Thermo-mechanical analysis of microcapsules containing phase change materials for cold storage

Abstract

Microencapsulated phase change material slurries (MEPCMSs) offer a potentially efficient and flexible solution for cryogenic-temperature cold storage. In this paper, the phase change material (PCM) microcapsules prepared to form MEPCMSs for cryogenictemperature cold storage consist of Dowtherm J (DJ) as core material and melamine formaldehyde (MF) as primary shell material. DJ is an aromatic mixture with diethylbenzene as the main component. Composite shell materials are adopted to avoid cracking by adding aluminium oxide (Al 2 O 3) nanoparticles or copper (Cu) coating into/on MF shell. In order to explore the heat transfer behaviour and mechanical stability of the microcapsules during the solidification process of PCM, a thermo-mechanical model is established by taking into account of energy conservation, pressure-dependent solid-liquid equilibria, Lamé's equations and buckling theory. Based on the proposed model, the effects of shell thickness, shell compositions and microcapsule size are therefore studied on the variations of pressure difference, freezing point, and latent heat. The cause of shell deformation is clearly explained and the shell buckling modes are predicted using the model, which agree well with the experimental observations. The critical core/shell size ratios of avoiding buckling are proposed for the microcapsules with different compositions. Simultaneously incorporation of Al 2 O 3 nanoparticles and Cu coating into/on MF shell can markedly enhance the resistant to buckling. In addition, special attention is paid to cold energy storage capacity of MEPCMSs, which has considerable superiority compared to packed pebble beds.

Cryogenic conditioning of microencapsulated phase change material for thermal energy storage

“…From the XRD results, it can be seen that the cryogenic treatment resulted in crystal structure changes and a slight increase in the crystallinity (for CMPCM1), which was similar to observations from studies related to cryogenic-treated polymers 36 . However, the peak intensity of CMPCM2 was quite low compared to that of CMPCM1, which could be attributed to its encapsulation properties.…”

“…However, research studies on powder-based materials treated with cryogen (cryogenic liquid) are limited. Interestingly, one study demonstrated the thermomechanical behavior of microspheres comprising a PCM for cryogenic-temperature cold storage applications 36 . The results infer that the buckling of the shell and freezing time of the PCM microspheres were vital parameters in determining the heat transfer and charging efficacy of cold storage.…”

Investigation of thermal management for lithium-ion pouch battery module based on phase change slurry and mini channel cooling plate

“…The phase change slurry (PCS) is made up of micro-encapsulated PCM (mPCM) and carrier fluid. The mPCM consists of PCM as core material and polymer as shell material [24] . PCS has high latent heat capacity and high energy density as it combines the properties of PCM with liquid coolant.…”

The Design and Manufacture of a Multilayer Low-Temperature Protective Composite Fabric Based on Active Heating Materials and Passive Insulating Materials

“…However, as solid-liquid PCMs, paraffin waxes are prone to leakage during the phase change process. To overcome this defect, many studies have been focused on the development of change phase microcapsules (microPCMs), which have a stable core-shell structure composed of an organic/inorganic shell and a PCM core [23,24,25]. In our previous work, we used microPCMs to prepare a low-temperature protective fabric [26].…”