Vehicle Thermal Management with Reconfigurable Coolant Paths
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Solution Overview
Problem
Existing thermal management systems for electric vehicles face challenges such as inefficient heating in cold weather, complex refrigerant networks, and reliance on ambient air for heat extraction, which limits their effectiveness.
Innovation Solution
A thermal management system utilizing a conventional refrigeration loop that reconfigures coolant flow paths to efficiently manage heating and cooling for both batteries and cabins, leveraging ambient air and waste heat from power electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If electric coolant heaters are used to heat the battery and cabin in cold weather, then heating function is provided, but the Coefficient of Performance (COP) is limited to 1
Solution Approach 1:
The patent introduces a refrigeration loop with a heat pump as an intermediary system to transfer heat from the ambient air to the coolant, which then heats the battery and cabin. This mediator system achieves a COP greater than 1 by utilizing the refrigeration cycle's heat transfer capability, overcoming the limitation of direct electric resistance heating.
Solution Approach 2:
The system changes the operating parameters by using the refrigeration loop to operate in reverse as a heat pump during cold weather. By controlling the refrigeration loop to extract heat from ambient air and transfer it to the coolant, the system achieves higher heating efficiency with COP > 1 compared to electric resistance heating with COP = 1.
2Use of energy by stationary object
If heat is extracted from ambient air using a heat pump system, then heating function is provided, but the system becomes ineffective when ambient air is too cold to evaporate refrigerant
Solution Approach 1:
The system utilizes waste heat from the power electronics (inverter, charger, DC-DC converter) to preheat the coolant before it reaches the battery and cabin. This self-service approach ensures that the coolant is warmed by available waste heat sources, maintaining heating effectiveness even when ambient air temperature is too low for the heat pump to operate efficiently.
Solution Approach 2:
The system recovers waste heat that would otherwise be discarded from power electronics components. By capturing and utilizing this waste heat to warm the coolant, the system maintains reliable heating function in cold conditions without relying solely on the heat pump's ability to extract heat from cold ambient air.
3Use of energy by stationary object
If heat is extracted from warm coolant with a complex refrigerant network, then heating function is provided, but system complexity and refrigerant charge increase
Solution Approach 1:
The refrigeration loop is designed to perform multiple functions: cooling the battery during operation, heating the battery and cabin during cold weather, and dissipating waste heat from power electronics. By making the refrigeration loop universal, the system eliminates the need for separate heating systems and complex refrigerant networks with multiple expansion valves and parallel evaporators.
Solution Approach 2:
The patent merges the heating and cooling functions into a single refrigeration loop system. By combining these functions and using a single refrigerant circuit with strategic heat exchanger placement, the system reduces complexity compared to separate heating and cooling systems with parallel refrigerant networks.
4Adaptability or versatility
If multiple expansion valves and evaporators are used in parallel for heat extraction, then heating coverage is improved, but refrigerant leak points and system complexity increase
Solution Approach 1:
The patent extracts the essential heating function from complex parallel refrigerant networks and implements it through a simplified single-loop configuration. By taking out only the necessary heat transfer components and arranging them in series, the system maintains heating coverage while eliminating multiple expansion valves and reducing refrigerant leak points.
Solution Approach 2:
Instead of using parallel evaporators with multiple expansion valves as in conventional heat pump systems, the patent inverts the approach by using a single refrigeration loop with series-connected heat exchangers. This inversion simplifies the refrigerant network while maintaining the ability to provide heating to multiple components (battery and cabin).
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 achieves efficient thermal management by maximizing heating COP, minimizing heat rejection, and optimizing coolant flow paths, thereby enhancing vehicle performance and comfort in varying temperatures.
Implementation Method 1
A thermal management system utilizing a conventional refrigeration loop that simultaneously removes heat from one coolant passage and adds heat to another coolant passage
Implementation Method 2
a compressor
Implementation Method 3
a condenser
Implementation Method 4
an expansion valve
Implementation Method 5
an evaporator
Implementation Method 6
vehicles utilize electric coolant heaters (ECHs), where a resistor converts electrical energy to heat energy
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
A thermal management system designed to provide efficient sources of heating and/or cooling to the battery and/or the cabin taking advantage of ambient air and/or waste heat from power electronics. A primary way that the system provides efficiency in thermal management is the ability to reconfigure the path that circulated coolant follows through the system's channels. By using the processes and systems described herein, efficient thermal management can be achieved.