Why Daikin Air-Cooled Chillers Are the Smart Choice for Data Centres

The data centre industry is growing at an unprecedented pace, with over 10,000 facilities globally. These critical hubs drive the digital economy but consume significant energy—approximately 1.3% of global electricity. From 2015 to 2022, this energy demand surged by 70%, creating urgency for more sustainable solutions as the world strives for net-zero emissions by 2050.

Cooling systems, responsible for about 30% of a data centre’s energy use, are key to cutting operational costs and reducing environmental impact. Choosing the right air-cooled chiller technology is a crucial step toward improving efficiency and lowering the carbon footprint of digital infrastructure.

This article highlights the challenges of selecting air-cooled chillers for data centres and explains how Daikin’s innovative solutions address these needs.

Overview of a data centre cooling system 

The schematic above illustrates a typical HVAC system for a data centre, highlighting the core components of Daikin’s solution, which include:

• Air-to-water chillers
• Computer Room Air Handling (CRAH) units
• Control systems
• After-sales services

This article explores the key challenges in selecting the right chillers for data centres and demonstrates how Daikin’s innovative solutions can help overcome these challenges effectively.

Challenge 1: Delivering Reliable Performance in Extreme Climates

Data centres are built in all types of environments, from the intense heat of the Middle East to freezing conditions in Northern Europe. Chillers need to function consistently, no matter the climate.

• Wide Ambient Temperature Range: Daikin’s chillers operate in temperatures from -30°C to +55°C, ensuring reliable performance across the globe.

Challenge 2: Maximising Space Efficiency

Cooling systems for data centres often require massive capacities, yet space is a premium in these facilities.

• Compact Design: Daikin’s air-cooled chillers are engineered with optimised condensing sections, reducing unit length while maintaining top-tier performance. This saves space and simplifies maintenance.

This optimisation stems from a redesign of the condensing section, resulting in a shorter unit length. This is particularly beneficial in space-constrained installations, as it not only saves valuable space but also allows for greater redundancy of capacity, where required, and simplifies maintenance activities.

Challenge 3: Reducing Energy Costs and Environmental Impact

With rising energy costs and increasing pressure to meet sustainability goals, data centres need chillers that deliver both efficiency and eco-friendliness.

Why Daikin is the Solution:

1. Efficient Part-Load Performance: Variable Volume Ratio (VVR) technology in Daikin’s compressors adjusts to conditions, enhancing efficiency.
2. Free Cooling Integration: Daikin offers configurations that reduce energy use and costs, with outputs ranging from 150 to 2,150 kW.
3. High Leaving Water Temperature: Daikin chillers can supply water at up to +30°C, increasing free cooling potential and boosting efficiency in warm climates.
4. Smart Controls with Machine Learning: The Intelligent Data Centre Manager (DCM) optimises the operation of up to 20 chillers, improving system efficiency by 15%.
5. Heat Recovery Systems: Daikin transforms waste heat into energy for district heating, adding value while reducing emissions.
6. Active Harmonic Filters (AHFs): These filters minimise energy losses and ensure compliance with international standards.

Optimising Performance at Part Loads

In most data centre operations, chillers run at part loads for over 95% of the time. This is due to fluctuating ambient conditions, such as temperature and humidity, at the installation site. Selecting the right compressor technology is crucial, particularly with the inclusion of a Variable Frequency Drive (VFD) to modulate the compressor’s capacity and improve efficiency under varying conditions.

Daikin’s Advanced Single-Screw Compressor

Daikin’s in-house single-screw compressor is designed for exceptional efficiency. It features Variable Volume Ratio (VVR) technology, which automatically adjusts the compressor’s geometry to suit real-time operating conditions. VVR uses a sliding valve to fine-tune the compression ratio, maximising efficiency even as ambient conditions change.

Additionally, Daikin’s single-screw compressor comes equipped with an integrated Variable Frequency Drive (VFD). Designed and manufactured by Daikin, the VFD is mounted directly onto the compressor and is cooled by refrigerant, ensuring reliable performance and optimal energy efficiency in all operating scenarios.

