Multi-Stage Evaporator Cooling for Data Center Heat Exchange
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Solution Overview
Problem
Existing cooling systems for data centers, such as those described in Japanese Patent Applications Laid-Open No. 2009-193244 and No. 2009-193137, face inefficiencies in heat exchange due to the use of large fin-and-tube evaporators and require external power sources like compressors, leading to increased electric power consumption.
Innovation Solution
A cooling system with a smaller-sized evaporator per electronic device, utilizing a multiple-stage evaporator structure with a bypass pipe and flexible refrigerant pipes, and a condenser with fins for enhanced heat exchange efficiency without the need for a compressor, employing hydrofluoroether as the refrigerant and optimizing air flow to improve thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large fin-and-tube evaporator is used for multiple servers, then the evaporator can serve multiple devices, but the upper part of the tube is occupied by vaporized refrigerant and heat exchange cannot be performed efficiently
Solution Approach 1:
The patent divides the cooling system into multiple independent evaporators, each dedicated to a specific server. This segmentation ensures that each evaporator maintains optimal refrigerant levels for efficient heat exchange, avoiding the problem of vaporized refrigerant occupying the upper tubes in a large evaporator serving multiple devices.
2Loss of energy
If a freezing cycle with fin-and-tube evaporators is used for each electronic device, then heat exchange can be performed efficiently, but an external power source such as a compressor is needed, resulting in increased electric power consumption
Solution Approach 1:
The patent employs a two-phase immersion cooling system where the refrigerant automatically circulates between evaporators and condensers based on temperature differences and phase changes. This self-service mechanism eliminates the need for external power sources like compressors, achieving efficient heat exchange without increased electric power consumption.
Solution Approach 2:
The system utilizes phase transitions of the refrigerant (hydrofluoroether) between liquid and vapor states to transfer heat. The refrigerant evaporates in the cooling liquid phase change heat exchanger and condenses in the heating liquid phase change heat exchanger, enabling efficient heat exchange without mechanical compression.
3Temperature
If air-conditioning equipment is installed in a server room to control temperature, then the room temperature can be controlled, but the load of air-conditioning equipment becomes large due to consolidation of electronic devices and increase of heat released
Solution Approach 1:
The patent extracts the heat generation function from individual servers by implementing immersion cooling directly within each server unit. Each server has its own cooling liquid phase change heat exchanger that directly contacts the heat-generating components, removing heat at the source rather than attempting to cool the entire room air, thereby significantly reducing the air-conditioning load.
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 enables efficient heat exchange with electronic devices, reducing the load on air-conditioning equipment and eliminating the need for compressors, thereby lowering energy consumption and improving cooling efficiency.
Implementation Method 1
an evaporator for evaporating a refrigerant by performing heat exchange with outside air
Implementation Method 2
a condenser for condensing a gas refrigerant into a liquid refrigerant by making a refrigerant and a cooling medium perform heat exchange with each other
Implementation Method 3
makes the refrigerant perform natural circulation using a difference in densities of the refrigerant in the vapor and liquid states
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A cooling system comprising: an evaporator for evaporating a refrigerant by performing heat exchange with outside air; a condenser for condensing a gas refrigerant into a liquid refrigerant by making a refrigerant and a cooling medium perform heat exchange with each other; a gas refrigerant pipe and a liquid refrigerant pipe connecting the evaporator and the condenser; and the evaporator including: an upper part header provided in a highest position of the evaporator, and connected with the condenser by the gas refrigerant pipe, through the gas refrigerant pipe a gas refrigerant flowing; a lower part header provided in a lowest position of the evaporator, and connected with the condenser by the liquid refrigerant pipe, through the liquid refrigerant pipe a liquid refrigerant flowing; a middle header provided in an intermediate position between the upper part header and the lower part header, and connected with the condenser by the liquid refrigerant pipe, through the liquid refrigerant pipe the liquid refrigerant flowing; an upper part evaporator, arranged between the upper part header and the middle header, including an upper part steam generating tube having a first flow path for leading a refrigerant of the middle header to the upper part header while making the refrigerant of the middle header perform heat exchange with outside air and having a second flow path for leading a refrigerant of the lower part header to the upper part header while making the refrigerant of the lower part header perform heat exchange with outside air; and a lower part evaporator, arranged between the lower part header and the middle header, including a lower part steam generating tube having a third flow path inserted into the middle header while making a refrigerant of the lower part header perform heat exchange with outside air, the lower part steam generating tube communicated with the second flow path of the upper part steam generating tube.