Alkali-Activation of Non-Wood Biomass Ash: Effects of Ash Characteristics on Concrete Performance

Combustion of biomass is increasingly practiced for power generation. Unlike coal ash, the combustion ashes of biomass do not offer significant value in Portland cement concrete production. An experimental study was conducted in order to assess the value of the combustion ashes of different non-wood biomass types towards production of alkali activated binders for concrete production. The results indicated that concrete materials with a desired balance of fresh mix workability, set time and compressive strength can be produced used alkali activated non-wood biomass ash binders. Correlations were drawn between the concrete engineering properties and different non-wood biomass ash characteristics. It was found that statistically significant relationships exist between the concrete properties and the non-wood biomass ash degree of crystallinity and solubility. These two ash characteristics were also found to be correlated. It was concluded that the suitability of non-wood biomass ash for use in production of alkali activated concrete can be assessed based on its degree of crystallinity

Surface grown copper nanowires for improved cooling efficiency

The interactions between heat sink surfaces and coolant play important roles in cooling methods. This study relies upon controlled nanostructuring of heat sink surfaces that produces orders of magnitude increases in surface area, excites local vortexes and improves the phase change mechanisms to enhance cooling efficiency. A scalable, economical and environmentally benign technique to grow copper nanowires with a strong/conductive base-anchorage on the surface of copper and related materials is described. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to monitor the reduction and morphology of the nanowires. Transmission electron microscopy (TEM), electron diffraction (ED) and X-ray diffraction (XRD) were employed to understand the structure of the as-grown copper hydroxide nanowires and reduced copper nanowires. The convective heat transfer of nanostructured surfaces was measured in the laboratory and compared to a theoretical treatment of the nanowire array effects on convective heat transfer. The various surface treatments tested showed heat transfer increases of up to 93% in good agreement with a theoretical analysis