Heat Pump Defrosting for EV Outside Air Heat Exchangers
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Solution Overview
Problem
Heat exchangers in electric motor vehicles tend to freeze at low temperatures, requiring energy-intensive defrosting, which affects the vehicle's range due to heat loss from the outside air during defrosting.
Innovation Solution
Operating the heat pump in a high defrosting mode with a heating output of at least 1 kW, utilizing heat from the battery or traction components, and reducing air flow through the heat exchanger to efficiently defrost the outside air heat exchanger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the heat pump operates at low power to conserve energy in electric vehicles, then energy consumption is reduced, but defrosting time increases and heat loss to ambient air increases
Solution Approach 1:
The system performs defrosting in advance during periods when the vehicle is stationary or when ambient air flow is minimal, before the heat exchanger becomes heavily iced. By detecting ice formation early and initiating defrosting proactively, the system eliminates the need for high-power defrosting later when ambient air would absorb the heating energy, thus resolving the contradiction between low power operation and heat loss prevention
Solution Approach 2:
The system utilizes the ambient air flow that normally causes heat loss during defrosting by timing the defrosting operation to occur when the vehicle is stationary or moving slowly. The ambient air that would otherwise absorb heating energy is converted into a beneficial cooling effect that prevents overheating during the defrosting process, allowing the system to maintain low power operation while effectively removing ice
2Productivity
If the heat pump uses high heating power for defrosting, then defrosting time is reduced, but energy consumption increases
Solution Approach 1:
Instead of continuous high-power defrosting, the system applies periodic heating pulses to the heat exchanger. The heating element is activated in cycles, providing sufficient thermal energy to melt ice while allowing cooling periods that prevent excessive energy accumulation. This periodic action maintains defrosting effectiveness while significantly reducing overall energy consumption compared to continuous high-power operation
Solution Approach 2:
The system employs a temperature-sensitive material on the heating element that automatically regulates heat delivery. When the heat exchanger surface reaches the melting point, the material's properties change to reduce further heating, allowing the system to self-regulate without continuous high power input. This self-service mechanism ensures complete defrosting while minimizing energy consumption by stopping heating as soon as the ice melts
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
Rapid defrosting reduces heat loss and increases overall efficiency by leveraging the higher temperature of the battery, minimizing the impact on traction components and ambient air heat loss.
Implementation Method 1
heat is taken from a battery or another traction component of the motor vehicle
Implementation Method 2
defrosting is carried out with a heating power of at least 1 kW
Data Source
AI summary
The invention relates to a method for defrosting an external-air heat exchanger of an electric vehicle. Contrary to the conventional principle of operating systems in an electric vehicle at the lowest possible output power, according to the invention, high output power is used for the defrosting process, to reduce the defrosting time and thus reduce heat loss.