Air Purifier Filter Stack for Formaldehyde and VOC Interference
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Solution Overview
Problem
Existing air purifiers are inefficient in removing gaseous pollutants like formaldehyde in real home environments due to interference from other volatile organic compounds (VOCs), leading to reduced performance compared to laboratory settings.
Innovation Solution
An air purifier with a filter stack configuration that includes a pre-filter, a first particulate filter, a general VOC filter, a target gas filter, and a second particulate filter, where the fan is positioned between the pre-filter and the second particulate filter, allowing for efficient removal of both particulate and gaseous pollutants by protecting the target gas filter from competing VOCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single gaseous absorbent filter is used to remove target pollutants like formaldehyde, then the filter shows suitable performance in laboratory tests, but the performance is markedly reduced in real home environments due to competition from other VOCs
Solution Approach 1:
The gaseous pollutant removal function is segmented into two distinct filters: a general VOC filter that removes competing volatile organic compounds, and a target gas filter that specifically removes formaldehyde and other target gaseous pollutants. This segmentation allows each filter to specialize in its function, preventing the target gas filter from being overwhelmed by competing VOCs in real home environments.
Solution Approach 2:
The general VOC filter acts as an intermediary component that preprocesses the air by removing competing VOCs before the air reaches the target gas filter. This intermediary filter protects the target gas filter from interference, ensuring it can maintain high efficiency in removing target gaseous pollutants even in complex real-world air quality conditions.
2Reliability
If multiple filters are arranged in sequence, then the target gas filter efficiency is improved, but the device complexity and filter stack length increase
Solution Approach 1:
The filter system is segmented into distinct functional zones: particulate matter filtration section, gaseous pollutant removal section with two specialized filters, and humidification section. Each segment performs a specific function, allowing the system to handle multiple pollutant types efficiently while maintaining a structured and manageable configuration.
Solution Approach 2:
The filter stack is designed with multi-functionality to address various air quality issues simultaneously. The same filter stack structure handles both particulate matter removal and gaseous pollutant removal, as well as humidification, making it a universal solution for comprehensive air purification without requiring separate systems for each function.
3Duration of action of stationary object
If the fan is positioned downstream of all filters, then the filter lifetime is extended, but the particulate filters become clogged with fine particles generated by the fan
Solution Approach 1:
The fan is positioned upstream of the second particulate filter, allowing the fan to operate before the final filtration stage. This preliminary positioning prevents the fan from being exposed to fine particles that would clog it, while the second particulate filter still effectively captures fine particles generated by the fan operation, maintaining both filter lifetime and filtration efficiency.
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 enhances the target gas filter's efficiency and extends its lifespan, providing a balanced solution for indoor air pollution by ensuring effective removal of specific gaseous pollutants like formaldehyde and other VOCs, with defined filter usage durations for compact design and maintenance simplicity.
Implementation Method 1
a pre-filter for coarse matter
Implementation Method 2
a first particulate filter for particles of a first size range with a first maximum size
Implementation Method 3
a general VOC filter
Implementation Method 4
a target gas filter
Implementation Method 5
a second particulate filter for particles of a second size range, with a second maximum size smaller than the first maximum size
Data Source
Figure 1
AI summary
An air purifier comprises a filter stack having, in order from the air intake side: a pre-filter, a first particulate filter, a general VOC filter, a target gas filter and a second particulate filter. A fan is between the pre-filter and the second particulate filter.