Multi-stage chiller
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Solution Overview
Problem
Electric vehicle thermal management systems face challenges in efficiently managing wide variations in load, particularly during high-power charging and aggressive driving, due to inefficiencies in heat exchange and refrigerant flow control.
Innovation Solution
A multi-stage thermal management system with a chiller and expansion valve that adjusts refrigerant flow through multiple passageways based on coolant temperature, using an actuator to control refrigerant distribution across different heat exchange paths, optimizing heat transfer capacity and reducing system load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-stage chiller system is used, then the system structure is simple, but the heat exchange efficiency is insufficient under wide load variations
Solution Approach 1:
The chiller system is divided into multiple stages with separate heat exchange paths (first and second refrigerant circuits). Each stage can operate independently or in combination, allowing the system to adapt to different load conditions by activating only the necessary stages, thereby improving heat exchange efficiency without requiring a completely complex multi-system architecture.
Solution Approach 2:
The expansion valve is designed with multiple valve outlets (first and second outlets) that can dynamically direct refrigerant flow to different heat exchange paths based on load conditions. The valve can transition between different opening positions (first, second, and third positions) to optimize refrigerant distribution, enabling the system to adapt dynamically to varying thermal management requirements.
2Reliability
If refrigerant flow is restricted to maintain oil circulation, then compressor protection is achieved, but cooling capacity is reduced
Solution Approach 1:
The expansion valve provides dynamic flow control with multiple operating positions. At low loads, it restricts refrigerant flow to maintain minimum oil circulation and protect the compressor. At high loads, it opens to multiple outlets to maximize refrigerant flow and cooling capacity. This dynamic adjustment resolves the contradiction by adapting the flow restriction level to the actual system demands.
Solution Approach 2:
The system changes the refrigerant flow parameters (flow rate, distribution ratio) based on operating conditions. The expansion valve adjusts the refrigerant flow rate and distribution between different circuits, allowing the system to maintain optimal oil circulation at low loads while achieving high cooling capacity at full load, thus resolving the trade-off between compressor protection and cooling performance.
3Productivity
If multiple heat exchange paths are activated, then heat transfer capacity increases, but system complexity increases
Solution Approach 1:
The heat exchange system is segmented into multiple independent paths (first refrigerant circuit with first evaporator, second refrigerant circuit with second evaporator). These segmented paths can be activated independently through the multi-position expansion valve, allowing the system to scale heat transfer capacity by activating only the necessary number of paths based on load requirements, avoiding the complexity of a fully integrated high-capacity system operating at partial load.
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 system effectively adapts to varying load conditions, enhancing heat exchange efficiency, protecting the compressor by maintaining healthy oil circulation rates, and customizing heat transfer capacity without additional hardware, thus optimizing performance.
Implementation Method 1
A multi-stage thermal management system with a chiller and expansion valve that adjusts refrigerant flow through multiple passageways based on coolant temperature
Implementation Method 2
An electric vehicle thermal management system includes a chiller, which draws heat from a coolant loop to a refrigerant loop to cool a battery of the electric vehicle
Data Source
AI summary
A thermal management system including a heat exchanger and an expansion valve. The expansion valve is in fluid communication with the heat exchanger to control flow of a first heat exchange medium to the heat exchanger. The expansion valve includes a valve inlet, a first valve outlet in fluid communication with a first inlet and first passageways of the heat exchanger, and a second valve outlet in fluid communication with a second inlet and second passageways of the heat exchanger. An actuator of the expansion valve is movable from a closed position to a first open position and a second open position.