{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,12]],"date-time":"2026-09-12T15:31:41Z","timestamp":1789227101554,"version":"build-2803163510"},"reference-count":50,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2025,7,11]],"date-time":"2025-07-11T00:00:00Z","timestamp":1752192000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100006541","name":"Comunidad de Madrid","doi-asserted-by":"publisher","award":["TEC-2024\/ECO-116"],"award-info":[{"award-number":["TEC-2024\/ECO-116"]}],"id":[{"id":"10.13039\/501100006541","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>Supercritical carbon dioxide (s-CO2) Brayton cycles have emerged as a promising technology for high-efficiency power generation, owing to their compact architecture and favorable thermophysical properties. However, their performance degrades significantly under cold-climate conditions\u2014such as those encountered in Greenland, Russia, Canada, Scandinavia, and Alaska\u2014due to the proximity to the fluid\u2019s critical point. This study investigates the behavior of the recompression Brayton cycle (RBC) under subzero ambient temperatures through the incorporation of low-critical-temperature additives to create CO2-based binary mixtures. The working fluids examined include methane (CH4), tetrafluoromethane (CF4), nitrogen trifluoride (NF3), and krypton (Kr). Simulation results show that CH4- and CF4-rich mixtures can achieve thermal efficiency improvements of up to 10 percentage points over pure CO2. NF3-containing blends yield solid performance in moderately cold environments, while Kr-based mixtures provide modest but consistent efficiency gains. At low compressor inlet temperatures, the high-temperature recuperator (HTR) becomes the dominant performance-limiting component. Optimal distribution of recuperator conductance (UA) favors increased HTR sizing when mixtures are employed, ensuring effective heat recovery across larger temperature differentials. The study concludes with a comparative exergy analysis between pure CO2 and mixture-based cycles in RBC architecture. The findings highlight the potential of custom-tailored working fluids to enhance thermodynamic performance and operational stability of s-CO2 power systems under cold-climate conditions.<\/jats:p>","DOI":"10.3390\/e27070744","type":"journal-article","created":{"date-parts":[[2025,7,11]],"date-time":"2025-07-11T13:44:19Z","timestamp":1752241459000},"page":"744","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Enhancing s-CO2 Brayton Power Cycle Efficiency in Cold Ambient Conditions Through Working Fluid Blends"],"prefix":"10.3390","volume":"27","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0760-6350","authenticated-orcid":false,"given":"Paul","family":"Tafur-Escanta","sequence":"first","affiliation":[{"name":"Facultad de Ingenier\u00eda en Ciencias Aplicadas, Universidad T\u00e9cnica del Norte, Ibarra 100150, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3655-2654","authenticated-orcid":false,"given":"Luis","family":"Coco-Enr\u00edquez","sequence":"additional","affiliation":[{"name":"Luxoft (DXC Technology), 28232 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1977-2118","authenticated-orcid":false,"given":"Robert","family":"Valencia-Chapi","sequence":"additional","affiliation":[{"name":"Facultad de Ingenier\u00eda en Ciencias Aplicadas, Universidad T\u00e9cnica del Norte, Ibarra 100150, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1980-0863","authenticated-orcid":false,"given":"Javier","family":"Mu\u00f1oz-Ant\u00f3n","sequence":"additional","affiliation":[{"name":"ETSI Industriales, Universidad Polit\u00e9cnica de Madrid, 28006 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,7,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"116447","DOI":"10.1016\/j.applthermaleng.2020.116447","article-title":"Review of supercritical CO2 technologies and systems for power generation","volume":"185","author":"White","year":"2021","journal-title":"Appl. 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