Rankine

The Rankine scale is an absolute temperature scale named after Scottish engineer William John Macquorn Rankine, who developed it in the 19th century. It uses the same degree increments as the Fahrenheit scale but starts at absolute zero, making it the absolute equivalent of Fahrenheit.

The Rankine scale has 0°R at absolute zero, with water freezing at 491.67°R and boiling at 671.67°R at standard atmospheric pressure. The scale provides 180 degrees between freezing and boiling points, just like Fahrenheit, but with an absolute zero reference.

Rankine was designed to provide an absolute temperature scale that would be familiar to engineers and scientists working with Fahrenheit units. It combines the absolute nature of Kelvin with the degree increments of Fahrenheit.

Rankine is primarily used in engineering applications, particularly in the United States, where it provides an absolute temperature scale that works well with Fahrenheit-based calculations and equipment. It is commonly used in thermodynamics and heat transfer calculations.

In industrial applications, Rankine is used for power plant design, HVAC systems, and thermal engineering where absolute temperature measurements are required but Fahrenheit units are preferred for practical calculations.

In thermodynamics and heat transfer, Rankine is used for calculations involving absolute temperature, such as the ideal gas law, entropy calculations, and efficiency analyses. It is particularly useful in power generation and refrigeration cycles.

In aerospace engineering, Rankine is sometimes used for high-temperature applications and propulsion systems where absolute temperature measurements are critical. It is also used in certain specialized chemical engineering processes.

The Rankine scale is defined as °R = °F + 459.67, where 459.67 is the offset between absolute zero and the Fahrenheit zero point. This relationship makes it easy to convert between Fahrenheit and Rankine for engineering calculations.

While Rankine is not part of the International System of Units (SI), it is recognized in the United States and is used in certain engineering disciplines where absolute temperature measurements are required but Fahrenheit units are preferred.