Ceiling Air Outlet Duct Layout to Prevent Air Stream Separation

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Solution Overview

Problem

In ceiling-concealed air conditioning apparatus, air stream separation at the air outlet inlet causes increased airflow resistance and dew condensation due to reduced airflow rate and noise, resulting from the design of guiding wall portions which reduce the air outlet area.

Innovation Solution

The air outlet is designed with a narrowed inner air duct approaching the downstream side and divided side walls extending towards the longitudinal center, with the length of the inner air duct wall being larger than the outer air duct wall, and the side walls are inclined to ensure efficient airflow and prevent stream separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If guiding wall portions are added to guide air from the heat exchanger to the air outlet, then air flow guidance is improved, but the air outlet area is reduced and airflow resistance increases

Engineering Contradiction:
Improveair flow guidanceVSAvoidair outlet area
Core Design Contradiction:
Ease of operationVSArea of stationary object

Solution Approach 1:

The air outlet is divided into multiple outlets, and guiding wall portions are selectively provided only at specific outlets where air stream separation is likely to occur. This segmentation approach provides guidance where needed while preserving the overall air outlet area and minimizing airflow resistance increase.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Guiding wall portions are provided locally at specific air outlets rather than uniformly across all outlets. The guiding walls are positioned only where corner portions of the heat exchanger connect to air duct walls, providing localized guidance to prevent separation at critical locations while maintaining sufficient area at other outlets.

Inventive Principle:
Principle #3Local quality

2Ease of operation

If the air outlet area is reduced due to guiding wall portions, then air flow guidance is improved, but airflow resistance increases and noise increases

Engineering Contradiction:
Improveair flow guidanceVSAvoidairflow resistance and noise
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The air outlet system is segmented into multiple outlets, with guiding wall portions provided only at specific outlets where separation problems occur. This selective approach provides necessary guidance while minimizing the overall impact on airflow resistance and noise by preserving area at other outlets.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Guiding wall portions are provided partially at only those air outlets where separation is most likely to occur, rather than at all outlets. This partial action provides sufficient guidance to prevent separation and reduce harmful effects without the excessive area reduction that would result from adding guiding walls at every outlet.

Inventive Principle:
Principle #16Partial or excessive action

3Ease of operation

If air stream separation occurs at the air outlet inlet, then air can be guided into the outlet, but airflow resistance increases and dew condensation occurs

Engineering Contradiction:
Improveair flow guidanceVSAvoidairflow resistance and dew condensation
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

Guiding wall portions are provided in advance at air outlets where separation is likely to occur, creating a preliminary structure that prevents air stream separation before it can cause harmful effects. The guiding walls are positioned to intercept and redirect air streams before they separate at the outlet inlet, thereby preventing increased airflow resistance and dew condensation.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

Guiding wall portions are provided locally at specific air outlets where separation problems are most likely to occur, such as where corner portions of the heat exchanger connect to air duct walls. This localized guidance prevents separation at critical locations without affecting other outlets, thereby preventing harmful effects only where they are most likely to occur.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3015774B1Air conditioner
Publication Date: 2019.10.16 MITSUBISHI ELECTRIC CORP
  • EP3015774B1 patent drawingFigure 1
  • EP3015774B1 patent drawingFigure 2~3
  • EP3015774B1 patent drawingFigure 4~5

AI summary

Provided is an air conditioning apparatus, including: a main body having at least one air inlet and at least one air outlet; and a heat exchanger (3) arranged in a flow passage of air to be sucked into the main body through the air inlet and blown out to a target space through the air outlet. The air outlet (9) is formed between the heat exchanger (3) and a side panel (4) of the main body in plan view. The air outlet is formed by an inner air duct wall (10) formed on the heat exchanger side, an outer air duct wall (11) formed on the side panel side of the main body, and a pair of side walls (12). A length (L2) of the inner air duct wall is larger than a length (L1) of the outer air duct wall.