Flat-Pipe Heat Exchanger Layout for Uniform Two-Phase Refrigerant Flow
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Solution Overview
Problem
The existing heat exchangers in refrigeration and air-conditioning systems face inefficiencies due to non-uniform gas-liquid distribution at low flow-rates, leading to reduced temperature efficiency and increased pressure loss at high flow-rates, making it difficult to achieve compact and high-performance operation.
Innovation Solution
A heat exchanger design where the second inlet header is positioned horizontally, allowing the low-temperature fluid to flow into the second flat pipes in a substantially horizontal direction, ensuring uniform gas-to-liquid distribution and minimizing pressure loss, even at varying flow-rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the header diameter is reduced to improve gas-liquid mixing at low flow-rates, then the gas-to-liquid distribution becomes more uniform, but the pressure loss increases significantly at high flow-rates
Solution Approach 1:
The patent applies local quality by creating different flow conditions in different regions of the header. The horizontal inlet section provides a specific flow pattern that promotes mixing, while the downstream section allows for pressure recovery. This localized optimization of flow characteristics resolves the contradiction between mixing quality and pressure loss.
Solution Approach 2:
The patent changes the flow direction parameter from vertical to horizontal at the inlet, which fundamentally alters the flow dynamics. This parameter change enables effective gas-liquid mixing at low flow-rates without creating excessive pressure losses at high flow-rates, as the horizontal flow allows for a more gradual pressure drop while maintaining mixing effectiveness.
2Productivity
If the heat exchanger size is increased to compensate for deteriorated heat exchanging performance, then the heat exchange capacity is maintained, but the compactness is reduced
Solution Approach 1:
By changing the inlet flow direction to horizontal, the patent improves heat exchange efficiency per unit volume. This parameter change allows the heat exchanger to maintain or enhance heat exchange capacity without increasing size, as the improved gas-liquid distribution maximizes the effectiveness of the existing heat transfer surfaces.
3Ease of manufacture
If the inlet header is positioned vertically to simplify structure, then the manufacturing is easier, but the gas-liquid mixing becomes insufficient at low flow-rates
Solution Approach 1:
The patent inverts the conventional vertical inlet orientation to a horizontal orientation. This inversion fundamentally changes the flow dynamics and mixing characteristics, enabling effective gas-liquid distribution that the vertical configuration cannot achieve, particularly at low flow-rates where mixing is most problematic.
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 enhances temperature efficiency and reduces pressure loss, resulting in a compact, high-performance heat exchanger that maintains effective heat transfer across a wide operating range.
Implementation Method 1
a low-temperature fluid in a two-phase gas-liquid state flows into the second flat pipes from the second inlet header in a substantially horizontal direction
Implementation Method 2
a heat exchanger that is adapted to exchange heat between a low-temperature fluid and a high-temperature fluid so as to transfer the heat from the high-temperature fluid to the low-temperature fluid
Data Source
Figure 1(a)~1(c)
Figure 2
Figure 3(a)~3(c)
AI summary
A heat exchanger (10) includes a first flat pipe (1) having a plurality of through-holes through which a high-temperature fluid flows, a second flat pipe (2) having a plurality of through-holes (21) through which a low-temperature fluid flows, a first inlet header (3) having a tubular shape and connected to one end of the first flat pipe (1), a first outlet header (4) having a tubular shape and connected to other end of the first flat pipe (1), a second inlet header (5) having a tubular shape and connected to one end of the second flat pipe (2), and a second outlet header (6) having a tubular shape and connected to other end of the second flat pipe (2). The first flat pipe (1) and the second flat pipe (2) are stacked such that flat surfaces thereof are in contact with each other. The low-temperature fluid flowing into the through-holes (21) in the second flat pipe (2) from the second inlet header (5) is a fluid in a two-phase gas-liquid state. The low-temperature fluid flows into the through-holes (21) in the second flat pipe (2) from the second inlet header (5) in a substantially horizontal direction or in an upward direction relative to the substantially horizontal direction.