Top-Flow Heat Exchanger Segmentation for Even Refrigerant Distribution
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Solution Overview
Problem
In top-flow type heat exchangers, refrigerant distribution is uneven due to thermal and air velocity gradients, leading to suboptimal heat exchange performance and incomplete defrosting in outdoor units of air conditioners, especially when header pipes are bent to accommodate multiple surfaces, increasing device size and cost.
Innovation Solution
A top-flow type air conditioner design with a refrigeration circuit featuring multiple heat exchange sections, each with liquid-side and gas-side header pipes and perforated pipes for even refrigerant distribution, along with a bypass pipe for defrosting, which includes flow control and branch sections to manage refrigerant flow and temperature distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If header pipes are bent to align with multiple surfaces of the outdoor unit casing, then the heat exchanger can be installed on multiple surfaces, but the device size and manufacturing cost increase due to large bending loads
Solution Approach 1:
The heat exchanger is divided into multiple independent heat exchange sections (first, second, third sections) that can be separately installed on different surfaces of the outdoor unit casing. Each section has its own header pipes that remain straight, avoiding the need to bend header pipes while still achieving multi-surface installation capability.
2Manufacturing precision
If a parallel-flow type heat exchanger is configured with horizontally disposed header pipes to reduce gravity effects, then refrigerant flow uniformity improves, but the header pipes require large bending loads when installed on multiple surfaces
Solution Approach 1:
The heat exchanger is segmented into multiple heat exchange sections with straight header pipes oriented in the same direction. This segmentation allows each section to maintain optimal horizontal header pipe configuration for uniform refrigerant flow while simplifying installation on multiple surfaces without requiring large bending operations.
Solution Approach 2:
The heat exchange sections are arranged in different spatial dimensions and orientations on the outdoor unit casing surfaces. By distributing sections across multiple surfaces rather than bending a single header pipe configuration, the system achieves multi-surface installation while maintaining straight header pipes for optimal refrigerant flow distribution.
3Device complexity
If refrigerant is distributed through a branch section assuming even distribution, then the system structure simplifies, but thermal load distribution in the horizontal direction causes uneven refrigerant distribution among blocks
Solution Approach 1:
Each heat exchange section is equipped with its own dedicated liquid-side header pipe and flow control section, allowing independent refrigerant flow control for each section. This local quality approach ensures that each section receives appropriate refrigerant flow according to its specific thermal load conditions, achieving uniform refrigerant distribution despite horizontal thermal load variations.
Solution Approach 2:
The refrigerant distribution system is segmented into multiple independent pathways, with each heat exchange section having its own header pipe and flow control section. This segmentation replaces the single branch section approach, enabling precise control of refrigerant distribution to each section based on local thermal conditions.
4Productivity
If refrigerant flow is controlled through multiple heat exchange sections connected in parallel, then heat exchange performance improves, but the system complexity increases with multiple header pipes and flow control sections
Solution Approach 1:
The heat exchanger is divided into multiple independent heat exchange sections connected in parallel, each with its own header pipes and flow control sections. This segmentation improves heat exchange performance by allowing each section to operate independently and efficiently while maintaining manageable system complexity through modular design.
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
Ensures even refrigerant distribution across multiple heat exchange sections, enhancing heat exchange performance and efficiently melting frost during defrosting operations without the need for complex branch designs, thus improving overall system efficiency and reducing ice buildup.
Implementation Method 1
a plurality of the liquid-side header pipes are connected to a liquid-side collecting pipe through an intermediation of a branch section and at least one flow control section
Implementation Method 2
a plurality of heat exchange pipes provided between the liquid-side header pipe and the gas-side header pipe
Implementation Method 3
the bypass pipe includes an on-off valve to be closed during cooling and heating, and to be opened during defrosting
Implementation Method 4
ice caused by frost formation in a lower section of the heat exchanger is not completely melted during a defrosting operation
Data Source
AI summary
The outdoor heat exchanger includes, on each of the three or more heat exchange sections, a liquid-side header pipe, a gas-side header pipe, and a plurality of heat exchange pipes, the three or more heat exchange sections are connected in parallel to one another, a plurality of the liquid-side header pipes are connected to a liquid-side collecting pipe through an intermediation of a branch section and at least one flow control section, each of the plurality of the liquid-side header pipes includes a perforated pipe, the refrigeration circuit further includes a bypass pipe for connecting a discharge side of the compressor and the liquid-side collecting pipe, and the bypass pipe includes an on-off valve to be closed during cooling and heating, and to be opened during defrosting.