Rankine scale
The Rankine scale (/ˈræŋkɪn/) is an absolute scale of thermodynamic temperature named after the Glasgow University engineer and physicist William John Macquorn Rankine, who proposed it in 1859 (the Kelvin scale was first proposed in 1848).[1] It is used in engineering systems where heat computations are done using degrees Fahrenheit.
| Rankine | |
|---|---|
| Unit of | Temperature |
| Symbol | °R, °Ra |
| Named after | William John Macquorn 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] Zero on both the Kelvin and 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.
Some important temperatures relating the Rankine scale to other temperature scales are shown in the table below.
| Kelvin | Celsius | Fahrenheit | Rankine | |
|---|---|---|---|---|
| Absolute zero (by definition) |
0 K | −273.15 °C | −459.67 °F | 0 °R |
| Freezing point of brine (zero point of Fahrenheit scale, old definition) |
255.37 K | −17.78 °C | 0 °F | 459.67 °R |
| Freezing point of water[Note 1] | 273.15 K | 0 °C | 32 °F | 491.67 °R |
| Boiling point of water[Note 2] | 373.1339 K | 99.9839 °C | 211.97102 °F | 671.64102 °R |
See also
- Comparison of temperature scales
Notes
- The ice point of purified water has been measured to be 0.000089(10) degrees Celsius – see Magnum 1995
- 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
- "Rankine". Merriam-Webster Dictionary. Retrieved 2019-11-07.
- B.8 Factors for Units Listed Alphabetically from Thompson & Taylor 2008, pp. 45–69
- Pauken 2011, p. 20
- Balmer 2011, p. 10
Sources
- Balmer, Robert (2011). Modern Engineering Thermodynamics. Oxford: Elsevier Inc. ISBN 978-0-12-374996-3.CS1 maint: ref=harv (link)
- Magnum, B.W. (June 1995). "Reproducibility of the Temperature of the Ice Point in Routine Measurements" (PDF). Nist Technical Note. 1411. Archived from the original (PDF) on 2007-03-07. Retrieved 2007-02-11.CS1 maint: ref=harv (link)
- Pauken, Michael (2011). Thermodynamics For Dummies. Indianapolis: Wiley Publishing Inc. ISBN 978-1-118-00291-9.CS1 maint: ref=harv (link)
- Thompson, Ambler; Taylor, Barry N. (2008). "Guide for the use of the International System of Units (SI)" (PDF). doi:10.6028/nist.sp.811e2008. Retrieved 2019-11-07.CS1 maint: ref=harv (link)
