EV Thermal Management Using a Low-Pressure Chiller
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Solution Overview
Problem
Conventional thermal management systems for electric vehicles suffer from low thermal efficiency due to significant heat loss as they rely on direct motor heating, where a substantial portion of generated heat is dissipated to the environment rather than being utilized to warm the battery or passenger compartment.
Innovation Solution
A thermal management system incorporating a refrigerant loop and a motor coolant loop with a low-pressure chiller, which absorbs heat from the motor coolant through evaporation to efficiently heat target temperature-controlled spaces or devices, reducing heat loss by minimizing the temperature difference between the motor coolant and ambient temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If motor heating is used to heat the battery or passenger compartment, then heating function is provided, but heat loss to environment increases due to large temperature difference
Solution Approach 1:
The patent introduces a refrigerant loop as an intermediary system between the motor and the heating targets (battery/passenger compartment). The refrigerant absorbs heat from the motor coolant through evaporation in the low pressure chiller, then transports this heat to the heating targets. This mediator system allows heat transfer without requiring direct thermal contact, enabling efficient heat utilization even when motor coolant temperature is relatively low, thereby reducing heat loss to environment.
Solution Approach 2:
The patent changes the thermal parameters by using phase change of refrigerant (evaporation at low pressure) to absorb heat from motor coolant. By operating the low pressure chiller, the refrigerant evaporates at temperatures that can efficiently absorb heat from motor coolant even when its temperature is not very high. This parameter change enables effective heat transfer across a smaller temperature difference, reducing the need for large temperature gradients that would cause environmental heat loss.
2Loss of energy
If motor coolant temperature is reduced to minimize heat loss, then heat loss decreases, but heating capability is insufficient
Solution Approach 1:
The patent utilizes phase transition of the refrigerant (from liquid to vapor through evaporation) in the low pressure chiller to absorb heat from the motor coolant. This phase change process occurs at relatively low temperatures, enabling efficient heat absorption even when motor coolant temperature is kept low to minimize environmental heat loss. The latent heat of vaporization provides substantial heating power without requiring high motor coolant temperatures.
3Device complexity
If direct motor heating is used, then system complexity is low, but thermal efficiency is low due to heat dissipation
Solution Approach 1:
The patent introduces a refrigerant loop as an intermediary system between the motor and the heating targets (battery/passenger compartment). The refrigerant absorbs heat from the motor coolant through evaporation in the low pressure chiller, then transports this heat to the heating targets. This mediator system allows heat transfer without requiring direct thermal contact, enabling efficient heat utilization even when motor coolant temperature is relatively low, thereby reducing heat loss to environment.
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 solution enhances the utilization of heat generated by the motor by maintaining efficient heating of the battery and passenger compartment, reducing energy consumption and improving thermal efficiency by leveraging the refrigerant loop to absorb heat from the motor coolant, even when the motor coolant temperature is low.
Implementation Method 1
the low pressure chiller is configured to enable a refrigerant in the refrigerant loop to absorb heat from a motor coolant in the motor coolant loop through evaporation
Data Source
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AI summary
This application provides a thermal management system capable of relatively efficiently using heat generated by a motor, a method for controlling a thermal management system, and an electric vehicle. The thermal management system in this application includes a refrigerant loop and a motor coolant loop. The refrigerant loop and the motor coolant loop jointly include a low pressure chiller. The low pressure chiller is configured to enable a refrigerant in the refrigerant loop to absorb heat from a motor coolant in the motor coolant loop, to heat a target temperature-controlled space and/or a target temperature-controlled device, that is, the heat from the motor coolant is absorbed by a heat pump to implement heating. Therefore, a temperature of the motor coolant may be relatively low on a basis that a required heating temperature can be achieved, so that a difference between the temperature of the motor coolant and an ambient temperature is relatively small. In this way, heat loss caused by dissipation of heat from a motor to a surrounding environment can be reduced, thereby improving utilization of the heat from the motor.