Why does direct-to-chip liquid cooling still require facility water filtration?

While direct-to-chip liquid cooling isolates the server racks in a closed loop (TCS), it relies on boundary plate heat exchangers in the CDU to transfer heat to the facility water loop (FCS). The facility water loop uses open cooling towers that pull in airborne dust and organic debris, which quickly foul the CDU heat exchangers, leading to server overheating and PUE degradation if not filtered

Can centrifugal separators handle the organic debris in data center cooling towers?

Centrifugal separators rely on specific gravity and centrifugal force to spin out heavy, inorganic particles like sand and scale. They may be less effective at removing light organic particles such as algae, pollen, leaves, and biological slime, which remain suspended in the flow and clog plate heat exchangers.¹ Amiad’s DATA Klin disc filters use efficient 3D depth filtration to capture both organic and inorganic solids regardless of their density.

Does the backwash cycle of the DATA Klin interrupt cooling water flow?

No. The DATA Klin utilizes a modular, multi-pod design and operates on a live side-stream loop. When a backwash is triggered (by differential pressure or time), individual filter pods are cleaned sequentially while the remaining pods continue to filter and supply water to the cooling circuit. Cooling water flow is maintained, and data center uptime is supported.

Data Center Water Treatment for Liquid Cooling

Table of Contents

Quick Summary

Direct-to-chip liquid cooling data center solutions protect high-density processors at the rack level, but they do not eliminate the need for facility water treatment. Heat absorbed from CPUs and GPUs must still pass through the Coolant Distribution Unit (CDU) and into the external facility cooling loop.5 Suspended solids in this loop can foul plate heat exchangers, reduce cooling efficiency, increase PUE, and create serious operational risks.

The rapid growth of AI and high-performance computing is driving higher server-rack power densities and accelerating the adoption of liquid cooling. However, even when coolant circulates directly across server cold plates, the captured heat must ultimately be transferred to the facility cooling system and rejected outside the building. This makes filtration of the external water loop essential for protecting heat exchangers and maintaining reliable cooling performance.

The Thermodynamics of the Primary Boundary: TCS to FCS

Direct-to-chip liquid cooling relies on a multi-stage heat transfer chain consisting of two cooling loops connected through the Coolant Distribution Unit (CDU):

The Technology Cooling System (TCS): A controlled, closed-loop circuit that circulates specialized fluids, such as treated water or water-glycol mixtures, directly across server cold plates.
The Facility Cooling System (FCS): The external loop that transfers and rejects heat through the facility’s cooling infrastructure, which may include chillers and evaporative cooling towers.

These two environments are connected through the CDU’s plate heat exchangers, which transfer thermal energy from the isolated TCS loop to the facility cooling system.

Because liquids transfer heat far more effectively than air, maintaining thermal conductivity across these boundary heat exchangers is paramount. To evaluate how effectively a data center manages this water-energy balance, facilities track two core performance metrics: Power Usage Effectiveness (PUE) and Water Usage Effectiveness (WUE):

PUE = Total Facility Annual Energy Use (kWh) / IT Equipment Annual Energy Use (kWh)

WUE = Annual Site Water Usage (Liters) / IT Equipment Annual Energy Use (kWh)

The Fouling Threat to Boundary Heat Exchangers

While the internal TCS loop is isolated, the external FCS loop is continuously exposed to environmental contaminants.Evaporative cooling towers act as massive “air scrubbers” pulling in ambient air and capturing airborne dust, sand, silt, and pollen directly into the circulating water supply.

As water evaporates, the concentration of these suspended solids increases. Without proper filtration, these contaminants circulate through the system and deposit directly onto the narrow channels of the plate heat exchangers within the CDU.

