Vehicle HVAC Supercooling Control for Stable Cabin Heating
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Solution Overview
Problem
Electric vehicle air conditioning systems face challenges in maintaining consistent interior temperatures and humidity due to variations in refrigerant temperature and heat exchange efficiency, particularly during heating and dehumidifying operations, especially when the outdoor temperature is low, leading to potential frost formation and reduced heating capacity.
Innovation Solution
The system incorporates a compressor, radiator, heat exchanger, and outdoor heat exchanger, with a target supercooling setting and valve control to regulate the expansion valve's opening based on air flow rates and refrigerant flow, ensuring consistent refrigerant supercooling and condensing pressure to maintain desired temperatures and prevent frost formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the degree of supercooling of the refrigerant is increased to improve radiator radiation performance, then the heating capacity is improved, but the temperature difference between upstream and downstream refrigerant increases causing air temperature variation
Solution Approach 1:
The patent dynamically adjusts the degree of supercooling of the refrigerant based on operating conditions such as outdoor temperature and air flow rate. By changing the supercooling parameter adaptively rather than maintaining a fixed high degree of supercooling, the system maintains heating capacity while reducing excessive temperature differences that cause air temperature variation.
Solution Approach 2:
The patent implements feedback control by monitoring the temperature difference between upstream and downstream refrigerant and adjusting the expansion valve opening accordingly. When the temperature difference becomes too large, the system reduces the degree of supercooling to maintain uniform air temperature distribution.
2Productivity
If the expansion valve opening is increased to improve heat exchange efficiency, then the refrigerant flow rate increases, but the condensing pressure decreases reducing heating performance
Solution Approach 1:
The patent optimizes the expansion valve opening by considering multiple parameters including outdoor temperature, air flow rate, and desired supercooling degree. This multi-parameter optimization ensures that the valve opening is adjusted to maintain both adequate refrigerant flow rate for heat exchange efficiency and sufficient condensing pressure for heating performance.
3Measurement precision
If the air flow rate from the fan is reduced to control temperature, then the temperature control precision improves, but the heat exchange efficiency decreases
Solution Approach 1:
The patent compensates for reduced air flow rate by adjusting the refrigerant supercooling degree and expansion valve opening to optimize heat exchange efficiency. When air flow is reduced for precise temperature control, the system modifies refrigerant parameters to maintain adequate heat transfer, balancing both temperature precision and heat exchange efficiency.
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 configuration reduces temperature variations within the vehicle, ensures reliable temperature control, and prevents frost formation, even at low outdoor temperatures, by optimizing refrigerant supercooling and condensing pressure, thus maintaining a preset interior temperature and humidity.
Implementation Method 1
a compressor configured to compress and discharge a refrigerant
Implementation Method 2
a radiator provided in the vehicle interior and configured to release the heat from the refrigerant
Implementation Method 3
a heat exchanger provided in the vehicle interior and configured to absorb the heat into the refrigerant
Implementation Method 4
an outdoor heat exchanger provided outside the vehicle interior and configured to release the heat from or absorb the heat into the refrigerant
Implementation Method 5
an expansion valve configured to decompress the refrigerant flowing through the refrigerant flow passage
Data Source
AI summary
A vehicle air conditioning apparatus is provided that can prevent temperature variations of the air after the heat exchange in a radiator to reliably control the temperature of the air supplied to the vehicle interior. During the heating operation and the heating and dehumidifying operation, target degree of supercooling SCt when target air-blowing temperature TAO is a predetermined temperature or higher is set to SCt1 that is greater than SCt2 when the target air-blowing temperature TAO is lower than the predetermined temperature. When amount of air Ga supplied from indoor fan 12 is lower than a predetermined value, the target degree of supercooling SCt is corrected, which is set such that the degree of supercooling is lower than target degree of supercooling corrected when the amount of air Ga supplied from the indoor fan 12 is a predetermined value or higher.