Frequently Asked Questions | FAQs | Rental Cooling Towers | Aggreko

ACTS FAQ

What is the coldest water temperature an Aggreko cooling tower can achieve?

How do you handle water treatment for rental cooling towers?

What is the cooling capacity of your largest cooling tower unit?

Do I need a pump with my rental cooling tower?

How do you predict or measure the capacity of a cooling tower?

What does cooling tower performance mean?

__________________________________________________________________

 

What is the coldest water temperature an Aggreko cooling tower can achieve?

The temperature that any cooling tower can achieve is limited by the wet bulb temperature. The wet bulb temperature is determined by the ambient humidity and dry bulb temperature. A cooling tower, in theory, can achieve a temperature equal to the wet bulb temperature. However, most experts agree that it is not always practical for a cooling tower to achieve a temperature colder than 5° F above the wet bulb temperature. Aggreko employs a custom water distribution system that makes it very effective at achieving an exceptionally close approach to wet bulb.

(top)

How do you handle water treatment for rental cooling towers?

All cooling water treatment programs should address four things: 1.) scale control, 2.) solids control, 3.) biological control, and 4.) corrosion control. The water treatment program should be designed to treat the cooling system, not just the cooling tower. Aggreko’s industrial cooling towers are constructed of superior materials (FRP and Stainless Steel) to minimize the potential for corrosion. Even though Aggreko’s industrial cooling towers are constructed of superior materials, proper water treatment is still recommended to prevent scale and biological growth. When selecting a water treatment program, the entire cooling system including the cooling tower, pumps, piping, and exchangers must all be considered. In most cases, the water treatment program that is in place prior to the rental cooling towers being placed into service will be adequate. In the case that no water treatment program is in place, Aggreko can provide water treatment as a part of our services or can assist the customer in the selection process.

(top)

What is the cooling capacity of your largest cooling tower unit?

The cooling capacity of Aggreko’s largest unit is best referenced by stating capacity in a maximum water flow rate. Our largest single unit is capable of flowing 4,500 gallons per minute. However, it is more important to understand that our industrial cooling towers are modular and can be interconnected to achieve any cooling requirement from 100 gallons per minute to in excess of 1,000,000 gallons per minute.

(top)

Do I need a pump with my rental cooling tower?

Depending on the application, additional cooling tower pumps may not be required. When being used for the purpose of supplementing an existing cooling tower, Aggreko cooling towers do not require pumps. The unique design utilizes an elevated water basin allowing water to be drained back to the basin/sump of the existing cooling tower without the aid of pumps. When the towers are utilized in a stand alone application, Aggreko can provide pumps that are designed to meet the head and flow requirements specific to the project.

(top)

How do you predict or measure the capacity of a cooling tower?

There are five basic temperature measurements used in rating cooling towers capacity: Hot Water Temperature; Cold Water Temperature; Wet Bulb Temperature, Range and Approach. The Hot Water Temperature (HWT) is the temperature of the water entering the cooling tower and the Cold Water Temperature (CWT) is the temperature leaving the cooling tower. Wet Bulb Temperature (WBT) is the lowest temperature that occurs on a surface when water is evaporated from the surface and is the most powerful variable in any given cooling tower's ability to reject heat. Range is the difference between the Hot Water Temperature and the Cold Water Temperature (HWT—CWT). Approach is the difference between the Cold Water Temperature and the Wet Bulb Temperature (CWT—WBT). These formulas calculate the cooling tower’s ability to get the CWT down to the WBT.

Generally speaking, a cooling tower will have a tighter approach when there is less water flowing and a bigger approach when there is more water flowing. The difference between the Hot and Cold Water Temperature is an element in the process of the water being cooled, and is not dependent on the cooling tower (except in a once-through discharge system like pond/river cooling). It is interesting to note that when cooling, the process will add a certain amount of energy in the form of heat regardless of the cooling tower's capability.

 (top)

What is meant by cooling tower performance?

A cooling tower is designed to produce certain results based on specific conditions, with variables due to conditions presented as curves. Standard conditions for a cooling tower are 95 degree Hot Water Temperature (HWT), 85 degree Cold Water Temperature (CWT), a 78 degree Wet Bulb Temperature (WBT), a 10 degree Range (HWT—CBT) and 7 degree approach (CWT—WBT). If a cooling tower is designed to be able to flow 3,000 gallons per minute at standard conditions and is flowing 3,000 gpm, then it is said to be performing at 100%. However, varying conditions will change what the cooling tower is able to produce, with the largest factor being the wet bulb temperature.

An Example: A process is delivering 105 degree HWT to the cooling tower. The cooling tower is producing 90 degree CWT with an 80 degree WBT (with a 15 degree Range and 10 degree Approach). If the tower's curves say it should deliver 3,000 gpm but it is measured at those conditions and is only producing 2,700 gpm; the tower is performing at 90%. If conditions change again, the tower’s flow rate is measured at 3,300 gpm, it performing at 110%.

(top)

get in touch

888.869.2108

Request a Quote