As a class of thermal energy-storage materials, phase change materials (PCMs) play an important role in sustainable development of economy and society with a rapid increase in energy demand. Microencapsulation of solid–liquid PCMs has been recognized as a vital technology to protect them from leakage and running off and to give them a shape stability in the liquid state to offer the ease of handling and thus received tremendous attention from fundamental studies to industrial development in recent decades. Aiming to provide the most complete and reliable source of information on recent progress and current development in microencapsulated PCMs, this review focuses on methodologies and technologies for the encapsulation of PCMs with a variety of wall materials from traditional organic polymers to novel inorganic materials to pursue high encapsulation efficiency, excellent thermal energy-storage performance and long-term operation durability. We attempt to clearly summarize the selection of core and wall materials, synthetic methods, formation mechanisms and characteristic performance of microencapsulated PCMs to help scientists better understand their design principles and synthetic mechanisms. This review also highlights the diverse design of bi- and multi-functional PCM-based microcapsules by fabricating various functional shells in a multilayered or hierarchical structure to provide a great potential to meet the growing demand for versatile applications. We also provide insights on the future research and development direction of microencapsulated PCMs with multifunctional applications in energy efficiency, sustainable processes, high-tech energy management and specific physicochemical effectiveness.

Innovative design of microencapsulated phase change materials for thermal energy storage and versatile applications: a review

Advanced thermal systems driven by paraffin-based phase change materials – A review

Different dimensional nanoadditives for thermal conductivity enhancement of phase change materials: Fundamentals and applications

Review of solar water heaters incorporating solid-liquid organic phase change materials as thermal storage

Phase change materials (PCMs) are gaining increasing attention and becoming popular in the thermal energy storage field. Microcapsules enhance thermal and mechanical performance of PCMs used in thermal energy storage by increasing the heat transfer area and preventing the leakage of melting materials. Nowadays, a large number of studies about PCM microcapsules have been published to elaborate their benefits in energy systems. In this paper, a comprehensive review has been carried out on PCM microcapsules for thermal energy storage. Five aspects have been discussed in this review: classification of PCMs, encapsulation shell materials, microencapsulation techniques, PCM microcapsules’ characterizations, and thermal applications. This review aims to help the researchers from various fields better understand PCM microcapsules and provide critical guidance for utilizing this technology for future thermal energy storage.

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Phase Change Material (PCM) Microcapsules for Thermal Energy Storage

Synthesis of novel microencapsulated phase change materials with copper and copper oxide for solar energy storage and photo-thermal conversion

Synthesis and light-heat conversion performance of hybrid particles decorated MWCNTs/paraffin phase change materials

Preparation of novel microencapsulated phase change material with Cu-Cu2O/CNTs as the shell and their dispersed slurry for direct absorption solar collectors

Paraffin wax (PW) is a solid–liquid organic phase change material (PCM). However, the low thermal conductivity and poor light–heat conversion performance limit its feasibility in solar thermal storage applications. In this paper, CuS-decorated carboxyl multi-wall carbon nanotubes (MWCNTs)/PW light–heat conversion composite PCMs were prepared by one step. The structure and properties of the composite PCMs were studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, differential scanning calorimeter, thermogravimetric analysis, coefficient of thermal conductivity, UV–visible–near infrared spectrometer and light–heat conversion testing. The results showed that the light–heat conversion performance of CuS–MWCNTs/PW composite PCMs were better than that of MWCNT/PW composite PCMs with the same mass fraction. Therefore, it is expected that this research will open up new avenues of study for the creation of advanced composite PCM with excellent light–heat conversion performance.

One-step synthesis of CuS-decorated MWCNTs/paraffin composite phase change materials and their light–heat conversion performance

The invention provides a preparation method of a paraffin/Cu-Cu2O/CNTs photothermal conversion phase-change energy storage composite material. According to the method, copper, cuprous oxide and a carbon nanotube are taken as carriers of a phase-change material, and the phase-change material paraffin is coated to form a phase-change microcapsule. By adopting the method provided by the invention, not only is the heat conductivity of the paraffin phase-change energy storage microcapsule improved, but also the light absorption is obviously improved, in addition, the carbon nanotube with high heatconductivity and light absorption is added, so that the heat conductivity and the light absorption of the microcapsule are further improved, in addition, the preparation method is simple, the cost islow, the problem of leakage of the paraffin in the phase change is effectively solved, and the energy absorption and release speeds of the paraffin are effectively improved in the application of solarenergy storage.

Jing Zhou

Papers

Synthesis of novel microencapsulated phase change materials with copper and copper oxide for solar energy storage and photo-thermal conversion

Synthesis and light-heat conversion performance of hybrid particles decorated MWCNTs/paraffin phase change materials

Preparation of novel microencapsulated phase change material with Cu-Cu2O/CNTs as the shell and their dispersed slurry for direct absorption solar collectors

One-step synthesis of CuS-decorated MWCNTs/paraffin composite phase change materials and their light–heat conversion performance

Preparation method of photothermal conversion phase-change energy storage composite material