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Optimising the efficiency of a nonwoven filter fabric is fundamentally about achieving the perfect balance between the engineered material’s capacity to capture and hold particles and its pressure drop – its resistance to the air, liquid or gas that is being passed through it.
There are however, a virtually unlimited number of parameters that can influence this essential balancing act and a huge amount of research continues to be undertaken with the aim of optimising it.
Already confirmed exhibitors at INDEX™26, taking place at Palexpo in Geneva, Switzerland from 19-22 May 2026 – including Fibertex, Magnera, Norafin and Sandler – strive continuously to engineer new media for improving filtration performance. They are backed by the key technology developers who will also be present, including Andritz, Farè, Ramina and Reicofil.
Behind the scenes, however, research institutes are also carrying out critical work, such as another INDEX™26 exhibitor, the Fraunhofer Institute for Industrial Mathematics (ITWM), based in Kaiserslautern, Germany.
FiltEST
ITWM has developed a ready-to-use simulation software program called FiltEST – the Filter Element Simulation Tool.
“With FiltEST, users can create digital twins of multilayered filter media, filter pleats and entire filter elements to study their performance in terms of efficiency, lifetime and particle holding capacity,” explains Dr Ralf Kirsch, team leader at the ITWM’s Flow and Material Simulation Department. “A digital twin is a computerised, virtual counterpart to a device or process in the real world, allowing us to study and predict its performance under varying operating conditions. In filtration, a classical application is the computer-aided optimisation of the design of a filter media or element to reduce the time and costs associated with manufacturing and testing prototypes.”
The relevance of such a digital twin for the prediction of the filter’s lifetime, he added, is underlined by the abundance of research and trial work devoted to the simulation of flow and filtration from the microscopic length scale of the nonwoven to the macroscopic scale of the filter element it is installed in.
“Digital twins interacting with the real filter device through data exchange will play an important role going forward, because they offer very interesting possibilities such as predictive maintenance, the automation of optimised operation and much more,” Dr Ralf Kirsch says. “Obviously, the digital twin must reflect the relevant properties of the real device and therefore, one of the challenges is to identify what is relevant so that computational resources do not prevent its beneficial use. In our work we have looked at improving digital twins of entire filter elements by taking a more integrated approach, with a focus on the filter media. More precisely, we have considered a chain of digital twins, representing the different stages the filter media goes through – from the laydown process to the formation, including pleating, to the media’s operation within a filter element.”
Pleating
The initial fibre laydown process prior to fabric formation and bonding determines a nonwoven filter media’s efficiency as a flat sheet material. Pleating, however – the mechanical folding of filter media to increase overall surface area – creates regions of compacted fibres, where the flow resistance and filtration properties can differ significantly from a flat sheet.
“In contrast to a quite common assumption of computer models, filter media are not rigid bodies, but they deform under the pressure of the fluid flow,” Dr Ralf Kirsch stresses. “Depending on the operating conditions, these deformations cannot be neglected in the digital twin of the filter element.”
The deformation of a pleated filter media during operation leads to acknowledged and unwanted effects such as pleat collapse, or pleat crowding.
Trade-off
One of the major goals is to identify an optimal trade-off between low flow resistance, a large filtration area and sufficient mechanical robustness of the design.
In order to assist filter element designers with this, the interaction of the deformable nonwoven with the air or liquid flow – called Fluid-Porous Structure Interaction or FPSI – has been simulated by ITWM’s Flow and Material Simulation Department using specialized mathematical models and numerical algorithms.
“The achievements of previous joint research projects have formed the basis of this approach, and a lot of ongoing and future developments will lead to further improvements of the simulation methods,” Dr Ralf Kirsch says. “In more and more fields of application, the deformation of filter media during operation is significant. In addition, our simulations can take into account the impact on filter performance and lifetime of the compression of the nonwoven material during manufacturing, such as the pleating process.”
ITWM already offers services for the integrated computer-aided optimisation of filter elements and their components by analysing variations in the geometry of filter pleats, panels, cartridges and housings, FPSI for advanced studies of the flow-induced deformation of the filter media, and a stress-strain analysis of the filter element’s housing, based on flow and pressure distribution.
Lower basis weights
Filtration industry visitors to INDEX™26 will discover many more services that are supplied for effectively identifying the correct engineered nonwoven filter media for every application.
The global market for nonwoven filter media was worth $6.1 billion in 2024 and will increase to $10.1 billion in 2029 at constant pricing, representing annual growth of 10.7%, according to Akron, Ohio headquartered consultant Smithers. By tonnage, consumption of 826,500 metric tons of nonwovens in 2024 will increase to 1.1 million tons in 2029, representing growth of 5.9%, illustrating how nonwovens are being engineered to achieve the necessary performance requirements for many applications at increasingly lower basis weights. This leads to savings in processing energy and raw materials and at the end of the day, a company’s bottom line.
You can learn about South Asia's
largest exhibition on this topic through this link: https://nonwovenexpo.com/
Source: Online/NAN
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