Multi-Function Heat Exchangers for High Density Rack Cooling
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Solution Overview
Problem
Existing cooling systems for high power density data center racks are inadequate, as they struggle to manage the increased heat load and require both air and liquid cooling, leading to inefficiencies and higher operational costs due to insufficient airflow and reliance on air cooling infrastructure.
Innovation Solution
A hybrid cooling system incorporating multi-function heat exchangers that include liquid-to-liquid and liquid-to-air heat exchangers, where the liquid-to-liquid heat exchanger is thermally coupled with a rack-liquid channel and an external-liquid channel, and the liquid-to-air heat exchanger transfers thermal energy between air and the external-liquid channel, allowing for efficient thermal management of both air-cooled and liquid-cooled components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional air cooling solutions are used for low power density racks, then the cooling system is simple and cost-effective, but the system becomes insufficient to meet air flow requirements when rack power density increases to high levels
Solution Approach 1:
The patent combines air cooling and liquid cooling systems into a hybrid cooling architecture. The liquid cooling subsystem handles high-density server heat loads through cold plates and liquid-to-liquid heat exchangers, while the air cooling subsystem manages ambient temperature through liquid-to-air heat exchangers. This merging allows the system to meet high power density requirements without proportionally increasing overall system complexity.
Solution Approach 2:
The cooling system is segmented into multiple independent subsystems: liquid-to-liquid heat exchangers for direct server cooling, liquid-to-air heat exchangers for ambient temperature control, and separate air cooling and liquid cooling pathways. This segmentation allows each subsystem to be optimized independently for its specific function while collectively solving the high power density cooling challenge.
2Temperature
If air flow is significantly increased to meet high power density cooling requirements, then cooling effectiveness improves, but operating costs such as energy consumed by fans and capital costs for air moving equipment increase dramatically
Solution Approach 1:
The patent replaces high-energy air moving with liquid-based thermal transport. Liquid-to-liquid heat exchangers use pumped liquid circulation to transfer heat from servers, and liquid-to-air heat exchangers use liquid as an intermediate medium to cool ambient air. This hydraulic approach is more energy-efficient than relying on high-power fans to move large volumes of air, as liquids have higher heat capacity and can be pumped more efficiently than air can be moved at equivalent cooling loads.
3Reliability
If liquid cooling solutions are implemented for high density racks, then cooling effectiveness improves, but the system still requires air cooling infrastructure which increases complexity
Solution Approach 1:
The liquid cooling infrastructure is designed to serve multiple functions: liquid-to-liquid heat exchangers provide direct server cooling, while liquid-to-air heat exchangers use the same liquid cooling loop to also cool the ambient air environment for air-cooled components. This multi-functionality eliminates the need for separate air cooling infrastructure, as the liquid cooling system handles both direct server cooling and ambient temperature control.
4Productivity
If rack power density is increased to accommodate more servers, then data center capacity increases, but thermal management becomes increasingly challenging
Solution Approach 1:
The patent changes the thermal management approach by transitioning from air cooling to liquid cooling parameters. Liquid cooling provides higher heat transfer coefficients and better thermal contact with high-density server components through cold plates. The system adjusts cooling parameters dynamically, using liquid-to-liquid heat exchangers for high-heat-load components and liquid-to-air heat exchangers for ambient control, enabling effective management of increased power densities of 20-30 kW per rack.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The hybrid cooling system effectively manages high power density racks by efficiently transferring thermal energy, reducing the need for air cooling infrastructure and minimizing operational costs, while maintaining suitable air temperatures for air-cooled components and managing heat loads for liquid-cooled components.
Implementation Method 1
the rack-liquid channel and the external-liquid channel being thermally coupled to each other to transfer thermal energy between rack-liquid
Implementation Method 2
rack-liquid that circulates through the rack-liquid channel and external-liquid that circulates through the external-liquid channel
Implementation Method 3
the air path being thermally coupled to an external-liquid channel to transfer thermal energy between the air and the external-liquid
Implementation Method 4
air path that circulates air between the electronics racks and ambient space around the electronics racks
Data Source
AI summary
A cooling system and a multi-function heat exchanger design for electronics racks has one or more liquid-to-liquid heat exchangers (or their functions) and one or more liquid-to-air heat exchangers (or their functions). Each liquid-to-liquid heat exchanger has a rack-liquid channel, and an external-liquid channel, the rack-liquid channel and the external-liquid channel being fluidly isolated from each other, and thermally coupled to each other to transfer thermal energy between rack-liquid that circulates through the rack-liquid channel and external-liquid that circulates through the external-liquid channel. The one or more liquid-to-air heat exchangers each have an air path that circulates air between the electronics racks and ambient space around the electronics racks, the air path being thermally coupled to an external-liquid channel of the liquid-to-air heat exchanger to transfer thermal energy between the air and the external-liquid.