Cross-Flow Air Conditioner Layout to Prevent Outlet Backflow
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Solution Overview
Problem
Air-conditioning devices with a thin shape, where the depth dimension is greater than the height dimension, face issues with unstable fan output flow and increased air flow resistance, leading to backflow and condensation risks, especially during cooling.
Innovation Solution
The air-conditioning device features a main body with a cross-flow fan and heat exchanger, where the ratio of height to fan outer diameter is between 2.2 and 2.7, and the heat exchanger's rear inclination angle is between 30° and 45°, ensuring stable airflow and minimizing backflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the main body is formed in a thin shape with depth dimension greater than height dimension, then the installation surface area on wall surface is suppressed and no sense of incongruity is produced in indoor interior, but the fan inlet region becomes small causing unstable fan output flow and back flow occurrence
Solution Approach 1:
The patent optimizes the ratio H/Df (main body height dimension to fan outer diameter) to be within 2.0 to 2.5, which maintains the thin shape aesthetic while ensuring sufficient fan inlet region for stable airflow. This parameter optimization resolves the contradiction by finding the optimal balance between form factor and functional performance.
2Shape
If the main body is formed in a thin shape, then the installation surface area is suppressed, but the distance between main body outlet port and fan outer periphery becomes small causing back flow when flow resistance has increased
Solution Approach 1:
The patent optimizes the ratio H/Df to be within 2.0 to 2.5, which ensures adequate distance between the outlet port and fan periphery even in a thin-shaped main body. This prevents back flow occurrence while maintaining the compact thin shape design.
3Device complexity
If the heat exchanger and fan are in close proximity on the fan inlet side, then the device can be compact, but the air is not readily taken in in a uniform manner causing increased air flow resistance
Solution Approach 1:
The patent optimizes the ratio H/Df to ensure proper spacing between the heat exchanger and fan while maintaining compact overall dimensions. This configuration allows uniform air intake across the fan inlet surface, preventing localized high flow resistance areas.
4Reliability
If fan output flow becomes instable due to increased inlet resistance, then back flow occurs from main body outlet port towards fan, but increasing fan inlet region contradicts the thin shape requirement
Solution Approach 1:
The patent identifies the optimal ratio H/Df range of 2.0 to 2.5, which simultaneously achieves fan output flow stability and maintains the thin shape aesthetic. This parameter optimization resolves the contradiction by finding the precise balance point where both requirements are satisfied.
Solution Approach 2:
The patent shifts the design focus from increasing horizontal inlet region area to optimizing the vertical height dimension H. By carefully controlling the H/Df ratio, the patent achieves stable airflow without compromising the thin shape profile, effectively using dimensional optimization to resolve the contradiction.
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 backflow at the outlet port due to inlet resistance, maintains airflow stability, and reduces the risk of condensation on the fan, enhancing the device's quality and energy efficiency.
Implementation Method 1
a heat exchanger provided in the main body
Implementation Method 2
a cross-flow fan provided inside the main body; wherein the main body includes a front surface, a rear surface, an upper surface and a lower surface
Implementation Method 3
a cross-flow fan provided inside the main body
Implementation Method 4
if the air flow resistance on the fan inlet side has increased due to the generation of condensed water in the heat exchanger during cooling
Data Source
AI summary
In an air-conditioning device, back flow is less likely to occur at an outlet port in relation to an inlet resistance, and the air-conditioning device includes: a main body having an inlet port and an outlet port; a cross-flow fan provided inside the main body; and a heat exchanger provided inside the main body, wherein the main body includes at least a front surface, a rear surface, an upper surface and a lower surface, the inlet port is formed in the upper surface, a ratio H/Df between the main body height dimension H and the fan outer diameter Df is 2.2 to 2.7, and an angle of inclination β between a rear part of an front upward inclination section of the heat exchanger and a vertical direction is 30° to 45°.