PM2.5 separation efficiency and energy assessment for cleanable dust- and oil-water soluble mist filter media

Abstract

In connection with rising energy prices have brought the energy consumption of air filters and their ability to separate fine PM2.5 particles into focus. For high particle concentrations, cleanable filters are in use, like cleanable dust filters and cooling lubricant oil-water mist filters. These two filter systems have similarities due to their rapid filter media clogging. The most expensive part of the cleanable filter is the filter medium itself. Latter will be tested by using corresponding test standards. For assessing these test results, the well-known quality factor QF is proposed. This includes the PM2.5 separation efficiency and the pressure drop with its unit [Pa]. As the SI unit [Pa] can be set equal to the SI unit [J/m³], the pressure drop term can be replaced by a so-called equivalent pressure drop, in which the filtration pressure can be added together with all other used energy parts. For the case of cleanable dust filter, the cleaning energy could be then included in the quality factor calculation. Filter test series executed on the VDI3926, ISO110572011 standard and quality factor evaluation without and with including the cleaning energy showed that the latter plays an essential role for filter media assessment. Other tests, using the quality factor evaluation showed, that different filter media assessments occur when the separation of PM2.5 or PM10 particles is the separation goal. In case of qualifying cooling liquid mist filters, the droplets to be separated consist of a mixture of water and oil, whereby only the oil content is of interest within the PM2.5 particle separation. A suitable measuring method has been developed for this purpose, which can determine the harmful PM2.5 oil content separation efficiency from the PM2.5 droplet separation efficiency. Tests using the corresponding standard ÖNORMZ1263 and this special PM2.5 oil content separation measurement technique were executed and a quality factor assessment for a series of different cooling liquid mist filter media is shown.