Owens Corning FOAMGLAS® Insulation said that the emissivity of an insulation system “has a large influence on process control, condensation control and personnel protection”.
It added: “The wide range of service temperatures and requirements for industrial applications create unique challenges for designers when specifying the correct insulation system.”
Emissivity is defined as the effectiveness of a surface of a material in emitting energy as thermal radiation. The emissivity (ε) of a surface material is measured on a scale where a reflective material that is not emitting any radiant energy is rated at 0, and a nonreflective material that is emitting all of its radiant energy is rated at 1.
In real world applications, both of these limits are impractical to attain, and measurements fall between these two extremes. A shiny piece of polished metal will have a low emissivity of around 0.07 whereas that same piece of metal, with a roughened and oxidised surface, will have a high emissivity of 0.80. If both materials are placed right next to each other, they could have the same kinetic temperature but different apparent radiant temperatures when measured with a thermal radiometer because their emissivity is different.
Owens said: “When looking at insulation systems, one can state the emissivity of the insulation material and the emissivity of the jacketing or coating should be considered when specifying the insulation system. The emissivity can affect heat loss or gain, on hot and/or cold piping systems. As a result, when designing a system, one should consider how emissivity affects personnel protection, process control and condensation control.”
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