{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,30]],"date-time":"2025-10-30T04:04:10Z","timestamp":1761797050540,"version":"build-2065373602"},"reference-count":28,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2025,10,26]],"date-time":"2025-10-26T00:00:00Z","timestamp":1761436800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Romanian Ministry of Education and the National University of Science and Technology Politehnica Bucharest"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Axioms"],"abstract":"<jats:p>Air liquefaction systems are essential in cryogenic engineering and energy storage, yet their performance is often constrained by significant exergy destruction. This study develops an exergy-based assessment of the Linde\u2013Hampson air liquefaction cycle to identify dominant sources of inefficiency and explore strategies for improvement. The analysis shows that throttling (\u224841%) and compression (\u224840%) represent the major contributions to exergy losses, followed by finite-temperature heat transfer (\u224815%) in the recuperative heat exchanger. To mitigate these losses, fractional throttling and optimized inlet conditions are proposed, leading to reduced compressor work and improved overall efficiency. A comparative study of a two-stage throttling configuration demonstrates a decrease in throttling-related exergy destruction to approximately 30%. Reverse Pinch analysis is employed to verify the thermal coupling of hot and cold streams and to determine the minimum feasible temperature difference. The design optimization of the recuperative heat exchanger identifies an optimal velocity ratio that minimizes pressure losses and quantifies how compression pressure affects the required heat transfer surface area. The results provide a systematic framework for improving the thermodynamic performance of air liquefaction cycles, highlighting exergy analysis as a powerful tool for guiding structural modifications and functional optimization.<\/jats:p>","DOI":"10.3390\/axioms14110785","type":"journal-article","created":{"date-parts":[[2025,10,30]],"date-time":"2025-10-30T03:44:39Z","timestamp":1761795879000},"page":"785","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Structural Optimization of Cryogenic Gas Liquefaction Based on Exergetic Principles\u2014The Linde\u2013Hampson Cycle"],"prefix":"10.3390","volume":"14","author":[{"given":"D\u0103nu\u021b Cristian","family":"Urduza","sequence":"first","affiliation":[{"name":"Department of Engineering Thermodynamics, National University of Science and Technology Politehnica Bucharest, 060042 Bucharest, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0861-3413","authenticated-orcid":false,"given":"Lavinia","family":"Grosu","sequence":"additional","affiliation":[{"name":"Laboratoire Energ\u00e9tique M\u00e9canique Electromagn\u00e9tisme (LEME), IUT de Ville d\u2019Avray, 50 rue de S\u00e8vres, 92410 Ville d\u2019Avray, France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-5317-5659","authenticated-orcid":false,"given":"Adalia Andreea","family":"Percembli (Chelmu\u0219)","sequence":"additional","affiliation":[{"name":"Department of Engineering Thermodynamics, National University of Science and Technology Politehnica Bucharest, 060042 Bucharest, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alexandru","family":"\u0218erban","sequence":"additional","affiliation":[{"name":"Department of Engineering Thermodynamics, National University of Science and Technology Politehnica Bucharest, 060042 Bucharest, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alexandru","family":"Dobrovicescu","sequence":"additional","affiliation":[{"name":"Department of Engineering Thermodynamics, National University of Science and Technology Politehnica Bucharest, 060042 Bucharest, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,10,26]]},"reference":[{"key":"ref_1","unstructured":"European Commision (2025, August 29). 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[8th ed.]."}],"container-title":["Axioms"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2075-1680\/14\/11\/785\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,30]],"date-time":"2025-10-30T04:00:32Z","timestamp":1761796832000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2075-1680\/14\/11\/785"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,10,26]]},"references-count":28,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2025,11]]}},"alternative-id":["axioms14110785"],"URL":"https:\/\/doi.org\/10.3390\/axioms14110785","relation":{},"ISSN":["2075-1680"],"issn-type":[{"value":"2075-1680","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,10,26]]}}}