Closed-loop process cooling systems are gaining attention among food processors in North America as a growing number of companies realize the efficiencies they provide in cooling plant equipment, especially when compared with traditional cooling towers.
Here’s what to know about closed-loop systems and how they differ from cooling towers — along with tips for how to ensure the best return on the investment, which can include water efficiencies, cost savings and improved sustainability.
Closed-loop process cooling: a primer
A closed-loop process cooling system uses ambient air to cool process water. The technology is a proven water- and energy-saving alternative to traditional cooling towers, which many companies use for process cooling.
The operation of closed-loop systems is straightforward. The system features a central cooler that provides clean water at the right temperature to processes year round. It uses heat exchangers and an internationally patented adiabatic chamber to cool water circulated to it from process machines.
In the central cooler’s adiabatic chamber, a fine mist of water is pulsed into the incoming air stream during high ambient temperature conditions. The mist evaporates instantly, cooling the air before it impinges on the cooling coils that carry the process water. The process drops the temperature at or below the setpoint. Cooled water is then re-circulated to the facility’s process machines. A microprocessor-based controller automatically maintains targeted cooling temperatures.
Closed-loop system advantages
The biggest and most obvious benefit of the closed loop? Resource efficiency – particularly in the form of water savings.
A closed-loop system reuses water, often translating into water savings of up to 98 percent. A cooling tower, conversely, is open-loop system that does not reuse water. The result is water waste in the form of evaporation.
Cooling tower systems also leave the water exposed to outside elements and surrounding communities exposed to waterborne illnesses such as Legionella, all while requiring costly chemical treatment and disposal. Closed-loop systems, conversely, minimize these issues – along with all the related maintenance costs.
Another advantage of a closed-loop system is the ability to adapt it to for optimum performance based on the local climate. Depending on the system, there are as many as four different stages with varying levels of energy use depending on ambient conditions and setpoint requirements:
Taken together, these capabilities mean that a closed-loop system can reduce energy consumption for process cooling by as much as 50 percent compared to a conventional cooling tower/central chiller system.
System design 101
A range of factors influences the design of a closed-loop system and its performance. When planning, consider:
Equipment considerations
As the popularity of closed-loop systems grows so does the number of equipment choices. Here’s a checklist of key considerations:
Functionality in tight spaces: A system might need to fit in a tight space, which is fine as long as airflow is unrestricted. Ensure the system is available with space-saving options, such as roof panels that allow multiple central cooling units to be positioned more closely together. Another example is extended legs that support the cooler to provide ample airflow in smaller confines, sometimes even side-by-side.
Putting the needs of the operation first
Selecting a closed-loop process cooling system for a new or existing facility requires careful planning given the importance of the application and the technology involved. Often the best advice is to partner with a proven supplier that not only has the cooling technologies expertise, but also a clear understanding of both the plant processes involved and the goals of the operation.
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