Wavelength converter increases energy efficiency in heating thin and "transparent" materials

Citation

(2001), "Wavelength converter increases energy efficiency in heating thin and "transparent" materials", Pigment & Resin Technology, Vol. 30 No. 1. https://doi.org/10.1108/prt.2001.12930aaf.001

Wavelength converter increases energy efficiency in heating thin and "transparent" materials

Wavelength converter increases energy efficiency in heating thin and "transparent" materialsKeywords: Heraeus Noblelight, Heating, Drying, Infra-red

A patented system for converting the wavelength of short wave and medium wave infra-red radiation into radiation of a longer wavelength and then reflecting it back through products to be heated is now available from Heraeus Noblelight, of Bromborough, UK. According to Heraeus, the new system has been shown to provide significant efficiency improvements and faster process times when used in the heating and drying of thin materials in the plastics, textiles and paper industries.

Infra-red (IR) heating finds application in virtually every industry sector. All infra-red emitters produce infra-red radiation at different wavelengths but are classified according to their peak wavelength into short wave, medium wave and long wave emitters. When IR is used for heating an object, it is found that some of the radiation is reflected from the object's surface, some is absorbed by the object, generating the heat, and some passes through the object. Generally speaking, long wave and, especially, medium wave radiation are best absorbed, while short wave radiation is the most penetrative. As the thickness of the object to be heated decreases, so the fraction of radiation which passes though the body increases, with the result that an increasing amount of effective heating energy is lost.

The new wavelength converter from Heraeus consists of a plate of ceramic fibres, which acts as a reflector in combination with a conventional IR module. The ceramic fibres are said to absorb around 95 per cent of any short wave radiation which passes through the product to be heated. This energy absorption reportedly heats the plate surface to an operating temperature of 500°C-600°C within seconds, so that the converter acts as a fast response secondary emitter, reflecting long and medium wave radiation back into the product.

Apart from allowing significant energy savings, the wavelength converter can also be used to reduce process times. It is reported that in recent tests the rate of heating of a 1mm thick glass plate was increased by a factor of 3 when a converter was used with conventional short wave emitters.

Heraeus believes that the new system will find application with all types of infra-red equipment. The company considers that its ability to heat up and cool down quickly makes it ideal for response, switched equipment and it can be combined with different IR emitters to optimise particular finishing processes. It is said to be easy to install with a small space requirement, it can be retrofitted to existing installations and it offers low capital and running costs.

Details available from Heraeus Noblelight Ltd. Tel: +44 (0) 151 343 0545; Fax: +44 (0) 151 343 9883.