This particulate accumulation leads to three major operational risks:

Thermal Barrier Formation: Suspended solids and mineral deposits can form an insulating layer on heat-transfer surfaces, reducing heat-transfer efficiency and increasing the energy required to maintain cooling performance.
Under-Deposit Corrosion: Accumulated solids can create localized conditions that promote corrosion and shorten the service life of heat exchangers.
CDU Flow Restriction: Fine particles and biological fouling can accumulate in narrow heat-exchanger passages, restrict water flow, and affect cooling stability.

Amiad’s Solution: DATA Klin Polymeric Disc Filtration

Traditional cooling tower filtration systems, such as cyclonic separators or sand media filters, may present operational limitations for modern data centers. Cyclonic separators rely on specific gravity and centrifugal force and may be less effective at removing lightweight organic particles such as algae or pollen. Sand filters, while effective, may require a large physical footprint and substantial backwash water.

Amiad’s data center filtration solutions include the DATA Klin system, powered by patented Spin Klin™ NOVA disc technology, engineered specifically to address these challenges in mission-critical environments.

Unlike surface-filtration screens, Spin Klin™ NOVA discs are diagonally grooved on both sides. Stacked and compressed on a specially designed spine, they form a 3D depth-filtration matrix that traps particles throughout the depth of the element.

Key Operational Advantages of DATA Klin:

Three-Dimensional Depth Filtration: Traps organic and inorganic particles throughout the full depth of the disc channels, providing superior dirt-holding capacity and consistent particle capture down to 55μm.
Designed for Continuous Operation: The system operates on a live side-stream loop treating 5% to 15% of the main circulating flow, and utilizes an automatic backwash sequence that cleans individual filter pods sequentially. Cooling water flow to the CDU is maintained, supporting continuous operation and uptime.
High Corrosion Resistance: Built with 100% polymeric construction, the filter pods and pipework are highly resistant to aggressive chemical biocides, scale inhibitors, and alternative water sources.
Eco-Efficient & Water-Saving: The low pressure-drop design minimizes pump energy consumption, directly supporting PUE goals. Furthermore, the backwash cycle uses a minimal volume of water and is engineered to integrate with the cooling tower’s existing blowdown process, preserving the facility’s WUE targets.

Parallel Industrial Validation: Cooling Tower Sidestream Filtration

To understand how this technology performs in parallel, high-capacity cooling environments, we can examine Amiad’s experience protecting industrial heat exchangers under severe environmental loading:

Case Study: Cooling Tower Sidestream Filtration, USA

A large electric utility company installed five new gas turbines to expand its power station in El Paso, Texas. The open-loop cooling towers at the site were subject to frequent desert dust storms, which heavily contaminated the tower basins with dust, pollen, and grass.

Filtering these contaminants was critical to prevent the fouling of the intercooler, a sensitive heat exchanger in the turbine systems. Because the original system did not include a sidestream filter, the startup team had a very short timeframe to design, build, and install a filtration solution.

Amiad designed and delivered a plug-and-play side-stream skid featuring an automatic SAF-X Series filter with a 25-micron screen, treating a flow rate of 700 GPM. Following the success of this initial installation, the utility designed the new power station with two double-filter skids, treating 1,400 GPM.

The automated filtration kept the cooling loops clean, successfully maintaining the water clarity so that the bottom of the cooling tower sumps remained clearly visible to the naked eye.

Are you managing an open-loop cooling tower under heavy environmental loading?

Read the full Cooling Tower Sidestream Filtration case study:

https://amiad.com/case-studies/cooling-tower-side-stream-filtration-usa/

Achieving Long-Term Operational Resilience

In the high-stakes world of next-generation computing, data center cooling directly influences uptime, sustainability, and operational efficiency. As chip densities increase and liquid cooling becomes more common, protecting the facility-side cooling system from particulate and biological fouling becomes increasingly important. By implementing automated side-stream disc filtration, data center operators can reduce suspended-solid loading, protect plate heat exchangers, and support broader energy- and water-efficiency objectives while maintaining reliable cooling performance under demanding operating conditions.