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Natural fiber reinforced composites are gaining attention nowadays due to their low cost, biodegradable characteristics, lower density and comparable mechanical properties with synthetic fibers reinforced composites. As the recyclable properties of these composites are still not fully explored and this could be the reason that these are not much used in domestic and other applications to their full potential. In the current experimental investigation, the effects of mechanical recycling on the properties of bagasse fiber reinforced polypropylene composites have been studied. Tensile properties, crystallinity and aspect ratio exhibits an increase, while flexural properties decrease with each recycling step. No significant change in thermal behavior has been detected even after 5 cycles but a slight increase in the hardness has been observed. SEM images confirmed the change in aspect ratio due to crushing of fibers as well as fiber fracture became more dominant after each recycling step. [ABSTRACT FROM AUTHOR]

Particle resolved direct numerical simulation (PR-DNS) has been used extensively to obtain closures for heat transfer from static particle arrays. However, most of the currently available closure models are valid for packings of spherical particles only. We present closure models for momentum and heat transfer in densely packed cylindrical particle assemblies of different aspect ratios (2, 4 and 6). Our packings are generated using the Discrete Element Method (DEM). Subsequently, the void space is meshed with a high quality computational grid, and steady-state DNS simulations are completed to provide insight into the local heat transfer and pressure drop characteristics. The variation observed in the values for the local heat transfer rates from our PR-DNS study implies the necessity of specifying confidence intervals when reporting a correlation for the corresponding Nusselt number. Our newly developed correlations are applicable to densely packed beds of cylindrical particles in the porosity range (0.405 < ε < 0.539), and allow the estimation of the variability of the Nusselt number. [ABSTRACT FROM AUTHOR]

A comparison of reactive flows on two distinct scales is presented here (i) Particle resolved direct numerical simulation (PR-DNS), and (ii) 1D packed bed model. The PR-DNS geometry is meshed with polyhedral elements both inside and outside the particle to directly resolve the phenomena of intra particle diffusion and external heat and mass transfer. In contrast, the 1D packed bed model incorporates appropriate closure models to compare against the PR-DNS solutions at a computational cost several magnitudes less. Simulations are performed for endothermic steam methane reforming reactions (SMR) over a range of inlet temperatures. The comparison of the results between the two approaches shows that the 1D model can adequately replicate the PR-DNS results with appropriate modifications to the closures. The resulting verified 1D model was then used to simulate the reforming stage of an industrial scale packed bed chemical looping reforming reactor. [ABSTRACT FROM AUTHOR]