As energy and water costs continue to rise, improving the efficiency of cooling tower operations has become a significant priority across industries. More efficient cooling towers reduce energy consumption through optimized heat transfer and can also conserve water through effective cycles of concentration and blowdown control. Even minor improvements in cooling tower performance can yield substantial cost savings and environmental benefits.
This article covers the fundamentals of cooling tower efficiency.
At its core, an efficient cooling tower maximizes heat rejection while minimizing water consumption. The key metrics used to gauge cooling tower efficiency focus on these areas:
This measures how much heat is dissipated by the cooling tower over a given timeframe, usually expressed in BTUs/hr or kW. Effective heat transfer depends on factors like airflow rate and the temperature differential between inlet and outlet water.
This refers to the accumulation of dissolved solids in the circulating water. Higher cycles translate to less bleed-off and make-up water required. Most cooling towers operate between two and four cycles of concentration.
By directly measuring makeup water consumption, operators can calculate cooling tower water usage on a gallons per minute (gpm) or gallons per hour (gph) basis. Lower water usage indicates higher efficiency.
This metric looks at the percentage of circulating water bled off to control cycles of concentration. Minimizing blowdown saves water and the energy needed to condition replacement water.
Tracking metrics like these over time is crucial for evaluating equipment upgrades, operational changes, and water treatment improvements that aim to enhance efficiency. Even small optimizations add up substantially for heavy-duty cooling tower applications across industries.
Properly monitoring and controlling what goes into and comes out of a cooling tower is central to efficient operation. The key inputs and outputs include:
Online instrumentation and data logging equipment make it easier than ever to monitor these parameters in real-time. Tracking output changes in response to input adjustments provides visibility on overall efficiency and opportunities for improvement.
Cycles of concentration is a critical metric for evaluating and optimizing cooling tower efficiency. This term refers to the accumulation of dissolved minerals and total dissolved solids (TDS) in the recirculating water.
As pure water evaporates out of a cooling tower, it leaves behind any contaminants that entered through the makeup water source. Over time this increases the concentration of TDS as compared to the new makeup water entering the system.
To help understand this concept, EAI&#;s Ryan Vargas shares a simple analogy: &#;As the water evaporates inside of a cooling tower, dissolved solids suspended inside the water get more and more concentrated. To oversimplify, it&#;s like making a bowl of ramen instant noodles. Have you ever put the spice packet into the water and when it starts to boil, forget about it? You come back when you smell something funny, all of your water is boiled off and the salt and spices are concentrated at the bottom.&#;
Cycles measure this increase&#;if the cooling water has a TDS level three times higher than the incoming makeup water, it is operating at three cycles of concentration. The higher the cycles, the less blowdown is required to purge contaminants. This conserves water and the energy needed to condition it.
In addition, elevated mineral concentration also raises the risk of scale formation on heat transfer surfaces. There is a practical limit around seven cycles for most towers, especially in the West and Southwest, after which scaling and deposition rapidly reduce efficiency.
Optimizing cycles of concentration requires balancing water savings against heat transfer impacts:
The cycles value that maximizes water conservation without excessive scaling varies. But understanding and controlling concentration is pivotal for getting the most out of a cooling tower system.
While advanced technology upgrades can improve efficiency, most towers benefit greatly from simpler operational measures first. Consistent cooling tower water treatment, monitoring, maintenance, and training helps optimize existing performance with little or no capital expenditure.
Key best practices include:
&#;I recommend checking the system once per week for facilities that have some type of a controller that is either wired into the system or is able to report out. The latter will alert your vendor if a measurement is abnormal,&#; says Vargas.
Many facilities find that consistency with basic operational diligence not only optimizes efficiency, it also reduces the risk of unplanned downtime events that can severely disrupt production. The fundamentals may not be glamorous, but excellent tower performance depends on their reliable execution.
Once sound operational practices are established, facilities seeking to stretch their cooling tower performance may consider advanced technologies and upgrades including:
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The feasibility and return on investment of advanced upgrades will vary for each facility. But where cost-effective, these measures can compound operational gains to reduce cooling tower overhead costs. Performance incentives and local regulations may also subsidize certain upgrades. For most operators, efficiency is a long game with no finish line.
While the core function of cooling towers remains the same across applications, factors like load size, environment, and downtime risk create differences in cooling tower design between industrial facilities and commercial buildings.
Industrial sites like oil refineries, petrochemical plants, and power plants often utilize very large, field-erected cooling towers. Their high heat loads and continuous uptime requirements call for robust construction with redundant fans and pumps. Materials also vary per the process environment&#;a refinery cooling tower handles hydrocarbons, while a nuclear plant contends with radioactive water.
