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unit of measure: the base unit | the supplementary unit | the derived unit

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unit

Superficial thermal resistance

Definition

The superficial thermal resistance is the physical measure, which defines the ability to prevent heat transfer through contact borders of two media with different temperatures.

1 square metre kelvin per watt is the superficial thermal resistance corresponding to a surface heat flow density of 1 watt per square meter for temperature difference of 1 kelvin.

It is the thermal resistance of unit area of a material. In terms of insulation, it is measured by the R-value.

 

system of units:   SI;
statute:   derived unit;
name the value:   κ;
unit name:   square metre kelvin per watt;
symbol unit:   m²·K/W;
relationship of definition:   κ = τ/q;
dimension:   L-1 T3 Θ;
expression in other units:   clo, °F·h·ft²/Btu(IT);

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Units of measurement

namesymbol value in SI unit:
m²·K/W
note
1 clo ≈ 0.155 
1 degree fahrenheit hour square foot per BtuIT °F·h·ft²/BtuIT)≈ 0.176 110 2(1), (2)
1 degree fahrenheit hour square foot per Btuth °F·h·ft²/Btuth)≈ 0.176 228(1), (3)
1 degree fahrenheit second square foot per BtuIT °F·s·ft²/BtuIT)≈ 4.891 9 × 10-5(1), (2)
1 degree fahrenheit second square foot per Btuth °F·s·ft²/Btuth)≈ 4.895 2 × 10-5(1), (3)

Note:

(1) - Btu - British thermal unit;

(2) - IT - common unit, international;

(3) - th - thermochemical unit;