Free Cooling to Reduce Energy Consumption

Free cooling is an excellent way to lower electricity consumption. When outdoor temperatures are favourable, chillers can switch off compressors and utilise the naturally cooler air to chill water, significantly reducing energy use.

Daikin offers a range of free-cooling configurations with capacities from 150 to 2,150 kW. These options include glycol-free systems, which further reduce energy consumption by minimising pumping system demands.

Higher Chiller Leaving Water Temperatures for System Optimisation

Another way to cut energy consumption is by designing data centres to operate at higher temperatures. For example, separating cold and hot aisles allows cooling systems to run with water temperatures as high as 25–30°C. This optimises the chiller’s efficiency and lowers running costs.

Daikin’s latest air-cooled chillers can supply evaporator leaving water temperatures of up to +30°C. This approach enhances free-cooling potential as ambient temperatures shift, particularly in regions with mild or warmer climates, such as Southern Europe or Australia.

Advanced System Control for Higher Efficiency

Data centres often require multiple chillers to meet cooling demands. To maximise overall efficiency, it's critical to optimise the performance of all units within the system, rather than focusing solely on individual chillers.

Daikin’s Intelligent Data Centre Manager (iDCM) is an external control panel that manages up to 20 chillers. It includes primary pump management and free cooling modes, ensuring maximum reliability. Using advanced machine learning algorithms, the iDCM leverages manufacturer and real-time site data to improve system efficiency by up to 10% for mechanical cooling systems and up to 15% for systems with integrated free cooling. It is fully compatible with TIER III data centres and can be customised for TIER IV compliance.

Recovering Waste Heat for District Heating

Nearly all the electricity used by IT equipment in data centres is converted into heat. While this heat is typically wasted, it can be transformed into a valuable resource if raised to a usable temperature. Recovering this heat and using it for district heating could repurpose up to 90% of energy consumed by IT equipment.

Daikin provides heat recovery solutions, such as water-source heat pumps, which extract heat from the data centre cooling loop and raise it to temperatures suitable for district heating networks. This process reduces the chiller’s cooling demand and boosts overall system efficiency. By transforming otherwise wasted heat into a usable commodity, Daikin solutions provide a sustainable approach to reducing the environmental impact of data centres.

Continuing with heat reuse, Daikin offers another innovative solution. The schematic outlines the plant layout, where heat is recovered directly from the air-cooled chiller while operating in mechanical cooling mode. This is achieved using an additional plate-to-plate heat exchanger installed in series with the condensing section. The recovered heat is then supplied to the district heating system.

This solution can also be integrated into a free-cooling chiller configuration, providing facility managers with a cost-effective alternative to meet heating demands while simultaneously reducing operating costs.

Reducing Harmonic Distortions

Harmonic distortion occurs when nonlinear loads, such as power electronics, variable frequency drives, or certain types of lighting, introduce harmonic currents into the power system. In data centres, harmonic distortion can lead to increased energy losses, reduced efficiency, and higher operational costs. Minimising harmonic distortion is critical for improving energy efficiency and maintaining compliance with international standards and regulations.

Active Harmonic Filters (AHFs) are advanced electronic devices designed to dynamically mitigate harmonic distortion in real-time. By monitoring harmonic currents and generating compensating currents to cancel out harmonics, AHFs significantly reduce Total Harmonic Distortion (THD) and improve overall power quality.

To address harmonic distortion from chillers, Daikin offers an innovative active harmonic filtration solution. Key features include:

• Fully Integrated AHF: Daikin’s active harmonic filter is built directly into the chiller’s electrical panel, utilising the same proprietary technology as the compressor drive.
• Refrigerant Cooling: The AHF is cooled using refrigerant from the chiller circuit, ensuring consistent performance regardless of environmental conditions.
• Space and Maintenance Savings: The fully integrated design eliminates the need for additional space, installation, or maintenance efforts.
• Factory-Assembled and Tested: Each AHF is assembled and rigorously tested at the factory to guarantee reliability and compliance.

By incorporating Daikin’s integrated AHF solution, data centres can reduce energy losses, enhance efficiency, and ensure compliance with global standards, all without added complexity.