HVAC operations in Police Training Institute (PTI) @ Doha, Qatar.

 SKM - Chilled Water System

Chilled water systems are used in a variety of settings, including commercial buildings, industrial facilities, and data centres, to provide air conditioning and cooling. Chilled water systems have high efficiency, they are used in many large buildings. A chilled water system can be divided into water-cooled and air-cooled. Water-cooled chilled water systems are larger and more efficient than air-cooled chilled water systems.

Main Features:

SKM APCN-S Air Cooled Packaged Screw Chiller Series is available in different models covering 81 TR– 441 TR (285 kW to 1547 kW). APCN-S Screw Chillers have a compact design and are supplied as a complete package. The units are suitable to operate in a wide range of ambient temperatures. (Minimum outdoor operating ambient temperature is 25°F (-4°C), maximum is 131.0°F (55°C).

Effectiveness:

APCN-S Screw Chillers use high-performance screw compressors (S-240*3, S-210*) with R-134a refrigerant along with high-efficiency Shell and Tube Evaporators. Heavy-duty condenser coil manufactured from seamless Hi-x copper tubes mechanically bonded to aluminium fins to ensure optimum heat transfer. Propeller-type condenser Fan direct driven by AC motor.

The same two chillers work according to the week-by-week by manual shifting.

Water-Cooled Chilled Water Systems

Components:

• Chillers: Primary components that can be centrifugal, screw, or absorption types.
• Cooling Towers: Dissipate heat from the water circulating through the chiller.
• Condenser Water Pumps: Circulate water between the chiller and cooling tower.
• Chilled Water Pumps: Circulate chilled water to air handling units (AHUs) or other cooling units.
• Heat Exchangers: Sometimes used to separate different loops in the system.

Advantages:

• Efficiency: More energy-efficient, especially for larger systems, due to water's higher heat capacity.
• Capacity: Suitable for larger facilities and higher cooling loads.
• Longevity: Typically longer lifespan compared to air-cooled systems.

Disadvantages:

• Initial Cost: Higher installation cost due to the need for cooling towers and associated piping.
• Maintenance: Requires more maintenance, particularly for the cooling towers.
• Water Usage: Consumes significant water, which can be problematic in areas with water scarcity.

Air-Cooled Chilled Water Systems

Components:

• Air-Cooled Chillers: Built-in fans dissipate heat directly to the ambient air.
• Chilled Water Pumps: Circulate chilled water to AHUs or other cooling units.
• Fans: Part of the chiller unit, used to expel heat to the atmosphere.

Advantages:

• Installation Cost: Lower initial installation cost as there’s no need for cooling towers.
• Maintenance: Easier and cheaper to maintain, with no cooling towers to manage.
• Water Usage: Do not consume water, making them ideal for areas with water scarcity.

Disadvantages:

• Efficiency: Generally less energy-efficient than water-cooled systems, particularly in hot climates.
• Noise: Fans can generate noise, which might be a consideration in some settings.
• Capacity: Typically less capable of handling large cooling loads compared to water-cooled systems.

How We Choosing Between Water-Cooled and Air-Cooled Systems?

The decision between water-cooled and air-cooled chilled water systems depends on various factors:

• Climate: Water-cooled systems are more efficient in hot climates, while air-cooled systems are suitable for milder climates.
• Size and Load: Large facilities with high cooling loads benefit more from water-cooled systems.
• Budget: Initial budget and ongoing maintenance costs influence the decision.
• Water Availability: In areas with limited water resources, air-cooled systems are preferable.
• Environmental Considerations: Water usage and energy efficiency impact the decision, especially with sustainability goals in mind.

Block diagram of Chilled water system 1

Block diagram of Chilled water system 2

Controlling a chilled water system using a graphical user interface (GUI)

Controlling a chilled water system using a graphical user interface (GUI) involves an intuitive and interactive platform that provides real-time monitoring and management of the system's components and operations. The GUI typically displays a comprehensive dashboard showing key parameters such as temperature, pressure, flow rates, and energy consumption. Operators can adjust setpoints for temperature and flow, monitor the performance of chillers, pumps, and cooling towers, and receive alerts for any system anomalies or maintenance needs. 

