Evaporator Header Layout for Uniform Two-Phase Refrigerant Flow
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Solution Overview
Problem
In a heat exchanger used as an evaporator, the inhomogeneous distribution of gas-liquid two-phase refrigerant leads to a decrease in performance due to the liquid phase refrigerant with high density failing to reach upper heat transfer tubes, resulting in a lower flow rate and inefficient heat exchange.
Innovation Solution
The heat exchanger incorporates a first and second header section with connecting tubes that separate and redistribute the refrigerant based on density, ensuring a homogeneous distribution by supplying high liquid phase content to the upper portion and high gas phase content to the lower portion of the second header section, allowing for uniform mixing and flow rates across all heat transfer tubes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single connecting tube is used to connect the header regions, then the structure is simple, but the refrigerant distribution becomes inhomogeneous causing performance decrease
Solution Approach 1:
The single connecting tube is divided into multiple connecting tubes (first connecting tube and second connecting tube) that connect different regions of the first header to different regions of the second header. This segmentation allows separate control of refrigerant flow paths, enabling homogeneous distribution of gas-liquid two-phase refrigerant to upper and lower heat transfer tubes, thereby resolving the contradiction between structural simplicity and performance.
2Ease of manufacture
If the connecting tube is positioned at the lower portion of the header, then the structure is simple, but the liquid phase refrigerant with high density cannot reach upper heat transfer tubes resulting in lower flow rate
Solution Approach 1:
The connecting tubes are arranged in multiple vertical positions (upper and lower portions) of the header, utilizing the vertical dimension to create separate flow paths. The first connecting tube connects the lower portion of the first header to the upper portion of the second header, while the second connecting tube connects the upper portion of the first header to the lower portion of the second header. This dimensional arrangement ensures that liquid phase refrigerant can reach upper heat transfer tubes through the first connecting tube, resolving the contradiction between manufacturing simplicity and refrigerant flow rate.
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 configuration stabilizes the gas-liquid ratios and flow rates, enhancing the heat exchange performance by ensuring uniform refrigerant distribution and reducing pressure loss, thus suppressing efficiency decreases in the heat exchanger and air conditioner.
Implementation Method 1
a refrigerant with a high liquid phase content and a high density, out of gas-liquid two phase refrigerants introduced in the first header section via the first heat transfer tubes, is introduced into the first connecting tube connected to the lower portion of the first header section
Data Source
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AI summary
A heat exchanger (10) is provided with: a plurality of first heat transfer tubes (21); a first header section (52); a plurality of second heat transfer tubes (22); a second header section (53); a first connecting tube (55); and a second connecting tube (56). The plurality of first heat transfer tubes (21) extend in the horizontal direction and are arranged with gaps therebetween in the vertical direction. One end of each of the plurality of first heat transfer tubes (21) is connected to the first header section (52) in a communicating state. The plurality of second heat transfer tubes (22) extend in the horizontal direction and are arranged with gaps therebetween in the vertical direction. One end of each of the plurality of second heat transfer tubes (22) is connected to the second header section (53) in a communicating state. The first connecting tube (55) connects a lower portion of the first header section (52) and an upper portion of the second header section (53). The second connecting tube (56) connects an upper portion of the first header section (52) and a lower portion of the second header section (53).