1D modelling of membrane-assisted chemical looping reforming

Membrane-assisted chemical looping reforming (MA-CLR) has been proposed as an alternative to the conventional CLR technology. In this work, a non-isothermal 1D model is used to simulate the MA-CLR fuel reactor. The effect of the resulting axial temperature gradients on the reactor performance is assessed, showing up to 10% declines in reactor performance (hydrogen extraction and fuel slip).The inclusion of the energy balance therefore appears to be important for this application, despite the high degree of mixing achievable in fluidized beds

Raw and steam exploded pine wood: Possible enhanced reactivity with gasification hydrogen

A commercial thermally treated biomass known as ‘steam exploded biomass’ or ‘black pellets’ was compared with the raw yellow pine wood feedstock to the process using the Hartmann dust explosion equipment. The aim was to investigate the difference in pulverised biomass reactivity and minimum explosible concentration, MEC. The reactivity was determined from the initial rate of pressure rise prior to the vent bursting in the Hartmann equipment. The flame speed in the vertical tube of the Hartmann equipment was also determined as a reactivity parameter. Steam exploded milled pellets (BP) was found to have a higher reactivity, leaner MEC and higher flame speed, than the raw pine. The enhanced reactivity of BP was due to the greater proportion of fine particles. Both raw pine and BP had a high reactivity for very rich mixtures and this was due to the gasification reactions in rich mixtures that released CO and hydrogen. The very lean MEC for both biomass also may have been enhanced by hydrogen release

Energy, Exergy and Friction Factor Analysis of Nanofluid as a Coolant for Electronics

Power dissipation, chip power consumption, and heat flux in electronic devices have been steadily increasing over the past decade, creating a need for improved methods of cooling them. Nanofluids can be used as coolant for these electronics to improve their thermal performance. This paper presents an analysis of the energy, exergy, and frictional efficiencies of different nanofluids that are used to cool electronics. This was done by creating an analytical model in which different nanofluids flowed (at 0.5 m/s) through a rectangular-shaped microchannel heat sink (with a constant heat flux). These different nanofluids consisted of water as a base fluid, with 0.4 to 2.0 vol % of copper oxide (CuO), aluminum oxide (Al2O3), and titanium dioxide (TiO2) nanoparticles. The results generally showed that thermal resistance decreases as the volume fraction of nanoparticles is increased. The CuO-water nanofluid was found to be the best coolant in terms of both minimizing thermal resistance and maximizing the pressure reduction. The energy efficiency of the heat sink increases as the volume fraction of nanoparticles increases. A maximum energy efficiency of 98.9% was obtained using the CuO-water nanofluid (at 2.0 vol %). The Al2O3-water and TiO2-water nanofluids (also at 2.0 vol %) produced a maximum energy efficiency of 77.5% and 68.4%, respectively. The lowest exergy losses were: 19.2, 20.9, and 25.1 W for TiO2-water, Al2O3-water, and CuO-water nanofluids (all at 0.4 vol %), respectively. The dimensionless friction factor was reduced as the nanoparticle volume concentration increased. Also, the pumping power increased (to a high of 0.0173 W) as the mass flow rate increased