Large Residence Times Research Articles

Aggregate Cloud Particle Effects in Exoplanet Atmospheres

Aerosol opacity has emerged as a critical factor controlling transmission and emission spectra. We provide a simple guideline for the effects of aerosol morphology on opacity and residence time in the atmosphere, as it pertains to transit observations, particularly those with flat spectra due to high altitude aerosols. This framework can be used for understanding complex cloud and haze particle properties before getting into detailed microphysical modeling. We consider high altitude aerosols to be composed of large fluffy particles that can have large residence times in the atmosphere and influence the deposition of stellar flux and/or the emergence of thermal emission in a different way than compact droplet particles, as generally modeled to date for extrasolar planetary atmospheres. We demonstrate the important influence of aggregate particle porosity and composition on the extent of the wavelength independent regime. We also consider how such fluffy particles reach such high altitudes and conclude that the most likely scenario is their local production at high altitudes via UV bombardment and subsequent blanketing of the atmosphere, rather than some mechanism of lofting or transport from the lower atmosphere.

Long‐Term Trends in Productivity Across Intermountain West Lakes Provide No Evidence of Widespread Eutrophication

AbstractEutrophication represents a major threat to freshwater systems and climate change is expected to drive further increases in freshwater primary productivity. However, long‐term in situ data is available for very few lakes and makes identifying trends and drivers of eutrophication challenging. Using remote sensing data, we conducted a retrospective analysis of long‐term trends in trophic status among lakes greater than 10 ha across the Intermountain West, a region with understudied water quality trends and limited long‐term data sets. We found that most lakes (55%) were not exhibiting shifts in trophic status from 1984 to 2019. Our results also show that increases in eutrophication were rare (3% of lakes) during this period, and that lakes becoming increasingly oligotrophic were more common (17% of lakes). Lakes that were not trending occupied a wide range of lake and landscape characteristics, whereas lakes that were becoming more oligotrophic tended to have larger residence times and were located in catchments with greater clay content and more development. Our results highlight that while there are well‐established narratives that climate change can lead to more eutrophication of lakes, this is not broadly observed in our data set, where we found more lakes in the Intermountain West becoming more oligotrophic than lakes becoming eutrophic.

Estimating lags in a kraft mill.

In pulp mills, lags obscure the effect of upstream operations on downstream measurements. Here, we estimate lags in a Canadian pulp mill using autoregressive exogenous (ARX) models. First, we show that ARX models can approximate lags in a process simulation that resembles the liquor storage tanks in pulp mills, a major source of lag inthe kraft recovery cycle. Then, we use ARX models to estimate the lagged effect of a change in species pulped on as-fired liquor heating value, viscosity, and boiling point rise. Additionally, we compare the predictions of the ARX models to autoregressive (AR) models and a persistence model. The estimated lags between a change in species and heating value (49 h) and boiling point rise (41 h) agree with a detailed simulation of the mill and are close to estimated hydraulic residence times, suggesting that the liquor tanks exhibit imperfect mixing. A lagged effect of species change on viscosity could not be identified. ARX and AR models produce similar predictions that are slightly better than those of a persistence model. Finally, we show that process measurements upstream of units characterized by large residence times will likely provide little benefit to prediction accuracy.

Binding and Sliding Dynamics of the Hepatitis C Virus Polymerase: Hunting the 3' Terminus.

The hepatitis C virus (HCV) nonstructural protein 5B (NS5B) polymerase catalyzes the replication of the (+) single-stranded RNA genome of HCV. In vitro studies have shown that replication can be performed in the absence of a primer. However, the dynamics and mechanism by which NS5B locates the 3'-terminus of the RNA template to initiate de novo synthesis remain elusive. Here, we performed single-molecule fluorescence studies based on protein-induced fluorescence enhancement reporting on NS5B dynamics on a short model RNA substrate. Our results suggest that NS5B exists in a fully open conformation in solution wherefrom it accesses its binding site along RNA and then closes. Our results revealed two NS5B binding modes: an unstable one resulting in rapid dissociation, and a stable one characterized by a larger residence time on the substrate. We associate these bindings to an unproductive and productive orientation, respectively. Addition of extra mono (Na+)- and divalent (Mg2+) ions increases the mobility of NS5B along its RNA substrate. However, only Mg2+ ions induce a decrease in NS5B residence time. Dwell times of residence increase with the length of the single-stranded template, suggesting that NS5B unbinds its substrate by unthreading the template rather than by spontaneous opening.

