Roomside Fan Filter Unit With Localized Aerosol Injection
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Solution Overview
Problem
Current roomside replaceable filter units in cleanrooms require large quantities of aerosol for testing, leading to wastefulness and reduced clean room availability due to the need for uniform aerosol concentration across multiple filters, which undesirably loads and reduces the lifespan of non-testing filters.
Innovation Solution
Integration of an aerosol injector upstream of the air moving blades in the fan module within each filter unit, allowing for localized aerosol challenge and uniform distribution, reducing the amount of aerosol needed and enabling individual filter testing without affecting adjacent units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If aerosol is provided to the entire plenum to test one filter, then uniform aerosol concentration is achieved for testing, but large quantities of aerosol are wasted and adjacent filters are undesirably loaded
Solution Approach 1:
The plenum is segmented into multiple independent testing zones, each with its own aerosol injector positioned upstream of individual filter units. This allows aerosol to be introduced locally at each filter location rather than flooding the entire plenum, enabling precise testing of one filter without wasting aerosol on adjacent filters.
Solution Approach 2:
Each filter unit is equipped with a dedicated aerosol injector that provides localized aerosol generation and distribution. This creates a high-concentration aerosol environment only in the immediate vicinity of the filter being tested, rather than requiring uniform aerosol distribution across the entire plenum volume.
2Quantity of substance
If large quantities of aerosol are used to charge the plenum, then sufficient aerosol concentration is achieved, but the time required to stabilize concentration increases
Solution Approach 1:
The testing system is segmented into independent zones with individual aerosol injectors for each filter unit. This eliminates the need to charge the entire plenum volume with aerosol, as each injector only needs to establish adequate concentration in its local vicinity, dramatically reducing stabilization time.
Solution Approach 2:
Instead of providing excessive aerosol to the entire plenum to ensure sufficient concentration, the system uses partial action by introducing aerosol only where needed at each filter location. This targeted approach achieves the required concentration with minimal aerosol quantity and faster stabilization.
3Reliability
If aerosol is introduced into a common plenum serving multiple filters, then testing can be performed, but adjacent filters are loaded and their lifespan reduced
Solution Approach 1:
The common plenum system is segmented into independent testing zones, each with its own aerosol injector positioned upstream of individual filter units. This segmentation allows testing to be performed on one filter without exposing adjacent filters to aerosol, thereby maintaining testing accuracy while preserving the lifespan of non-tested filters.
Solution Approach 2:
The aerosol introduction function is extracted from the common plenum and assigned to individual aerosol injectors at each filter location. This extraction allows testing to be performed in isolation for each filter, preventing aerosol exposure to adjacent filters and eliminating the harmful loading effect while maintaining reliable testing capability.
4Measurement precision
If the clean room is taken offline for filter testing, then thorough certification can be performed, but normal operations are disrupted
Solution Approach 1:
The clean room environment is segmented into independent testing zones with localized aerosol injectors for each filter unit. This allows filter certification to be performed in-situ without shutting down the entire clean room, as aerosol is confined to local testing areas and does not compromise overall environmental control or normal operations in other areas.
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 solution reduces aerosol usage, enhances uniformity of aerosol distribution, and allows for efficient filter testing without disrupting normal clean room operations, ensuring accurate certification and extending the lifespan of filters not under test.
Implementation Method 1
an aerosol injector coupled to the housing and disposed upstream of an air moving blade of the fan module
Implementation Method 2
a fan module coupled to the housing and includes an air moving blade disposed between the aerosol injector and the filter receiving aperture
Data Source
AI summary
Embodiments described herein relate to roomside replaceable fan filter units. In one embodiment, a roomside replaceable fan filter unit includes a housing having a filter receiving aperture and an air inlet, an aerosol injector, and a fan filter unit. The fan filter unit is coupled to the housing between the aerosol injector and the filter receiving aperture. In another embodiment, a roomside replaceable fan filter unit includes a housing having a sidewalls and a top wall that define an interior volume, an air inlet formed in the top wall, and a filter receiving aperture disposed opposite the top wall. The roomside replaceable fan filter unit also includes a fan filter unit disposed in the interior volume between the air inlet and the filter receiving aperture. The roomside replaceable fan filter unit includes an aerosol injector disposed upstream of the fan filter unit in the interior volume.