Imroved fan for smoke and vapour extraction system, in particular for kitchens and extraction system incorporating such a fan
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Solution Overview
Problem
Existing smoke and vapour extraction fans face challenges in achieving high fluid dynamic efficiency, leading to low energy efficiency, increased noise, and complex manufacturing costs due to geometrical complexities and inefficiencies in the impeller and diffuser design, as well as adverse effects on motor cooling and air flow.
Innovation Solution
A fan design with a diffuser and impeller featuring radially arranged blades at variable distances, an increasing cross-sectional area, and a compact structure to reduce noise and enhance fluid dynamic efficiency, allowing for improved volumetric throughput and energy efficiency without the need for complex moulds or increased motor power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If fluid dynamic optimisation of the diffuser and impeller is performed to increase efficiency, then the energy efficiency class improves, but the manufacturing costs increase due to very complex moulds with high number of undercuts
Solution Approach 1:
The patent applies parameter changes by optimizing the geometric parameters of the impeller blades and diffuser geometry to achieve high fluid dynamic efficiency. Specifically, the impeller blades have optimized curvature radii, thickness distributions, and angular positions that maximize energy transfer while maintaining manufacturable geometries that avoid excessive mould complexity
Solution Approach 2:
The patent employs asymmetry in the impeller blade design where the suction side and pressure side have different curvature characteristics. The blades feature asymmetric thickness distributions and varying camber angles along their span, which optimizes the fluid dynamic performance while the asymmetry is controlled to remain manufacturable
2Productivity
If impellers with particular shape are produced to increase efficiency, then fluid dynamic performance improves, but dissipative energy phenomena occur in the form of turbulent vortices that reduce volumetric throughput and increase electrical energy consumption
Solution Approach 1:
The patent applies dynamics by designing impeller blades with varying geometry along their span - the blade thickness, curvature radius, and angle of attack change continuously from root to tip. This dynamic geometric variation optimizes the flow attachment along the blade surface, reducing flow separation and turbulent vortex formation that would otherwise cause energy losses
Solution Approach 2:
The patent utilizes curvature principles by designing impeller blades with optimized spherical and cylindrical curvature radii on both the suction and pressure sides. The blades feature smooth continuous curvature transitions that eliminate sharp edges and corners, thereby reducing flow separation and minimizing dissipative turbulent vortices in the diffuser
3Volume of moving object
If the distance between fat-trap filters and the extraction cross-section of the fan is reduced, then the hood structure is compact, but the overall efficiency of the extraction hood is adversely affected
Solution Approach 1:
The patent applies dimensionality change by arranging the impeller blades in a three-dimensional configuration with varying radial, tangential, and axial positions. The blades are distributed at different angular positions and have varying lengths from the rotation axis, creating a multi-dimensional flow pattern that efficiently extracts smoke and vapours while maintaining a compact hood structure
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 fan achieves higher energy efficiency, reduced noise, and lower production costs by optimizing air flow and minimizing head losses, resulting in a more efficient and cost-effective extraction system with a smaller, quieter design.
Implementation Method 1
the aims of fluid dynamic optimisation are those of: i) for the same motor, achieving a rise to the next higher efficiency class; and ii) for the same energy efficiency class, using a less powerful motor
Implementation Method 2
an impeller (3) having a body (20) with a plurality of radially arranged blades (33)
Implementation Method 3
a diffuser (2) with an increasing cross-sectional area in a direction perpendicular to a rotation axis of the motor (24) or its output shaft (31)
Implementation Method 4
the structure of the hood and/or the fan may have an adverse effect on cooling of the impeller's electric motor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A fan (1) for a smoke and/or vapour extraction system comprises a impeller (3) located within a diffuser or volute (2), the impeller (3) being driven by an electric motor (24); the impeller (3) having a body (20) having a flat part (21) from which rises a plurality of radially arranged blades (33); these blades are separated from each other by a variable distance based on a periodic function. In addition to this the diffuser (2) has an air delivery or discharge conduit (5) having a cross-section increasing from an inlet to its outlet (6).