Two-Row Heat Exchanger Layout for Better Refrigerant Subcooling
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Solution Overview
Problem
The existing two-row-configuration heat exchanger with flat multi-hole pipes in air-conditioning apparatuses faces challenges in maintaining a temperature difference between air and refrigerant, particularly in the subcooling region, leading to suppressed heat-exchanging performance.
Innovation Solution
The indoor unit is configured with a first heat exchanger on the air upstream side and a second heat exchanger on the air downstream side, featuring a unique arrangement of flat multi-hole pipes and headers that allow refrigerant flow direction to optimize subcooling and reduce temperature irregularity, enhancing the temperature difference and heat-exchanging performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a two-row-configuration heat exchanger with flat multi-hole pipes is used, then the heat exchanger can be mounted on an air-conditioning apparatus, but the temperature difference between air and refrigerant is not easily assured in the subcooling region, suppressing heat-exchanging performance
Solution Approach 1:
The patent applies the inversion principle by reversing the conventional refrigerant flow arrangement. Instead of having refrigerant flow in the same direction through both heat exchangers, the patent configures the refrigerant to flow in opposite directions: upward through the first heat exchanger (air upstream side) and downward through the second heat exchanger (air downstream side). This inversion of flow direction ensures that the subcooling region of the second heat exchanger receives cooler air from the first heat exchanger, maintaining a sufficient temperature difference and improving heat-exchanging performance.
2Temperature
If air flows through the superheating region of the heat exchanger on the air upstream side, then the refrigerant can be superheated, but the heated air flows into the heat exchanger on the air downstream side, making it difficult to assure temperature difference for subcooling
Solution Approach 1:
The patent uses the inversion principle by reversing the refrigerant flow direction in the second heat exchanger. While air flows sequentially from the first heat exchanger to the second heat exchanger, the refrigerant flows downward through the second heat exchanger (opposite to the upward flow in the first heat exchanger). This creates a counter-current flow arrangement where the coldest refrigerant meets the coolest air in the subcooling region, maximizing the temperature difference and the amount of refrigerant that can be subcooled.
Solution Approach 2:
The patent applies the local quality principle by creating different flow patterns in different regions of the heat exchanger system. The first heat exchanger uses upward refrigerant flow for superheating, while the second heat exchanger uses downward refrigerant flow for subcooling. This localized differentiation of flow directions optimizes the temperature difference in each region, allowing effective superheating in the first heat exchanger and effective subcooling in the second heat exchanger despite the sequential air flow path.
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 increases the amount of refrigerant subcooled, improves heat-exchanging performance, reduces heat conduction loss, and optimizes refrigerant flow, leading to enhanced efficiency as both a condenser and evaporator.
Implementation Method 1
heat exchanger unit... heat-exchanging performance
Implementation Method 2
fan to generate an air flow... air flow generated by the fan
Data Source
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AI summary
There is provided a heat exchanger unit configured to improve heat-exchanging performance in an air-conditioning apparatus. A heat exchanger unit (42) includes a first heat exchanger (52) and a second heat exchanger (62). The first heat exchanger (52) includes a first header (523) and a second header (524), and a first flat pipe group (500) including a plurality of flat multi-hole pipes connected to each of the first header (523) and the second header (524). The second heat exchanger (62) is arranged in parallel with the first heat exchanger (52) and disposed on an air downstream side, from the first heat exchanger (52), of an air flow generated by an indoor fan (41). The second heat exchanger (62) includes a third header (623) and a fourth header (624), and a second flat pipe group (600) including a plurality of flat multi-hole pipes connected to each of the third header (623) and the fourth header (624). The fourth header (624) causes a refrigerant that flows in from the third header (623) to flow out to the first header (523).