This comprehensive review explores the multifaceted world of natural fiber applications within the domain of composite materials. Natural fibers are meticulously examined in detail, considering their diverse origins, which encompass plant-derived fibers (cellulose-based), animal-derived fibers (protein-based), and even mineral-derived variations. This review conducts a profound analysis, not only scrutinizing their chemical compositions, intricate structures, and inherent physical properties but also highlighting their wide-ranging applications across various industries. The investigation extends to composites utilizing mineral or polymer matrices, delving into their synergistic interplay and the resulting material properties. Furthermore, this review does not limit itself to the intrinsic attributes of natural fibers but ventures into the realm of innovative enhancements. The exploration encompasses the augmentation of composites through the integration of natural fibers, including the incorporation of nano-fillers, offering a compelling avenue for further research and technological development. In conclusion, this review synthesizes a comprehensive understanding of the pivotal role of natural fibers in the realm of composite materials. It brings together insights from their diverse origins, intrinsic properties, and practical applications across sectors. As the final curtain is drawn, the discourse transcends the present to outline the trajectories of future work in the dynamic arena of natural fiber composites, shedding light on emerging trends that promise to shape the course of scientific and industrial advancements.

Globally, industrialisation and urbanisation have led to the generation of hazardous waste (HW). Sustainable hazardous waste management (HWM) is the need of the hour for a safe, clean, and eco-friendly environment and public health. The prominent waste management strategies should be aligned with circular economic models considering the economy, environment, and efficiency. This review critically discusses HW generation and sustainable management with the strategies of prevention, reduction, recycling, waste-to-energy, advanced treatment technology, and proper disposal. In this regard, the major HW policies, legislations, and international conventions related to HWM are summarised. The global generation and composition of hazardous industrial, household, and e-waste are analysed, along with their environmental and health impacts. The paper critically discusses recently adapted management strategies, waste-to-energy conversion techniques, treatment technologies, and their suitability, advantages, and limitations. A roadmap for future research focused on the components of the circular economy model is proposed, and the waste management challenges are discussed. This review stems to give a holistic and broader picture of global waste generation (from many sources), its effects on public health and the environment, and the need for a sustainable HWM approach towards the circular economy. The in-depth analysis presented in this work will help build cost-effective and eco-sustainable HWM projects.

Slurry polymerization processes using Zeigler–Natta catalysts, are most widely used for the production of polyethylene due to their several advantages over other processes. Significant advancements have been made in the modeling of these processes to obtain high-quality final products. The modeling work in this field has a very wide scope due to the great diversity of the catalyst types, polymerization processes, polymerization conditions, product qualities and microstructures that exist at the commercial scale. In this article, we have reviewed and discussed the slurry polymerization processes for the production of polyethylene and the multiscale modeling and simulation framework in slurry reactors. The multiscale modeling framework mainly comprises of the kinetic model, single-particle diffusion models, multiphase hydrodynamics, phase equilibria, reactor residence time distribution and the overall mass and heat balances. Guidelines to implement the multiscale mathematical modeling and simulation in slurry-phase olefin polymerization processes are proposed. Special focus is given on the need to reduce the computational effort for the simulation of industrial reactors so that the models can be used as an effective tool-kit for optimization studies using state-of-art algorithms.

Higher density heat flux is the major cause of damage to the electronic component; therefore, cooling such components are of the utmost importance to operate in a safe zone and to increase their life. For this purpose, Microchannel heat sinks (MHSs) are among the most practical methods for dissipating unwanted heat. In this regard, the novel lozenge-shaped pin-fins in the flow passage of the microchannel heat sink (MHS) have been designed and proposed to achieve higher cooling performance. Aspect ratios ( λ = 0.30, 0.39, 0.52, 0.69, 1.00) of several lozenge-shaped pin-fins have been used into the design of MHS to investigate their impact on heat transmission and fluid flow characteristics. A three-dimensional model of MHS with a lozenge-shaped has been generated and simulated numerically in the following range of Reynolds numbers, starting from 100 to 900. Heat transmission and flow characteristics have been presented and discussed in detail. It has been found that introducing lozenge-shaped pin-fins in MHS has greatly improved cooling performance. The highest improvement in Nusselt number has been observed when aspect ratio ( λ ) of lozenge-shaped pin-fins was 1.00. The Nusselt number have been varied in the following ranges of 6.96–12.34, 6.97–12.72, 7.01–13.62, 7.09–14.43, and 7.12–15.26 at λ = 0.30, λ = 0.39, λ = 0.52, λ = 0.69, and λ = 1.0, respectively. In addition, a study of the thermohydraulic performance of the proposed lozenge-shaped pin-fins in the MHS found that this design is an effective means of lowering operating temperature.