Low Flammability Limit of Mixtures of Natural Refrigerants: Standards vs Theory

Matteo Caramaschi, Laure Meljac, Stefano Poppi, Kasper Østergaard, Martin Kærn, Torben Ommen, Brian Elmegaard

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Abstract

Natural refrigerants are being increasingly adopted by heat pump manufacturers. Heat pumps using flammable refrigerants need to satisfy charge limit requirements from standard IEC/EN 60335-2-40 and EN 378. The allowed refrigerant amount for the specific application is directly related to the Low Flammability Level (LFL). A possibility to reduce refrigerant flammability and allow a higher refrigerant charge is to adopt or design mixtures in which a hydrocarbon is mixed with a less flammable refrigerant. This work investigated the differences between LFL data available in international and European standards, and those calculated using theoretical methods. In the case of natural refrigerant mixtures R-432A, R-433B, and R-433C, approved in ASHRAE 34 and ISO817, it was found that the differences were between 26 % and 52 %. Differences in LFL test results for pure refrigerants, caused by the inter-laboratory spread, may partly explain the inconsistencies in the LFL of mixtures. Moreover, if not printing errors, unit conversion errors were found in ASHRAE 34 for the mixtures R-429A, R-430A, R-431A, R-433A, R-433C, and in EN 378-1 for mixture R-433B.
Original languageEnglish
Title of host publicationProceedings of ECOS 2022 - The 35th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems 2022
Number of pages8
PublisherECOS
Publication date2022
Publication statusPublished - 2022
Event35th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems
- DGI-Byen, Copenhagen, Denmark
Duration: 3 Jul 20227 Jul 2022
Conference number: 35
https://ecos2022.dtu.dk/

Conference

Conference35th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems
Number35
LocationDGI-Byen
Country/TerritoryDenmark
CityCopenhagen
Period03/07/202207/07/2022
Internet address

Bibliographical note

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Keywords

  • Heat pumps
  • Refrigerants
  • Charge
  • Flammability
  • Low Flammability Limit

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