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Title:
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High efficiency radiant burners greatly enhance heat transfer
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Author(s):
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Published by:
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Publication date:
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ECN
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1995
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ECN report number:
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Document type:
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ECN-I--95-058
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Other
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Number of pages:
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Full text:
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17
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Download PDF
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Abstract:
Transfer of heat by thermal radiation usually is more efficient thanconvective heat transfer. This can result in higher productivity and/or lower
operating costs. Apart from this, radiative heat transfer needs no direct
contact between product and hot combustion gases. For this reason radiation
can also improve product quality. For several years ECN has been developing
ceramic foam burners by order of the Netherlands Agency for Energy and the
Environment (Novem). Apart from the standard surface burner ECN develops new
types of radiant burners. Whereas a normal surface burner radiates 25% of the
energy input in the best case, the other burners can reach up to 70%.
However, not only the radiant intensity incident on a product is important.
Only if the radiation is actually absorbed in the product heat transfer is
realised. This can be improved by matching the emission spectrum of the
burner with the absorption spectrum of the product. A spectro-radiometer is
used to develop and optimise coatings for radiant burners. Some experimental
results of the multi-layer burner (100-250 kW/m2 radiant output, about 50%
efficiency) and multi-stage radiant burner (50- 100 kW/m2 radiant output,
about 70% efficiency) will be discussed. These include radiant output for
several cases. Some numerical results will be presented to help understanding
the different processes going on with a radiant burner. 8 figs., 5 refs.
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