Reversible Air-Side Heat Exchangers for EV Heat Pump Deicing
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Solution Overview
Problem
Heat pump systems in electric vehicles face evaporator icing due to frost accumulation in cold ambient conditions, leading to reduced heat transfer and airflow, while battery heating consumes electrical power and lacks sufficient waste heat for cabin heating.
Innovation Solution
A thermal management system with reversible air-side heat exchangers and a reversible impeller adjusts airflow direction to deice the exchangers, using a heat source to elevate thermal fluid temperature and operate as heat rejecting or absorbing exchangers, recovering rejected heat for efficient thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the external heat exchanger operates in cold ambient conditions to draw heat from ambient air, then heat transfer efficiency is improved, but frost accumulates on the heat exchanger surface leading to reduced heat transfer and airflow
Solution Approach 1:
The patent reverses the airflow direction through the heat exchanger to prevent frost accumulation on the surface. By switching the flow direction periodically, frost formation is inhibited while maintaining effective heat transfer in cold ambient conditions.
Solution Approach 2:
The system implements periodic reversal of airflow direction through the heat exchanger. This periodic action prevents continuous frost accumulation by disrupting the frost formation process, thereby maintaining heat transfer efficiency in cold conditions.
2Temperature
If electric heating is used to heat the battery to threshold temperatures, then battery performance targets are achieved, but electrical power consumption increases
Solution Approach 1:
The patent converts the waste heat generated by the heat pump operation into a useful resource for heating the battery. Instead of dissipating this heat, it is captured and transferred to the battery, eliminating the need for separate electric heating and reducing electrical power consumption.
Solution Approach 2:
The thermal management system uses its own operational waste heat to serve the heating requirement of the battery. The heat pump system essentially heats itself and the battery simultaneously, reducing external energy input requirements.
3Loss of energy
If waste heat from battery heating is used for cabin heating, then energy efficiency is improved, but sufficient waste heat is not available in cold ambient conditions
Solution Approach 1:
The patent introduces a heat exchanger as an intermediary to capture waste heat from the heat pump operation and transfer it to the cabin. This intermediary device enables the utilization of waste heat that would otherwise be lost, improving energy efficiency even in cold ambient conditions where battery heating generates limited waste heat.
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 prevents frost formation and recovers rejected heat, enhancing heat transfer and reducing electrical power consumption for heating, thus improving vehicle performance and efficiency.
Implementation Method 1
select, from a plurality of heat sources, a first heat source to supply heat to elevate a temperature of a first thermal fluid to supply a heated first thermal fluid to the air-side heat exchanger
Implementation Method 2
By operation of a reversible impeller, the airflow can be directed in a reverse direction as the air-side heat exchanger is operated as the heat rejecting heat exchanger
Implementation Method 3
operate, as the air-side heat exchanger is operated as the heat rejecting heat exchanger, another air-side heat exchanger as a heat absorbing heat exchanger to recover at least a portion of a heat rejected
Data Source
Figure 1
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Figure 2B
AI summary
A method (200) of operating a thermal management system (100, 100', 100") is disclosed. The method (200) comprising: identifying (210), as an airflow is in a forward direction across an air-side heat exchanger (116), a formation of ice on the air-side heat exchanger (116); selecting (212), from a plurality of heat sources (122, 128, 136), a first heat source to supply heat to elevate a temperature of a first thermal fluid to supply a heated first thermal fluid to the air-side heat exchanger (116); operating (216), using the heated first thermal fluid, the air-side heat exchanger (116) as a heat rejecting heat exchanger to deice the air-side heat exchanger (116); directing, by operation of a reversible impeller (128), the airflow in a reverse direction as the air-side heat exchanger (116) is operated as the heat rejecting heat exchanger, the reverse direction being opposite of the forward direction; and operating (218), as the air-side heat exchanger (116) is operated as the heat rejecting heat exchanger, another air-side heat exchanger (114) as a heat absorbing heat exchanger to recover at least a portion of a heat rejected by the operation of the air-side heat exchanger (116) as the heat rejecting heat exchanger, wherein the other air-side heat exchanger (114) is, relative to a direction of the airflow, upstream of the air-side heat exchanger (116) when the airflow is in the forward direction and downstream of the air-side heat exchanger (116) when the airflow is in the reverse direction. Further, a thermal management system (100, 100', 100") is disclosed.