A thermal energy storage composite by incorporating microencapsulated phase change material into wood

Sustainability in Wood Products: A New Perspective for Handling Natural Diversity

Wood is a renewable resource with excellent qualities and the potential to become a key element of a future bioeconomy. The increasing environmental awareness and drive to achieve sustainability is leading to a resurgence of research on wood materials. Nevertheless, the global climate changes and associated consequences will soon challenge the wood-value chains in several regions (e.g., central Europe). To cope with these challenges, it is necessary to rethink the current practice of wood sourcing and transformation. The goal of this review is to address the intrinsic natural diversity of wood, from its origin to its technological consequences for the present and future manufacturing of wood products. So far, industrial processes have been optimized to repress the variability of wood properties, enabling more efficient processing and production of reliable products. However, the need to preserve biodiversity and the impact of climate change on forests call for new wood processing techniques and green chemistry protocols for wood modification as enabling factors necessary for managing a more diverse wood provision in the future. This article discusses the past developments that have resulted in the current wood value chains and provides a perspective about how natural variability could be turned into an asset for making truly sustainable wood products. After briefly introducing the chemical and structural complexity of wood, the methods conventionally adopted for industrial homogenization and modification of wood are discussed in relation to their evolution toward increased sustainability. Finally, a perspective is given on technological potentials of machine learning techniques and of novel functional wood materials. Here the main message is that through a combination of sustainable forestry, adherence to green chemistry principles and adapted processes based on machine learning, the wood industry could not only overcome current challenges but also thrive in the near future despite the awaiting challenges.

Form-Stable Phase Change Material with Wood-Based Materials as Support

Building shape-stable phase change materials (PCMs) are crucial for their practical applications. Particularly, it is vital to utilize renewable/recyclable biomass media as the support material of form-stable PCMs. In this review article, we summarized the recent developments for building form-stable PCMs consisting of wood as a supporting material, either carbonized wood or wood composites. Moreover, the electrothermal conversion and photothermal conversion of form-stable PCMs based on carbonized wood are also demonstrated. In addition, the current technical problems and future research developments of wood-based PCMs are discussed, especially the leakage problem of PCMs during the phase change transition process. All of this information will be helpful for the in-depth understanding and development of new PCMs suitable for wide application perspectives.

Cellulose nanofibril/carbon nanotube composite foam-stabilized paraffin phase change material for thermal energy storage and conversion

The leakage and low thermal conductivity of paraffin phase change material (PCM) must be addressed to achieve a more efficient energy storage process. In this study, cellulose nanofibril (CNF) foams were prepared as the porous support of paraffin to prevent its leakage, and multiwalled carbon nanotubes (CNTs) were incorporated in the foams to improve heat transfer performance. Treatment of CNF with methyltrimethoxysilane improved compatibility between the foams and paraffin. The prepared highly porous (porosity >96%) foams had paraffin absorption capacities exceeding 90%. The form-stable PCM composites displayed negligible paraffin leakage and had a compact structure. The prepared PCM composites had enhanced heat transfer performance, reasonable phase change properties and thermal stabilities. The enthalpy of the SCNF/CNT₅₀-Pw PCM composite decreased by 6% after 100 melting/freezing cycles. Compared with pristine paraffin, the PCM composites exhibited superior form-stabilities and improved thermal properties, which suggested application in a solar-thermal-electricity energy harvesting and conversion system.