Sirocco Fan Scroll Asymmetry to Reduce Noise and Reverse Flow
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Solution Overview
Problem
Sirocco fans in air-conditioning systems face issues with reduced air-blowing capacity and increased noise due to reverse flow phenomena, leading to higher compressor loads and lower COP (coefficient of performance), which are exacerbated by attempts to increase air-blowing capacity, resulting in uncomfortable noise levels for users.
Innovation Solution
A sirocco fan design featuring a scroll with two straight line portions parallel to each other, where the motor's rotation shaft is positioned closer to one of the straight line portions near the tongue, along with a rib at the ends of the scroll and an airflow duct in the motor-supporting stand, to reduce noise and maintain air-blowing capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the air-blowing amount is increased to suppress COP lowering, then the COP is improved, but the noise value is increased
Solution Approach 1:
The patent applies asymmetry by positioning the motor rotation shaft closer to one of the two parallel straight line portions of the scroll rather than at the center. This asymmetric positioning creates an optimized airflow pattern that reduces reverse flow phenomena, allowing the system to achieve higher air-blowing capacity at lower noise levels, thus resolving the contradiction between COP improvement and noise reduction
2Loss of energy
If the air-blowing amount is increased to suppress COP lowering, then the COP is improved, but the number of revolutions is increased
Solution Approach 1:
The asymmetric positioning of the motor rotation shaft relative to the scroll geometry optimizes the airflow distribution, enabling the fan to achieve required air-blowing capacity with fewer revolutions. This reduces the mechanical workload while maintaining or improving COP, resolving the contradiction between energy efficiency and operational speed
3Device complexity
If a conventional scroll shape is used, then the device complexity is simple, but reverse flow phenomenon occurs reducing air-blowing capacity
Solution Approach 1:
The patent introduces asymmetry into the scroll design by featuring two parallel straight line portions and positioning the motor shaft closer to one of them. This asymmetric geometry fundamentally alters the airflow pattern within the scroll, preventing reverse flow phenomena and significantly improving air-blowing capacity while maintaining relatively simple device complexity
Solution Approach 2:
The patent changes the geometric parameters of the scroll by introducing two parallel straight line portions in the whorl-like outer shape, deviating from conventional curved scroll designs. This parameter change optimizes the airflow path and pressure distribution, eliminating reverse flow and enhancing productivity without substantially increasing device complexity
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 design enhances air-blowing capacity while reducing noise and compressor load, improving COP and minimizing reverse flow phenomena, thus providing a more efficient and quieter air-conditioning experience.
Implementation Method 1
a reverse flow phenomenon, in which a part of airflow that is blown out from a whorl-shaped scroll flows from an outer part of the sirocco fan to an inner part thereof occurs
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3~4
AI summary
A sirocco fan capable of reducing a noise value and a number of revolutions when obtaining a predetermined airblowing amount, and an air-conditioning apparatus provided with the sirocco fan are provided. In the sirocco fan provided with a scroll 6, a fan body, which is rotatably disposed in the scroll 6 and includes a large number of blades arranged in a cylindrical manner, and a motor for rotationally driving the fan body, the scroll 6 is provided with two straight line portions 12 and 13 being approximately in parallel with each other on a whorl-like outer shape thereof, and a rotation shaft of the motor is positioned nearer to the straight line portion 12 situated nearer a tongue portion 8 of the scroll.