In the context of cooling tower terminology, "TR" stands for "Tons of Refrigeration." It is a unit of measurement used to quantify the cooling capacity of a cooling tower or other cooling systems.
Originally, the term "ton of refrigeration" was coined in the early days of refrigeration systems when ice was used for cooling. It refers to the amount of heat required to melt one ton (2,000 pounds) of ice in 24 hours. In modern usage, a ton of refrigeration is defined as the cooling capacity equivalent to removing 12,000 BTUs (British Thermal Units) of heat per hour.
Cooling towers are designed to dissipate heat from industrial processes or air conditioning systems. The cooling capacity of a cooling tower is often expressed in terms of the number of "tons" it can handle. For example, a cooling tower with a rating of 100 TR can remove 100 tons of heat from a system per hour.
It's important to note that the term "ton" in this context does not refer to the weight of the cooling tower or the physical mass of ice. Instead, it is a unit of measurement for cooling capacity and is based on the historical concept of melting ice.