Stacked Electronic Rack Cooling with Pulsating Heat Pipes
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Solution Overview
Problem
Current cooling technologies for high-density electronic racks, such as datacenter servers and telecom equipment, face challenges in efficiently managing heat without high energy consumption, complexity, and maintenance issues, particularly with air-cooling, water-cooling risks, and immersion cooling's space and maintenance demands.
Innovation Solution
A cooling system incorporating pulsating heat pipes and loop thermosyphon circuits with independent fluid flow circuits for each unit, coupled to a stack cooling system via a riser pipe, allowing for efficient heat transfer and easy integration and replacement of electronic units, while minimizing energy use and maintenance complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional thermosyphon cooling systems are used for stacked servers, then heat transfer efficiency is improved, but system complexity increases and unit replacement becomes time-consuming
Solution Approach 1:
The cooling system is divided into independent modular units, each containing its own thermosyphon heat sink that can be independently attached to or removed from servers. This segmentation allows individual server replacement without affecting the cooling system configuration, reducing complexity while maintaining high heat transfer efficiency through passive thermosyphon operation.
2Temperature
If air-cooling with fans is used, then heat dissipation is achieved, but electrical energy consumption increases
Solution Approach 1:
The active mechanical cooling system (fans driven by electrical motors) is replaced with a passive thermosyphon system that utilizes natural convection and phase change of working fluid. This eliminates the need for electrical energy input while maintaining effective heat dissipation through gravity-driven fluid circulation and evaporative cooling.
3Temperature
If air-cooling with fans is used, then heat dissipation is achieved, but fan noise becomes prohibitive
Solution Approach 1:
The noisy mechanical fan system is replaced with a silent passive thermosyphon system that relies on natural convection currents and phase change of working fluid for heat transfer. This eliminates mechanical moving parts that generate noise, providing effective cooling without prohibitive noise levels.
4Temperature
If water-cooling is used, then heat transfer efficiency is improved, but risk of leaks and drips increases
Solution Approach 1:
The cooling system uses phase change of a working fluid (evaporation and condensation) instead of relying on continuous liquid flow through pipes. This parameter change from liquid-phase cooling to two-phase cooling eliminates the risk of leaks and drips while maintaining high heat transfer efficiency through latent heat absorption during evaporation.
5Temperature
If immersion cooling is used, then heat dissipation is improved, but floor space requirements double
Solution Approach 1:
The cooling system transitions from horizontal immersion cooling that requires doubled floor space to a vertical configuration where thermosyphon heat sinks are stacked along the vertical dimension. This dimensional change allows efficient heat dissipation while maintaining compact footprint and original floor space utilization.
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 system achieves high heat transfer efficiency with reduced energy consumption and simplified maintenance, enabling reliable and adaptable cooling for varying numbers of electronic units within compact configurations.
Implementation Method 1
a pulsating heat pipe (PHP) including a pipe having a plurality of channels therein arranged in a serpentine shape to form the pulsating heat pipe (PHP), the channels containing a coolant fluid
Implementation Method 2
the pipe extending between a condenser end and an evaporator end
Implementation Method 3
a stack cooling system comprising a principal condenser and a fluid flow circuit including a downcomer and a riser configured as a loop thermosyphon (LTS) cooling system
Implementation Method 4
the riser comprising a riser pipe extending vertically across a plurality of stacked electronic units
Implementation Method 5
each of the unit cooling systems comprising a thermal interface coupling clamped and thermally coupled to the riser pipe
Implementation Method 6
the pipe extending between a condenser end and an evaporator end
Data Source
AI summary
Cooling system for a multi-unit electronic apparatus stack (1) comprising a plurality of stacked electronic units (3), the cooling system comprising a plurality of unit cooling systems (6) incorporated in, on or between each electronic unit, each unit cooling system (6) comprising one or more fluid flow circuits (13) configured as: —a pulsating heat pipe (PHP) including a pipe (34) having one or more channels (36) therein containing a coolant fluid, the pipe (34) extending between a condenser end (16) and an evaporator end (15), or —a thermosyphon (LTS) cooling system comprising pipes (14a, 14b) extending between a condenser end (16) and an evaporator end (15); the cooling system (2) further comprising a stack cooling system (4) comprising a principal condenser (12) and a fluid flow circuit (8) including a downcomer (8a) and a riser (8b) configured as a loop thermosyphon (LTS) cooling system, the riser comprising a riser pipe (24) extending vertically across a plurality of stacked electronic units (3), each of the unit cooling systems (6) comprising a thermal interface coupling (16) thermally coupled to the riser pipe (24), the fluid flow circuits (13) of the unit cooling systems being independent from the fluid flow circuit (8) of the stack cooling system (4).