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Federal Register / Vol. 86, No. 115 / Thursday, June 17, 2021 / Proposed Rules
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those of 10 F freezers. Therefore, proper accounting for defrost of hightemperature freezer refrigeration systems requires developing a modified calculation. The equation found in section 3.4.2.4 of Appendix C used to calculate freezer equipment daily defrost energy use DF uses as inputs the condenser capacity qmix,cd and the number of defrost cycles per day NDF. The daily defrost heat load QDF is directly dependent on DF
see relevant equation in section 3.4.2.5
of Appendix C. DOE anticipates that a calculation of defrost impacts for hightemperature freezers, if adopted, would use similar equations with different magnitudes.
Issue 49: DOE requests information or data that would indicate whether and how the equations used to calculate daily defrost energy use and heat addition in the test procedure should be modified for high-temperature freezer refrigeration systems rated as standalone condensing units e.g., defrost heater wattage and daily energy use as a function of capacity for a 10 F walkin temperature. If testing at the lowest application temperature is adopted, DOE requests comment on how the defrost equations should be modified to account for each model being tested at different conditions, and why. DOE
requests information on whether frost loads and/or defrost frequency are different for hightemperature freezers than for 10 F freezers. DOE requests that commenters include any available supporting information when responding.
8. Consideration for Refrigerant Glide The analysis for the June 2014 ECS
final rule assumed that the refrigerant R404A would be used in all new refrigeration equipment meeting the standard. 79 FR 32050, 32074. In its subsequent negotiated rulemaking effort in 2015, WICF Working Group members suggested that DOE revise this approach by accounting for the use of a different refrigerant, R407A, which was expected to become more commonly used for WICF applications. Consistent with that suggestion, DOE conducted the analysis for the July 2017 ECS final rule using R407A as the refrigerant. 82
FR 31808, 3183531836.
On July 20, 2015, the U.S.
Environmental Protection Agency EPA published a final rule under the Significant New Alternatives Policy SNAP program listing as unacceptable the use of certain hydrofluorocarbons HFCs, including the use of R404A in WICF refrigeration systems. 80 FR 42870 July 2015 EPA
SNAP Rule. In October 2016, the 28th
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Meeting of the Parties to the Montreal Protocol adopted the Kigali Amendment on HFCs, which, upon ratification, requires parties to the protocol to reduce consumption and production of HFCs.41
On December 1, 2016, EPA published a final rule December 2016 EPA SNAP
Rule that listed a number of refrigerants for use in certain refrigerant applications as unacceptable, starting January 1, 2023 for cold storage warehouse application, and January 1, 2021 for retail food refrigerant applications. 81 FR 86778. The list of unacceptable refrigerants included R
407A. The validity of the SNAP
approach, however, has been the subject of a legal challenge regarding EPAs use of its SNAP authority to require manufacturers to replace HFCs with a substitute substance.
In August 2017, the U.S. Court of Appeals for the District of Columbia Circuit vacated and remanded the July 2015 EPA SNAP Rule to the extent that it required manufacturers to replace HFCs with a substitute substance.42 Mexichem Fluor, Inc. v.
EPA, 866 F.3d 451 D.C. Cir. 2017.
Subsequently, the December 2016 SNAP
Rule was partially vacated by the court.43 While the United States has not ratified the Kigali Amendment, a significant portion of walk-in refrigeration systems currently use HFCbased refrigerants and may become affected by this Amendment to the Montreal Protocol. DOE plans to consider the potential impact if any of both the courts decision and remand as well as the Amendment to the Montreal Protocol on the test procedure issues addressed in this RFI.
Notwithstanding these legal developments, key differences between the refrigerants used in DOEs separate analyses of walk-in refrigeration systems merit discussion. Both R404A and R407A are blends of refrigerants that have different boiling points. This means that, unlike pure substances such 41 http www.unep.org/ozonaction/Portals/105/
documents/7809-e-Factsheet_Kigali_Amendment_
to_MP.pdf last viewed February 3, 2017.
42 The vacatur and remand in Mexichem, Inc. v.
EPA was of the July 2015 EPA SNAP Rule and did not directly address the December 2016 EPA SNAP
Rule. At issue was EPAs use of its SNAP authority as a means to remove HFCs from the agencys list of acceptable substitutes. On April 27, 2018, EPA
published a notice stating that in the near-term it will not apply the HFC listings in the July 2015
final rule pending a rulemaking and that it plans to begin a notice-and-comment rulemaking process to address the remand. 83 FR 18431.
43 Following the decision in the Mexichem case, the court vacated the December 2016 SNAP Rule to the extent it requires manufacturers to replace HFCs that were previously and lawfully installed as substitutes for ozone-depleting substances. Case No.
171024 D.C. Cir. April 5, 2019.

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as water, the temperature of the refrigerant changes as it boils or condenses, because one of the refrigerants in the blend, having a lower boiling point, boils off sooner than the others. This phenomenon is called glide. The refrigerants that make up R404A have nearly identical boiling points, so this refrigerant has very little glide. In contrast, R407A undergoes a much more significant temperature change when it boilsthe temperature can rise as much as 8 degrees between the saturated liquid condition the temperature at which a liquid begins to boil, also called the bubble point and the saturated vapor condition the temperature at which a vapor begins to condense, also called the dew point.
The average of these two temperatures, bubble point and dew point, is called the mid-point temperature.
The current DOE test procedure specifies that test conditions are based on dew point. DOE notes that if the refrigerant condition for a unit cooler is specified by dew point, the average refrigerant temperature would be significantly lower for a high-glide than for a low-glide refrigerant. As mentioned previously, DOE is considering changing its test procedure to be based on a refrigerant-neutral approach. One specific option would be to use the mid-point temperature.
However, with walk-in refrigeration systems, the refrigerant entering the unit cooler is typically a two-phase refrigerant with a temperature higher than the bubble point. This scenario results in the average evaporator temperature being slightly greater than a mid-point equal to the average of bubble and dew point temperatures. To account for this difference, DOE could develop an approach to calculate and specify refrigerant temperatures in terms of a modified mid-point, which would be a calculated value slightly higher than the mid-point of the selected refrigerant.
Issue 50: DOE requests comment on the appropriateness of specifying refrigerant temperatures in terms of mid-point or a modified mid-point, rather than dew point, which is currently used. DOE seeks feedback on potential definitions to use for a modified mid-point temperature as applied to WICF refrigeration system testing. In addition, DOE requests comments on what other factors should be considered when modifying the refrigeration system test conditions from dew point to mid-point or modified mid-point specifications.
III. Submission of Comments DOE invites all interested parties to submit in writing by the date specified
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