Measurement of the deposition of submicron particles in gradients of vapour pressure and of the efficiency of this mechanism in the capture of particulate matter by cloud droplets in nature

Goldsmith, P.; Delafield, H.J.; Cox, L. C.

doi:10.1007/bf02000654

Cited by 10 publications

(7 citation statements)

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“…The experimental results of Rosenblatt and LaMer(40) obtained with tricresyl particles also agreed well with Equations (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28) and (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29) This is follo wed by a deta iled discu ssion of the particle equa tions , the Kutta -Mer son integ ratio n techn ique , and the Newt on-Ra phson meth od. The latte r was empl oyed to determ ine the corr ect grad ients of the conc entra tion, velo city, and temp eratu re prof iles from the appro xima te grad ients .…”

Section: B Thermoph Orèsissupporting

confidence: 78%

“…= (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23) where u and m are the velocity and mass of the. gas molecules, respectively.…”

Section: B Thermoph Orèsismentioning

confidence: 99%

“…Equation (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24) indicates that the particles experience a force in the direction of declining temperature. This is in agreement with Aitken's finding(l) that "Particles are 'attracted '…”

Section: B Thermoph Orèsismentioning

confidence: 99%

“…Equations (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24) and (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) …”

Section: B Thermoph Orèsisunclassified

“…Goldsmith , Delafield , and Cox (23,24 ) were the first to show experime ntally that diffusiop horesis could be employed to separate very small particles (Kn»l) continuou sly from 18 a. gas strea m. The appar atus used cons isted of two paral 1e1 plate s (30 cms long, 10 cms wide) which were kept a few mi11 imeter s apart by means of space rs. One surfa ce was lined with absor bent paper and satur ated with wate r. Water vapou r diffu sed from this plate thro~g h the parti cle -beari~g air strea m to the oppo site plate which was lined with paper satur ated with sulphuri c acid.…”

mentioning

confidence: 99%

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The separation of micron‐size particles from air by diffusiophoresis

et al. 1971

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The separation of micron-size particles from air by diffusiophoresis in a parallel plate collector was studied theoretically and experimentally. Particle-bearing air flowed under laminar conditions between two plates saturated with water and maintained at different temperatures. Water vapour diffused towards the cooler plate on which the particles deposited due to diffusiophoresis.The collector performance was predicted by assuming that the particles adopt the fluid velocity and this was calculated numerically from the transport equations. These results· (subsequently refined) were the basis for the design of the experimental apparatus.Good agreement between experimental data and theoretical predictions was obtained and diffusiophoresis was found to de pend strongly on the water vapour concentration and concentration gradient. To achieve complete particle removal approximately 1.5 lbs of water vapour per pound of air were required.The effect of the momentum equation on diffusion through a stagnant gas was shown to be negligible under most conditions. ABSTRACTThe removal of micron-size c~garette smoke particles from air by diffusi"ophoresisin a' simple, .parallel plate particle collector was studied theoretically and experimentally.When a vapour diffuses thro~gh a st~gnant. gas which contains small particles, the particles are found to move in the same direction as the vapour and this phenomenon is termed "Diffusiophoresis". The primary cause of diffusiophoresis is that diffusion through a stagnant gas. gives rise to a "bulk" flow in the fluid (Stefan flow). In the present study this effect was utilized by passing particle-bearing air under laminar conditions between two parallel plates (80 11 long, 12" wide) which were saturated with water and maintained at different temperatures. Water vapour thus diffused through the air towards the lower and cooler plate and the particles were deposited on this plate by diffusiophoresis. The performance of the particle collector was predicted theoretically by assuming that the particles move with the local fluid velocity and the design of the experimental apparatus was based on these predictions. It was subsequently found that the experimental data agreed quantitatively with the theoretical results based on the afore-mentioned assumption.The velocity field of the fluid was calculated by solving the fluid transport equations numerically with a minimum number of simplifying assumptions. From this work it was apparent that the diffusiophoretic velocity is a strong function of the vapour concentration and concentration. gradient in the particle collect~r·.

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Section: B Thermoph Orèsissupporting

confidence: 78%

“…= (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23) where u and m are the velocity and mass of the. gas molecules, respectively.…”

Section: B Thermoph Orèsismentioning

confidence: 99%

Section: B Thermoph Orèsismentioning

confidence: 99%

“…Equations (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24) and (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) …”

Section: B Thermoph Orèsisunclassified

mentioning

confidence: 99%

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The separation of micron‐size particles from air by diffusiophoresis

et al. 1971

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Removal of micron‐size particles from gases by turbulent deposition and diffusiophoresis

et al. 1975

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When one gaseous or vapour component diffuses across a space occupied by another component, there is a tendency to entrain and remove particles in the micron size range suspended in that space. This phenomena is called diffusiophoresis. The object of this work was to study the application of this phenomenon as a means of air pollution control when pollutant particles are suspended in a gas stream in turbulent flow. Under these conditions turbulent deposition also results in removal of particles from the gas stream. The test system chosen for study was sulfuric acid droplets suspended in air, with water vapour as the diffusing component. A concentration gradient was established by passing the mixture through a vertical tube whose walls were cooled. Experimental particle collection efficiencies agreed with efficiencies calculated from a theoretical model of the system. The energy requirement of this pollution control technique was analyzed.

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