Dual-mode thermal management loop
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Solution Overview
Problem
Conventional heat exchanger systems face inefficiencies due to high operating costs, complexity, and susceptibility to pump failure, particularly in managing varying heat loads and low heat situations.
Innovation Solution
A dual-mode thermal management loop system that toggles between powered-pump and passive-capillary modes, utilizing a pump, evaporator, condenser, accumulator, and valves to optimize fluid circulation and heat transfer based on heat load thresholds, with a controller managing operation between the two modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pump is used to drive fluid circulation in a heat exchanger system, then heat transfer efficiency is improved, but system complexity and susceptibility to pump failure increase
Solution Approach 1:
The system dynamically switches between two operational modes: pump-driven mode for high heat transfer efficiency and passive capillary mode for simplified operation. The controller activates or deactivates the pump based on system requirements, allowing the system to adapt its complexity level to match operational needs while maintaining effective heat transfer capability in both modes
Solution Approach 2:
The evaporator incorporates capillary wick structures that enable passive fluid circulation through capillary action when the pump is deactivated. This self-service mechanism allows the system to maintain heat transfer functionality without external mechanical assistance, reducing system complexity and eliminating pump failure risks during passive operation
2Productivity
If a pump is used to drive fluid circulation, then heat transfer performance is improved, but reliability decreases due to pump failure risks
Solution Approach 1:
The evaporator incorporates capillary wick structures that enable passive fluid circulation through capillary action when the pump is deactivated. This self-service mechanism allows the system to maintain heat transfer functionality without external mechanical assistance, reducing system complexity and eliminating pump failure risks during passive operation
Solution Approach 2:
The controller continuously monitors pump operation status and proactively switches to passive capillary mode when pump failure is detected or anticipated. This preventive switching strategy ensures continuous heat transfer functionality by having a backup passive circulation mechanism ready, cushioning against the reliability risks of pump-dependent operation
3Temperature
If single phase liquid heat exchangers are used, then heat transfer is achieved through sensible heat capacity, but large volumes of liquid are required increasing operating costs
Solution Approach 1:
The system utilizes phase change heat transfer in the evaporator where liquid refrigerant transforms to vapor, absorbing latent heat. This phase transition mechanism enables significantly higher heat transfer efficiency per unit volume of liquid compared to single-phase sensible heat transfer, reducing the required liquid volume while maintaining or improving heat transfer performance
Solution Approach 2:
The evaporator employs porous capillary wick materials that provide large surface area for heat transfer and facilitate efficient capillary action. The porous structure enables intimate contact between the liquid refrigerant and heat transfer surface, maximizing heat transfer efficiency and reducing the volume of liquid needed to achieve the same thermal performance
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
Enhances operating efficiency, mitigates pump failure risks, and effectively manages varying heat loads by adapting fluid circulation and heat transfer mechanisms, reducing overall system complexity and costs.
Implementation Method 1
the pump drives fluid circulation, the first valve prevents fluid circulation through the pump bypass line, the pump pumps liquid from the accumulator to the evaporator
Implementation Method 2
In the passive-capillary mode, capillary pressure in the evaporator drives fluid circulation, the first valve prevents fluid circulation through the pump, liquid flows from the accumulator, through the pump bypass line, and to the evaporator
Implementation Method 3
Single phase liquid heat exchangers, for example, are often used to cool and/or heat components of a system. In such heat exchangers, a liquid is pumped across a component and sensible heat is transferred between the liquid and the component
Implementation Method 4
In the passive-capillary mode all the liquid entering the evaporator evaporates to gas
Implementation Method 5
gas exiting the evaporator flows to the condenser, liquid exiting the evaporator flows through the second valve to the accumulator, and liquid exiting the condenser flows to the accumulator
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A system (100) may include a pump (110), an evaporator (120), a condenser (130), an accumulator (140), a pump bypass line (151), a first valve (161), and a second valve (162). The system (100) may operate in a powered-pump mode, in which the pump (110) drives fluid circulation, the first valve (161) prevents fluid circulation through the pump bypass line (151), the pump (110) pumps liquid from the accumulator (140) to the evaporator (120), gas exiting the evaporator (120) flows to the condenser (130), liquid exiting the evaporator (120) flows through the second valve (162) to the accumulator (140), and liquid exiting the condenser (130) flows to the accumulator (140). The system (100) may operate in a passive-capillary mode, in which capillary pressure in the evaporator (120) drives fluid circulation, the first valve (161) prevents fluid circulation through the pump (110), liquid flows from the accumulator (140), through the pump bypass line (151), and to the evaporator (120), gas exiting the evaporator (120) flows to the condenser (130), the second valve (162) is closed, and liquid exiting the condenser (130) flows to the accumulator (140).