Everything You Need to Know About Water Usage in Cooling Towers
In the US, groundwater, a primary source for agriculture, industrial, and domestic use, is depleting at an alarming rate. According to a recent survey by the NY Times, nearly 40% of the water wells in the country have hit record-low levels during the past decade.
Water is a precious resource, but it’s often taken for granted. From daily household use to industrial operations, water gets consumed like there is no tomorrow. Cooling towers are highly water-intensive, consuming approximately 1.8 gallons per ton-hour of cooling.
As water becomes scarcer, it’s necessary to focus on reducing water usage in cooling towers. By cutting back on waste and using water efficiently, you can help preserve this valuable resource.
Here’s a quick lowdown on water usage in cooling towers.
A Quick Look at Water Usage in Cooling Towers
All cooling towers, commercial or residential, are heat exchangers that rely on water. As the water circulates through your HVAC system, it absorbs heat. The warm water gets pumped to the top of the cooling tower, passing through the fill media, where it cools down through evaporation. Cooled water then returns to your HVAC system. Some of the water evaporates in the process.
Water usage in cooling towers typically involves:
1. Makeup Water
Makeup water is the fresh water needed to replace losses from evaporation, blowdown, and drift. Makeup water often comes from local sources like municipal water supplies, rivers, or wells. The amount of makeup water required depends on your cooling tower’s water efficiency and the local climate. Generally, cooling towers need 1-2% of makeup water.
2. Evaporation Loss
Evaporation is the heart of cooling tower performance and function. When the hot water gets sprayed over the fill media, some of it evaporates, removing heat in the process. It is the largest source of water loss in a cooling tower.
For example, in a system designed to cool water by 10°F, approximately 10 gallons of water evaporates for every 1,000 gallons circulated. However, this cooling tower water efficiency can fluctuate depending on temperature, humidity, and the design of your cooling tower.
3. Blowdown
Blowdown, or bleed-off, refers to water discharged from the cooling tower to maintain water quality. As water evaporates, it leaves behind minerals and other impurities that build up in your system. If left unchecked, these solids can cause scaling, corrosion, and biological growth, affecting cooling tower performance.
Although blowdown is necessary, it results in water loss. It also depends on the water quality and the number of cycles of concentration. Most systems operate at two to four cycles of concentration, but six or more cycles are possible. To reduce water usage in cooling towers, you would want to maximize cycles of concentration.
Factors Affecting Water Usage in Cooling Towers
Several factors affect cooling tower water efficiency, including:
1. Climate
Weather conditions play a big role in water use. Hot temperatures and high humidity in the summer speed up evaporation, while freezing winter temperatures can affect system performance. Strong winds can also lead to water loss through drift.
2. Cooling Load
Cooling load means the amount of heat your tower needs to remove. It is typically higher in summer when your tower has to work harder. Ensuring higher cooling tower water efficiency can help you reduce consumption.
3. Tower Design
The design of the cooling tower affects water efficiency. Efficient designs, like counter-flow or mechanical draft towers, typically use less water.
4. Maintenance
How you maintain and operate the tower matters. Regular maintenance, like cleaning, descaling, and water treatment, reduces water waste from blowdowns and leaks, helping you save more water.
5. Timely Upgrades
Timely cooling tower field upgrades can greatly improve water efficiency. The latest cooling tower materials, designs, and parts, like water flow meters, are designed to help you save more water without affecting performance.
How Can You Reduce Water Usage in Cooling Towers
Reducing water usage in cooling towers helps you save money and protect the environment.
Here’s how you can do this:
1. Increase Cycles of Concentration
One of the easiest ways to reduce water usage in cooling towers is by increasing the cycles of concentration. While two to four is the standard, try to reach six cycles if possible. Increasing cycles from three to six can cut makeup water consumption by 20% and blowdown by 50%. But keep an eye on the water quality to prevent scaling or corrosion.
2. Maintain Water Quality
Proper water treatment can significantly reduce the need for blowdown. You can use filtration, softening, or chemical treatment to remove impurities from the makeup water before it enters the system. This can help you increase cycles of concentration and reduce overall water usage in cooling towers.
3. Install Drift Eliminators
Drift eliminators can capture water droplets that escape into the environment. Installing high-efficiency drift eliminators can reduce water loss by up to 0.2% of the total flow, which may seem small but adds up over time, especially in large systems.
4. Install Flow Meters
Install flow meters on makeup water and blowdown lines. It will help you check the ratio of makeup flow to blowdown flow. A lower ratio means your cooling tower is keeping the water loss at its minimum. Additionally, you can use handheld conductivity meters to track the mineral concentration of makeup and recirculating water.
5. Recycle and Reuse Water
Recycling and reusing as much water as possible is another way to save this precious resource. Instead of discharging blowdown water, you can treat and reuse it within your tower or for other purposes, such as landscaping or industrial processes. It will not only conserve water but also reduce the amount of wastewater that needs to be treated and discharged.
6. Keep Air Handler Coils Well-Maintained
Dirty air handler coils mean your HVAC system has to put in extra effort to maintain the desired temperature. In addition to consuming more electricity, this also wastes water. Keeping these coils clean and well-maintained can help you save water.
Keep Your Water Usage in Cooling Towers Under Control
Water is a vital resource for cooling towers, but it’s also a limited one. Knowing how your cooling tower uses water can help you reduce consumption, save money, boost efficiency, and help save this precious natural resource. This includes everything from increasing cycles of concentration to recycling water, and Pinnacle CTS can help you make that happen.
We offer all-inclusive cooling tower services, from installation to maintenance. Our clients are located all over the tri-state area.
Contact us today to start saving water and boost performance.