Characteristics of Butane Combustion in Mesoscale–Combustor Due to Stainless Steel Flame Holder Type

Mesoscale–combustor is one component of the micropower generator. The mesoscale–combustor function is to produce heat energy from the combustion of chemical hydrocarbon compounds. The small dimensions of the meso-combustor cause large losses and short residence times for the reactants. These two factors lead to narrow flame flammability limits. This study aims to increase flammability limits by lengthening the reactant residence time and increasing reactant mixing with inserts of flow retardants called flame holders. There are two kinds of flame holders used in this study, namely holes and lines. Lines type produces flames at an equivalent ratio of Φ0.83–1.76 and speeds of 17.01 cm/s to 72.93 cm/s, while holes type produces flames at an equivalent ratio of Φ0.91–1.71 and a flow rate of 24.94 cm/s to 54.95 cm/s. This phenomenon shows that the line type flame holder is able to inhibit flow better and form vortices better, thereby increasing heat recirculation, flame stability, and widening flammability limits.

Anomalous transport in a porous medium with randomly packed ellipse cavities

We investigate the transport of nonreactive tracers in a binary porous medium with randomly packed ellipse fluid-filled cavities. Anomalous transport features, such as early arrival time and long tailing, are observed due to the high contrast in medium properties and highly complex structure of fluid velocity. We use a particle tracking method to quantify transport features of the domain. Then, a continuous time random walk (CTRW) framework builds on tracer transitions in time and space to represent an upscaled model. We study the effect of several key parameters on the anomalous transport process. The parameters include the cavity aspect ratio, porous background permeability, and the Peclet (Pe) number. With the increase in Pe, a longer tailing and a larger residence time are observed, which presents a stronger anomalous feature. A similar situation corresponds to decreased porous medium permeability, which results in wider breakthrough curves. A longer tailing arises in the case of more elongated cavity of larger aspect ratio. The purely advective transport in the medium is investigated at Pe = ∞. This is considered a limit case for the anomalous behavior of the system. One can refer to this case as the most extended tail possible for each cavity arrangement. The widest breakthrough curves for a Pe = ∞ correspond to larger aspect ratios of the cavity and a lower permeable matrix. We show that the upscaled CTRW model can closely predict breakthrough curves in a binary medium with randomly distributed ellipse cavities. These findings give new insight into transport in vesicular and vuggy porous media.

The physical oceanography of Fortune Bay, an overview

This paper describes the physical oceanography of Fortune Bay, a broad, mid-latitude fjord located in Newfoundland (Canada). Fortune Bay is subject to a strong seasonal stratification (0–16 °C sea-surface temperature range with up to 1 °C/m vertical gradient) influenced by local freshwater runoff, wind forcing and shelf inputs. Sea-ice is seldom present in the bay and unlikely to be of importance on the seasonal stratification and mixing processes. Fortune Bay is warmer than its adjacent shelf both at the surface (by about 2 °C) and at intermediate depths (by about 1 °C from 50–150 m). While the former is likely due to local freshwater runoff stratification influence, the latter is probably related to the warm, deep water input occurring in winter below sill depth and subsequently mixed with the intermediate layer via the input of a colder water mass flowing in summer and which eventually reaches the bottom as well. Currents are dominated by the ‘weather band’ (2–20 d) and characterized by energetic pulses associated with downwelling and upwelling events. Mean circulation is rather weak and the seasonal pattern obtained here did not reveal either the presence of a distinct estuarine circulation nor a strong influence of the main coastal current. Tidal currents are weak also and no inertial signal was observed. Estimates of water exchange between the inner and outer part of the bay were calculated using several methods and led to residence times of the order of a few to several months for the upper layers and of the order of a year for the bottom layer with a probable strong seasonal variability (larger residence time in summer for the upper layers). The “baroclinic pumping” processes, which include the downwelling/upwelling events, appear to be important players but more work is needed to better understand their nature and actual contribution.

