The importance of water in the cooling tower industry – Water (part 3)
Temperature is a physical quantity that expresses the thermal state of an object. It is closely correlated to the amount of heat contained in the object itself.
A hot body is characterized by the amount of energy stored as heat. The amount of heat depends on the body mass and its specific heat (heat retention capacity).
When we speak of cooling we always almost think of refrigerators or temperatures that are lower than those of the environment we live in; on the other hand, when we speak of heating we think of fireplaces, electric heaters, etc., that is, temperatures that are higher than then the environment we live in. Hence. “hot” and “cold” are physical states which we are accustomed to “feel” or “perceive”.
Temperature and heat measurements
The temperature measurement is the degree “°C” for Celsius or “K” for Kelvin (K = ° C + 273).
The energy-heat measurement is the “J” (Joule).
How to cool water in an economical way
In evaporative cooling, however, the heat is transferred to air according a physical principle that exploits the characteristics of the air to absorb moisture. This is very advantageous.
Hence, hot and dry air can cool the water even at temperature lower than air itself.
The importance of choosing the cold water temperature according to the process plant to cool
As we have seen, the cold water temperature is not very important as the difference in temperature at the outlet and inlet water liquor used as heat transport.
Condensers or heat exchangers of any one type are correlated to the cold water temperatures.
The choice of the outlet water temperature of the tower is, hence, of fundamental importance.
Please note that the tower is a machine that uses air as a cooling element.
A slight degree over the wet bulb air temperature forces us to increase the size of the tower, sometimes even double it!
Considering that the wet bulb temperature is very high for a few hours a year, we would have doubled the size of a plant for a few hours a year: an unforgivable economical mistake!
Hence, just imagine the waste and design error.
We can emphasize the fact that the difference in temperature between cold water and air, at wet bulb temperature, is a very important design piece of data because it is closely correlated with the size of the tower.