Electrochemically Printed Wicking Structures for Dry-Out Control
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Solution Overview
Problem
Conventional multiphase heat exchangers face limitations such as instability during flow boiling, leading to 'dry-out' conditions, poor uniformity of wicking structures, weak thermal contact, and inability to tailor geometrically complex features, hindering efficient fluid distribution and heat transfer.
Innovation Solution
A multiphase heat exchanger with electrochemically integrated wicking structures, fabricated using ECAM, which allows precise customization of geometry, location, and density to enhance capillary-driven flow and mitigate vapor entrapment, featuring tailored wicking structures on sidewalls, channel bases, or fin surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If powder-based sintering or foamed metal techniques are used to fabricate wicking structures, then wicking structures can be formed, but uniformity is poor and thermal contact with base plates is weak
Solution Approach 1:
The wicking structure is integrated as a single piece with the base plate, eliminating the interface between separate components. This merging of the wick and base plate into one monolithic structure ensures continuous thermal contact and eliminates gaps that would reduce thermal efficiency.
Solution Approach 2:
The wicking structure features spatially varying pore sizes and densities tailored to specific locations. Near the heating surface, smaller pores are used to maintain liquid supply, while larger pores are used farther away to facilitate vapor escape and liquid return, optimizing local heat transfer conditions throughout the structure.
2Adaptability or versatility
If conventional fabrication techniques are used, then wicking structures can be manufactured, but geometrically complex features cannot be tailored
Solution Approach 1:
The fabrication method enables continuous variation of geometric parameters including pore size, pore shape, wall thickness, and spatial distribution throughout the wicking structure. This allows optimization of capillary pressure, permeability, and surface area-to-volume ratio to match specific heat transfer requirements.
Solution Approach 2:
The wicking structure is designed with functionally distinct regions: a first portion near the heating surface with smaller pores for liquid supply, and a second portion farther away with larger pores for vapor escape and liquid return. This segmentation allows each region to be optimized for its specific function.
3Reliability
If wicking structures are not optimized, then manufacturing is simpler, but fluid distribution and vapor entrapment control are hindered
Solution Approach 1:
The wicking structure features spatially varying pore sizes and densities tailored to specific locations. Near the heating surface, smaller pores are used to maintain liquid supply, while larger pores are used farther away to facilitate vapor escape and liquid return, optimizing local heat transfer conditions throughout the structure.
Solution Approach 2:
The wicking structure is designed to dynamically adapt to changing operating conditions through its graded pore structure, which automatically balances liquid supply and vapor escape based on local pressure and temperature conditions without requiring external control.
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 solution supports higher thermal loads, improved reliability, and consistent manufacturing for advanced heat transfer applications by maintaining fluid distribution and phase-change efficiency.
Implementation Method 1
the wicking structures promote capillary-driven liquid transport
Implementation Method 2
wicking structures electrochemically deposited on a base surface formed by at least one of (a) the evaporator base forming an evaporator
Implementation Method 3
the evaporator is configured to evaporate the heat-transfer fluid, from a liquid phase to a gas phase, upon receiving heat from the heat source
Implementation Method 4
heat-transfer fluids change phase (e.g., liquid-gas) to provide additional heat transfer capabilities
Implementation Method 5
the condenser is configured to condense the heat-transfer fluid, from the gas phase to the liquid phase, by releasing heat through the external heat-release interface
Implementation Method 6
heat-transfer fluids change phase (e.g., liquid-gas) to provide additional heat transfer capabilities
Data Source
AI summary
A method of fabricating a multiphase heat exchanger for thermal coupling to a heat source is provided. The method includes submerging a build plate having a deposition surface into an electrolyte, the deposition surface comprising at least one of an evaporator base, a condenser base, or a liquid-return base. A printhead comprising pixelated electrodes and electrode-array drivers is submerged proximate to the deposition surface. A subset of the pixelated electrodes is selectively activated to generate an ionic flow through the electrolyte between the electrode subset and a portion of the deposition surface, thereby electrochemically depositing wicking structures on the base surface. Any two adjacent wicking structures positioned on the evaporator base are spaced apart by an average pitch selected to maintain a heat-transfer fluid, in a liquid phase, in contact with the evaporator base during operation of the multiphase heat exchanger.