Closed Circuit Cooling Tower

Description

The Closed Circuit Cooling Tower is designed to cool water with minimal operating cost thanks to two operating methods: dry and wet. In dry operation, the medium to be cooled is cooled by ambient temperature. In wet operation, the humidity conditions of the air are changed to obtain cooler air than the ambient temperature. Colder air cools the environment and thus saves energy.

Cooling towers are often used in residential areas such as the roofs of hospitals or shopping malls because they operate quietly thanks to their radial design. Basic types provide a starting point for independent planning. But in principle, only a little knowledge is enough to design the most efficient or most cost-effective cooling tower, depending on the customer’s requirements.

Closed Type Cooling Tower Working Principle

Closed-loop cooling towers work similarly to open cooling towers except that the heat load to be rejected is transferred from the process fluid (cooled fluid) to the ambient air by means of a heat exchange coil. The coil serves to isolate the process fluid from the outside air, keeping it clean and free from contamination in a closed loop. This creates two distinct fluid circuits: an external circuit in which the spray water circulates over the serpentine and mixes with the outside air, and an internal circuit in which the process fluid circulates inside the coil. During operation, heat is transferred from the internal circuit to the spray water by means of the coil, and then transferred to the atmosphere as part of the water evaporates.

The closed-loop cooling tower system includes a separate heat exchanger package along with an open cooling tower. The fluid on the hot side of the heat exchanger also never comes into direct contact with the air. This allows the heat exchanger to be placed inside, protected from external weather conditions along with other system advantages. This closed system lasts much longer than the outer serpentine type closed loop cooling tower.

EFFICIENCY

If an application needs to produce full capacity throughout the year, maintaining a clean and reliable system cycle is critical. Insulating the process fluid in a closed-loop system prevents airborne contaminants from entering and contaminating the system. Maintaining optimum performance in an open-loop system will require regular maintenance to ensure similar efficiency. High-efficiency chillers and heat exchangers require clean process water to function properly and are significantly affected by even small amounts of contamination.

COST

The initial equipment cost of an open-loop system will be less than that of a closed-loop system of similar size, since the open system does not include the intermediate heat exchanger component. However, the initial cost of a closed-loop system, which is higher, will be reimbursed during the working years through the following savings:

Cleaner process fluid results in a cleaner internal surface area and higher efficiency components (e.g., chiller) in the system.
Reduced system maintenance costs.
Reduced water treatment costs for evaporative equipment.
It works in the “free cooling” mode during the winter months to save energy consumption.

MAINTENANCE

Since the process fluid of a closed-loop system is completely isolated from the environment, routine maintenance is only necessary in the heat disposal equipment itself. The need to periodically turn off the system to clean the heat exchanger is significantly reduced, if not completely eliminated. Providing clean process fluid to the system will extend the life of other components in the system (condenser bundles, compressors, etc.).

TREATMENT & FILTRATION

Maintaining proper process fluid quality in a system can include several steps, such as chemical treatment, filtration equipment and the addition of clean completion water. A closed-loop cooling tower can provide the following advantages over an open cooling tower:

Lower volume of circulating water for treatment.
The trading cycle requires minimal processing.
During periods of dry work, the need for reinforcing water disappears.

OPERATIONAL FLEXIBILITY

Closed-loop towers allow the following modes of operation, which are not possible in open towers:

Free cooling process without the need for an intermediate heat exchanger: Chiller off.
Dry running: Protect water and purification chemicals, prevent icing and lint formation.
Variable pumping: The closed condenser water cycle allows variable speed pumping to save energy.