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 capacity of
refrigeration and
air conditioning
Air conditioning, often abbreviated as A/C or AC, is the process of removing heat from an enclosed space to achieve a more comfortable interior environment (sometimes referred to as 'comfort cooling') and in some cases also strictly controlling ...
equipment.
It was originally defined as the rate of
heat transfer
Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy ( heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conducti ...
that results in the freezing or melting of of pure
ice 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
Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are t ...
and
candlepower
Candlepower (abbreviated as cp or CP) is a unit of measurement for luminous intensity. It expresses levels of light intensity relative to the light emitted by a candle of specific size and constituents. The historical candlepower is equal to 0.981 ...
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 million yea ...
to steam power
"Horsepower"
''Encyclopædia Britannica Online''. Retrieved 4 July 2022. and from flame-based to electric lighting, so was the ton of refrigeration an intuitive unit of measure during a technological change, as the ice trade
The ice trade, also known as the frozen water trade, was a 19th-century and early-20th-century industry, centering on the east coast of the United States and Norway, involving the large-scale harvesting, transport and sale of natural ice, and ...
gradually included growing percentages of artificial ice (ice from ice-making plant
Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae excl ...
) 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
A trade association, also known as an industry trade group, business association, sector association or industry body, is an organization founded and funded by businesses that operate in a specific industry. An industry trade association partici ...
(the Ice Machine Builders Association of the United States) along with standardization
Standardization or standardisation is the process of implementing and developing technical standards based on the consensus of different parties that include firms, users, interest groups, standards organizations and governments. Standardizatio ...
of several equipment specifications.ASHRAE
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE ) is an American professional association seeking to advance heating, ventilation, air conditioning and refrigeration (HVAC&R) systems design and constructi ...
.
See also
* Heating, ventilation, and air conditioning
* Joule
The joule ( , ; symbol: J) is the unit of energy in the International System of Units (SI). It is equal to the amount of work done when a force of 1 newton displaces a mass through a distance of 1 metre in the direction of the force appli ...
* Ton
Ton is the name of any one of several units of measure. It has a long history and has acquired several meanings and uses.
Mainly it describes units of weight. Confusion can arise because ''ton'' can mean
* the long ton, which is 2,240 pounds
...
References
Bibliography
*
{{United States Customary Units
Units of power
Customary units of measurement in the United States
pt:TR