As data centers race to meet the demands of next-generation hardware, direct-to-chip (DTC) liquid cooling has emerged as a highly efficient solution.
Unlike immersion cooling, which submerges entire systems, DTC cooling delivers precision cooling by targeting the dominant heat source itself—CPUs and GPUs. This focused approach maximizes heat transfer efficiency, reduces energy waste, and saves space—ideal for high-density environments.
Single-Phase vs. Two-Phase Direct-to-Chip Cooling
Direct-to-chip cooling is available in two primary forms, with unique advantages depending on the application and specific requirements:
Single-Phase DTC Cooling: Uses water-based coolant that remains liquid as it absorbs heat. Cost-effective and reliable for moderate heat loads, this method is ideal for data centers prioritizing affordability and simplicity, though it may have lower heat transfer capacity and requires managing potential risks associated with water-based coolants.
Two Phase DTC Cooling: Uses waterless nonconductive and noncorrosive fluids that change from liquid to vapor as they absorb heat. This phase change dramatically boosts heat transfer efficiency, making it an excellent choice for high-power workloads like AI and HPC. While these fluids can be more expensive upfront, they offer long-term reliability by avoiding the risks of water-based coolants and require minimal maintenance.
Preparing your data center for single-phase cooling inherently sets the foundation for two-phase systems, as both rely on a similar Primary Cooling Loop (Facility Water System or FWS). With processor roadmaps advancing to 2kW and beyond, two-phase cooling is becoming the go-to solution to handle higher heat flux efficiently and meet the demands of next-generation workloads.
How Two-Phase Direct to Chip Cooling Works
Two-phase DTC systems use a closed-loop process to manage heat efficiently:
- Cold Plate: A cold plate is mounted directly onto the chip's surface (e.g., CPU or GPU), allowing cooling liquid to flow through it and form a cooling layer. As the refrigerant absorbs heat from the chip, it undergoes a phase change, transforming from liquid to vapor. The rising vapor rapidly removes heat from the surface of the chip.
- The HRU (Heat Rejection Unit): The vaporized refrigerant travels to an HRU, a self-contained unit, where it is condensed back into liquid. Depending on the setup, the HRU can use:
- Air: Fans force air from the cold aisle across a heat exchanger, condensing the vapor and releasing the heat into the hot aisle.
- Water: For higher cooling demands, a water-cooled heat exchanger condenses the vapor and carries the heat away through the water loop, offering a more efficient option for high-heat applications.
- Manifold: Once condensed, The HRU directs the liquid refrigerant back to the manifold in the back of the cabinet, which distributes it to each server for the next cycle.
An example of the process shown with Zutacore’s HyperCool® two-phase, closed-loop liquid cooling solution.
Addressing Residual Heat with Airflow Management
Direct-to-chip cooling removes the heat from the highest heat emitting components such as CPU, GPU, and FPGA; effectively 70% of the device’s thermal load – the remaining 30% from memory modules, PDUs, networking cards, and storage drives—requires supplemental cooling strategies.
Precise airflow management at the cabinet level provides a powerful solution for managing this residual heat.
Advanced cabinet designs and tools such as air dams, chimneys, perforated door panels, and blanking plates direct and optimize airflow, ensuring cool air reaches critical air-cooled components while preventing hot air recirculation. This hybrid approach not only enhances energy efficiency but also provides comprehensive thermal management across the entire infrastructure.
A Scalable, Hybrid Approach: Integrating Two-Phase DTC Cooling with ZetaFrame® Cabinet System
Chatsworth Products (CPI) delivers a complete thermal management solution with the ZetaFrame® Cabinet System, now integrated with ZutaCore’s waterless, two-phase liquid cooling technology.
This hybrid system seamlessly merges cutting-edge two-phase direct-to-chip cooling with a robust, highly customizable cabinet, creating an ecosystem designed to efficiently handle high heat loads while streamlining data center operations.
Seamless Heat Management:
ZutaCore: HyperCool® Waterless Liquid Cooling Solution:
ZetaFrame: Advanced Airflow Management:
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Handles the remaining 30% of heat with an advanced cabinet design and airflow management tools such as air dams, chimneys, perforated door panels, and blanking plates that ensure cool air reaches critical air-cooled components while preventing hot air recirculation.
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Beyond thermal management, fully integrates eConnect® Power Distribution Units (PDUs), cable management, airflow management, DCIM, and access control into one optimized cabinet system.
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Cabinet supports up to 5,000 lb. (2268 kg) static and 4,000 lb. (1814 kg) dynamic loads, ensuring scalability for future demands.
The Advantage: Streamlined Deployment
At CPI, we can pre-install everything you need—the HRU, manifold, hoses associated with the cooling solution, along with other components such as eConnect® Power Distribution, access control, and more—so whether it's heading to your site or your integrator, it arrives ready to go.
We pressure-test the HyperCool Solution to ensure everything is leak-free and ready for immediate server installation, so you can get up and running without any surprises.
Through pre-installation, CPI manages the packaging required for each component, reducing excess waste at the jobsite and saving you the hassle of handling it yourself.
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