Induced Circulation by Plunging and Submerged Jets in Circular Water Storage Tanks Using CFD

Water circulation in storage tanks significantly impacts water quality in distribution networks since old water tends to have low residual chlorine concentrations that are insufficient to neutralize microbial regeneration. Their large capacity and long residence times result in uneven mixing, which can accelerate the disinfectant decay and the formation of potentially carcinogenic disinfection by-products. The phenomenon is strongly related to the tank inflow conditions, since there are no active mixing devices. This paper presents a comprehensive analysis of the flow dynamics in circular storage tanks using a three-dimensional computational fluid dynamics model. The main motivation is that the inflow—which mixing processes rely on—strongly influences the circulations. The numerical analysis provided includes a thorough investigation of interest in understanding flow dynamics for two inflow configurations: (i) the plunging jet modelling and comparison with published experimental data and (ii) the submerged jet as an improvement measurement for these storage tanks.

Investigation on pool-scrubbing hydrodynamics with VOF interface-capturing method

Pool scrubbing with bubble swarm generated by gas jet is an effective technique for aerosol retention at severe accidents, owing to large interfacial area and long residence time. Correct understanding of the process and thus enhancing its efficiency relies on analysis of the hydrodynamic behaviour of the gas, since it affects particle removal mechanisms directly. The objective of the present work is to explore the gas jet structure in detail by means of VOF interface-capturing method and additional techniques for tracking bubble characteristics and trajectories. The main findings are: (a) The breakup of globules in the injection zone becomes significant at high gas flow rates and has a great contribution in particle removal; (b) The increase of bubble size and velocity with the injection velocity will promote the inertial and centrifugal deposition of aerosol particles; (c) However, the coalescence probability of rising bubbles is found to increase with the gas flow rate, which may influence particle retention by re-enclosing particles from liquid film and reducing surface area; (d) Furthermore, the reduction in bubble residence time as they rise through the pool is unfavourable for particle removal. Nevertheless, liquid recirculation originated from violent interaction between the gas jet and the pool surface as well as swarm effects helps to prolong the residence of bubbles. The effect of gas flow rates on the decontamination factor is found to be associated with a variety of gas–liquid hydrodynamic phenomena. The proposed numerical approach is capable of acquiring detailed local information that is required for model development. Both the time-averaged spatial distribution of void fraction and the instantaneous size/rise velocity of individual bubbles obtained from the simulation conform to the experimental data. In the next step it will be extended to include aerosol particles.

Demographic composition, not demographic diversity, predicts biomass and turnover across temperate and tropical forests.

The growth and survival of individual trees determine the physical structure of a forest with important consequences for forest function. However, given the diversity of tree species and forest biomes, quantifying the multitude of demographic strategies within and across forests and the way that they translate into forest structure and function remains a significant challenge. Here, we quantify the demographic rates of 1961 tree species from temperate and tropical forests and evaluate how demographic diversity (DD) and demographic composition (DC) differ across forests, and how these differences in demography relate to species richness, aboveground biomass (AGB), and carbon residence time. We find wide variation in DD and DC across forest plots, patterns that are not explained by species richness or climate variables alone. There is no evidence that DD has an effect on either AGB or carbon residence time. Rather, the DC of forests, specifically the relative abundance of large statured species, predicted both biomass and carbon residence time. Our results demonstrate the distinct DCs of globally distributed forests, reflecting biogeography, recent history, and current plot conditions. Linking the DC of forests to resilience or vulnerability to climate change, will improve the precision and accuracy of predictions of future forest composition, structure, and function.

Structure and propagation speed of autoignition-assisted flames of jet fuels

The flame structure and propagation speed of autoignition-assisted fuel-lean and fuel-rich flames of jet fuels are numerically and analytically investigated at elevated pressures and temperatures. The results show that while the propagation speed increases dramatically for large residence time, for fuels with strong low temperature chemistry (LTC), the propagation speed may first increase slightly at relatively small residence time. The species evolution in time shows that with the increase of propagation speed, the trajectories for autoignition-assisted flames first rapidly and then gradually converge to the autoignition trajectory. Furthermore, transport budget analysis shows that as the propagation speed increases, the balance in the high temperature reaction zone evolves from reaction-diffusion balance to reaction-convection balance, demonstrating the transition from flame propagation to autoignition. An analytical model, which only needs to calculate the corresponding 0D autoignition process, is proposed to predict the autoignition-assisted flame speed. The good qualitative agreement with the 1D simulation result indicates that the autoignition assistance on the propagation speed mainly results from the temperature rise ahead of the preheat zone. Finally, different scaling correlations for the normalized flame propagation speed Sl/Sl0 are compared, showing a universal scaling for n-heptane, n-dodecane, and Jet-A over a wide range of pressures (5–35 atm), temperatures (600–1015 K), and equivalence ratios (0.5–1.2) with the normalized maximum mole fractions of CO.

