A flame in which you can stick your fingers without burning them could revolutionise the way buildings are heated. 'Cool flame', a phenomenon first noticed in 1805, is generated not by combustion but by oxidation.
Cool flame can develop in the vapours of organic chemicals such as alcohols and ethers, explains John Griffiths, emeritus professor of combustion at the University of Leeds. It forms spontaneously when a mix of air and vapour reaches 250 ¦C. Though a cool flame releases some heat, says Griffiths, generally its temperature stops rising at about 500 ¦C.
The BioFlam research project is developing an oil-fired boiler using cool flame's ability to stabilise at such a low temperature, capitalising on work done at the non-profit-making Oil and Heat Institute in Aachen, Germany.
The project consortium, headed by Franz von Issendorff - head of the combustion group, Institute of Fluid Mechanics at the University of Erlangen-Nuremberg, Germany - includes OMV, the Austrian MineralOil Company, and Hovalwerk AG, a boiler manufacturer in Lichtenstein.
The project is funded by the European Union.
The BioFlam boiler uses cool flame to heat vaporised, not atomised, fuel oil, and a porous-ceramic burner that conducts very little heat.
Compared to conventional liquid-fuel boilers, BioFlam boilers are more compact,10 per cent more energy efficient, have half the N 2O (nitrous oxide) and lower CO 2 emissions, and are compatible with renewable liquid fuels such as FAME (fatty-acid methyl ester).
'Their main advantage is that you can modulate the whole system, ' says von Issendorff. 'You can run the boiler and burner all the time; you don't have to start and stop them, just adjust the heat produced to what the demand is. It's starting and stopping a burner that creates emissions; the porous burner reduces emissions to almost nothing.' The project begins field tests this autumn and expects to have results next March. Venture capital-financed spin-off Promeos hopes to put BioFlam boilers into production by 2007, costing roughly the same as conventional boilers.
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