Michael McPherson

This article presents the use of a wire mesh in optimising the performance of two volumetric solar receivers that use oil as a heat transfer fluid. Computational fluid dynamics models have been used to optimise the receivers. Varied parameters (including the use of a wire mesh) of the receiver models were changed in the optimisation process. Based on the models, prototype receivers were developed and tested. After that, the models were validated against experiments and the results compare well. The results indicate that the use of a wire mesh placed inside a receiver improves its performance. An optimal wire mesh porosity was found as ≈0.95 mainly because the efficiency is increased without inducing an adverse pressure drop inside the receiver.

The effective space charge density Neff is the average density of carriers over the depletion layer in a semiconductor diode and is measured from the capacitance-voltage curve extrapolated to full depletion Vd. Full semiconductor modeling has been performed for PIN diodes made of materials with a large density of generation-recombination (g-r) centers, such as irradiated or semi-insulating semiconductors. The results show that this extrapolation method can give incorrect values for the introduction rate of charged traps and g-r centers with large irradiation fluence. This is because the introduction of midgap g-r centers moves the Fermi level toward midgap which allows existing traps to change their ionization state. We propose an alternative approach to evaluate the effective density from the C-V characteristics without the need to evaluate the depletion voltage.

A sago starch biopolymer with embedded silver nanoparticles has been studied as a material for the prevention of microbial growth. Approximately 8 nm in size, silver nanoparticles have been synthes...