A coupled CFD–DEM approach to model the in-trough mixing in a multi-stage solar particle receiver

Concentrated solar power (CSP) is expected to reach economic competitiveness with conventional power plants in the foreseeable future. The use of fine-grained ceramic particles as a heat transfer fluid (HTF) for CSP is a promising alternative to other HTFs such as molten salts and nanofluids. However, research on ceramic particle based CSP is stymied due to the inherent difficulty in obtaining in-depth particle mixing processes. Acquiring this highly sought information would allow engineers and scientists to improve the design and optimization of next-generation CSP receivers thereby potentially leading to improved thermal efficiencies. To this end, a high-fidelity numerical model, namely a coupled computational fluid dynamics and discrete element method (CFD–DEM) is developed and implemented on a novel multi-stage solar particle receiver to provide an in-depth analysis of the dynamical and temporal evolution of the in-trough particle mixing processes. The results obtained from this numerical model will assist engineers and scientists to better optimize particle based CSP systems. The validated numerical model accounts for particle–particle, particle–wall, particle–fluid interactions of multiphase solid-gas flows in a novel multi-stage solar particle receiver. This study is the first attempt to conceptualize a novel multi-stage solar and to develop and implement a high-fidelity numerical model to provide an in-depth analysis of the in-trough particle mixing processes. For the first time, important flow characteristics, namely particle mixing, of the particle curtain are investigated. The results showed that the ‘catch-and-release’ troughs have a profound implication on the in-trough mixing process depending on the location of the particle in the particle curtain. The numerical model revealed that specific regions of the multi-stage receiver exhibit high particle residence times and low particle velocities. The rear particle of a curtain takes about 15% longer to reach the 2nd bin compared to the front and centre particle, and the rear particle remains immersed in the 2nd bin for about 14% longer compared to the front and centre particle. As such, the large particle residence time due to the in-trough mixing could potentially lead to better heat transfer performance of a solar receiver. The high-fidelity numerical model could potentially serve as an advanced tool for engineers and scientists to carefully design, optimize, and guide-the scale up and commercialization of novel solar particle receivers, particle heat exchangers, and various other industrial applications such as solar gasification (syngas) and green hydrogen technologies.

New and old invaders in forests in eastern Austria: The role of species attributes and invasion history

Recent studies have shown that temperate forests are susceptible to the invasion of alien species. However, it is less known how species attributes such as functional traits, invasion success on large scales (e.g. globally or in Europe), residence time and pathways of introduction interact in shaping the distribution of alien species in forests. Here, we analyse the distribution of alien species species introduced long ago (i.e. archaeophytes, introduced before 1492) and of more recently introduced aliens (i.e. neophytes, i.e. introduced after 1492) in 43 study sites (5 ha size) in forest remnants in a cultural landscape in eastern Austria.We recorded 167 alien species (112 neophytes, 55 archaeophytes). There was a significant, yet moderate correlation between number of neophyte and archaeophyte species per site. Life form composition of archaeophytes differed substantially from that of neophytes: archaeophytes mostly were short-lived (76%) and long-lived (22%) herbs. For neophytes, life-form composition was much more even, with long-lived herbs being most abundant (36%), and all other life forms being similarly represented (21-23%). While the dominant pathway for archaeophytes was unintentional introduction (51 species), neophytes were mostly introduced by horticulture (90 species).Year of first record in Austria, and the number of European regions a species has invaded highly significantly explain local invasion success, i.e. the number of invaded study sites. Further, the number of short-distance dispersal mechanisms highly significantly explained the number of invaded sites, while the number of long-distance dispersal mechanisms was insignificant. The maximum height of a species had also a significant positive influence on the number of invaded sites. Our results show that the composition of old and more recently introduced alien species in forests differs substantially in terms of regions of origin, life-form and pathways, and that basic species attributes contribute to local invasion success.

Surface Engineering of Ceramic Nanomaterials for Separation of Oil/Water Mixtures.

