Vapor Injection Heat Pump Circuit for EV Heating Below -10°C
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Solution Overview
Problem
Traditional heat pump systems in electric vehicles cannot operate effectively below -10°C, leading to high energy consumption and reduced vehicle range due to the need for electric heaters, which also affects the vehicle's performance at low temperatures.
Innovation Solution
An enhanced vapor injection heat pump air-conditioning system with a specific circuit configuration including a compressor, condensers, expansion valves, and shutoff valves, allowing for efficient heat transfer and operation even at low temperatures by maintaining a lower coolant temperature throughout the circuit, preventing compressor overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional heat pumps are used for heating the passenger compartment in electric vehicles, then energy consumption is reduced compared to electric heaters, but the system cannot operate effectively below -10°C, requiring electric heaters to be activated which increases energy consumption and reduces vehicle range
Solution Approach 1:
The heating system is divided into two independent circuits: a first heating circuit that operates effectively at lower temperatures and a second heating circuit that activates when temperatures drop below -10°C. This segmentation allows each circuit to be optimized for its specific temperature range, ensuring reliable heating operation across all environmental conditions while managing energy consumption efficiently
Solution Approach 2:
The system changes operational parameters by switching between different heating circuits based on ambient temperature. The first heating circuit uses a first coolant with optimized properties for low-temperature operation, while the second heating circuit uses a second coolant formulated for extreme cold conditions. This parameter change enables the heat pump to maintain effective operation below -10°C without excessive energy consumption
2Temperature
If the heat pump system operates at low ambient temperatures below -10°C, then heating effectiveness is improved, but the compressor temperature increases which may cause overheating and system shutdown
Solution Approach 1:
A heat exchanger is introduced as an intermediary component between the heating circuit and the compressor. This heat exchanger actively cools the compressor by transferring excess heat to the coolant circulating in the heating circuit, thereby preventing compressor overheating while maintaining effective heating operation at low ambient temperatures
Solution Approach 2:
The system incorporates temperature sensing and control mechanisms that monitor compressor temperature and ambient conditions. When the compressor approaches overheating thresholds during low-temperature operation, the system automatically adjusts coolant flow rates and heat exchanger operation to maintain safe compressor temperatures, preventing system shutdown while preserving heating effectiveness
3Temperature
If electric heaters are activated to provide heating below -10°C, then adequate heating is achieved, but energy consumption increases significantly reducing vehicle range
Solution Approach 1:
The heating system segments heating responsibilities between a primary heat pump circuit optimized for efficiency and a secondary supplemental heating circuit activated only when necessary. This segmentation minimizes the use of high-consumption electric heating to only the extent needed to maintain comfort below -10°C, thereby preserving vehicle range while ensuring adequate heating
Solution Approach 2:
The system changes the thermal properties of the coolant by using different coolant formulations in different circuits. The first coolant is optimized for heat pump operation with higher heat transfer efficiency, while the second coolant is designed for extreme cold temperatures. This parameter change allows the system to maintain heating effectiveness below -10°C with minimal reliance on energy-intensive electric heaters
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
Enables heating of the vehicle compartment even at temperatures below -10°C without disabling the compressor, reducing energy waste and improving the vehicle's range by maintaining a safe compressor operating temperature.
Implementation Method 1
a compressor (1), a first condenser (3), a first heat exchanger (6), a first expansion valve (7) and a second condenser (9) which are connected end to end in sequence
Implementation Method 2
a first condenser (3)... for the heat exchange between the refrigerant and the environment
Implementation Method 3
a first expansion valve (7)
Implementation Method 4
a second condenser (9) for supplying heat from the refrigerant to the air supply to be conditioned for the passenger space
Implementation Method 5
achieve a cooling effect through a pressure change and phase-change heat transfer
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Provided are an enhanced vapor injection heat pump air-conditioning system and an electric vehicle comprising the heat pump air-conditioning system. The heat pump air-conditioning system comprises a compressor (1), a first condenser (3), a first heat exchanger (6), a first expansion valve (7) and a second condenser (9) which are connected end to end in sequence, wherein the first heat exchanger (6) comprises a first channel (61) and a second channel (62), a first end of the first channel (61) is in communication with the first condenser (3), and a second end of the first channel (61) is in communication with the first expansion valve (7); and a first end of the second channel (62) is in communication with the first condenser (3) through a second expansion valve (8), and a second end of the second channel (62) is in communication with the compressor (1). The temperature of a coolant entering the second channel (62) is lower than that of the coolant in the first channel (61) due to the decompression and vaporization effects of the second expansion valve (8). Therefore, when the coolant in the first channel (61) flows through the compressor (1) again, the temperature of the compressor (1) can be prevented from being too high, so that the heat pump air-conditioning system can heat even below -10°C to supply hot air to the interior of the electric vehicle.