Indoor Unit Drain Pan Layout for Divided Evaporator Condensate
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Solution Overview
Problem
In air-conditioning apparatuses with divided heat exchangers, dew condensation water tends to disperse from the joints between the upper and lower heat exchangers due to gravity and wind, leading to leakage and operational issues, especially when the secondary side of the heat exchanger is at a lower position.
Innovation Solution
The indoor unit incorporates a sub-drain pan positioned downstream of the joint between the upper and lower heat exchangers, which collects dew condensation water that would otherwise disperse, utilizing an inclined design to effectively capture the water and prevent leakage into the ventilation passage and underfloor duct.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the heat exchanger is divided into upper and lower heat exchangers to reduce production costs, then manufacturing cost decreases, but dew condensation water disperses from the joint between the divided portions
Solution Approach 1:
The heat exchanger is divided into an upper heat exchanger and a lower heat exchanger to reduce production costs. The sub-drain pan is positioned to receive dew condensation water that disperses from the joint between these segmented portions, solving the reliability issue created by the segmentation.
Solution Approach 2:
A sub-drain pan is introduced as an intermediary component between the joint of the divided heat exchangers and the main drain pan. This intermediary structure captures dispersing dew condensation water and directs it to the main drain pan, preventing leakage while maintaining the cost benefits of the divided design.
2Reliability
If the sub-drain pan is provided to collect dispersing dew condensation water, then dew condensation water collection reliability improves, but ventilating resistance increases
Solution Approach 1:
The sub-drain pan is positioned locally at the downstream side of the joint between the upper and lower heat exchangers, specifically where dew condensation water disperses. This localized placement provides targeted water collection without creating unnecessary obstruction to air flow throughout the entire ventilation passage.
Solution Approach 2:
Instead of providing a complete alternative drainage system, only a partial sub-drain pan is added at the specific location where dew condensation water disperses from the joint. This partial action is sufficient to solve the problem while minimizing impact on ventilation.
3Productivity
If the heat exchanger is positioned with the secondary side at a lower position for downward air blow-out, then air circulation efficiency improves, but dew condensation water cannot be collected by the main drain pan alone
Solution Approach 1:
The solution adds a spatial dimension to the drainage system by positioning the sub-drain pan at the downstream side of the joint in the vertical arrangement. This dimensional placement allows the sub-drain pan to capture water that flows downward due to gravity, complementing the main drain pan's collection capability.
Solution Approach 2:
The sub-drain pan is positioned upstream of the main drain pan in the drainage path, performing preliminary collection of dispersing dew condensation water before it reaches the main drain pan. This preliminary action ensures that water is captured early in its dispersal path, preventing leakage.
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 prevents dew condensation water from dispersing into the secondary side and underfloor duct, ensuring reliable collection and reducing production costs by minimizing the need for extensive modifications to the heat exchanger design.
Implementation Method 1
Dew condensation water accumulated by surface tension on portions where the fins are divided is dispersed by gravitation and the action of wind that passes through the heat exchanger
Implementation Method 2
Dew condensation water accumulated by surface tension on portions where the fins are divided is dispersed by gravitation and the action of wind that passes through the heat exchanger
Data Source
AI summary
An indoor unit of an air-conditioning apparatus includes a body casing having an air inlet formed in an upper portion of the body casing and an air outlet formed in a lower portion of the body casing; a ventilation passage formed in the body casing; an evaporator provided to a refrigerant circuit, disposed in an inclined manner in the ventilation passage, and covering the ventilation passage such that air freely passes; a main drain pan disposed below the evaporator; and a fan disposed in the ventilation passage. The evaporator is divided into an upper heat exchanger and a lower heat exchanger. A sub-drain pan that receives dew condensation water coming out from a gap of the joint is disposed at a downstream side in a ventilation direction of a joint between the upper heat exchanger and the lower heat exchanger.