced by 90%
  • Compression ratio relaxed by as much as 43%
  • Manufacturer exceeds ENERGY STAR performance levels
  • Utilizes a future-oriented, low-GWP natural refrigerant

For end users of this enhanced refrigeration equipment, these efficiencies can result in:

  • Faster pull-downs to setpoint temperatures
  • More precise temperature holding
  • Less wear and tear on system components
  • Lower energy bills

In addition, the breadth of the Copeland variable speed reciprocating hermetic compressor line gives system design engineers a variety of compressor options with which to achieve significant energy efficiency improvements for refrigeration equipment of varying types and sizes.

The regulatory advantages of R-290

The Copeland variable speed reciprocating hermetic compressor line is designed to utilize R-290, a natural refrigerant, with an ultra-low global warming potential (GWP) of 3. This allows OEMs to offer their customers a refrigeration option that meets some of the most stringent refrigerant and energy efficiency regulations to date, such as:

  1. Potential impending DOE 2024 standard
  2. California Air Resources Board (CARB)
  3. Potential Environmental Protection Agency (EPA) refrigerant requirements
  4. ENERGY STAR® certification

Emerson’s test labs have confirmed that the use of R-290 in variable speed compressors can deliver superior annual energy efficiency ratio (EER) ratings compared to using R-404A in a fixed-speed compressor.

Helping OEMs meet DOE 2024 and beyond

The estimated timeline for the DOE’s next phase-down in commercial refrigeration equipment energy consumption is 2024. If current equipment does not meet DOE requirements, most OEMs will soon need to integrate new components into their next design cycle to comply with the next generation of energy reduction mandates.

The Copeland variable speed reciprocating hermetic compressor line delivers the energy efficiency levels that will help your equipment meet the upcoming DOE requirements — all while giving your customers the reliability and performance improvements they’ll need to succeed. With our extensive design and testing resources, Emerson can help to guide you through this transition. We’re ready to help you meet the next round of DOE efficiency standards and beyond — and achieve the ENERGY STAR® certification to differentiate you from your competitors. Visit our website to learn more about the Copeland variable speed reciprocating hermetic compressor line.

 

[E360 Webinar Wrap-up] Refrigerant Rulemaking Recap: Regulatory Uptick Expected for 2021

RajanRajendran2 Rajan Rajendran | V.P., System Innovation Center and Sustainability

Emerson’s Commercial & Residential Solutions Business

 

The commercial refrigeration and air conditioning sectors are currently experiencing an active period of refrigerant rulemaking. As we move through the first quarter of 2021, our industry is evaluating a variety of regulatory activities and climate initiatives — at both the state and federal levels — that govern the transition to lower global warming potential (GWP) refrigerants and the safe use of flammable alternatives. I recently co-hosted an E360 webinar with Jennifer Butsch, Emerson’s regulatory affairs director, to discuss current developments and explore their potential impacts on our industry. We were joined by Helen Walter-Terrinoni, vice president of regulatory affairs for the Air-Conditioning, Heating, and Refrigeration Institute (AHRI).

As global regulatory efforts to phase down the use of HFC refrigerants continue in earnest, the transition to alternatives with lower GWP is gaining momentum in the U.S. At the state level, California is preparing for its next phase of rulemaking, while more U.S. Climate Alliance states leverage the Environmental Protection Agency’s (EPA) Significant New Alternatives Policy (SNAP) Rules 20 and 21 as the bases for their own environmental initiatives. In addition, a new presidential administration and the passing of new federal legislation represent significant shifts in U.S. regulatory dynamics — resuming our global participation in combating climate change and giving the EPA authority to govern HFCs.

But the progression of refrigerant rulemaking along both state and federal lines continues to create complexity for an industry that seeks guidance in understanding and applying an ever-evolving, complex mix of regulations.