The interface may include graphical representations of the entire system, allowing for easy visualization of processes and quick identification of issues. Advanced features might offer historical data analysis, predictive maintenance insights, and energy efficiency optimization, enabling precise and efficient control of the chilled water system to ensure optimal performance and reliability.

GUI of Chiller plant

*** These four AHUs, and six FAHUs operated by two chillers one by one.

Pre Filter Dirty Alarm indicate the AHU (Air handling unit) 04 in GUI

When an alarm is indicated in the GUI of a chilled water system, troubleshooting begins with acknowledging the alarm to log it and prevent duplication. Next, identify the alarm by examining its details, such as the type of fault, affected component, and severity. Review real-time data and historical trends provided by the GUI to understand the context. Perform a physical inspection of the indicated component for visible signs of malfunction. Consult the system’s documentation and manuals for specific troubleshooting steps. If the issue involves temporary glitches or incorrect settings, reset or reconfigure the component through the GUI. 

Utilize built-in diagnostic tools to run tests on the affected component, checking sensor accuracy and mechanical operations. Review recent changes or maintenance activities that might have triggered the alarm. If the issue persists, seek advice from maintenance personnel or experts for advanced troubleshooting. 

AHU and FAHU

Air Handling Units (AHUs) and Fresh Air Handling Units (FAHUs) are critical components in HVAC systems, serving distinct yet complementary roles in maintaining indoor air quality and comfort. AHUs are responsible for conditioning and circulating air within a building by regulating temperature, humidity, and air distribution. They consist of components such as filters, fans, coils, and sometimes humidifiers or dehumidifiers, working together to ensure optimal indoor environments. 

FAHUs, on the other hand, specifically handle the intake of fresh outdoor air, filtering and conditioning it before introducing it into the building's ventilation system. This process helps to dilute indoor pollutants, maintain air quality, and meet ventilation standards. By integrating both AHUs and FAHUs, HVAC systems can provide a balanced approach to managing indoor air conditions, combining recirculated conditioned air with a constant supply of fresh, filtered air, thereby enhancing both comfort and health in indoor spaces.

Industrial vertical multistage pump motors

The image depicts two industrial vertical pumps, commonly used in various mechanical and HVAC systems for circulating water. These pumps are characterized by their robust construction and efficient design, which include powerful electric motors mounted above cylindrical stainless steel bodies. The blue housing and motor casings are likely indicative of their use in industrial settings, where durability and performance are critical. The stainless steel sections help prevent corrosion and ensure longevity in challenging environments. These pumps are connected to a network of pipes and are equipped with electrical connections for power and control.

These multistage pumps are characterized by their ability to generate high pressure and maintain steady flow rates, making them ideal for applications requiring precise fluid handling. The pumps are connected to a network of pipes and electrical conduits, indicating their integration into a larger system. The electrical connections suggest that the pumps are controlled and monitored via a centralized system, which could include features for adjusting speed and pressure to meet varying demands.

Inside side view of chiller plant room

Inside side view of chiller plant room. 

S.K.M Chiller

Good maintenance of a chilled water system is essential for ensuring energy efficiency, system longevity, and reliability. Regular upkeep helps the system operate efficiently, reducing energy consumption and lowering utility costs, while also extending the lifespan of equipment and minimizing costly repairs. Consistent maintenance prevents unexpected failures, ensuring reliable performance and minimizing downtime, which is especially important in critical environments. It also enhances system performance by keeping it in optimal condition, contributes to safety by identifying potential hazards, and supports compliance with regulatory standards. Additionally, effective maintenance helps reduce environmental impact by minimizing energy use and refrigerant leaks, ultimately contributing to overall cost savings and sustainability.

Thank you,
UBApepi team