Bent-Header Heat Exchanger for Residential HVAC
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Solution Overview
Problem
Current outdoor heat exchangers for residential air conditioning and heat pump systems are large due to non-optimized designs, leading to higher costs and refrigerant charge inefficiencies, and microchannel heat exchangers are sensitive to refrigerant imbalances, causing performance degradation and shutdowns.
Innovation Solution
A heat exchanger design featuring parallel flow with bent headers and optimized tube and fin configurations, including specific dimensions and orientations, to reduce size and refrigerant charge while improving airflow and refrigerant distribution, allowing for multi-pass configurations and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional heat exchanger designs are used, then the heat exchanger can provide adequate heat transfer capacity, but the size and refrigerant charge become excessively large
Solution Approach 1:
The patent applies parameter changes by optimizing the tube depth (changing from conventional depths to specific ranges like 8-20mm), adjusting tube pitch (8.9-15.5mm), and modifying fin density (10-25 fins per inch) to achieve compact size while maintaining heat transfer capacity and reducing refrigerant charge by 50-70%
Solution Approach 2:
The patent utilizes another dimension by implementing multi-pass configurations (first pass and second pass with tube ratios of 0.3-3) that arrange tubes in multiple rows deep, effectively using the depth dimension to increase heat transfer surface area within a compact footprint, reducing the overall volume while maintaining capacity
2Volume of moving object
If microchannel heat exchangers are used to reduce size, then the heat exchanger becomes more compact, but sensitivity to refrigerant imbalance increases causing performance degradation
Solution Approach 1:
The patent applies local quality by creating different flow paths with varying numbers of tubes in first pass and second pass configurations (ratio 0.3-3), where each pass is optimized for specific flow conditions, ensuring balanced refrigerant distribution across different zones of the heat exchanger and reducing sensitivity to overall refrigerant charge variations
Solution Approach 2:
The patent segments the heat exchanger into multiple passes with distinct tube groups, where the first pass and second pass are separated by headers with bends, allowing independent optimization of each pass's refrigerant flow characteristics and improving overall distribution tolerance
3Volume of moving object
If heat exchanger size is reduced, then cost and refrigerant charge decrease, but heat transfer capacity may be compromised
Solution Approach 1:
The patent employs composite heat transfer surfaces by combining tubes with fins attached, creating a composite structure that maximizes heat transfer area. The fin density (10-25 fins per inch) and louver configurations (pitch 1-1.7mm, angle 28-45 degrees) are optimized to enhance heat transfer capacity within the reduced volume
Solution Approach 2:
The patent maintains heat transfer capacity through optimized parameters including tube depth (8-20mm), tube pitch (8.9-15.5mm), and fin density (10-25 fins per inch), which collectively ensure adequate heat transfer surface area and thermal conductivity within the compact 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
The design results in a substantial size and cost reduction of up to 70% and a 50-70% reduction in refrigerant charge, with improved performance through enhanced refrigerant and air distribution, and optimal heat transfer and hydraulic resistance balance.
Implementation Method 1
a plurality of heat exchange tubes arranged in a spaced parallel relationship and fluidly coupling the first and second headers
Implementation Method 2
The plurality of fins may be disposed in thermal communication with the plurality of heat exchanger tubes
Data Source
Figure 1
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Figure 4~5
AI summary
A heat exchanger is provided including a first header, a second header, and a plurality of heat exchange tubes arranged in a spaced parallel relationship and fluidly coupling the first and second headers. At least one of the first header, second header and the plurality of heat exchange tubes includes a bend. The heat exchanger having an aspect ratio between about 2 and 6 after formation of the bend.