Compact Air Conditioning System for Public Transport

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Solution Overview

Problem

Conventional air conditioning devices for public transport vehicles are bulky and uncomfortable due to large air circulation systems and inefficient air distribution.

Innovation Solution

A compact air conditioning system using liquid conditioning means and tangential fans for air circulation, with air outlets at ground level promoting natural convection and a control unit that adjusts airflow based on temperature and passenger density for enhanced comfort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If central air conditioning means are used, then air conditioning function is provided, but the device becomes bulky

Engineering Contradiction:
Improveair conditioning functionVSAvoiddevice size
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent divides the air conditioning system into multiple independent modular units, each capable of providing air conditioning function locally. This segmentation allows the system to maintain full air conditioning coverage while reducing the size of each individual component and eliminating the need for large central equipment and extensive ductwork.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses liquid circulation (hydraulic principle) instead of air circulation through large ducts. By pumping conditioned liquid through small-bore pipes to heat exchangers in each modular unit, the system achieves the same air conditioning effect with dramatically reduced piping and equipment size.

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Quantity of substance

If large cross-section pipes are used for air circulation, then sufficient air flow is achieved, but the circulation circuit becomes bulky

Engineering Contradiction:
Improveair flowVSAvoidcirculation circuit
Core Design Contradiction:
Quantity of substanceVSVolume of stationary object

Solution Approach 1:

The patent replaces air circulation through large ducts with liquid circulation through small pipes. The liquid carrier transports thermal energy efficiently through compact piping to heat exchangers that condition the air locally, achieving sufficient air flow and cooling/heating capacity without requiring bulky circulation infrastructure.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent changes the physical state and properties of the circulation medium from gas (air) to liquid. Liquid has higher density and specific heat capacity, allowing much smaller pipe cross-sections to transport the same thermal energy, thereby reducing the volume of the circulation circuit while maintaining effective air conditioning.

Inventive Principle:
Principle #35Parameter changes

3Quantity of substance

If air outlets are positioned high, then air distribution is achieved, but air circulation speed is high causing discomfort

Engineering Contradiction:
Improveair distributionVSAvoidair circulation speed
Core Design Contradiction:
Quantity of substanceVSSpeed

Solution Approach 1:

The patent inverts the conventional air outlet positioning from high to low. By placing air outlets at ground level, the system allows conditioned air to rise naturally through buoyancy-driven convection currents created by occupied zones, achieving effective air distribution while maintaining low air circulation speeds that prevent discomfort.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent enables the air conditioning system to utilize natural convection currents generated by the occupants themselves (body heat creating upward air movement) to distribute conditioned air throughout the space. This self-service mechanism eliminates the need for high-velocity forced air circulation, reducing noise and discomfort while maintaining effective air distribution.

Inventive Principle:
Principle #25Self-service

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

The system reduces bulkiness and improves comfort by utilizing compact liquid conditioning and natural convection, while allowing passengers to control temperature and airflow for personalized comfort.

Implementation Method 1

a circuit (16) for circulating a heat transfer liquid, passing through the central conditioning means (14)

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

a heat exchanger (32), connected to the circulation circuit (16), capable of exchanging calories between the heat transfer liquid and the air circulating in the enclosure (22)

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 3

a ventilation member (30), housed in the enclosure (22), suitable for circulating air in the enclosure (22) from the inlet opening (24) to the outlet opening (26)

Methodology Applied
Scientific EffectForced convection: Forced Convection

Implementation Method 4

the conditioned air only rises in the room by natural convection linked to the people present in this room

Methodology Applied
Scientific EffectNatural convection: Free Convection

Data Source

PatentEP3205547B1An air conditioning device for a room, in particular a passenger room of a public transport vehicle, having reduced size and reduced air speed
Publication Date: 2018.12.26 ALSTOM TRANSPORT TECH SAS
  • EP3205547B1 patent drawingFigure 1~2

AI summary

The air conditioning system comprises central means for temperature-controlling a heat transfer fluid, a heat transfer fluid circulation circuit, and at least one air conditioning unit (20), intended to be housed in the room (12), comprising: an enclosure (22) having an air inlet (24) from the room (12) and an air outlet (26) for the conditioned air returning to the room (12), the air inlet (24) and outlet (26) openings both being arranged at floor level (28) of the room (12), a ventilation unit (30), housed in the enclosure (22), for circulating air within the enclosure from the inlet (24) to the outlet (26), and a heat exchanger (32), connected to the circulation circuit (16), for exchanging heat between the heat transfer fluid and the air circulating within the enclosure (22) under the effect of the ventilation device (30),the presence of people in the room allowing for the generation of an upward movement of air from the air outlet (26) into the room.