Heat Exchanger Header Wicking Insert for Uniform Microtube Refrigerant Flow
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Solution Overview
Problem
Traditional microtube heat exchangers face inefficiencies due to poor refrigerant distribution, leading to phase separation and reduced heat exchange effectiveness, especially when dealing with thousands of microtubes, as conventional technologies can only supply approximately 40-50 channels and are not suitable for larger tube stacks.
Innovation Solution
Incorporating a porous insert with capillary force into the heat exchanger header to evenly distribute refrigerant across microtubes, utilizing capillary action to maintain a uniform mixture and minimize phase separation, thereby enhancing the heat exchange process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional refrigerant distribution technology is used, then the system can supply approximately 40-50 channels, but it cannot effectively distribute refrigerant to thousands of microtubes
Solution Approach 1:
The patent employs a porous wicking material in the header that utilizes capillary forces to distribute refrigerant across thousands of microtube inlets. The porous structure enables uniform refrigerant flow distribution to a large number of channels without requiring complex mechanical distribution systems, thereby scaling from 40-50 channels to thousands of microtubes.
2Loss of energy
If refrigerant enters the header and spreads freely, then the vapor occupies disproportionate volume, but this causes phase separation and reduces heat exchange efficiency
Solution Approach 1:
The porous wicking material in the header uses capillary forces to control refrigerant flow distribution, preventing vapor from occupying disproportionate volume and maintaining uniform two-phase mixture across all microtube inlets, thereby eliminating regional phase separation and improving heat exchange efficiency.
Solution Approach 2:
The patent replaces traditional mechanical mixing devices with capillary forces generated by the porous wicking material to achieve uniform refrigerant distribution. This substitution eliminates the need for complex mechanical components while maintaining stable two-phase mixture composition across all channels.
3Stability of the object's composition
If a mixing device or orifice is used to combine vapor-liquid, then homogenous mixture is achieved, but this increases device complexity and weight
Solution Approach 1:
The patent extracts and eliminates the need for separate mixing devices or orifices by integrating the mixing function directly into the header through the porous wicking material. The capillary forces within the porous structure perform the mixing function, removing unnecessary components and reducing overall system weight.
Solution Approach 2:
The header with porous wicking material performs multiple functions simultaneously: it distributes refrigerant, mixes vapor-liquid phases, and maintains uniform composition across all microtube inlets. This multi-functionality eliminates the need for separate mixing devices, reducing weight and simplifying the system.
4Ease of operation
If open header configuration is used to introduce two-phase liquid, then refrigerant can enter freely, but this exacerbates expansion and separation issues
Solution Approach 1:
The porous wicking material in the header provides a controlled interface for refrigerant entry and distribution. While maintaining ease of operation with simple refrigerant introduction, the capillary forces in the porous structure prevent uncontrolled expansion and phase separation, ensuring uniform two-phase distribution across all microtube inlets.
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 use of a porous insert with capillary force improves refrigerant distribution, increasing the efficiency of the heat exchanger by promoting liquid flow through more microtubes, eliminating the need for mixing devices, and maintaining high efficiency without significant weight or pressure drop.
Implementation Method 1
By way of capillary force, working fluid is pulled through the pores and ultimately saturates a section of the porous insert
Implementation Method 2
utilizing capillary action to maintain a uniform mixture and minimize phase separation
Data Source
AI summary
A heat exchanger including a tube stack having a plurality of microtubes configured to transfer heat from a refrigerant to an external fluid. The heat exchanger includes an inlet housing disposed adjacent to a fluid-inlet side of the tube stack. The inlet housing includes a reservoir where refrigerant is stored and where, due to gravity, liquid of the refrigerant pools in a bottom of the reservoir. The heat exchanger includes a wicking insert disposed at a tube stack opening of inlet housing adjacent to and covering the fluid-inlet side of the tube stack. The wicking insert has a porous structure configured to provide a capillary force within the porous structure, and is disposed within the pooled liquid to draw the liquid from the bottom of the reservoir through the porous structure of the wicking insert by the capillary force.