Counterflow Flat-Tube Heat Exchanger for Even Refrigerant Distribution
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Solution Overview
Problem
Heat exchangers with flat tubes face challenges in evenly distributing refrigerant due to increased refrigerant pressure loss, leading to reduced heat transfer performance and potential frost formation when refrigerant temperature drops below 0°C, especially in high-density arrangements.
Innovation Solution
The heat exchanger design features flat tubes arranged in multiple levels and columns with U-shaped bent portions, allowing counterflow of refrigerant and air, and utilizing a header system to distribute refrigerant evenly across multiple paths, reducing pressure loss and maintaining efficient heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If flat tubes are used for high-density arrangement, then fin efficiency and heat transfer area are improved, but refrigerant pressure loss increases
Solution Approach 1:
The refrigerant passage is segmented into multiple paths by dividing the flat tubes into multiple sections. Each section has its own refrigerant flow path, allowing the refrigerant to be distributed more effectively and reducing the pressure loss in each individual path while maintaining the high-density arrangement of flat tubes.
Solution Approach 2:
The patent introduces a new dimension by arranging flat tubes in multiple levels (stacked configuration) rather than a single plane. This three-dimensional arrangement increases the heat transfer area and fin efficiency while managing the refrigerant pressure loss through multi-level path distribution.
2Loss of energy
If the number of refrigerant streams is increased to reduce pressure loss, then pressure distribution is improved, but refrigerant distribution evenness deteriorates
Solution Approach 1:
The patent applies local quality by creating different refrigerant flow paths with different characteristics. Each path is designed with specific local features (different numbers of flat tubes, different path lengths) to balance the refrigerant distribution, ensuring that refrigerant flows evenly across all paths despite the increased number of streams.
Solution Approach 2:
The patent changes the parameters of the refrigerant passage configuration, including the number of paths, the arrangement of flat tubes in each path, and the connection points between paths. By optimizing these parameters, the system achieves both reduced pressure loss and improved refrigerant distribution evenness.
3Productivity
If refrigerant pressure is reduced due to pressure loss, then heat transfer performance may improve through better distribution, but refrigerant temperature drops below 0°C causing frost formation
Solution Approach 1:
The patent incorporates a feedback mechanism where the refrigerant passage configuration is designed to monitor and adjust refrigerant distribution based on pressure and temperature conditions. The multi-path arrangement allows the system to self-regulate refrigerant flow to maintain temperatures above 0°C while optimizing heat transfer performance.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the refrigerant passage paths and flat tube arrangements to anticipate and prevent frost formation. The system is designed beforehand with adequate pressure loss compensation and temperature maintenance features, ensuring refrigerant stays above freezing point before entering the heat exchange zones.
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
This design ensures even refrigerant distribution, reduces pressure loss, and maintains heat transfer performance while preventing frost formation by maintaining refrigerant temperature above 0°C, enhancing the overall efficiency of the heat exchanger.
Implementation Method 1
a plurality of flat tubes 101 through which refrigerant flows to exchange heat with the gas
Implementation Method 2
The flat tubes in at least two levels bent or connected to each other at one end in an axial direction of the flat tubes and the flat tubes in at least two columns connected to each other are included in refrigerant passages through which the refrigerant flows
Implementation Method 3
The flow direction of the gas is counter to flow of the refrigerant through the refrigerant passages in the column direction while the heat exchanger serves as a condenser
Data Source
AI summary
A heat exchanger is configured such that flat tubes in at least two levels bent or connected to each other at one end in an axial direction of the flat tubes and the flat tubes in at least two columns connected to each other are included in refrigerant passages through which refrigerant flows, and a flow direction of gas is counter to flow of refrigerant through the refrigerant passages in a column direction while the heat exchanger serves as a condenser.