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The therm (symbol, thm) is a non-SI unit of heat energy equal to 100,000 British thermal units (BTU), [1] and approximately 105 megajoules, 29.3 kilowatt-hours, 25,200 kilocalories and 25.2 thermies. One therm is the energy content of approximately 100 cubic feet (2.83 cubic metres) of natural gas at standard temperature and pressure .
The Btu should not be confused with the Board of Trade Unit (BTU), an obsolete UK synonym for kilowatt hour (1 kW⋅h or 3,412 Btu). The Btu is often used to express the conversion-efficiency of heat into electrical energy in power plants. Figures are quoted in terms of the quantity of heat in Btu required to generate 1 kW⋅h of electrical energy.
In the United States, U-value is expressed as British thermal units (Btu) per hour-square feet-degrees Fahrenheit: Btu/(h⋅ft 2 ⋅°F) Within this article, U-values are expressed in SI unless otherwise noted. To convert from SI to US customary values, divide by 5.678. [1]
The BTU was originally defined so that the average specific heat capacity of water would be 1 BTU/lb⋅°F. [19] Note the value's similarity to that of the calorie - 4187 J/kg⋅°C ≈ 4184 J/kg⋅°C (~.07%) - as they are essentially measuring the same energy, using water as a basis reference, scaled to their systems' respective lbs and °F ...
These thermal greases have low electrical conductivity and their volume resistivities are 1.5⋅10 15, 1.8⋅10 11, and 9.9⋅10 9 Ω⋅cm for 860, 8616 and 8617 respectively. The thermal grease 860 is a silicone oil with a Zinc Oxide filler and 8616 and 8617 are synthetic oils with various fillers including Aluminum Oxide and Boron Nitride.
The energy content of ethanol is 76,100 BTU/US gal (5.89 kilowatt-hours per litre), compared to 114,100 BTU/US gal (8.83 kWh/L) for gasoline. (see chart above) A flex-fuel vehicle will experience about 76% of the fuel mileage MPG when using E85 (85% ethanol) products as compared to 100% gasoline.
[10] since there is typically a 10% difference between the two methods for a power plant burning natural gas. For simply benchmarking part of a reaction the LHV may be appropriate, but HHV should be used for overall energy efficiency calculations if only to avoid confusion, and in any case, the value or convention should be clearly stated.
The shrubs usually grow 3–8 metres (10–26 feet) tall. The nut is round, in contrast to the longer filbert nut. Common hazel is native to Europe and Western Asia. The species is mainly cultivated for its nuts. The name 'hazelnut' applies to the nuts of any species in the genus Corylus, but in commercial contexts usually describes C. avellana.