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R-value R-value at 1 m (m 2 ·K/W) (cm) (in) (m 2 ·K/W) (ft 2 ·°F·h/BTU) Vacuum insulated panel: 2.54: 1 5.28–8.8: 14–66 [1] 208–346 Silica aerogel: 2.54: 1 1.76: 10.3 [2] 69 Polyurethane rigid panel (CFC/HCFC-expanded) initial 2.54: 1 1.23–1.41: 7–8: 48–56 Polyurethane rigid panel (CFC/HCFC-expanded) aged 5–10 years 2.54: 1 1 ...
The lowest-density silica nanofoam weighs 1,000 g/m 3, [59] which is the evacuated version of the record-aerogel of 1,900 g/m 3. [60] The density of air is 1,200 g/m 3 (at 20 °C and 1 atm). [61] The silica solidifies into three-dimensional, intertwined clusters that make up only 3% of the volume. Conduction through the solid is therefore very low.
An average R-value is 1/(average U-value). For example, if 10% of the area is 4 inches of softwood (R-value 5.6) and 90% is 2 inches of silica aerogel (R-value 20), the area-weighted U-value is 0.1/5.6 + 0.9/20 ≈ 0.0629 and the weighted R-value is 1/0.0629 ≈ 15.9.
It quantifies how effectively a material can resist the transfer of heat through conduction, convection, and radiation. It has the units square metre kelvins per watt (m 2 ⋅K/W) in SI units or square foot degree Fahrenheit–hours per British thermal unit (ft 2 ⋅°F⋅h/Btu) in imperial units. The higher the thermal insulance, the better a ...
Based on a typical k-value of 0.007 W/(m·K), the R-value of a typical 25-millimetre-thick (1 in) VIP would be 3.5 m 2 ·K/W (20 h·ft 2 ·°F/BTU). To provide the same R-value, 154 millimetres (6 in) of rockwool or 84 millimetres (3 in) of rigid polyurethane foam panel would be required.
The Lankford coefficient (also called Lankford value, R-value, or plastic strain ratio) [1] is a measure of the plastic anisotropy of a rolled sheet metal. This scalar quantity is used extensively as an indicator of the formability of recrystallized low-carbon steel sheets. [2]
SEAgel is made of agar, a carbohydrate material that comes from kelp and red algae, and has a density of 200 mg/cm 3. [1] SEAgel can be made lighter than air using hydrogen, causing it to float or hang in the air. It insulates against temperature, noise, and electric current.
Aerographene or graphene aerogel is the least dense solid known to exist, at 160 g/m 3 (0.0100 lb/cu ft; 0.16 mg/cm 3; 4.3 oz/cu yd). [1] The material reportedly can be produced at the scale of cubic meters.