Filters are used in a large variety of applications, ranging from air supply in households, office buildings or cleanrooms via mobile air purification devices to the removal of mainly oil droplets for the provision of clean compressed air. The requirements for all filtration solutions have in common that they should provide a high particle (or gas) collection efficiency, while keeping the pressure drop and thus energy consumption low.
Classical mechanical fibrous filters show an increase of both filtration efficiency and pressure drop over time. A filter is therefore exchanged when the pressure drop exceeds a certain threshold. Electret filters typically have a looser structure than classical filters, resulting in a lower pressure drop. At the same time, the initial efficiency can be similarly high as with classical filters, making electret filters appear as a perfect solution. However, the particle removal efficiency of electret filters decreases over time, due to the decay of the fiber charges. The criterion for a filter exchange is therefore usually based on the filtration efficiency rather than the pressure drop. The choice of a filter therefore depends very much on the application. While a decrease of the filtration efficiency is not acceptable in cleanrooms or operating theaters, therefore excluding the use of electret filters, their beneficial effect of the low pressure drop on the energy consumption is well received in e.g. household applications like mobile air purifiers.
The presentation will cover means for evaluating the interplay between long term stability of filter efficiency and pressure drop and discuss the role of pressure drop on the overall energy efficiency of various filtration solutions.
Session: K1 - Keynote Lecture I
Day: 11 October 2016
Time: 13:00 - 14:15 h