Plate Heat Exchanger Dual-Scale Pattern High Pressure
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Solution Overview
Problem
Brazed plate heat exchangers are not strong enough to withstand high pressures, particularly when using carbon dioxide as a refrigerant, and they have uniform flow channel lengths which are inefficient for varying heat transfer rates between different media.
Innovation Solution
A plate heat exchanger design featuring stacked plates with a large-scale pressed pattern for distance and contact points, combined with a small-scale pattern for varying flow channel lengths and pressures, allowing for brazing and selective fluid flow through channels of different sizes and shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the pressed pattern of the heat exchanger plates is made narrow to increase design pressure, then the design pressure increases, but the pressure drop increases and the small distance between plates reduces heat transfer efficiency
Solution Approach 1:
The pressed pattern is segmented into two distinct scales: a large-scale pattern that defines the overall plate spacing and flow channel geometry, and a small-scale pattern that creates local contact points for brazing. This segmentation allows the large-scale pattern to maintain larger plate distances (reducing pressure drop) while the small-scale pattern provides concentrated support points (increasing design pressure).
Solution Approach 2:
The small-scale pressed pattern creates localized contact points between adjacent plates at specific positions, while the large-scale pattern maintains the overall spacing. This local quality differentiation allows high pressure resistance at contact points without requiring small distances throughout the entire plate structure, thus reducing overall pressure drop.
2Ease of manufacture
If all flow channels have the same length, then the manufacturing is simplified, but the heat transfer efficiency decreases for media requiring longer passages
Solution Approach 1:
The flow channels are designed with asymmetric lengths by utilizing the large-scale pressed pattern to create different channel geometries. Some channels have longer passages to enhance heat transfer for media like brine solutions, while others have shorter passages, all within the same plate stack configuration. This asymmetric design maintains manufacturing simplicity through a standardized pressing process while achieving varied heat transfer performance.
3Area of stationary object
If the distance between plates is reduced to increase heat transfer surface density, then the heat transfer area increases, but the design pressure decreases
Solution Approach 1:
The plate spacing function is segmented between two pattern scales: the large-scale pattern establishes the primary flow channel geometry with adequate spacing for pressure containment, while the small-scale pattern creates localized contact points that provide structural support for high pressure resistance. This allows maintaining both reasonable plate distances for pressure integrity and sufficient heat transfer surface density.
Solution Approach 2:
The dual-scale pressed pattern creates a composite structural effect where the large-scale pattern provides the overall flow channel architecture and pressure containment, while the small-scale pattern adds localized reinforcement at contact points. This composite approach allows the plate structure to withstand high pressures while maintaining adequate spacing for heat transfer.
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 burst pressure and heat exchange efficiency by allowing varying channel lengths and pressures, improving performance with carbon dioxide and brine solutions without increasing the heat exchanger's physical length.
Implementation Method 1
The plates are provided with a first, large scale pressed pattern comprising ridges and grooves intended to keep first and second pairs of stacked plates on a distance from one another, such that flow channels for a first medium is formed in spaces between said plate pairs
Implementation Method 2
The plates of each plate pair are kept on a distance from one another by a small-scale pressed pattern comprising ridges and grooves
Implementation Method 3
contact points are provided between the plate pairs in points where the large scale pressed pattern of neighboring plate pairs contact one another
Implementation Method 4
a plate heat exchanger for exchanging heat between media, the heat exchanger comprising a number of stacked plates
Data Source
AI summary
A plate heat exchanger for exchanging heat between mediacomprises a number of stacked plates (A, B, C, D), the plates being provided with a first, large scale pressed pattern comprising ridges (R) and grooves (G) intended to keep first (A, B) and second (B,C) pairs of stacked plates on a distance from one another, such that flow channels for a first medium is formed in spaces between said plate pairs. Contact points are provided between the plate pairs in points where the large scale pressed pattern of neighboring plate pairs contact one another. The plates of each plate pair (A, B; C, D) are kept on a distance from one another by a small-scale pressed pattern comprising ridges (r) and grooves (g).