Rankine scale: Difference between revisions
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Revision as of 04:35, 6 April 2022
| Rankine | |
|---|---|
| Unit of | Temperature |
| Symbol | °R, °Ra |
| Named after | Macquorn Rankine |
| Conversions | |
| x °R in ... | ... corresponds to ... |
| SI base units | 5/9 x K |
| SI units | 5/9 x − 273.15 °C |
| Imperial/US units | x − 459.67 °F |
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] Similar to the Kelvin scale, which was first proposed in 1848,[1] zero on the Rankine scale is absolute zero, but a temperature difference of one Rankine degree (°R or °Ra) is defined as equal to one Fahrenheit degree, rather than the Celsius degree used on the Kelvin scale. 1 °R = 5⁄9 K. Thus, a temperature of 0 K (−273.15 °C; −459.67 °F) is equal to 0 °R.
The Rankine scale is still used in engineering systems where heat computations are done using degrees Fahrenheit.[citation needed]
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[a] | 255.37 K | −17.78 °C | 0 °F[citation needed] | 459.67 °R |
| Freezing point of water[b] | 273.15 K | 0 °C | 32 °F | 491.67 °R |
| Boiling point of water[c] | 373.1339 K | 99.9839 °C | 211.97102 °F | 671.64102 °R |
See also
Notes
- ^ The freezing point of brine is the zero point of Fahrenheit scale, old definition[citation needed]
- ^ 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
- ^ a b "Rankine". Merriam-Webster.com Dictionary. Merriam-Webster. 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.
- 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.
- Pauken, Michael (2011). Thermodynamics For Dummies. Indianapolis: Wiley Publishing Inc. ISBN 978-1-118-00291-9.
- 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.
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