Intermittent thermosyphon
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Solution Overview
Problem
Conventional thermosyphon designs for electronics cooling face limitations due to high pressure loss and flow instabilities caused by vapor expansion in confined channels, which restrict the maximum heat transport distance and power that can be supported, and are hindered by the limited pressure head provided by gravity.
Innovation Solution
A thermosyphon design featuring a looped flow pattern through channels with fins in both the evaporator and condenser, utilizing intermittent liquid supply regulated by vapor backflow and minor vapor and liquid distribution channels to stratify fluids, allowing for low pressure loss and stable performance, and incorporating vapor flow to drag liquid and maintain a wetted region on fins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid is pumped through capillarity from the condenser to the evaporator using a wick, then the heat transfer process can be maintained, but the high pressure loss limits the maximum heat transport distance and power that can be supported
Solution Approach 1:
The patent removes the wick component from the heat pipe system, replacing the capillary pumping mechanism with a gravity-driven thermosyphon system. This extraction eliminates the pressure loss associated with wick flow while maintaining the essential heat transfer function through phase change and gravitational circulation.
Solution Approach 2:
The patent replaces the mechanical capillary pumping system with a gravity-based natural circulation system. By substituting the wick's mechanical capillary action with gravitational force driving liquid flow from condenser to evaporator, the system achieves reduced pressure loss and extended heat transport capability.
2Ease of operation
If vapor expands in a confined channel, then the vapor can be contained and directed, but the expansion causes liquid to flow outwards and creates flow instabilities that increase pressure drop
Solution Approach 1:
The patent segments the confined channel into multiple smaller channels. This segmentation prevents vapor expansion from causing liquid to flow outward in a single large channel, as the smaller channels provide better control over two-phase flow patterns and reduce flow instabilities that lead to pressure drop.
Solution Approach 2:
The patent introduces a new dimension to vapor containment by using a meandering channel path rather than a straight confined channel. This dimensional change allows vapor to expand and change direction gradually through the meandering path, preventing sudden liquid outward flow and reducing flow instabilities.
3Volume of moving object
If the channel size decreases to the same size of a vapor bubble, then the vapor can be contained, but the expansion of vapor causes liquid to flow outwards irrespective of the desired flow rate
Solution Approach 1:
The patent divides the channel into multiple smaller channels, each capable of containing vapor bubbles. This segmentation maintains the small channel size needed for vapor containment while preventing liquid outward flow by distributing the vapor expansion across multiple channels rather than allowing it to occur in a single channel.
Solution Approach 2:
The patent uses a meandering channel configuration that adds a spatial dimension to the flow path. This meandering design allows the channel to accommodate vapor bubble expansion and liquid flow in a controlled manner, maintaining flow rate control even with small channel dimensions by utilizing the extended path length and directional changes.
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 configuration enables high heat transfer rates and stable performance by maximizing solid/liquid/vapor contact and minimizing impedance, allowing for effective heat transfer in low profile systems with limited gravitational pressure head, while reducing the required refrigerant charge and preventing flow instabilities.
Implementation Method 1
liquid 104 is vaporized in an evaporator 101
Implementation Method 2
Heat is removed from the condenser 100 causing the liquid 104 to accumulate at the bottom
Implementation Method 3
The accumulated liquid 104 in the condenser is driven by gravity through a liquid line 103 back to the evaporator 101
Implementation Method 4
The liquid supplied to the evaporator is intermittent, and passively regulated by the back flow of vapor bubbles
Implementation Method 5
the vapor flow helps drag liquid along with it from the vapor intake orifices to the liquid exit orifice
Data Source
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AI summary
The device and methods described herein relate to the isothermal heat transport through an intermittent liquid supply to an evaporator device, thereby enabling high evaporative heat transfer coefficients. A liquid and vapor mixture flows through miniature and micro-channels in an evaporator and addresses flow instabilities encountered in these channels as bubbles rapidly expand. Additionally, a high percentage of the fins are exposed to vapor and limit the required charge of refrigerant within the system due to effective condensate removal in the condenser.