Analysis of the thermal behavior in single-loop pulsating heat pipe paved of porous layers with gradual-changing porosity

Analysis of the thermal behavior in single-loop pulsating heat pipe paved of porous layers with gradual-changing porosity | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Analysis of the thermal behavior in single-loop pulsating heat pipe paved of porous layers with gradual-changing porosity wei chen, Yuqiao Fu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9175951/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 13 You are reading this latest preprint version Abstract In current study, the single-loop pulsating heat pipe paved of porous layer with gradual-changing porosity is proposed to obtain better thermal performances, in which the increase in solid matrix benefits for heat transfer, and decrease in dry out during operation duo to capillary force. The volume of fluid (VOF) multiphase relation and Darcy model together with evaporation-condensation and species transport equations are employed to describe heat and mass transfer in loop pulsating heat pipe paved of porous layer, in which the variation of vapor density, liquid saturation temperature and latent heat relates to local pressure and temperature. The effects of porosity distribution and its variation amplitude, as well as layer thickness in porous layer on fluid flow state and heat transfer in pulsating heat pipe are numerically analyzed. The equivalent thermal conductivity, \(\:{\lambda\:}\) , is employed to evaluate the thermal performance of pulsating heat pipe. The fluid flow direction variation during operation relates to gas column volume corresponding with evaporation and porosity distribution in heat pipe. The higher equivalent thermal conductivity and more heat flux to be transferred occur in case with of 0.5mm thick porous layer, and the increase in porosity distribution from 0.6 near inner wall surface to 0.8 near flowing channel in porous layer at 50% liquid filling rate. The simulations agree with experimental data from reference. All results can be considered into the application of porous layer with gradual-changing porosity in pulsating heat pipe. Gradual-changing porosity Single-loop pulsating heat pipe Heat and mass transfer Numerical simulation Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 12 May, 2026 Reviews received at journal 12 May, 2026 Reviews received at journal 11 May, 2026 Reviews received at journal 07 May, 2026 Reviewers agreed at journal 29 Apr, 2026 Reviewers agreed at journal 27 Apr, 2026 Reviewers agreed at journal 26 Apr, 2026 Reviewers agreed at journal 25 Apr, 2026 Reviewers agreed at journal 24 Apr, 2026 Reviewers invited by journal 24 Apr, 2026 Editor assigned by journal 01 Apr, 2026 Submission checks completed at journal 23 Mar, 2026 First submitted to journal 20 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9175951","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":634109293,"identity":"b0428bc0-57f1-41c4-96c2-8aba6bfa8b25","order_by":0,"name":"wei chen","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA10lEQVRIiWNgGAWjYFACxgZmICnHIAHjEqvFGKgFrJoYLQwMIC2JDURrMTje3Pi5oOJO+vzZ3emPeRhsZDccYH72AK+WMwebpWeceZa74c7Zjc08DGnGGw6wmRvg02J2I7GNmbftcO4GiVyQlsOJGw7wsEng1XL/IVDLv8Pp8jPAWv4ToeUGI1BLw+EEhhtgLQcIa7E/k9gszXPssOEGoJaZcwySjWceZjPDq0Wy/fjDzzw1h+WBDtvw4U2FnWzf8eZneLWgAVBQMZOgfhSMglEwCkYBdgAA3gZNzB0thAEAAAAASUVORK5CYII=","orcid":"","institution":"","correspondingAuthor":true,"prefix":"","firstName":"wei","middleName":"","lastName":"chen","suffix":""},{"id":634109297,"identity":"48dd4604-4b3e-448b-b1a4-f1c4640c0713","order_by":1,"name":"Yuqiao Fu","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Yuqiao","middleName":"","lastName":"Fu","suffix":""}],"badges":[],"createdAt":"2026-03-20 07:29:31","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9175951/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9175951/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108804317,"identity":"0c708ca2-b121-42b7-886e-5fc6646e7857","added_by":"auto","created_at":"2026-05-08 15:19:15","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1682928,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript2.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9175951/v1_covered_80a04bba-35e1-48eb-a562-998961551580.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Analysis of the thermal behavior in single-loop pulsating heat pipe paved of porous layers with gradual-changing porosity","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"heat-and-mass-transfer","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"hamt","sideBox":"Learn more about [Heat and Mass Transfer](https://www.springer.com/journal/231)","snPcode":"231","submissionUrl":"https://submission.nature.com/new-submission/231/3","title":"Heat and Mass Transfer","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Gradual-changing porosity, Single-loop pulsating heat pipe, Heat and mass transfer, Numerical simulation","lastPublishedDoi":"10.21203/rs.3.rs-9175951/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9175951/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn current study, the single-loop pulsating heat pipe paved of porous layer with gradual-changing porosity is proposed to obtain better thermal performances, in which the increase in solid matrix benefits for heat transfer, and decrease in dry out during operation duo to capillary force. The volume of fluid (VOF) multiphase relation and Darcy model together with evaporation-condensation and species transport equations are employed to describe heat and mass transfer in loop pulsating heat pipe paved of porous layer, in which the variation of vapor density, liquid saturation temperature and latent heat relates to local pressure and temperature. The effects of porosity distribution and its variation amplitude, as well as layer thickness in porous layer on fluid flow state and heat transfer in pulsating heat pipe are numerically analyzed. The equivalent thermal conductivity,\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\lambda\\:}\\)\u003c/span\u003e\u003c/span\u003e, is employed to evaluate the thermal performance of pulsating heat pipe. The fluid flow direction variation during operation relates to gas column volume corresponding with evaporation and porosity distribution in heat pipe. The higher equivalent thermal conductivity and more heat flux to be transferred occur in case with of 0.5mm thick porous layer, and the increase in porosity distribution from 0.6 near inner wall surface to 0.8 near flowing channel in porous layer at 50% liquid filling rate. The simulations agree with experimental data from reference. 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