Impact of relative humidity on a nanostructured filter cake – Experimental and modelling approaches

Abstract

In this paper, three different non-hygroscopic nanostructured powders were dispersed in dry air and filtered to create a nanostructured deposit. The relative humidity was then gradually increased from 0 to 85% and the thickness of the deposit continuously measured using a laser trigonometry device. Experimental results showed that for each sample, the pressure drop of the deposit increases when the relative humidity increases, while the bed thickness decreases. The modelling of the pressure drop upon increasing humidity was conducted using two pressure drop models available in the literature and specifically developed for nanostructured deposits. The variations in porosity and in cake thickness were included in the pressure drop models. This was achieved using a semi-predictive model of adsorption-condensation on nanoparticle beds developed to calculate the water mass sorbed by a powder. The modified models represent the experimental results with a maximum deviation of 10%. HIGHLIGHTS ► Pressure drop and thickness variations of a humid nanostructured deposit are presented. ► An equation allowing porosity determination for a humid nanostructured deposit is proposed. ► The porosity equation was implemented in two pressure drop models. ► A good match between modelled and experimental results was found.

Humidity Considerations in Filter Testing Based on Analysis of Filters from Gas Turbine Applications

“…3). These results agree with previous studies investigating the effect of RH on the evolution of the Δp of depth filters loaded with soluble or insoluble particle materials [7][8][9][10][11][12][13][14].…”

“…They found that a higher operating RH correlates with an increase in the filter dust holding capacity. Results by Ribeyre et al from experiments with nanosized Al-Zn, C, and SiO 2 on sintered plates at RH up to 85 % support these findings [10].…”

Association of fibrous filters for aerosol filtration in predominant Brownian diffusion conditions

“…The thickness and packing density of each filter have been determined by two methods: § A laser trigonometry method (LTM), inspired by the study of Altmann and Ripperger [11], allows obtaining the filter thickness by the measurement of the displacement of a laser between two pictures. For more details, readers may refer to Ribeyre et al [12]. The packing density may be deduced from this thickness and the weighing of a filter with a known surface.…”

Probing the Nanoparticle Loading Characteristics and the Filtration Performance with the Continuous and Intermittent Use of Disposable Filtering Masks

“…The resistance at 100% RH remained consistent from the initial value throughout the whole intermittent exposure tests. Numerous studies have investigated the interactions of environmental moisture with hygroscopic particles. − From a study that examined the growth factor (GF) of aerosol particles in humid conditions, the GF increased with the elevated relative humidity, subsequently to an onset of deliquescence. During INT with 100% RH storage, the particles would dissolve by the environmental moisture, then the particles recrystallize in the supersaturated state when the humidity was lowered.…”