A Ton of Refrigeration (symbol: TR) is a historic unit that represents the amount of heat removal required to melt one short ton (2000 lb) of ice at 0 °C in 24 hours. In SI terms this equals approximately 3.517 kW of cooling capacity. It is widely used in HVAC and commercial refrigeration to size chillers, condensers, and evaporators.
Understanding Electric Horsepower (hp)
Electric horsepower is a unit of mechanical power commonly used in the United States to rate electric motors. One mechanical horsepower equals 745.7 W, while the electric‑horsepower rating already accounts for motor efficiency and is used for specifying motor size.
Why Convert TR to hp (Electric)?
When selecting a motor to drive a refrigeration compressor, engineers often start with the cooling load expressed in TR and need to know the motor power required. The conversion factor links the thermal load to the electrical power needed, assuming typical compressor efficiency.
Design of commercial chillers
Sizing of motor‑driven compressors
Energy‑consumption estimations for building simulations
Therefore, a 10 TR refrigeration system requires roughly 47.14 hp of electric motor power.
A Ton of Refrigeration corresponds to a continuous heat‑removal rate of 12,000 BTU/h, which is about 3.517 kW. This definition stems from the energy needed to melt one short ton of ice over a 24‑hour period.
The factor 4.714276139410187 hp/TR incorporates the exact relationship between 1 TR = 3.517 kW and 1 hp = 0.7457 kW, plus typical compressor efficiency assumptions. Rounded values (e.g., 4.73) are acceptable for quick estimates but introduce small errors.
"On fait la science avec des faits, comme on fait une maison avec des pierres ; mais une accumulation de faits n'est pas plus une science qu'un tas de pierres n'est une maison." "Science is built up of facts, as a house is built of stones; but an accumulation of facts is no more a science than a heap of stones is a house." — Henri Poincaré (French Mathematician, Theoretical Physicist & Mining Engineer)