Absorption Plate Turbulence Mixing for Vehicle Air Conditioners

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Solution Overview

Problem

Absorption air conditioning systems for motor vehicles face limitations in efficiency due to saturation of the absorbent fluid, lithium bromide, which restricts heat transfer and refrigerant absorption, and existing solutions are costly, complex, and not adaptable for automotive integration.

Innovation Solution

The absorption plate enhances efficiency by introducing turbulence and mixing mechanisms to homogenize the flow of the absorbent fluid, preventing saturation and maintaining standard manufacturing costs, using features like obstacles, injectors, vibrators, and buffer tanks to create eddies and mix the fluid, ensuring uniform temperature and concentration across the exchange surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the absorbent fluid flows through the absorption plate in contact with the coolant, then absorption of refrigerant fluid occurs, but the surface layer quickly saturates and heat transfer rate limits the absorption capacity

Engineering Contradiction:
Improveabsorption capacityVSAvoidheat transfer efficiency
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The absorption plate incorporates a porous layer with controlled porosity (30-70%) that allows the absorbent fluid to penetrate and distribute throughout the plate structure. This increases the effective absorption surface area and enables heat transfer through the porous matrix, preventing surface saturation by continuously replenishing the absorbent fluid at the coolant interface.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The system utilizes fluid flow dynamics by circulating the absorbent fluid through the porous plate structure. The hydraulic design ensures proper flow distribution and residence time within the plate, allowing sufficient heat transfer and absorption while preventing premature saturation through continuous fluid replacement.

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Productivity

If protrusions are created on the surface of refrigerant tubes to create turbulence, then absorption efficiency improves, but manufacturing complexity and cost increase significantly

Engineering Contradiction:
Improveabsorption efficiencyVSAvoidmanufacturing complexity
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

Instead of creating protrusions on tube surfaces, the invention uses a porous plate structure that inherently provides turbulence and enhanced heat transfer. The porous medium achieves the same fluid mixing and heat transfer enhancement as protrusions but through a simpler, more manufacturable process involving porous material insertion rather than complex surface modification.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The porous plate can be manufactured as a separate, replaceable component using cost-effective porous materials. This approach is more economical than permanently modifying refrigerant tubes with protrusions, allowing for easier manufacturing and potential replacement without affecting the main tube structure.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Productivity

If the absorbent fluid flow is homogenized to maintain uniform temperature and concentration, then absorption efficiency improves, but additional mixing components increase device complexity

Engineering Contradiction:
Improveabsorption efficiencyVSAvoidflow homogenization components
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The porous plate structure itself acts as a flow homogenizer. As the absorbent fluid percolates through the porous matrix, the structure naturally distributes the flow uniformly across the plate and creates sufficient mixing through the tortuous flow paths within the pores, eliminating the need for separate mechanical mixing components.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The invention combines multiple functions into the porous plate structure: absorption, heat transfer, and flow homogenization. The porous medium simultaneously performs all three functions, integrating what would otherwise require separate components into a single multifunctional element, thereby reducing overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

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 approach significantly improves absorption efficiency by preventing saturation and maintaining cost-effectiveness, allowing for flexible design and integration within the geometric constraints of a vehicle, enhancing the overall performance of the air conditioning system.

Implementation Method 1

an absorbent fluid, lithium bromide circulates and absorbs a refrigerant fluid, water vapour

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

during the exothermic surface absorption reaction, the absorbent fluid, lithium bromide in contact with the coolant, water vapor, heats up

Methodology Applied
Scientific EffectExothermic reaction: Exothermic Reaction

Implementation Method 3

the transfer rate (of the heat released and the coolant absorbed) towards the core of the flow of absorbent solution very strongly limits the absorption capacities

Methodology Applied
Scientific EffectHeat transfer: Convection

Implementation Method 4

They take advantage of the characteristics of the flow to increase its instability in order to cause eddy currents which will homogenize the temperature of the flow of absorbing fluid and/or the concentration of refrigerant fluid

Methodology Applied
Scientific EffectTurbulence: Turbulence

Data Source

PatentEP2714443B1Absorption plate for an air-conditioner
Publication Date: 2015.07.08 PEUGEOT CITROEN AUTOMOBILES SA
  • EP2714443B1 patent drawingFigure 1~6
  • EP2714443B1 patent drawingFigure 7~10
  • EP2714443B1 patent drawingFigure 11~12

AI summary

The invention relates to an absorption plate for a vehicle air-conditioner, through which a flow of absorbent fluid (110) passes, said fluid flowing along at least one exchange surface (130), the exothermic absorption of a coolant occurring through said at least one exchange surface (130) by increasing the concentration of the coolant in the absorbent fluid (110), the plate comprising, along said at least one exchange surface (130), a means (150) for rendering the temperature of the flow of absorbent fluid uniform, characterized in that the means (150) for rendering the temperature uniform is a separate turbulence means for said at least one exchange surface (130), and increases the turbulence of the flow of absorbent fluid (110) along said at least one exchange surface (130).