Oil/water mixtures are a potentially major source of environmental pollution if efficient separation technology is not employed during processing. A large volume of oil/water mixtures is produced via many manufacturing operations in food, petrochemical, mining, and metal industries and can be exposed to water sources on a regular basis. To date, several techniques are used in practice to deal with industrial oil/water mixtures and oil spills such as in situ burning of oil, bioremediation, and solidifiers, which change the physical shape of oil as a result of chemical interaction. Physical separation of oil/water mixtures is in industrial practice; however, the existing technologies to do so often require either dissipation of large amounts of energy (such as in cyclones and hydrocyclones) or large residence times or inventories of fluids (such as in decanters). Recently, materials with selective wettability have gained attention for application in separation of oil/water mixtures and surfactant stabilized emulsions. For example, a superhydrophobic material is selectively wettable toward oil while having a poor affinity for the aqueous phase; therefore, a superhydrophobic porous material can easily adsorb the oil while completely rejecting the water from an oil/water mixture, thus physically separating the two components. The ease of separation, low cost, and low-energy requirements are some of the other advantages offered by these materials over existing practices of oil/water separation. The present review aims to focus on the surface engineering aspects to achieve selectively wettability in materials and its their relationship with the separation of oil/water mixtures with particular focus on emulsions, on factors contributing to their stability, and on how wettability can be helpful in their separation. Finally, the challenges in application of superwettable materials will be highlighted, and potential solutions to improve the application of these materials will be put forward.

Experimental & Computational Fluid Dynamics Study of the Suitability of Different Solid Feed Pellets for Aquaculture Systems

Fish feed delivery is one of the challenges which fish farmers encounter daily. The main aim of the feeding process is to ensure that every fish is provided with sufficient feed to maintain desired growth rates. The properties of fish feed pellet, such as water stability, degree of swelling or floating time, are critical traits impacting feed delivery. Some considerable effort is currently being made with regard to the replacement of fish meal and fish oil with other sustainable alternative raw materials (i.e., plant or insect-based) with different properties. The main aim of this study is to investigate the motion and residence time distribution (RTD) of two types of solid feed pellets with different properties in a cylindrical fish tank. After experimental identification of material and geometrical properties of both types of pellets, a detailed 3D computational fluid dynamics (CFD) study for each type of pellets is performed. The mean residence time of pellets injected at the surface of the fish tank can differ by up to 75% depending on the position of the injection. The smallest residence time is when the position is located at the center of the liquid surface (17 s); the largest is near the edge of the tank (75 s). The maximum difference between the two studied types of pellets is 25% and it increases with positions closer to the center of the tank. The maximum difference for positions along the perimeter at 3/4 tank radius is 8%; the largest residence times are observed at the opposite side of the water inlet. Based on this study, we argue that the suitability of different solid feed pellets for aquaculture systems with specific fish can be determined, and eventually the pellet composition (formula) as well as the injection position can be optimized.

Forecast of AMD Quantity by a Series Tank Model in Three Stages: Case Studies in Two Closed Japanese Mines

There are about 100 sites of acid mine drainage (AMD) from abandoned/closed mines in Japan. For their sustainable treatment, future prediction of AMD quantity is crucial. In this study, AMD quantity was predicted for two closed mines in Japan based on a series tank model in three stages. The tank model parameters were determined from the relationship between the observed AMD quantity and the inflow of rainfall and snowmelt by using the Kalman filter and particle swarm optimization methods. The Automated Meteorological Data Acquisition System (AMeDAS) data of rainfall were corrected for elevation and by the statistical daily fluctuation model. The snowmelt was estimated from the AMeDAS data of rainfall, temperature, and sunshine duration by using mass and heat balance of snow. Fitting with one year of daily data was sufficient to obtain the AMD quantity model. Future AMD quantity was predicted by the constructed model using the forecast data of rainfall and temperature proposed by the Max Planck Institute–Earth System Model (MPI–ESM), based on the Intergovernmental Panel on Climate Change (IPCC) representative concentration pathway (RCP) 2.6 and RCP8.5 scenarios. The results showed that global warming causes an increase in the quantity and fluctuation of AMD, especially for large reservoirs and residence time of AMD. There is a concern that for mines with large AMD quantities, AMD treatment will be unstable due to future global warming.

The effect of hemicylindrical disruptors on the cell free layer thickness in animal blood flows inside microchannels

AbstractBlood-side resistance to oxygen transport in extracorporeal membrane blood oxygenators (MBO) depends on fluid mechanics governing the laminar flow in very narrow channels, particularly the hemodynamics controlling the cell free layer (CFL) built-up at solid/blood interfaces. The CFL thickness constitutes a barrier to oxygen transport from the membrane towards the erythrocytes. Interposing hemicylindrical CFL disruptors in animal blood flows inside rectangular microchannels, surrogate systems of MBO mimicking their hemodynamics, proved to be effective in reducing (ca. 20%) such thickness (desirable for MBO to increase oxygen transport rates to the erythrocytes). The blockage ratio (non-dimensional measure of the disruptor penetration into the flow) increase is also effective in reducing CFL thickness (ca. 10–20%), but at the cost of risking clot formation (undesirable for MBO) for disruptors with penetration lengths larger than their radius, due to large residence times of erythrocytes inside a low-velocity CFL formed at the disruptor/wall edge.

