Single-Row Heat Exchanger Flow Path Switching to Reduce Pressure Loss
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Solution Overview
Problem
Conventional single-row and multiple-row heat exchangers face efficiency issues due to uneven refrigerant distribution and pressure loss, leading to reduced heat exchange efficiency, particularly when operating as evaporators or condensers.
Innovation Solution
A refrigeration cycle apparatus with a single-row outdoor heat exchanger featuring multiple flat heat transfer tubes and a flow path switching unit that adjusts the refrigerant flow paths and flow rates between condenser and evaporator operations, optimizing the arrangement of pipes and heat exchange units to enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the length of refrigerant flow path in each flat heat transfer tube is increased to improve condensation capacity, then condensation capacity is improved, but pressure loss of refrigerant increases when operating as evaporator
Solution Approach 1:
The patent applies dynamics by making the refrigerant flow path configuration adjustable between series and parallel connections based on operational mode. The flow path switching unit dynamically reconfigures the refrigerant flow paths: in cooling mode, tubes are connected in series to maximize condensation capacity with longer effective flow paths; in heating mode, tubes are connected in parallel to reduce pressure loss and improve evaporator performance. This dynamic reconfiguration resolves the contradiction between condensation capacity and pressure loss.
2Productivity
If multiple rows of flat heat transfer tubes are arranged to improve heat exchange capacity, then heat exchange capacity is improved, but refrigerant distribution becomes uneven between windward and leeward rows
Solution Approach 1:
The patent applies segmentation by dividing the heat transfer tubes into distinct groups (windward row tubes and leeward row tubes) with separate flow path connections. The flow path switching unit can selectively connect or disconnect specific tube groups, allowing independent control of refrigerant flow to each segment. This segmentation enables balanced refrigerant distribution by directing flow appropriately to each row, resolving the uneven distribution problem while maintaining high heat exchange capacity.
3Productivity
If switching mechanism is added to adjust refrigerant flow paths between cooling and heating operations, then heat exchange efficiency is improved, but structure of heat exchanger becomes complicated
Solution Approach 1:
The patent applies universality by designing the flow path switching unit to perform multiple functions: it switches between series and parallel connections, selects which tube groups are active, and adapts to different operational modes (cooling, heating, defrosting). This multi-functional switching unit consolidates what would otherwise require multiple separate mechanisms, improving heat exchange efficiency while minimizing the increase in structural complexity through a unified control system.
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 solution simplifies the structure and improves heat exchange efficiency by optimizing refrigerant flow and distribution, reducing pressure loss and enhancing performance compared to conventional systems.
Implementation Method 1
a plurality of flat heat transfer tubes (7A, 7B, 7C) arranged in one row in a third direction (Y direction) crossing the first direction (Z direction) and the second direction (X direction)
Implementation Method 2
configured to exchange heat between refrigerant that flows in each flat heat transfer tube and air
Data Source
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AI summary
A refrigeration cycle apparatus (100) includes a refrigerant circuit in which refrigerant circulates. The refrigerant circuit includes a compressor (1), a first flow path switching unit (2), an outdoor heat exchanger (3), a decompressor (4), an indoor heat exchanger (5), and a second flow path switching unit (6). The outdoor heat exchanger has a plurality of first flat heat transfer tubes (7A), a plurality of second flat heat transfer tubes (7B), and a plurality of third flat heat transfer tubes (7C). The number of one ends of the plurality of flat heat transfer tubes in a second direction (X) is equal to the number of the other ends of the plurality of flat heat transfer tubes in the second direction. The plurality of flat heat transfer tubes are arranged in one row in a third direction (Y) which is orthogonal to a first direction (Z) and the second direction (X). The second flow path switching unit is configured to switch the refrigeration cycle apparatus between a third state and a fourth state. In the third state, the plurality of first flat heat transfer tubes and the plurality of third flat heat transfer tubes are sequentially connected in series, and the plurality of second flat heat transfer tubes and the plurality of third flat heat transfer tubes are sequentially connected in series. In the fourth state, the plurality of first flat heat transfer tubes, the plurality of second flat heat transfer tubes, and the plurality of third flat heat transfer tubes are connected in parallel to each other.