Vehicle HVAC Heat Exchanger Layout for Refrigerant Subcooling
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Solution Overview
Problem
Air-conditioning apparatuses for vehicles without internal combustion engines face inefficiencies in heating operations due to the lack of a effective heat source, leading to increased component complexity, weight, and reduced performance in refrigerant flow resistance and air-conditioning efficiency.
Innovation Solution
An air-conditioning apparatus with a heat exchange unit where a subcooler is positioned below the evaporator to subcool refrigerant, allowing for efficient refrigerant cooling before expansion, and the condenser and evaporator are arranged side by side with a heat-insulating member to reduce pressure loss and component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a refrigerant flow passage is switched between cooling operation and heating operation using a heat pump cycle, then heating operation can be achieved in vehicles without internal combustion engines, but the number of incidental components such as pipes, valves, and fittings increases, leading to increased product cost and weight
Solution Approach 1:
The patent combines the condenser and evaporator into a single heat exchange unit where the same heat exchange structure serves both heating and cooling functions. By switching the refrigerant flow direction within this unified structure rather than using separate components for each function, the number of incidental components is reduced while maintaining heating and cooling capabilities.
Solution Approach 2:
The heat exchange unit is designed to perform multiple functions - serving as both condenser and evaporator depending on the refrigerant flow direction. This multi-functional design eliminates the need for separate heating and cooling components, reducing overall system complexity and component count.
2Adaptability or versatility
If a refrigerant flow passage is switched between cooling operation and heating operation, then heating and cooling functions are achieved, but the weight of the air-conditioning apparatus increases due to additional components
Solution Approach 1:
By merging the condenser and evaporator into a single heat exchange unit with shared structural components, the overall weight of the air-conditioning apparatus is reduced compared to having separate heating and cooling systems.
3Device complexity
If the refrigerant outlet of the condenser is connected to the refrigerant inlet of the evaporator in a heat exchange unit, then the structure is simplified, but the refrigerant compressed in the compressor condenses but is not effectively cooled in the condenser, and the refrigerant is hard to subcool before expansion
Solution Approach 1:
The patent introduces a vertical dimension to the refrigerant flow path by adding a subcooling section at the bottom of the heat exchange unit. This allows the refrigerant to flow downward through multiple zones (condensation zone, subcooling zone, evaporation zone) within the same heat exchange structure, achieving effective subcooling without increasing horizontal complexity.
4Device complexity
If the number of components is reduced by using a heat exchange unit with condenser and evaporator connected in sequence, then product cost and weight are reduced, but refrigerant subcooling before expansion is insufficient, reducing air-conditioning efficiency
Solution Approach 1:
The heat exchange unit is segmented into distinct functional zones along the refrigerant flow path: condensation section, subcooling section, and evaporation section. This segmentation allows each zone to perform its specific function effectively, ensuring adequate subcooling is achieved within the simplified single-unit structure.
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 enhances air-conditioning efficiency by improving refrigerant subcooling, reducing the number of components, and minimizing weight and cost, while maintaining effective heating and cooling operations.
Implementation Method 1
a condenser (19) that radiates heat of refrigerant discharged from a compressor (18)
Implementation Method 2
an evaporator (21) that expands the refrigerant flowing out of the condenser (19) using an expanding device (20) and then absorbs ambient heat into the evaporator
Implementation Method 3
a subcooler (25) that cools the refrigerant flowing out of the condenser (19) before the refrigerant is expanded by the expanding device (20)
Data Source
AI summary
An air-conditioning apparatus includes a heat exchange unit including a condenser that radiates heat of refrigerant discharged from a compressor, and an evaporator that expands the refrigerant flowing out of the condenser using an expanding device and then absorbs ambient heat into the evaporator, the condenser and the evaporator being connected to each other. According to operation mode, air to be supplied to a vehicle interior selectively exchanges heat with the condenser or the evaporator, or sequentially exchanges heat with the condenser and the evaporator. A subcooler that cools the refrigerant flowing out of the condenser before the refrigerant is expanded by the expanding device is provided. The subcooler is disposed at a position below the evaporator and to which condensed water flows down.