ECN publication
High efficiency radiant burners greatly enhance heat transfer
Published by: Publication date:
ECN 1995
ECN report number: Document type:
ECN-I--95-058 Other
Number of pages: Full text:
17 Download PDF  

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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