Rankine explained

The Rankine temperature scale is an absolute temperature scale that uses degrees Fahrenheit for its units. Zero on the Rankine scale represents absolute zero, the point at which molecular energy is minimal. This scale is primarily used in engineering fields, particularly in the United States, where calculations involving thermodynamic temperature are conducted using Fahrenheit-based measurements.

Symbol

The symbol for degrees Rankine is °R. To avoid confusion with other scales like Réaumur, the notation °Ra is sometimes used.

Comparison with Other Temperature Scales

The Rankine scale parallels the Kelvin scale but is based on Fahrenheit degrees instead of Celsius. While both scales start at absolute zero, a change of one degree Rankine is equivalent to one degree Fahrenheit, whereas a change of one Kelvin corresponds to one degree Celsius. This relationship simplifies conversions between Fahrenheit and absolute temperatures in engineering contexts.

Applications and Uses

The Rankine scale is utilized in various engineering applications, especially in the United States, including:

• Thermodynamics: Used for calculations involving heat and energy where Fahrenheit measurements are standard.
• Aerospace Engineering: Applied in the analysis of propulsion systems and thermodynamic cycles.
• Power Plants: Employed in the study and design of steam and gas turbines operating with Fahrenheit-based systems.

Origin

The Rankine scale was developed in 1859 by Scottish engineer and physicist William John Macquorn Rankine. He was a prominent figure in the field of thermodynamics and sought to create an absolute temperature scale analogous to Kelvin but based on Fahrenheit degrees.

FAQs

How do you convert Fahrenheit to Rankine?

To convert a temperature from Fahrenheit to Rankine, add 459.67 to the Fahrenheit temperature. For example, 32°F + 459.67 = 491.67°R.

What is absolute zero in Rankine?

Absolute zero is 0°R on the Rankine scale, equivalent to -459.67°F or 0K.

Why was the Rankine scale created?

The Rankine scale was created to provide an absolute temperature scale that aligns with the Fahrenheit system, facilitating thermodynamic calculations in engineering contexts where Fahrenheit is used.

How does Rankine compare to Kelvin?

Both Rankine and Kelvin are absolute temperature scales starting at absolute zero. However, Rankine uses Fahrenheit degree increments, while Kelvin uses Celsius degree increments. One degree Rankine is equivalent to one degree Fahrenheit, making it suitable for use with the Fahrenheit-based system.