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% H<sub>2</sub> 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.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:599745 |
| Date | January 2007 |
| Creators | Grimwood, Claire Jennifer |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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