Loop Heat Pipe Evaporator Protrusions for Thin Device Thermal Management
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Solution Overview
Problem
Conventional heat transfer methods in small and thin mobile electronic devices, such as smartphones and tablets, are inadequate for efficiently managing high heat generation due to limitations in thermal conductivity and the challenges of integrating larger heat pipes, which can obstruct fluid flow and reduce heat transfer efficiency.
Innovation Solution
A loop heat pipe design featuring an evaporator, condenser, and interconnected vapor and liquid lines formed by bonding metallic plates with specific protrusions and recesses to enhance capillary force and fluid flow, allowing efficient heat transfer while maintaining a thin profile suitable for mobile devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional thermally-conducting sheets are used for heat transfer, then the device structure remains simple, but heat transfer efficiency is insufficient for high heat generation
Solution Approach 1:
The patent employs phase transition of working fluid (liquid to vapor in evaporator, vapor to liquid in condenser) to achieve high heat transfer efficiency. This resolves the contradiction by providing superior heat transfer capability through latent heat utilization while maintaining a relatively simple planar structure suitable for mobile devices.
Solution Approach 2:
The heat transfer system is segmented into distinct functional components: evaporator with vaporization chambers, condenser with condensation chambers, and connecting channels. This segmentation allows each component to perform its specific function efficiently while integrating into a compact overall structure.
2Reliability
If larger diameter heat pipes are used for efficient heat transfer, then heat transfer ability increases, but mounting becomes difficult and device integration is problematic
Solution Approach 1:
The patent transitions from three-dimensional cylindrical heat pipes to a two-dimensional planar loop heat pipe structure. This dimensional change enables efficient heat transfer pathways to be integrated within the flat device plane, solving the mounting difficulty while maintaining heat transfer effectiveness.
Solution Approach 2:
The loop heat pipe utilizes thin planar structures with flexible channel configurations that can be integrated into the device's thin profile. The working fluid channels are formed as thin film structures allowing easy integration without obstructing device assembly.
3Length of stationary object
If heat pipes are flattened to fit thin devices, then device thickness is reduced, but working fluid flow is blocked and heat transfer ability decreases
Solution Approach 1:
The evaporator is segmented into multiple vaporization chambers separated by partition walls, and the condenser into multiple condensation chambers. This segmentation creates independent flow paths that prevent fluid flow blockage while maintaining thin overall structure, resolving the contradiction between thin profile and heat transfer ability.
Solution Approach 2:
Different regions of the loop heat pipe are designed with locally optimized structures: the evaporator has vaporization chambers with specific geometries for efficient boiling, the condenser has condensation chambers for effective heat release, and connecting channels are designed for smooth fluid transition. This local optimization maintains heat transfer efficiency in the flattened configuration.
4Reliability
If loop heat pipe with independent vapor and liquid channels is used, then heat transfer efficiency improves, but structural complexity increases
Solution Approach 1:
The vaporization chambers and condensation chambers are merged into a single integrated loop structure with shared working fluid. The partition walls serve dual functions: separating vapor and liquid phases while also acting as structural support. This merging reduces overall structural complexity compared to multiple separate components.
Solution Approach 2:
The partition walls in the evaporator and condenser serve multiple functions: they separate vaporization and condensation zones, provide structural support for the thin plate structure, and guide working fluid flow between chambers. This multi-functionality reduces the need for additional components, lowering structural 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
The loop heat pipe design effectively transfers heat by leveraging increased capillary force and reduced fluid flow resistance, enhancing heat transfer efficiency and enabling thinner, more practical implementations in mobile devices.
Implementation Method 1
Heat pipes are heat transfer devices which use latent heat of vaporization of a working fluid
Implementation Method 2
Heat pipes are heat transfer devices which use latent heat of vaporization of a working fluid
Implementation Method 3
the plurality of first recesses face either or both of the plurality of third protrusions and the plurality of fourth protrusions while each of the plurality of first recesses communicates with the second recesses located on both sides of a corresponding third or fourth protrusion
Data Source
AI summary
A loop heat-pipe includes an evaporator; a condenser; a first line which connects the evaporator to the condenser and in which working fluid of vapor phase flows; and a second line which connects the condenser to the evaporator and in which working fluid of liquid phase flows, wherein each of the evaporator, the condenser, the first line, and the second line is bonded to a first and second plate, the first plate includes in a region for the evaporator: first protrusions that extend in a length direction, and second protrusions that extend in a width direction, which intersects with the length direction; the second plate includes in a region for the evaporator: either or both of third protrusions extending in the length direction and fourth protrusions extending in the width direction, and recesses partitioned by either or both of the third protrusions and the fourth protrusions.