What is Cooling Tower Capacity?

What is Cooling Tower Capacity?

When you’re first selecting a cooling tower, it’s important to know some of the basic functions regarding how it works and factors that affect its performance, so you can make an educated decision when it comes to selecting size and type. Sometimes selecting a size is an easy process if your cooling needs is for one piece of equipment with a known heat load (BTU/HR).

However, if you are in charge of an industrial power plant, you will most likely select a larger cooling tower. Often the cooling tower is cooling several pieces of equipment which requires multiple calculations. In large HVAC applications the building size and capacity is utilized along with the local environment to determine the needed capacity.

What Is a Cooling Tower?

One of a cooling tower's main functions is to reject heat into the atmosphere by removing the heat from cooling water. They are one of the most efficient and reliable cooling methods for cooling large structures, such as chemical plants and power plants.

Many different types of cooling towers are used for various cooling needs.

These include:

• Crossflow cooling towers. These types of towers have air that moves horizontally, perpendicular to the water dripping vertically. These can be some of the easiest towers to maintain; however, they are very susceptible to frost.
• Hyperbolic cooling towers. Theseare the largest used in nuclear plants and largest power plants.
• Induced draft cooling towers. These use a fan system on top to pull air into and through the blower. This style can be used in either counterflow or crossflow systems.
• Passive draft cooling towers. Air is naturally pushed upward in this type of tower. Hyperbolic towers can only be a passive draft.
• Forced draft cooling towers. These use a fan or centrifugal blower to force air through the cooling tower.

Performance of Cooling Towers

It is important to understand the performance of cooling towers. As time goes on, you’ll want to know if your tower is performing efficiently, so you’ll want to know how to calculate cooling tower capacity as well as some other parameters.

You should be aware of the cooling tower’s design parameters:

• Range. This is the temperature difference between the outlet temperature of the cooling tower and the water inlet.
• Approach. This is the difference between the outlet temperature and the ambient wet-bulb temperature. While range is important, the calculation of the approach is a better indicator of your cooling tower’s efficiency.
• Capacity. The cooling tower's capacity is the product of the mass flow rate of water, specific heat, and temperature difference. This can also be expressed as heat rejected in kCal/hr (Btu/h).
• Evaporation loss. This is the amount of water that is evaporated during the cooling process. This can be calculated using (m³/hr) = 0.00085 x 1.8 x Circulation Rate (m/hr) x (T1-T2). Where T1 is the inlet temperature and T2 is the outlet temperature.

Selecting a Cooling Tower

Cooling tower capacity calculation is important because it helps you select the right model from water cooling tower manufacturers. Knowing the nominal cooling load, along with the desired approach, enables you to determine the correction factor, so you know which cooling tower will work for your specific industry. As a cooling tower is an investment you’ll own for many years, you want to make the correct choice.

To learn more about sizing and selecting, and cooling tower capacities, or if you need repair or regular maintenance on your tower, contact Delta Cooling Towers, Inc. today. We have modern, corrosion-resistant designs, towers constructed with high-density polyethylene, and offer a 20-year warranty.