Refrigeration cycle device
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Solution Overview
Problem
Refrigeration cycle devices in vehicle air conditioners face challenges in maintaining the optimal temperature range for lithium-ion batteries, as their performance decreases at low temperatures and deteriorates at high temperatures, necessitating efficient heating and cooling mechanisms to ensure proper charge/discharge capacity.
Innovation Solution
The refrigeration cycle device incorporates a compressor, outside heat exchanger, cooling and heating expansion valves, an evaporator, temperature adjusting unit, and bypass passages to switch between various operation modes, using HFO-based refrigerant and refrigerating machine oil, allowing for efficient heating and cooling of both the vehicle compartment and the battery, maintaining the battery's temperature within an appropriate range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the refrigeration cycle device uses a conventional single-mode configuration, then the structure is simple, but it cannot efficiently maintain battery temperature within the optimal range (10°C to 50°C) under varying operating conditions
Solution Approach 1:
The refrigeration cycle device is designed to perform multiple functions: it can cool the battery when temperature exceeds 50°C, heat the battery when temperature drops below 10°C, and provide air conditioning for the vehicle compartment. This is achieved by configuring heat exchangers that can switch between acting as condensers and evaporators, and by providing multiple refrigerant flow paths that enable different operational modes (cooling mode, heating mode, and air conditioning mode), allowing a single device to serve multiple temperature control needs.
Solution Approach 2:
The system employs dynamic switching between different operational modes based on real-time temperature conditions. The control unit monitors battery temperature and refrigerant states, then dynamically adjusts the configuration of refrigerant flow paths by activating or deactivating specific valves and switching heat exchanger functions. This dynamic adaptability allows the system to respond to varying thermal conditions and maintain optimal battery temperature across different operating scenarios.
2Measurement precision
If the refrigeration cycle device adds multiple heat exchangers and control units for precise battery temperature management, then temperature control precision improves, but device complexity and cost increase
Solution Approach 1:
The heat exchangers in the system are designed with multi-functionality, serving as either condensers or evaporators depending on the operational mode. The first and second heat exchangers can switch roles based on refrigerant flow direction and valve configurations, eliminating the need for separate dedicated heat exchangers for different functions. This reduces the total number of components while maintaining precise temperature control capability through intelligent configuration switching.
Solution Approach 2:
The system utilizes the thermal energy from the refrigerant discharged from the compressor directly for heating the battery when needed, without requiring additional external heating sources. The refrigerant's discharge temperature and pressure are leveraged to provide efficient heating, and the system automatically switches between cooling and heating modes based on battery temperature conditions, reducing the need for complex external temperature management systems.
3Temperature
If the refrigeration cycle device operates in cooling mode with the outside heat exchanger as a radiator, then cooling performance is improved, but heating capability is reduced
Solution Approach 1:
The system dynamically switches the functional role of the outside heat exchanger between radiator and evaporator based on operational mode. In cooling mode, the outside heat exchanger acts as a radiator to reject heat to the environment. In heating mode, the refrigerant flow path is reversed and the outside heat exchanger functions as an evaporator to absorb heat from the environment. This dynamic switching is controlled by valve configurations that redirect refrigerant flow, enabling the system to adapt to both cooling and heating requirements efficiently.
Solution Approach 2:
The refrigeration cycle device employs reverse cycle operation to switch between cooling and heating modes. By inverting the refrigerant flow direction through valve switching, the system transforms the thermal roles of the heat exchangers: the outside heat exchanger alternates between rejecting heat (radiator mode) and absorbing heat (evaporator mode), while the battery heat exchangers switch between being cooled and heated. This inversion principle enables dual-season adaptability from a single refrigeration cycle 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
This configuration enables effective temperature adjustment of the battery, ensuring its optimal functioning by maintaining the temperature between 10° C. and 50° C., thereby enhancing the battery's performance and longevity, while also providing efficient air conditioning for the vehicle compartment.
Implementation Method 1
the evaporator function as heat absorbers
Implementation Method 2
the outside heat exchanger functions as a radiator
Implementation Method 3
the heat of the discharged refrigerant is used as a heat source for heating the temperature adjustment target object
Data Source
AI summary
The refrigeration cycle device includes a compressor, an outside heat exchanger, a cooling pressure reducing unit, an evaporator, a branch portion, a cool down pressure reducing unit, a temperature adjusting unit, a merging portion, a bypass passage, and a first on-off valve. The temperature adjusting unit includes a temperature adjusting heat exchange unit and adjusts a temperature of a temperature adjustment target object. During a cooling and cool down mode, the outside heat exchanger functions as a radiator, and the evaporator and the temperature adjusting heat exchange unit function as heat absorbers. During a target object warm up mode, the refrigerant discharged from the compressor is guided to the temperature adjusting heat exchange unit via the bypass passage, and the heat of the discharged refrigerant is used as a heat source for heating the temperature adjustment target object.