Aerosol mass deposition: The importance of gravitational agglomeration

Bamford, G.J.; Ketchell, N.; Dunbar, I.H.

doi:10.1016/0021-8502(92)90353-w

Cited by 4 publications

(2 citation statements)

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“…As the mass concentration reaches a particular stage, the pace at which particle settling rate becomes steady (Bomford et al, 1992) and deposition velocity also becomes steady. It is found from the Fig.…”

Section: Sodium Aerosolsmentioning

confidence: 99%

Investigation of Aerosol Mass and Number Deposition Velocity in a Closed Chamber

Misra

Subramanian

Kumar

et al. 2013

Aerosol Air Qual. Res.

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In the event of a core disruptive accident in a sodium cooled fast reactor, the Reactor Containment Building (RCB) is bottled-up with coolant (sodium), fuel and fission product aerosols. The aerosols suspended in the closed environment undergo coagulation and gravitational settling. Sodium aerosols are generated by combustion, while fission product aerosols are generated by vaporization and condensation, with the resulting particles having two flow regimes. It is expected that the mass concentration of sodium aerosols is relatively high, on the order of a few g/m 3 , while that of the fuel and fission products is only a few mg/m 3 . Taking into account the concentration criteria, experiments are carried out by generating sodium aerosols (mono dispersed) with the concentration of 3.0 g/m 3 , and the deposition velocity over time is determined by mass measurements (concentration and flux). Similarly, non-radioactive species of SrO 2 aerosols are generated (mono dispersed) with a number concentration of 10 6 /cm 3 , and their deposition velocity over time is determined by number measurements (concentration and flux). The mass deposition velocity of sodium aerosols was found to be more than two orders of magnitude greater than the number deposition velocity of SrO 2 aerosols. As the SrO 2 aerosols are generated in the free molecular regime, the depletion pattern of the number concentration of suspended aerosols follows a process of simultaneous coagulation and settling. A theoretical formulation for the rate of depletion of the number concentration is developed, and the rate coefficients of coagulation and deposition velocity are determined from the theoretically fitted equation. The experimental and theoretical results are compared and found to be nearly same. The deposition velocity of sodium aerosols is used to predict the deposition time for the suspended aerosol mass concentration inside the RCB. The mass and number deposition velocities are determined by using a state of art Turn Table Instrument fabricated in our lab.

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Section: Sodium Aerosolsmentioning

confidence: 99%

Investigation of Aerosol Mass and Number Deposition Velocity in a Closed Chamber

Misra

Subramanian

Kumar

et al. 2013

Aerosol Air Qual. Res.

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“…From table 1, the increasing temperature of the discharge solution with increasing discharge time resulted in more rapid growth of the particles in solution. The enlargement in particle size, moreover, affected the decrease in the charge on the particle, which has an important role in stabilizing the particle due to the good colloidal conditions, and it then led to the particle agglomeration [22,23]. To support the results of the HRTEM, the compositional mapping mode of EDX was used to confirm the form of the synthesized nanoparticles.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and characteristics of Ag/Pt bimetallic nanocomposites by arc-discharge solution plasma processing

et al. 2012

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Arc discharge in solution, generated by applying a high voltage of unipolar pulsed dc to electrodes of Ag and Pt, was used as a method to form Ag/Pt bimetallic nanocomposites via electrode erosion by the effects of the electric arc at the cathode (Ag rod) and the sputtering at the anode (Pt rod). Ag/Pt bimetallic nanocomposites were formed as colloidal particles dispersed in solution via the reduction of hydrogen radicals generated during discharge without the addition of chemical precursor or reducing agent. At a discharge time of 30 s, the fine bimetallic nanoparticles with a mean particle size of approximately 5 nm were observed by transmission electron microscopy (TEM). With increasing discharge time, the bimetallic nanoparticle size tended to increase by forming an agglomeration. The presence of the relatively small amount of Pt dispersed in the Ag matrix could be observed by the analytical mapping mode of energy-dispersive x-ray spectroscopy and high-resolution TEM. This demonstrated that the synthesized particle was in the form of a nanocomposite. No contamination of other chemical substances was detected by x-ray photoelectron spectroscopy. Hence, solution plasma could be a clean and simple process to effectively synthesize Ag/Pt bimetallic nanocomposites and it is expected to be widely applicable in the preparation of several types of nanoparticle.

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