A ton of refrigeration (TR or TOR), also called a refrigeration ton (RT), is a
unit of
power used in some countries (especially in North America) to describe the heat-extraction rate of
refrigeration
Refrigeration is any of various types of cooling of a space, substance, or system to lower and/or maintain its temperature below the ambient one (while the removed heat is ejected to a place of higher temperature).IIR International Dictionary of ...
and
air conditioning
Air conditioning, often abbreviated as A/C (US) or air con (UK), is the process of removing heat from an enclosed space to achieve a more comfortable interior temperature, and in some cases, also controlling the humidity of internal air. Air c ...
equipment.
It was originally defined as the rate of
heat transfer that results in the freezing or melting of of pure
ice
Ice is water that is frozen into a solid state, typically forming at or below temperatures of 0 ° C, 32 ° F, or 273.15 K. It occurs naturally on Earth, on other planets, in Oort cloud objects, and as interstellar ice. As a naturally oc ...
at in 24 hours.
The modern definition is exactly . Air-conditioning and refrigeration equipment capacity in the U.S. is often specified in "tons" (of refrigeration). Many manufacturers also specify capacity in Btu/h, especially when specifying the performance of smaller equipment.
History
The ton of refrigeration is equivalent to the consumption of one ton of ice per day and originated during the transition from
stored natural ice to
mechanical refrigeration. Just as
horsepower and
candlepower were intuitive units of measure for people living through the transition from
horse
The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 mi ...
to steam power
"Horsepower"
''Encyclopædia Britannica Online''. Retrieved 4 July 2022. and from flame-based to electric
Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...
lighting, so was the ton of refrigeration an intuitive unit of measure during a technological change
Technological change (TC) or technological development is the overall process of invention, innovation and diffusion of innovations, diffusion of technology or business process, processes.From ''The New Palgrave Dictionary otechnical change by S. ...
, as the ice trade gradually included growing percentages of artificial ice (ice from ice-making plant
Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...
) in addition to its natural ice supplies. The TR unit was developed during the 1880s. Its definition was set at the level of an industry standard in 1903, when Thomas Shipley of the York Manufacturing Company led the formation of an industry association (the Ice Machine Builders Association of the United States) along with standardization of several equipment specifications.
See also
* Heating, ventilation, and air conditioning
Heating, ventilation, and air conditioning (HVAC ) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. H ...
* Joule
The joule ( , or ; symbol: J) is the unit of energy in the International System of Units (SI). In terms of SI base units, one joule corresponds to one kilogram- metre squared per second squared One joule is equal to the amount of work d ...
* Ton
References
Bibliography
*
{{United States Customary Units
Units of power
Customary units of measurement in the United States
pt:TR