California Air Resources Board (CARB) Seeks to Finalize Proposals

In 2019, California was the first state to adopt EPA SNAP Rules 20 and 21 in their entirety. Since then, CARB has developed additional proposals to meet its stated 2030 emissions-reduction targets. For commercial refrigeration, these proposed refrigerant regulations target the installation of new refrigeration systems greater than 50lbs:

  • 150 GWP limit for systems installed in new facilities
  • In existing facilities, food retailers must choose from one of the following company-wide reduction targets:
    • Reduce their weighted average GWP below 1,400
    • Achieve a 55% or greater reduction in their greenhouse gas potential (GHGp) below 2019 baseline levels by 2030
  • Other GWP limits for systems in existing facilities include a 750 limit for ice rinks and a 1500 – 2000 limit for industrial refrigeration

In air conditioning applications, the CARB proposal targets a 750 GWP limit across multiple end uses in the coming years:

  • 2023: room AC and dehumidifiers
  • 2024: AC chillers (consistent with SNAP Rule 21)
  • 2025: residential and commercial AC
  • 2026: variable refrigerant flow (VRF) systems

CARB has also introduced its Refrigerant Recycle, Recovery and Reuse (R4) program, which proposes new air conditioning equipment in 2023 and 2024 to use reclaimed R-410A refrigerant in an amount equal to 10% of equipment operating charge in California. In addition, CARB has stated that it will expand its R4 program by introducing new rulemaking this year.

U.S. Climate Alliance States Adopt Legislation

Among the 25 member states that have joined the U.S. Climate Alliance, nine have finalized legislation for adopting SNAP Rules 20 and 21 into law. Like the original EPA rules, the timings of enforcement dates are end-use specific and designed to be phased in over several years. But because the start dates of these rules differ among the nine member states, our industry faces an increasingly complex patchwork of compliance schedules.

As Walter-Terrinoni pointed out in the webinar, the prospect of new federal legislation may give these and other states the option to pursue a consistent, nationwide approach to the refrigeration phase-down. States could place their focus on the local level, where they can further the advancement of building codes and safety standards.

Federal HFC Phase-down Takes AIM

Regulatory activity is also picking up at the federal level, starting with the EPA’s proposed SNAP Rule 23, which reaffirms its commitment to approve low-GWP refrigerants. The proposal lists several mildly flammable (A2L) refrigerants, including R-452B, R-454A, R-454B, R-454C, R-457 and R-32 as acceptable, subject to use conditions in new residential and light commercial air conditioners and heat pumps. For retail food refrigeration — medium-temperature, stand-alone units — SNAP Rule 23 lists A1 refrigerants R-448A, R-449A and R-449B as acceptable, subject to narrowed use limits. Emerson and other industry stakeholders have asked for further clarification on these restrictions, as these A1s have already been listed as acceptable without limitations in many other commercial refrigeration applications.

As part of major pandemic relief legislation, the American Innovation and Manufacturing (AIM) Act was passed and signed into law in late 2020. This legislation gives the EPA the authority to phase down HFC production and consumption limits in a manner consistent with the Kigali Amendment to the Montreal Protocol within nine months. It also authorizes the EPA to regulate HFCs through sector based rulemaking and establish standards for HFC management — servicing, repair, recover, recycle and reclaim — similar to CARB’s R4 program. This is welcome news for our industry, as it paves the way for a federally guided, low-GWP refrigerant transition, which would minimize the complexities of differing state-led regulations.

Under the new Biden administration, the U.S. has rejoined the Paris Agreement and is taking steps to ratify the Kigali Amendment. These are among many early indications of this administration’s commitment to combat climate change at home and abroad.

A2L, A3 Standards and Codes Progress

With the industry moving toward the use of flammable A2L and A3 refrigerants to achieve lower-GWP goals, the technical committees and governing bodies who provide guidelines on how to safely use these refrigerants and related equipment are currently updating their safety standards. Among the updates that many are closely watching are the proposed changes to the Underwriter’s Laboratory (UL) 60335-2-89 standard, which would increase the charge limits in self-contained and remote refrigeration applications. While the industry expects this proposal potentially to be finalized by the end of the year, it’s important to remember that once established, these standards will take several years to make their way into the building codes and local standards needed to permit the widespread use of flammable refrigerants.

To learn more details about each of these important regulatory developments, please view our on-demand webinar.

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.

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