Effect of air layer thickness on melting kinetics and heat transfer in horizontally oriented hemispherical phase change material enclosures

Phase change materials (PCMs) in thermal energy storage systems often encounter unintended air gaps that critically affect performance, yet their effects in hemispherical enclosures remain unexplored. This research delves into the critical role of air layer thickness in modulating the melting kineti...

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Main Authors: Abbas Fadhil Khalaf, Farhan Lafta Rashid, Mudhar A. Al-Obaidi, Hayder I. Mohammed, Arman Ameen, Ephraim Bonah Agyekum
Format: Article
Language:English
Published: Elsevier 2025-05-01
Series:International Journal of Thermofluids
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Online Access:http://www.sciencedirect.com/science/article/pii/S2666202725002083
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author Abbas Fadhil Khalaf
Farhan Lafta Rashid
Mudhar A. Al-Obaidi
Hayder I. Mohammed
Arman Ameen
Ephraim Bonah Agyekum
author_facet Abbas Fadhil Khalaf
Farhan Lafta Rashid
Mudhar A. Al-Obaidi
Hayder I. Mohammed
Arman Ameen
Ephraim Bonah Agyekum
author_sort Abbas Fadhil Khalaf
collection DOAJ
description Phase change materials (PCMs) in thermal energy storage systems often encounter unintended air gaps that critically affect performance, yet their effects in hemispherical enclosures remain unexplored. This research delves into the critical role of air layer thickness in modulating the melting kinetics and heat transfer performance of PCM within horizontally oriented hemispherical enclosures—a configuration with considerable applications for thermal energy storage (TES) systems. This research has systematically quantified how air layer thickness (0–3 mm) affects PCM melting dynamics using advanced ANSYS/FLUENT 16 simulations. The absence of an air layer (0 mm) affords the fastest melting, driven by unobstructed natural convection and conduction. In other hand, incremental air layer thicknesses (1 mm, 2 mm, 3 mm) have introduced enlightened thermal resistance, delaying melting completion by 15 %, 30 %, and 45 %, respectively. In this regard, a 3 mm air layer has exhibited the most noticeable insulating effect, overwhelming the convective flow velocities by 35–40 % and creating non-uniform temperature distributions of 18–22 °C gradients. The obtained results disclose an essential trade-off. This is specifically disclosed as while air layers can enhance insulation, they obstruct heat transfer competence, extending the melting duration from 85 min (0 mm) to 123 min (3 mm). This research delivers actionable visions for optimising air gap design in PCM-based systems, balancing thermal regulation requirements with energy storage performance. The associated results are predominantly relevant for applications necessitating detailed thermal management, such as building-integrated TES and electronic cooling, where hemispherical enclosures offer geometric advantages.
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publisher Elsevier
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spelling doaj-art-b80cbf15cd274c60b76d08d0636937db2025-08-20T02:33:18ZengElsevierInternational Journal of Thermofluids2666-20272025-05-012710126110.1016/j.ijft.2025.101261Effect of air layer thickness on melting kinetics and heat transfer in horizontally oriented hemispherical phase change material enclosuresAbbas Fadhil Khalaf0Farhan Lafta Rashid1Mudhar A. Al-Obaidi2Hayder I. Mohammed3Arman Ameen4Ephraim Bonah Agyekum5Department of Petroleum Engineering, Engineering College, University of Kerbala, Karbala 56001, IraqDepartment of Petroleum Engineering, Engineering College, University of Kerbala, Karbala 56001, IraqTechnical Instructor Training Institute, Middle Technical University, Baghdad 10074, IraqDepartment of Physics, College of Education, University of Garmian, Kurdistan, Kalar 46021, IraqDepartment of Building Engineering, Energy Systems and Sustainability Science, University of Gävle, 801 76 Gävle, Sweden; Corresponding author.Department of Nuclear and Renewable Energy, Ural Federal University Named after the First President of Russia, Boris Yeltsin, 19 Mira Street, Ekaterinburg, 620002, Russia; Western Caspian University, 31, Istiglaliyyat Street, AZ1001, Baku, Azerbaijan; Istanbul Okan University, Tuzla Campus, 34959 Tuzla, Istanbul, TurkeyPhase change materials (PCMs) in thermal energy storage systems often encounter unintended air gaps that critically affect performance, yet their effects in hemispherical enclosures remain unexplored. This research delves into the critical role of air layer thickness in modulating the melting kinetics and heat transfer performance of PCM within horizontally oriented hemispherical enclosures—a configuration with considerable applications for thermal energy storage (TES) systems. This research has systematically quantified how air layer thickness (0–3 mm) affects PCM melting dynamics using advanced ANSYS/FLUENT 16 simulations. The absence of an air layer (0 mm) affords the fastest melting, driven by unobstructed natural convection and conduction. In other hand, incremental air layer thicknesses (1 mm, 2 mm, 3 mm) have introduced enlightened thermal resistance, delaying melting completion by 15 %, 30 %, and 45 %, respectively. In this regard, a 3 mm air layer has exhibited the most noticeable insulating effect, overwhelming the convective flow velocities by 35–40 % and creating non-uniform temperature distributions of 18–22 °C gradients. The obtained results disclose an essential trade-off. This is specifically disclosed as while air layers can enhance insulation, they obstruct heat transfer competence, extending the melting duration from 85 min (0 mm) to 123 min (3 mm). This research delivers actionable visions for optimising air gap design in PCM-based systems, balancing thermal regulation requirements with energy storage performance. The associated results are predominantly relevant for applications necessitating detailed thermal management, such as building-integrated TES and electronic cooling, where hemispherical enclosures offer geometric advantages.http://www.sciencedirect.com/science/article/pii/S2666202725002083Air gapMelting kineticsPhase change materials (PCMs)Hemispherical enclosuresNatural convectionThermal energy storage
spellingShingle Abbas Fadhil Khalaf
Farhan Lafta Rashid
Mudhar A. Al-Obaidi
Hayder I. Mohammed
Arman Ameen
Ephraim Bonah Agyekum
Effect of air layer thickness on melting kinetics and heat transfer in horizontally oriented hemispherical phase change material enclosures
International Journal of Thermofluids
Air gap
Melting kinetics
Phase change materials (PCMs)
Hemispherical enclosures
Natural convection
Thermal energy storage
title Effect of air layer thickness on melting kinetics and heat transfer in horizontally oriented hemispherical phase change material enclosures
title_full Effect of air layer thickness on melting kinetics and heat transfer in horizontally oriented hemispherical phase change material enclosures
title_fullStr Effect of air layer thickness on melting kinetics and heat transfer in horizontally oriented hemispherical phase change material enclosures
title_full_unstemmed Effect of air layer thickness on melting kinetics and heat transfer in horizontally oriented hemispherical phase change material enclosures
title_short Effect of air layer thickness on melting kinetics and heat transfer in horizontally oriented hemispherical phase change material enclosures
title_sort effect of air layer thickness on melting kinetics and heat transfer in horizontally oriented hemispherical phase change material enclosures
topic Air gap
Melting kinetics
Phase change materials (PCMs)
Hemispherical enclosures
Natural convection
Thermal energy storage
url http://www.sciencedirect.com/science/article/pii/S2666202725002083
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