Periodic structures for melting enhancement

Periodic structures for melting enhancement: observation of critical cell size and localized melting

Zhao, Chunrong (University of Queensland)
Opolot, Michael (University of Queensland)
Liu, Ming (University of South Australia)
Wang, Ji (University of South Australia)
Bruno, Frank (University of South Australia)
Mancin, Simone (Università degli Studi di Padova)
Hooman, K. (TU Delft Process and Energy)

Process and Energy

2022

The use of metallic periodic structures was considered for melting rate enhancement of a phase change material (PCM) contained in a rectangular enclosure isothermally heated from the side. The critical (optimized) cell size, or pore size, of a periodic structure with fixed porosity, realising the shortest melting time by maximizing the convection and conduction heat transfer rate into the PCM, was studied. Furthermore, the effects of material properties (copper, aluminium, nickel, and stainless steel), enclosure length, wall-melting temperature difference and porosity were numerically investigated. It was observed that increasing porosity and/or reducing thermal conductivity enlarged the critical cell size (i.e. the optimal cell size that minimizes the melting time). The critical PPIs (pores per inch) of copper and aluminium periodic structures for all studied porosities were 10; for nickel, the critical values were 10 PPIs for porosity values of 0.75, 0.8 and 0.85 while it reduces to 5 PPI for the highest porosity considered here being 0.95. Interestingly, showing a different trend, the critical PPI of stainless-steel structures was 5 for the lowest porosity (0.75) and reduced to 3 for higher porosities. The results clearly demonstrated localised melting which was observed in all periodic structures except for the 10 PPI stainless-steel case. Scattered melting islands are observed as opposed to a moving interface when ϕ=(d_p/L)α_ligament/α_PCM>1. For such cases, localized melting occurs and the PCM is melted at the ligaments away from the heated wall before the melt front reaches those ligaments.

Critical cell size
PCM melting
Periodic structure

http://resolver.tudelft.nl/uuid:68c0cc39-bbcb-4bff-a336-e45bbb53fa39

https://doi.org/10.1016/j.ijheatmasstransfer.2022.123107

2022-12-20

0017-9310

International Journal of Heat and Mass Transfer, 195

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

journal article

© 2022 Chunrong Zhao, Michael Opolot, Ming Liu, Ji Wang, Frank Bruno, Simone Mancin, K. Hooman