Vehicle Ejector Refrigeration Cycle With Low-Temperature Refrigerant Injection
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Solution Overview
Problem
Conventional refrigeration cycles with ejectors face challenges in securing additional refrigerant flow rates, especially in low temperature states, which affects the efficiency and range of electric vehicles by requiring separate heating energy and reducing fuel efficiency.
Innovation Solution
A thermal management system is proposed that incorporates an injection function to supply a refrigerant of relatively high temperature/high pressure in a gas phase to the compressor, enhancing the refrigeration cycle by using a main refrigerant line, branch lines, a gas-liquid separator, and a two-stage compressor with an adjustable nozzle ejector, along with additional chillers and a recycle line to optimize refrigerant flow and heat exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional ejector is applied to a refrigeration cycle, then power consumption of the compressor is reduced and refrigerant flow rate is increased, but additional refrigerant flow rate cannot be secured in low temperature state
Solution Approach 1:
The invention divides the refrigerant flow path into multiple segments: a first path through the ejector for general cooling, and a second path through the gas-liquid separator and injection nozzle for additional refrigerant supply in low temperature conditions. This segmentation allows the system to optimize performance for different operating conditions independently.
Solution Approach 2:
The system dynamically switches between different refrigerant flow paths based on operating conditions. The injection nozzle is activated specifically in low temperature states to provide additional refrigerant flow, while the ejector handles normal operation. This dynamic adaptation resolves the contradiction between general performance and low-temperature specificity.
2Ease of operation
If separate heating energy is used in electric vehicles, then heating function is provided, but fuel efficiency decreases and driving range is shortened
Solution Approach 1:
The refrigeration cycle system provides heating functionality as a byproduct of its cooling operation. The high-temperature refrigerant from the compressor can be directed to heat exchangers for interior heating, allowing the system to serve dual purposes (cooling and heating) without requiring separate energy input, thereby improving fuel efficiency and extending driving range.
Solution Approach 2:
The refrigeration cycle system is designed to perform multiple functions: cooling the interior, cooling electronic components, and heating the interior using the same refrigerant loop. This multi-functionality eliminates the need for separate heating energy sources, directly addressing the fuel efficiency and range problems.
3Productivity
If integrated thermal management is implemented, then thermal efficiency is increased, but system complexity and manufacturing difficulty increase
Solution Approach 1:
The invention merges the cooling and heating functions into a single integrated refrigeration cycle system. By combining the ejector, gas-liquid separator, injection nozzle, and heat exchangers into one unified system, it achieves high thermal efficiency while managing complexity through functional integration rather than separate systems.
Solution Approach 2:
The integrated system provides multiple thermal management functions (interior cooling, component cooling, interior heating) through a single refrigerant loop, increasing thermal efficiency by utilizing waste heat and eliminating the need for separate heating and cooling systems.
4Loss of energy
If ejector is used to reduce compressor power consumption, then energy savings are achieved, but refrigerant flow rate is insufficient in low temperature conditions
Solution Approach 1:
The refrigerant supply is segmented into two paths: the ejector path for normal operation where power consumption reduction is prioritized, and the injection nozzle path activated in low temperature states where additional refrigerant flow rate is prioritized. This segmentation allows optimization for different operational priorities.
Solution Approach 2:
The system changes operational parameters by activating the injection nozzle specifically in low temperature conditions to increase refrigerant flow rate, while relying on the ejector for normal temperature operation to minimize power consumption. This parameter-based control resolves the contradiction between energy savings and flow rate requirements.
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 increases refrigerant flow rates, reduces power consumption, and improves thermal management efficiency, enabling effective heating and cooling of both the vehicle interior and electronic components, thereby enhancing the driving range and energy savings of electric vehicles.
Implementation Method 1
a refrigeration cycle, to which the conventional ejector is applied, has a structure in which a refrigerant condensed in a condenser flows to a gas-liquid separator using a compression recovery function utilizing a venturi effect of the ejector
Implementation Method 2
a refrigerant is compressed in a compressor and then is condensed in a condenser
Implementation Method 3
a refrigerant condensed in a condenser flows to a gas-liquid separator
Implementation Method 4
the refrigerant in a liquid phase circulates through an expansion valve and an evaporator
Implementation Method 5
a first chiller connected to the evaporator in parallel so as to bypass the evaporator and configured to exchange heat with cooling water of the first cooling circuit
Data Source
AI summary
A thermal management system for a vehicle includes an ejector, which includes a main refrigerant line connected to allow a refrigerant to sequentially circulate through a compressor, a condenser and an evaporator, a first branch line which branches between the condenser and the evaporator of the main refrigerant line and which is connected to an inside of the nozzle of the ejector, a second branch line which branches between the evaporator and the compressor of the main refrigerant line and which is connected to an outside of the nozzle of the ejector, and a refrigerant increase line which is connected to an outlet of the ejector and which joins to the main refrigerant line through the compressor.