Heat Pipe Traction Battery Heating
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Solution Overview
Problem
Existing systems for heating traction energy storage devices in electric vehicles suffer from inefficiencies due to high thermal resistance and the need for electrical energy to power coolant circulation, leading to exergy losses and slower, less homogeneous heating.
Innovation Solution
Incorporating heat pipes that passively transport heat from a heat-absorbing end to a heat-emitting end, with the heat-emitting end in direct contact with the cell wall or electrolyte, and an external heat source in contact with the heat-absorbing end, reducing thermal conduction resistance and eliminating the need for a circulating pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a coolant circuit with convective heat exchanger is used to heat the traction energy store, then the traction energy store can be heated, but high thermal resistance leads to slow and non-uniform heating
Solution Approach 1:
The patent extracts the heat transfer medium (coolant) from the system and replaces it with direct solid-to-solid thermal contact between the heating element and battery cells. This eliminates the convective heat transfer step that caused high thermal resistance, enabling direct conduction heating that is both faster and more energy-efficient.
Solution Approach 2:
The patent introduces a thermal conductive medium (such as thermal paste or conductive grease) as an intermediary between the heating element and battery cells. This intermediary improves thermal contact and reduces thermal resistance at the interface, enabling more efficient heat transfer without requiring a circulating coolant system.
2Reliability
If a circulating pump is used to deliver coolant through the traction energy store, then heat can be managed, but electrical energy is consumed increasing system complexity
Solution Approach 1:
The patent employs passive thermal management where the heating element directly contacts the battery cells through thermal conduction. The system self-regulates heat transfer through inherent thermal gradients without requiring active pump control or complex circulation systems, thereby maintaining reliability while reducing device complexity.
3Temperature
If electrical energy is used to power the coolant circulation and heating, then temperature control is achieved, but energy efficiency decreases due to high thermal resistance
Solution Approach 1:
The patent removes the inefficient coolant circulation system and replaces it with direct thermal contact heating. This extraction of the intermediary coolant eliminates the energy losses associated with pumping and convective heat transfer, significantly improving overall energy efficiency while maintaining effective temperature control.
Solution Approach 2:
The patent replaces the mechanical coolant circulation system with a thermal conduction-based heating system. By substituting the mechanical pump and convective heat transfer mechanism with direct thermal conduction, the system achieves the same temperature control function with much lower energy consumption.
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 minimizes exergy losses, enables faster and more homogeneous heating, and reduces energy consumption by eliminating the need for electrical drive energy for the pump, thus enhancing the overall system efficiency and service life of the traction energy storage.
Implementation Method 1
designed to passively transport heat from a heat-absorbing end of the heat pipe to a heat-emitting end of the heat pipe spaced apart from the heat-absorbing end, using vaporization heat
Implementation Method 2
latent heat during the transition between a liquid and a gaseous state of aggregation of a refrigerant enclosed in the pressure-tight closed heat pipe can be supplied to the respective secondary cell
Data Source
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AI summary
A traction energy storage device (100) for storing electrical energy in a motor vehicle powered or capable of being powered by the stored energy is described. The traction energy storage device (100) comprises at least one electrochemical secondary cell (102), each with at least one cell wall (104). Furthermore, the traction energy storage device (100) comprises at least one pressure-tight closed heat tube (106) designed to passively transport heat from a heat-absorbing end (108) of the heat tube (106) to a heat-emitting end (110) of the heat tube (106) spaced apart from the heat-absorbing end (108), utilizing the heat of vaporization. The heat-emitting end (110) is part of the cell wall (104) or projects through the cell wall (104) into the respective secondary cell (102).Furthermore, the traction energy storage device (100) comprises at least one heat source (118) arranged outside the at least one secondary cell (102), which is in direct contact (120) with the heat-absorbing end (108).