Definition of 1TR

The roots for refrigeration are in the ice making industry, and the ice manufacturers wanted an easy way of understanding the size of a refrigeration system in terms of the production of ice. 

If 288,000 Btu are required to make one ton of ice, divide this by 24 hours to get 12,000 Btu/h required to make one ton of ice in one day. This is the requirement for the phase change from liquid to solid — to convert water at 0°C (+32°F) into ice at 0°C (+32°F). As a practical matter, additional refrigeration is required to take water at room temperature and turn it into ice. To be specific, one ton of refrigeration capacity can freeze one short ton of water at 0°C (32°F) in 24 hours. So, a ton of refrigeration is 3.517 kW. 

This is derived as follows: The latent heat of ice (also the heat of fusion) = 333.55 kJ/kg = 144 Btu/lb One short ton = 2000 lb Heat extracted = 2000 x144/24 hr = 288000 Btu/24 hr = 12000 Btu/hr = 200 Btu/min 1 ton refrigeration = 200 Btu/min = 3.517 kJ/s = 3.517 kW = 4.713 HP.

A much less common definition is: 1 tonne of refrigeration is the rate of heat removal required to freeze a metric ton (1000 kg) of water at 0°C in 24 hours. Based on the heat of fusion being 333.55 kJ/kg,1 tonne of refrigeration = 13,898 kJ/h = 3.861 kW. Thus,1 tonne of refrigeration is 10% larger than 1 ton of refrigeration. 

Another unit of measure is the calorie which is the amount of heat removal required to raise or lower the temperature of one gram of water by one °C. A kilo-calorie is the amount of heat required to raise or lower1 kg of water by 1°C. One ton of refrigeration is equal to 3024 kilo-calories per hour. This is 12,000 BTU/ h divided by 2.204 (pounds per kilogram) divided by 1.8 (°C to °F).

What is a Short Ton and Long Ton ? 

The British ton is the long ton, which is 2240 pounds, and the U.S. ton is the short ton which is 2000 pounds.

Both tons are actually defined in the same way. 1 ton is equal to 20 hundredweight. It is just the definition of the hundredweight that differs between countries. In the U.S. there are 100 pounds in the hundredweight, and in Britain there are 112 pounds in the hundredweight. This causes the actual weight of the ton to differ between countries.

To distinguish between the two tons, the smaller U.S. ton is called short, while the larger British ton is called long.

There is also an third type of ton called the metric ton, equal to 1000 kilograms, or approximately 2204 pounds. The metric ton is officially called tonne. The SI standard calls it tonne, but the U.S. Government recommends calling it metric ton.