No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

A high throughput methodology for the synthesis and screening of hydrogen storage materials has been developed. Synthesis of these materials is achieved through the combination of a high throughput physical deposition method and a hydrogen source. A screening methodology has been developed which is based on temperature programmed desorption from an array of micro mechanical electrical systems (MEMS) hotplates. The heating characteristics of these hotplates have been determined under both vacuum and ambient conditions. To achieve this, the infra red and electrical properties of the devices are characterised. Temperature programmed desorption results for the magnesium hybride thin film system are presented. The hydrogen storage characteristics of this material are determined, including information about the peak temperature, onset temperature, gravimetric capacity and activation energy of the decomposition process. The magnesium nickel binary system was selected to demonstrate the capabilities of this novel technique, since the system is well characterised in the literature. Screening results for this material are presented, and found to compare well to the literature values. Peak temperatures are found to exhibit the expected trend, and the gravimetric capacities are found to agree with both the existing literature, and the modelled phases. The kinetics of the observed decomposition channels are also determined using this screening technique. The high throughput nature of this work enabled the determination of the effective activation energy across a wide compositional range. The effective activation energies determined are found to agree with the existing literature; in addition a non activated, catalytic decomposition process is identified. Initial results are presented on the Mg-B, B-Ti and Mg-Ti binary systems. These are indicative of the application of this methodology to synthesise and characterise a wider range of potential hydrogen storage materials.

No description available.

Oxygen-carriers were prepared by supporting CuO on Al₂O₃, using three methods: mechanical-mixing, wet-impregnation and co-precipitation. The co-precipitated particles (containing 82.5 wt.% CuO) were best; they managed to maintain full conversion for 20 cycles of reduction (either in 2.6 vol% CO or 2.6 vol% H₂, or mixtures thereof) and re-oxidation in a fluidised bed. The kinetics of the reduction (by CO and H₂) and oxidation (by O₂) of the co-precipitated particles were fast and controlled primarily by external mass transfer from the bulk gas to the external surface of the particles. At high temperatures (between 700 and 900°C), the reduction and oxidation took place <i>via</i> the intermediate of Cu₂O: the reactions of the particles also followed the shrinking core mechanism. At low temperatures (~ 300°C), no shrinking core mechanism was detected. The particles are surprisingly reactive at temperatures as low as 250°C; the reduction proceeded directly to Cu and was controlled by the nucleation of cooper atoms to form bigger nuclei, which subsequently initiated the reaction between CuO and CO or H₂. To gauge the impact of hydrocarbons present in the gasifier gases, the reaction between the co-precipitated particles and CH₄ and C₃H₈was studied. It was confirmed, using XRD, that these gases also reduce the oxide fully to Cu. The formation of carbon was observed. It was catalysed by the reduced carrier when CH₄ was the fuel. With propane, the decomposition to carbon was dominated by reactions in the homogeneous gas phase and appeared to be unaffected, substantially, by the presence of reduced oxygen-carrier. When steam or CO₂ was added to the feed gases, the formation of carbon was totally suppressed for CH₄ and partially suppressed for C₃H_8.

The need of Rolls-Royce Fuel Cell Systems for an efficient and practical design of off-gas combustor for their new power system stimulated research into the possibilities of a low pressure drop, low emissions burner. After preliminary analysis of different combustor designs that might suit the imposed constraints, the micromixing burner design was chosen and explored. It has been found to meet all imposed requirements. The burner of the fuel cell system is fed a fuel gas consisting of natural gas reformate with 10-20% H₂ and 5-10% CO and an oxidizer with 5-20% oxygen. These gases enter the burner at around 1110-1170 K and 7 bar. The prototype micromixing burners tested in this dissertation consisted of interspaced fuel and oxidizer slots of around 109 mm wide. Several of the prototypes used angle corrugated strips in the slots which were aimed at promoting mixing through shear. Carbon monoxide emissions also showed different behaviour at atmospheric and high temperature. This was due to the effect of temperature quenching of the flame front products by the unreacted oxidizer stream. Contrary to expectations, it was found that mixing was not promoted through the use of angled corrugated strips at atmospheric conditions; however, a lack of mixing is desirable at low equivalence ratios when the oxidiser temperature was low. When the oxidizer temperature was increased past 1100 K, the effect of mixing on carbon monoxide emissions became less important as quenching was less likely.