Evidence for large carbon sink and long residence time in semiarid forests based on 15 year flux and inventory records.

The rate of change in atmospheric CO2 is significantly affected by the terrestrial carbon sink, but the size and spatial distribution of this sink, and the extent to which it can be enhanced to mitigate climate change are highly uncertain. We combined carbon stock (CS) and eddy covariance (EC) flux measurements that were collected over a period of 15years (2001-2016) in a 55 year old 30km2 pine forest growing at the semiarid timberline (with no irrigating or fertilization). The objective was to constrain estimates of the carbon (C) storage potential in forest plantations in such semiarid lands, which cover ~18% of the global land area. The forest accumulated 145-160gCm-2 year-1 over the study period based on the EC and CS approaches, with a mean value of 152.5±30.1gCm-2 year-1 indicating 20% uncertainty in carbon uptake estimates. Current total stocks are estimated at 7,943±323gC/m2 and 372gN/m2 . Carbon accumulated mostly in the soil (~71% and 29% for soil and standing biomass carbon, respectively) with long soil carbon turnover time (59years). Regardless of unexpected disturbances beyond those already observed at the study site, the results support a considerable carbon sink potential in semiarid soils and forest plantations, and imply that afforestation of even 10% of semiarid land area under conditions similar to that of the study site, could sequester ~0.4PgC/year over several decades.

Intensified Liquid-Liquid Extraction Technologies in Small Channels: A Review

Solvent extraction is a key separation process in several industries. Mixer-settlers and agitated or pulsed columns are mainly used as liquid-liquid contactors. However, these units require large solvent inventories and long residence times, while flow fields are often not uniform and mixing is poor. These drawbacks can be overcome with process intensification approaches where small channel extractors are used instead. The reduced volumes of small units in association with the increased efficiencies facilitate the use of novel, often expensive, but more efficient and environmentally friendly solvents, such as ionic liquids. The small throughputs of intensified contactors, however, can limit their full usage in industrial applications, thus robust scale-up strategies need to be developed. This paper reviews promising intensified technologies for liquid-liquid extractions based on small channels. In particular, extractions in single channels and in confined impinging jets are considered. The increase in throughput via scale-out approaches with appropriate manifolds is discussed, based on the use of many channels in parallel. The combination of small channels and centrifugal forces is exploited in counter-current chromatography (CCC) systems where many mixing and settling steps are combined within the contactors. Scale up is possible via centrifugal partition chromatography (CPC) configurations.

Preliminary Experimental Investigation on the Filtration Performance of Submicron Insoluble Aerosol in a Bubble Column

Pool scrubbing is a representative process for aerosol retention involved in the LWR severe accidents and has proved to be a potential method to removal micron-sized aerosol. Bubble scrubbing as the key component of pool scrubbing, has the advantages of large gas-liquid contact area and long residence time. However, the filtration mechanism of submicron aerosol by bubble scrubbing is still not clear. Therefore, the goal of this research is to evaluate the filtration performance of submicron insoluble aerosol in a bubble column. Some preliminary experiments were carried out to investigate the influence of operation parameter on aerosol filtration efficiency, such as inlet aerosol concentration, gas flow rate and pool temperature. Mass method was used to analyze the aerosol filtration efficiency. The results show that the aerosol filtration efficiency independent of inlet aerosol concentration when inlet aerosol concentration is in the range of 0.2-0.5 g/m3. Besides the aerosol filtration efficiency is influenced by the superfical gas velocity. With the increase of superfical gas velocity, homogeneous bubbling, transition and heterogeneous bubbling regime will appear in turn. The aerosol filtration efficiency decreases in transition regime due to the appearance of large bubble, but increases in heterogeneous bubbling regime account for intense gas-liquid interaction. Moreover, the aerosol filtration efficiency significantly decreases with pool temperature. Because the evaporation rate at the gas-liquid interface will significantly increase as the boiling point is approached, which gives retroaction to aerosol filtration efficiency.