Controlled-Flow Grease Filter for Low-Loss Hood Filtration
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Solution Overview
Problem
Labyrinth filters in cooking fume extractor hoods face limitations in narrower flow sections, leading to reduced air processing capacity, increased noise, and lower particle retention efficiency, despite wider sections improving fluid dynamics but compromising particle retention.
Innovation Solution
A grease filter design featuring two walls with alternating first and second openings, where the second openings are narrower, dividing the flow into macroscopic and microscopic paths, enhancing particle retention while minimizing energy loss and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the flow section of a labyrinth filter is made narrower, then the particle retention efficiency is improved, but the air processing capacity is reduced and flow speed increases leading to higher energy loss and noise
Solution Approach 1:
The filter divides the total flow into multiple parallel labyrinth paths through the first openings, allowing each path to be narrow enough for good particle retention while the collective width maintains high air processing capacity. The flow is segmented into many small streams that can each effectively trap particles.
Solution Approach 2:
The invention transitions from a single wide flow path to a three-dimensional array of narrow pathways by creating multiple walls with numerous openings. This multiplies the effective filtering surface area while maintaining compact dimensions, allowing narrow paths for particle retention without sacrificing overall air processing capacity.
2Manufacturing precision
If the flow section of a labyrinth filter is made narrower, then the particle retention efficiency is improved, but the flow speed increases exponentially leading to higher energy load loss and noise
Solution Approach 1:
The total flow is divided into multiple parallel streams through numerous narrow openings distributed across multiple walls. This segmentation allows each individual stream to maintain low velocity for effective particle retention while the aggregate flow capacity remains high, preventing excessive energy loss.
Solution Approach 2:
The invention changes the flow parameters by creating a distributed array of openings with specific dimensional relationships. The first openings provide narrow paths for particle retention while the second openings with different dimensions balance the flow velocity, maintaining optimal conditions for particle trapping without excessive speed that would cause energy loss.
3Loss of energy
If wider flow sections are used to improve fluid dynamic properties, then energy loss and noise are reduced, but particle retention efficiency decreases
Solution Approach 1:
The filter structure segments the flow into multiple narrow labyrinth paths through closely spaced openings in multiple walls. This creates numerous individual filtering channels that maintain the narrow dimensions necessary for particle retention while the collective structure provides sufficient overall flow capacity with acceptable energy loss.
Solution Approach 2:
The invention adds dimensional complexity by creating a multi-wall structure with openings distributed in three-dimensional space. This transforms a simple wide channel into a complex array of narrow pathways, multiplying the effective filtering surface area and maintaining particle retention efficiency without requiring a single excessively wide flow section.
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 design achieves high particle retention efficiency with reduced energy load loss and noise, allowing for adaptable performance across various extractor hood configurations.
Implementation Method 1
The fumes flowing through the filter are forced to follow a complex path having specially designed twists and turns. The part of the fumes constituted by air easily follows the path and flows out to the other side of the filter, whilst the suspended liquid droplets and solid particles are unable to change their direction suddenly on account of their high inertia and remain trapped inside the filter.
Implementation Method 2
the first and second openings combining to divide the total flow passing through the filter into two component flows which are in turn divided into a first plurality of macroscopic flows following a labyrinth path through the first openings and a second plurality of microscopic flows passing through the second openings
Data Source
AI summary
A grease filter (1) for domestic extractor hoods comprises at least two walls (2, 3) placed face to face and having first through openings (4) made in them arranged in such a way as to cause sudden changes of direction in the fumes flowing through them. At least one of the walls (2, 3) includes a plurality of second openings (5) whose flow section is considerably narrower than that of the first openings (4). The first openings (4) and the second openings (5) combine to divide the total flow passing through the filter (1) into two component flows which are in turn divided into a first plurality of macroscopic flows (6) following a labyrinth path through the first openings (4) and a second plurality of microscopic flows (7) passing through the second openings (5).