Rankine scale

The Rankine scale (/ˈræŋkɪn/) is an absolute scale of thermodynamic temperature named after the Glasgow University engineer and physicist Macquorn Rankine, who proposed it in 1859.[1] Just like the Kelvin scale, which was first proposed in 1848,[1] Zero on the Rankine scales is absolute zero, but a temperature difference of one Rankine degree is defined as equal to one Fahrenheit degree, rather than the Celsius degree used on the Kelvin scale. Thus, a temperature of 0 K (−273.15 °C; −459.67 °F) is equal to 0 °R, and a temperature of −458.67 °F equal to 1 °R. The Rankine scale is used in engineering systems where heat computations are done using degrees Fahrenheit.

This article is about the temperature scale. For the idealized thermodynamic cycle for a steam engine, see Rankine cycle. For the scale measuring recovery after stroke, see Modified Rankin Scale.
Rankine
Unit ofTemperature
Symbol°R, °Ra
Named afterMacquorn Rankine

The symbol for degrees Rankine is °R[2] (or °Ra if necessary to distinguish it from the Rømer and Réaumur scales). By analogy with the SI unit, the kelvin, some authors term the unit rankine, omitting the degree symbol.[3][4]

Some important temperatures relating the Rankine scale to other temperature scales are shown in the table below.

Temperature Kelvin Celsius Fahrenheit Rankine
Absolute zero 0 K −273.15 °C −459.67 °F 0 °R
Freezing point of brine[lower-alpha 1] 255.37 K −17.78 °C 0 °F 459.67 °R
Freezing point of water[lower-alpha 2] 273.15 K 0 °C 32 °F 491.67 °R
Boiling point of water[lower-alpha 3] 373.1339 K 99.9839 °C 211.97102 °F 671.64102 °R

See also

Notes
  1. The freezing point of brine is the zero point of Fahrenheit scale, old definition
  2. The ice point of purified water has been measured to be 0.000089(10) degrees Celsius – see Magnum 1995
  3. For Vienna Standard Mean Ocean Water at one standard atmosphere (101.325 kPa) when calibrated solely per the two-point definition of thermodynamic temperature. Older definitions of the Celsius scale once defined the boiling point of water under one standard atmosphere as being precisely 100 °C. However, the current definition results in a boiling point that is actually 16.1 mK less. For more about the actual boiling point of water, see VSMOW in temperature measurement.

References
  1. "Rankine". Merriam-Webster Dictionary. Retrieved 2019-11-07.
  2. B.8 Factors for Units Listed Alphabetically from Thompson & Taylor 2008, pp. 45–69
  3. Pauken 2011, p. 20
  4. Balmer 2011, p. 10

Sources
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