Indirect reversible air-conditioning circuit for a motor vehicle and corresponding operating method
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Solution Overview
Problem
Conventional motor vehicle air conditioning circuits face challenges in achieving satisfactory performance in both cooling and heat pump modes, particularly in indirect reversible systems that use two distinct fluid loops for heat exchange.
Innovation Solution
The proposed indirect reversible air conditioning circuit includes a first refrigerant fluid loop with a compressor, expansion devices, and internal heat exchangers, along with a second heat transfer fluid loop and a two-fluid heat exchanger, allowing for heat exchange between the loops. This configuration includes a device to redirect refrigerant fluid and heat transfer fluid, coaxial internal heat exchangers, and an electrical heating element, enabling operation in various modes such as cooling, dehumidification, heat pump, and defrosting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an indirect reversible air conditioning circuit is used, then the system can operate in both cooling and heat pump modes, but the performance is unsatisfactory in both modes simultaneously
Solution Approach 1:
The patent segments the refrigerant loop into multiple pathways with separate expansion devices (first and second expansion devices) and heat exchangers (first and second heat exchangers). This segmentation allows independent optimization of cooling and heating pathways, enabling the system to achieve satisfactory performance in both cooling mode and heat pump mode simultaneously by selecting appropriate pathways for each operating condition.
Solution Approach 2:
The patent employs a redirecting device that dynamically switches refrigerant flow paths between different components based on operating mode. The system transitions between configurations: in cooling mode, refrigerant flows through the first heat exchanger for interior cooling; in heat pump mode, the redirecting device alters the flow path to enable heating of interior airflow through the first heat exchanger while the second heat exchanger absorbs heat from exterior airflow. This dynamic reconfiguration resolves the performance contradiction.
2Productivity
If internal heat exchangers are added to optimize heat exchange, then cooling performance and COP improve, but device complexity increases
Solution Approach 1:
The patent merges the functions of cooling and heating optimization into a unified circuit architecture. The first internal heat exchanger combines subcooling of high-pressure refrigerant with preheating of low-pressure refrigerant, while the second internal heat exchanger similarly combines these functions for the alternative pathway. This merging allows the system to achieve improved cooling performance and COP without proportionally increasing complexity, as the same components serve multiple functions across different operating modes.
Solution Approach 2:
The internal heat exchangers are designed with multi-functionality: they serve as subcoolers during cooling mode, preheaters for both cooling and heating modes, and heat recovery devices during heat pump mode. The first internal heat exchanger handles high-pressure refrigerant from the two-fluid heat exchanger, while the second internal heat exchanger handles high-pressure refrigerant from the first heat exchanger. This universal design allows a single circuit configuration to optimize performance across multiple operating modes without requiring separate dedicated components for each function.
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 enhances cooling performance and coefficient of performance (COP) while allowing efficient operation in multiple modes, including heat pump and defrosting, by optimizing heat exchange and fluid circulation pathways, thereby improving the overall efficiency and effectiveness of the air conditioning system.
Implementation Method 1
a two-fluid heat exchanger arranged jointly on the first refrigerant loop and on the second heat transfer fluid loop, in order to allow heat exchange between the first refrigerant loop and the second heat transfer fluid loop
Implementation Method 2
a first internal heat exchanger, allowing heat exchange between the high-pressure refrigerant at the outlet of the two-fluid heat exchanger and the low-pressure refrigerant at the outlet of the second heat exchanger or bypass pipe
Implementation Method 3
a compressor
Implementation Method 4
a first expansion device, a second expansion device
Data Source
Figure 1
Figure 2~3
Figure 4a~4b
AI summary
The invention relates to an indirect air-conditioning circuit (1) for a motor vehicle, comprising: a first refrigerant loop (A) comprising a compressor (3), a first depressurising device (7), a first heat exchanger (9), a second depressurising device (11), a second heat exchanger (13), and a pipe for bypassing (30) the second heat exchanger (13); a second heat-transfer fluid loop (B); a dual-fluid heat exchanger (5) arranged both on the first refrigerant loop (A) downstream from the compressor (3), and on the second heat-transfer fluid loop (B); and a first internal heat exchanger (19), the first refrigerant loop (A) also comprising a second internal heat exchanger (19') allowing heat exchange between the high-pressure refrigerant at the outlet of the first internal heat exchanger (19) and the low-pressure refrigerant circulating in the bypass pipe (30).