Commercial cooling towers for offices, hospitals, and district energy systems tend to be smaller prefabricated units mounted on rooftops or along HVAC equipment. Their intermittent operation allows for simpler systems, often with a single fan. Cost and footprint are bigger considerations. Additionally, commercial towers must account for winter shutdowns and legionella control given their integration with human-occupied buildings.
While tower specifics differ across sites, employing efficiency best practices and advanced technologies can benefit both industrial and commercial operators. The potential savings make optimization worth pursuing, even for smaller commercial towers. Efficiency gains at scale translate to even more dramatic reductions for high-capacity industrial towers.
The reality is that most facilities leave substantial efficiency improvements on the table with their existing cooling tower assets. By monitoring key parameters and proactively adjusting operations and upkeep, operators can extend the life of cooling equipment, curb overhead costs, and reduce environmental impacts. The incentives are stacked for those who prioritize efficiency across their thermal management systems.
With this foundation on maximizing cooling tower performance, commercial buildings and industrial sites alike have actionable best practices to start driving efficiency gains today. Consistent incremental improvements over months and years ultimately accumulate to optimize these critical assets for the long run. If you need help improving the efficiency of your cooling towers, contact us today for a free on-site analysis.
Your facility&#;s cooling tower (or towers) serves as an often overlooked but important aspect of your overall costs, not only in repairs but also utility and water bills. Your towers require water to run and energy to operate, which means that it is in your best interest to make sure that they are as efficient as possible.
However, doing so may sound more difficult or overwhelming than it actually is. If you would like to improve your cooling tower&#;s efficiency, you can begin by checking the following items as a great place to start.
If you want to improve efficiency in your towers, you must understand how to measure that idea as a tangible metric. In general, cooling tower efficiency is measured in two ways: how much energy it takes to achieve the desired output and how much water it uses (and wastes).
Multiple measures can help you to shore up both of these areas, leading to less waste and therefore lower bills. Investing in efficiency changes now will save you money in the long run, and many of these changes are simple and in your best interest for other, non-monetary reasons as well.
One of the first areas to consider when trying to boost your cooling tower&#;s efficiency is how your piping is set up. Simply altering your piping to discharge blowdown water to return hot water is enough to boost the overall effectiveness of your system by as much as 2%.
That may not seem like a large number, but consider how much water and energy your system uses every month or even every year and then deduct 2%. Suddenly, this seemingly minor change can be significant. Be aware that pipe replacement is a relatively simple job, but it is best handled by a professional for safety reasons.
Your cooling tower uses water, but that does not mean that it cannot keep using the same water repeatedly. The highest-quality towers are designed with this idea in mind, and they will generally recycle as much as 98% of the water they use. Gather data on how much water your tower wastes or does not recapture and determine why. Reusing water is a great way to help the environment, save money and become more efficient in your operations.
Inspecting your cooling towers is a task that can fall by the wayside, especially if your tower is not outwardly displaying any problems. However, regular maintenance is critical for efficiency&#;as well as for regulatory compliance.
Consistent inspections will reveal problems with corrosion, scaling, biofilms and more that indicate that your water treatment plan may need adjustment. If you allow scaling and other issues to worsen, your system will need to work harder to exchange heat through the new, thicker layer of unwanted sediment, meaning that you are paying for more energy to do the same intended task. Keeping your system clean is a simple and effective way to maintain high efficiency.
When you think of the number of cycles that your tower uses, you may imagine that cutting that number down would save on energy. However, increasing cycles from three to six actually improves how effectively the tower operates, which can result in water reduction by as much as 20%, as well as cutting the blowdown of your system by up to half.
This simple change may be all that you need in order to begin to significantly reduce the energy and water usage at your facility that is attributed to cooling towers. Your towers&#; efficiency should see a relatively significant improvement by implementing one or more of these strategies, helping you to save money, keep your tower in good condition for longer and protect the environment against unnecessary waste.
Each building and water system is unique, which means that so too is each building&#;s cooling tower setup. How your specific system can be improved for greater efficiency may involve one or more of the previously mentioned strategies, but you do not need to figure this out on your own.
The experts at Tower Water set the standard in water treatment and cooling tower management and would be happy to help you understand your options for boosting efficiency and cutting down on waste. We will provide a customized strategy that is suited to your specific needs. Reach out to learn more about how we can help or to set up an appointment to discuss your options.
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