HYSYS中k值是什么意思？代表什么？

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小柳

K-Value

The wall is called a ‘thermal object’ above because its U-value can be calculated from each of the components it is made of.

Each component, say the outer skin of brickwork in a cavity wall, will let heat pass through it based on two factors:
•        its thermal conductivity;
•        how thick it is.

Thickness matters because the thicker something is, the slower heat will pass through it – a thick jumper keeps heat in better than a thin jumper.

The thermal conductivity is a measure of how easily heat passes through the material and is called the k-value (little ‘k’ which helps stop confusing it with big ‘K’ degrees Kelvin!). k-value is measured in W/mK. Thermal conductivity is an inherent property of a material, like stiffness or density.

The U-value of a single component is given by the formula U = k / l, conductivity divided by thickness (in thermal calcs the thickness always seems to be represented by ‘l’, not ‘t’ as you might expect).

So that outer skin of brickwork, on its own, might have a thermal conductivity, k of 0.84 W/mK and a thickness of 100mm (or 0.10m), so U = 0.84/0.10 = 8.4 W/m2K – yes, worse than a single-glazed window!

Typical limits of k-value in building materials are a maximum of around 2.0 W/mK for concrete and sandstone to a minimum of about 0.025 W/mK for polyisocyanurate (PIR) foam insulation.

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pl283600780

应该是平衡常数吧

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pl283600780 发表于 2014-7-26 12:07
应该是平衡常数吧

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