Heat Exchanger Duct Width Function for Thermal Isolation
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Solution Overview
Problem
Microchannel heat exchangers face efficiency issues due to low flow rates in corner areas of triangular channels and require precise alignment of layers to prevent thermal contact, which can lead to reduced performance if not aligned correctly.
Innovation Solution
A heat exchanger design featuring flat sheets and profiled sheets with a specific width function that creates parallel ducts with varying cross-sections, minimizing thermal contact between layers and optimizing heat transfer by forming a combination of triangular and rectangular shapes, allowing for improved flow balance and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If triangular shaped channels are used, then the structure is simple, but the flow rate in outer corners is low reducing heat transfer efficiency
Solution Approach 1:
The channel cross-section is segmented into multiple zones with different widths. The width function w(d) creates distinct regions: a narrow triangular zone near the flat sheet (0≤d<d1) and a wider rectangular zone (d1≤d<d2), allowing each zone to serve different functions - the triangular zone minimizes thermal contact while the rectangular zone enhances heat transfer surface area
Solution Approach 2:
The channel width parameter is changed as a function of distance from the flat sheet. By using a piecewise linear width function with different slopes (c1, c2, c3) in different zones, the channel transitions from triangular to rectangular cross-section, optimizing both flow characteristics and heat transfer efficiency
2Stability of the object's composition
If flat sheets are added to stabilize the structure, then structural stability improves, but precise alignment is required preventing thermal contact between same-type channels
Solution Approach 1:
The harmful thermal contact between same-type channels is extracted/eliminated by designing the channel width to be zero at the flat sheet interface (w(0)=0). This creates a natural thermal isolation without requiring precise alignment, as the minimal width inherently prevents thermal coupling between adjacent layers
Solution Approach 2:
The design preliminarily prevents thermal contact by making the channel width zero at the interface with the flat sheet. This preliminary anti-action (minimal thermal contact) is built into the geometry itself, preventing the harmful effect before it can occur, regardless of alignment precision
3Ease of operation
If rectangular shaped channels are used, then flow speed is more homogeneous, but the structure requires precise alignment to avoid thermal contact between layers
Solution Approach 1:
Different parts of the channel have different local qualities - the lower zone (near flat sheet) has triangular cross-section for minimal thermal contact, while the upper zone has rectangular cross-section for homogeneous flow. This local differentiation allows each zone to optimize for its specific function
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 design enhances the effective heat exchanging surface area and maintains efficiency even if layers are not perfectly aligned, while being easier to manufacture and assemble, resulting in improved thermal performance and stability.
Implementation Method 1
the profiled sheets and the flat sheets together create a plurality of parallel ducts arranged in layers... Each duct has a width w(d) which is a function of a distance d... the width linearly increases until the distance d is equal to a value d1... A substantially rectangular shape, which is formed by the second part, will result in an improved effective heat exchanging surface
Data Source
AI summary
A heat exchanger including a plurality of flat sheets arranged in parallel and a plurality of profiled sheets, each of which including a number of straight segments and being arranged between two subsequent flat sheets and having a repeating profile. The profiled sheets and the flat sheets together create a plurality of parallel ducts arranged in layers. The parallel ducts are divided by the profiled sheets into ducts of a first type and ducts of a second type, the ducts of the second type neighboring the ducts of the first type. Each duct of the first and second type has a width w(d) which is a function of a distance d with d the distance from a first flat sheet.