Author: Vanessa 10 Apr. 2025 Category: Applications
Ⅰ. Basic principles of affinity coalescence
(1) Definition and core concepts
The core of affinity coalescence technology lies in its unique surface engineering design and fluid dynamics optimization. Through plasma enhanced chemical vapor deposition (PECVD) technology, nano-scale rough structures (50-200nm) are constructed on the surface of polypropylene fibers, and combined with fluorosilane modification, the surface energy can be precisely controlled to 22.5±1.5mN/m. This design reduces the material’s contact angle to mineral oil to below 8°, while the contact angle to water remains above 150°, forming a perfect selective wetting property.
(2) Mechanism of action
- Selective wetting: The surface of the coalescing material has been specially treated (such as hydrophobic and lipophilic modification) and has a strong affinity for the oil phase
- Capillary adsorption: The micron-scale fiber structure generates capillary force to promote the adsorption of oil droplets (contact angle <90°)
- Dynamic coalescence: The captured oil droplets collide and merge under the disturbance of the airflow to form large droplets (the diameter increases by 10-100 times)
- Gravity sedimentation: The coalesced oil droplets are separated from the airflow due to the increase in weight (governed by Stokes’ law)
- Influence of key parameters
| Parameter | Ideal range | Influence rule |
| Fiber diameter | 1-20μm | The smaller the capture efficiency, the higher the pressure drop |
| Porosity | 85-95% | Too high reduces coalescence efficiency, too low increases resistance |
| Surface energy | 20-30mN/m | Need to be between the surface energy of the oil phase and the gas phase |
| Airflow velocity | 0.1-0.5m/s | Too high leads to secondary entrainment |
II. Technological evolution of agglomeration materials
(1) Limitations of traditional materials
- Glass fiber: easily destroyed by emulsion (lifespan <3 months)
- Stainless steel wire mesh: capture rate of oil droplets <1μm <60%
- Ordinary PP fiber: surface energy mismatch (large fluctuation in separation efficiency)
(2) New functional materials
- Surface layer: perfluorinated modification (surface energy 18mN/m)
- Transition layer: silane grafting
- Base layer: PET support
- Effect: mineral oil capture rate >99.5%
Intelligent response materials:
- Thermosensitive type (PNIPAM modification): automatic shrinkage of pores above 25°C
- pH sensitive type: acidic environment enhances lipophilicity
Nanocomposite fibers:
- PVDF/graphene fibers prepared by electrospinning
- Specific surface area increased by 5-8 times
- The capture efficiency of nano oil mist (0.1μm) is 98%
Self-healing material:
- Microencapsulated repair agent, trigger temperature: 80℃, repair efficiency: >85%
Photocatalytic regeneration:
- TiO2/g-C3N4 heterojunction
- Visible light response range: 420-650nm
- Oil degradation rate: 95%/24h
Digital twin system:
- Multi-physics field coupling model
- Real-time simulation step: 1ms
- Virtual debugging accuracy: 98%
With the advent of the Industrial 4.0 era, intelligent affinity coalescence systems are emerging. Integrated thin film sensors can monitor the working status of coalescers in real time, and artificial intelligence algorithms can predict the best maintenance time. This “thinking” oil mist treatment solution is redefining the standards of industrial clean production worldwide. From precision electronics workshops in Tokyo to oil drilling platforms in Houston, affinity coalescence technology is providing tailor-made solutions for different industries, demonstrating unprecedented technological inclusiveness.
According to the ISO 29463-3 standard test, the latest generation of affinity coalescence system performs as follows:
| Performance parameters | Test standard | Test results |
| 0.3μm oil droplet filtration efficiency | ISO 16890 | 99.97% |
| Maximum operating temperature | ASTM D638 | 120℃ |
| Pressure drop | EN 1822 | <200Pa @1m/s |
| Dust holding capacity | ISO 11057 | >500g/m² |
| Service life | Continuous operation test | 18-24 months |
Comparative tests by the Fraunhofer Institute in Germany show that under the same working conditions, affinity coalescence technology saves 62% energy compared to traditional electrostatic precipitators (ESP) and saves 75% space compared to gravity sedimentation systems.
With the emergence of innovative technologies, oil mist treatment is rapidly developing in a more efficient, intelligent and sustainable direction, providing key technical support for the green transformation of the global manufacturing industry. According to the forecast of MarketsandMarkets, by 2028, the global oil mist treatment market will reach US$4.78 billion, with a compound annual growth rate of 8.7%, of which affinity coalescing technology will account for more than 60% of the market share. Trenntech Filtration has made breakthrough achievements in the affinity coalescing filter element segment, solving the oil mist treatment problem for global customers.