Rankine scale
Absolute temperature scale using Fahrenheit degrees
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The Rankine scale (/ˈræŋkɪn/ RANG-kin) is an absolute scale of thermodynamic temperature named after the University of Glasgow engineer and physicist W. J. M. 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. In converting from kelvin to degrees Rankine, 1 °R = 5/9 K or 1 K = 1.8 °R. A temperature of 0 K (−273.15 °C; −459.67 °F) is equal to 0 °R.[2][3]
| Rankine | |
|---|---|
| Unit of | Temperature |
| Symbol | °R, °Ra |
| Named after | W. J. M. Rankine |
| Conversions | |
| 491.67 °R in ... | ... corresponds to ... |
| Kelvin | 273.15 K |
| Celsius | 0.00 °C |
| Fahrenheit | 32.00 °F |
Usage
The Rankine scale is used in engineering systems where heat computations are done using degrees Fahrenheit.[4][better source 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 kelvin, some authors term the unit Rankine, omitting the degree symbol.[5][6]
Some temperatures relating the Rankine scale to other temperature scales are shown in the table below.
| Scale | ||||||
|---|---|---|---|---|---|---|
| Kelvin | Rankine | Fahrenheit | Celsius | Réaumur | ||
| Temperature | Absolute zero | 0 K | 0.00 °R | −459.67 °F | −273.15 °C | −218.52 °Ré |
| Freezing point of brine[a] | 255.37 K | 459.67 °R | 0.00 °F | −17.78 °C | −14.22 °Ré | |
| Freezing point of water[b] | 273.15 K | 491.67 °R | 32.00 °F | 0.00 °C | 0 °Ré | |
| Boiling point of water[c] | 373.1339 K | 671.641 °R | 211.971 °F | 99.9839 °C | 79.9871 °Ré | |
See also
Notes
- 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.[citation needed]
