Counter-Flow Flat Tube Heat Exchanger for Low-Pressure Data Center Cooling
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Solution Overview
Problem
Cooling systems for data centers face challenges in efficiently managing the increasing heat loads from high-density computer servers, with existing solutions experiencing pressure drops and compromised performance due to high temperature differences and fluid phase changes.
Innovation Solution
The use of a single-phase fluoroketone fluid with micro-encapsulated phase-change material in a multi-row counter-flow heat exchanger system, which includes flat tubes and fins, to enhance heat transfer efficiency and reduce pressure drops, while being safer and more environmentally friendly compared to traditional refrigerants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional refrigerants are used in heat exchangers, then cooling capacity is maintained, but pressure drops increase and performance is compromised due to high temperature differences and fluid phase changes
Solution Approach 1:
The patent changes the physical parameters of the coolant by using a single-phase fluid with enhanced thermal properties (specific heat capacity, thermal conductivity) instead of traditional refrigerants that undergo phase changes. This parameter change eliminates pressure drops associated with phase transitions while maintaining effective heat transfer at high temperature differences
Solution Approach 2:
The patent employs a composite cooling approach by combining a single-phase base fluid with micro-encapsulated phase-change material particles suspended within it. This composite formulation allows the fluid to maintain single-phase flow characteristics (avoiding pressure drops) while the encapsulated particles provide latent heat absorption capabilities
2Use of energy by moving object
If high temperature difference cooling is implemented, then heat transfer efficiency improves, but fluid phase changes occur causing system instability
Solution Approach 1:
The patent modifies the fluid's thermal parameters by selecting a single-phase coolant with high specific heat capacity and thermal conductivity, enabling efficient heat transfer across large temperature differences without the fluid undergoing phase changes, thus maintaining compositional stability
Solution Approach 2:
The micro-encapsulated phase-change material particles act as intermediaries that absorb latent heat within the single-phase fluid, enabling the system to utilize phase-change benefits without disrupting the single-phase flow regime and maintaining fluid stability
3Use of energy by moving object
If counter-flow circuiting is used in heat exchanger, then heat transfer performance increases, but system complexity increases
Solution Approach 1:
The heat exchanger is segmented into multiple passes with explicit counter-flow circuiting, where the coolant flows through tubes in one direction while air flows across the fins in the opposite direction. This segmentation enables efficient heat transfer by maintaining optimal temperature differences throughout the exchanger
Solution Approach 2:
The flat tube heat exchanger design serves multiple functions: it provides counter-flow circuiting for efficient heat transfer, maintains structural simplicity for ease of installation, and accommodates the single-phase fluid with enhanced thermal properties, achieving performance without excessive complexity
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
This solution achieves higher energy efficiency, reduced leakage risk, and increased 'free cooling' hours, with improved heat transfer performance and lower fluid flow rates, addressing the limitations of traditional cooling systems.
Implementation Method 1
a single-phase fluid of a fluoroketone (FK) including micro-encapsulated phase-change material
Implementation Method 2
micro-encapsulated phase-change material
Implementation Method 3
heat exchanger disposed at or near a hot aisle formed by the plurality of IT racks
Implementation Method 4
The fan moves air from the hot aisle through the heat exchanger
Implementation Method 5
single-phase fluid circuit circulates a single-phase fluid through the heat exchanger
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A cooling system includes a heat exchanger having one or more rows of multiple flat tubes, louvered fins disposed between pairs of flat tubes, and special header tube connections to form a counter flow heat exchanger. Heat exchangers having multiple rows may be placed near or close to the server racks and may be in fluid communication with an outdoor heat exchanger having one or more rows. A single-phase fluid is pumped through the fluid circuit or loop, which includes the heat exchangers at the server racks and the outdoor heat exchanger. The single-phase fluid circuit including the heat exchangers at the IT racks may alternatively be in thermal communication with a water circuit that includes an outdoor fluid cooler. The flat tubes can be formed tubes with one or more channels, or extruded tubes with multiple channels. The heat exchangers include header tubes/connections, which facilitate easy fabrication and connection between rows and inlet/outlet, and lower the pressure drop.