Dual Cold Storage Layout for Idle-Stop Vehicle Air Conditioning
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Solution Overview
Problem
Vehicle air conditioners face challenges in maintaining cooling performance during extended periods of internal combustion engine idle stops, as the refrigerant circulation stops, leading to increased vehicle interior temperatures and discomfort, while increasing cold storage materials obstructs air flow and requires larger evaporator sizes.
Innovation Solution
An air conditioner configuration that includes a first cold storage unit adjacent to the evaporator tubes and a second cold storage unit at a different position, utilizing phase-change materials like paraffin to maintain cooling by using a refrigerant-cooled second cold storage material even after refrigerant circulation stops, ensuring continuous cooling without enlarging the evaporator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If cold storage materials are increased to extend cooling duration, then cooling duration is improved, but air flow is obstructed and evaporator size must be increased
Solution Approach 1:
The cold storage system is divided into two separate units: a first cold storage unit integrated with the evaporator and a second cold storage unit positioned at a different location in the circulation flow channel. This segmentation allows the cold storage materials to be distributed across different locations, extending cooling duration without concentrating excessive material in one location that would obstruct air flow or require larger evaporator size.
Solution Approach 2:
The refrigerant circulation system serves as an intermediary medium that transfers cooling from the second cold storage unit to the first cold storage unit and subsequently to the air. This intermediary mechanism allows the second cold storage unit to replenish the first cold storage unit's cooling capacity without requiring direct contact between the cold storage materials and the air stream, thus avoiding air flow obstruction.
2Use of energy by moving object
If idle stop is implemented to reduce fuel consumption, then fuel consumption is reduced, but cooling performance deteriorates due to refrigerant circulation stop
Solution Approach 1:
The cold storage materials in both cold storage units are pre-cooled by the refrigerant during periods when the engine is running and cooling is needed. This preliminary cooling action stores thermal energy in the phase-change materials, enabling them to provide cooling independently when the engine stops and refrigerant circulation ceases, thus maintaining cooling performance during idle stop to reduce fuel consumption.
Solution Approach 2:
The cold storage materials serve themselves by utilizing their phase-change properties to automatically provide cooling without requiring active refrigerant circulation. When the engine stops and the refrigerant circulation stops, the first cold storage unit directly cools the air passing through the evaporator, while the second cold storage unit can replenish the first unit's cooling capacity, enabling the system to maintain cooling performance autonomously during idle stop periods.
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 allows for extended cooling periods without increasing the evaporator size, maintaining cooling performance for up to 3 minutes after engine stop, while minimizing the size and fuel consumption, and reducing wasteful fuel usage during idle stops.
Implementation Method 1
a first cold storage unit that is provided in the evaporator at a position adjacent to a tube in which the refrigerant flows in the evaporator, and is configured to store therein a first cold storage material which changes in phase by the heat exchange with the refrigerant passing through the tube
Implementation Method 2
a first cold storage material which changes in phase by the heat exchange with the refrigerant passing through the tube
Implementation Method 3
the first cold storage material and the second cold storage material are cooled by the refrigerant and undergo phase change
Implementation Method 4
maintain cooling by using a refrigerant-cooled second cold storage material even after refrigerant circulation stops
Data Source
AI summary
An air conditioner includes a circulation flow channel in which a refrigerant circulates, an evaporator provided in the circulation flow channel to cool air by heat exchange with the refrigerant passing through the circulation flow channel, a first cold storage unit provided in the evaporator at a position adjacent to a tube in which the refrigerant flows in the evaporator, and a second cold storage unit provided in the circulation flow channel at a position different from the evaporator. The first cold storage unit is configured to store therein a first cold storage material which changes in phase by the heat exchange with the refrigerant passing through the tube, and the second cold storage unit is configured to store therein a second cold storage material which changes in phase by the heat exchange with the refrigerant passing through the circulation flow channel.