The rankine scale It is an absolute scale of thermodynamic temperature in which all its values are positive, since they are referred to absolute zero; the lowest theoretical temperature that a body can reach, but experimentally and thermodynamically impossible to achieve.
It was proposed in 1859 by the Scottish engineer William John MacQuorn Rankine (bottom image), eleven years after William Thomson (Lord Kelvin, 1848) published his absolute temperature scale as a function of degrees Celsius, ° C.
Absolute zero on the kelvin scale has a value of -273.15 ° C. The rest of the temperatures on this scale are obtained by adding 273.15 to the value of the temperatures in degrees Celsius (or better known as centigrade)..
The Rankine scale is related to degrees Fahrenheit. Therefore, the absolute zero value for this scale is expressed in degrees Fahrenheit; this is -459.67ºF. Thus, to obtain the other temperatures, it is enough to add 459.67 to the value of the temperatures (° R = ° F + 459.67).
Rankine degrees came to be used in engineering activities in the United States and England. However, today its use is practically extinct.
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Andrés Celsius published his scale in 1742, indicating the boiling temperature of water as 0 ºC and its freezing temperature as 100 ºC. But Jean-Pierre Christin (1743) and Carlos Linneo (1745), placed the temperature scale in reverse, as it is known today.
The Fahrenheit scale was proposed by Daniel Gabriel Fahrenheit in 1724. The scale establishes a temperature of 32ºF as the freezing point of water, and the boiling point of water 212ºF..
Fahrenheit noted that a mixture of water, ice, and an ammonium salt had a temperature of 0ºF; while a mixture of water and ice, it had a temperature of 32ºF.
Rankine degrees are also often expressed as ° R or simply R units. However, for Kelvin degrees, they are in fact often referred to solely as Kelvin, and are written K and not ° K.
Even the National Institute of Standards and Technology recommends not using the degree symbol when using the Rankine temperature scale in NIST publications..
Radiation heat transfer, entropy change, Carnot heat engine thermal efficiency, and heat pump coefficient of performance require the use of absolute temperature in Rankine degrees when working on the American Engineering System..
In some engineering fields in the United States, they measure thermodynamic temperature using the Rankine temperature scale; However, throughout the scientific world, thermodynamic temperature is measured using the Kelvin scale..
It has even been pointed out that the Rankine temperature scale is used mainly because of its relationship with the Fahrenheit temperature scale..
The Kelvin and Rankine temperature scales have absolute zero as their starting point. But what is sneaky zero?
Absolute zero is the lowest temperature that can possibly be reached. It is said that the internal energy of the system reaches its lowest level, lacking the particles of movement; all its vibrations and displacements would be frozen.
According to the third law of thermodynamics, absolute zero is an unattainable limit.
The temperature closest to absolute zero is 5 ∙ 10-10 K above absolute zero, obtained in an MIT laboratory in 2003, by cooling a gas in a magnetic field.
Who was William John Macquorn Rankine (1820-1872)? He was one of the pioneers in the study of thermodynamics. Developed a complete theory on the steam engine and heat engines, as well as on thermal energy.
Born in Edinburgh, Rankine was educated at Edinburgh University. He worked as a civil engineer and published articles on practical engineering topics, and later on molecular physics, as well as on thermodynamics..
In 1855 he was appointed President of the Chair of Civil and Mechanical Engineering at the University of Glasgow.
He wrote more than 150 scientific articles and manuals, as well as books for the use of his students. He was elected to the Royal Society in 1853 and was the first president of the Scottish Institution of Engineers.
In addition to his immense scientific and academic activity, Rankine was very fond of music, both as a performer and as a composer. Thus, he composed a song called "The Three Foot Rule", where he defends the British tradition of his measures threatened by the invasion of the centesimal system.
[º C] = ([ºR] - 491.67) ∙ 5/9
The value 491.67 is equal to 459.67 (Rankine's absolute zero) plus 32ºF (freezing temperature of water). And 5/9 is a conversion factor from degrees Celsius to degrees Rankine or Fahrenheit; since, in these temperature scales, 100 ºC is equivalent to 180 ° R or ºF.
[ºF] = [° R] - 459.67
[K] = [ºR] ∙ 5/9
-[ºR] = ([ºC] + 273.15) ∙ 9/5
The value 273.15 is absolute zero on the Kelvin temperature scale. And 9/5 is a conversion factor, since 180 ºF or ºR is equivalent to 100 ºC.
-[ºR] = [ºF] + 459.67
-[ºR] = [K] ∙ 9/5
-Kelvin 0 (by definition).
-Celsius -273.15 ºC.
-Fahrenheit -459.67 ºF.
-Rankine 0 ºR (by definition).
(Zero point of the Fahrenheit Scale)
-Kelvin: 255.37 K.
-Celsius: -17.78 ºC.
-Fahrenheit: 0º F.
-Rankine: 459.67 ºR.
-Kelvin: 273.15 K.
-Celsius: 0 ºC.
-Fahrenheit: 32ºF.
-Rankine: 459.67 ºR.
-Kelvin: 273.16 K.
-Celsius: 0.01 ºC.
-Fahrenheit: 32,018ºF.
-Rankine: 491,688 ºR.
-Kelvin: 373.1339 K.
-Celsius: 99.9839 ºC.
-Fahrenheit: 211.97102ºF.
-Rankine: 671.64102 ºR.
-Kelvin: 310 K.
-Celsius: 37ºC.
-Fahrenheit: 98º F.
-Rankine: 558 ºR.
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