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Author : Hod Wirzberger
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (87 download)
Download or read book Prevention of Particle Deposition from Duct Flows by Means of Heating the Deposition Surface written by Hod Wirzberger and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Particle Deposition in Ventilation Ducts written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In ventilation duct flow the turbulent flow profile is commonly disturbed or not fully developed and these conditions are likely to influence particle deposition to duct surfaces. Particle deposition rates at eight S-connectors, in two 90{sup o} duct bends and in two ducts where the turbulent flow profile was not fully developed were measured in a laboratory duct system with both galvanized steel and internally insulated ducts with hydraulic diameters of 15.2 cm. In the steel duct system, experiments with nominal particle diameters of 1, 3, 5, 9 and 16 [mu]m were conducted at each of three nominal air speeds: 2.2, 5.3 and 9.0 m/s. In the insulated duct system, deposition of particles with nominal diameters of 1, 3, 5, 8 and 13 [mu]m was measured at nominal air speeds of 2.2, 5.3 and 8.8 m/s. Fluorescent techniques were used to directly measure the deposition velocities of monodisperse fluorescent particles to duct surfaces. Deposition at S-connectors, in bends and in straight ducts with developing turbulence was often greater than deposition in straight ducts with fully developed turbulence for equal particle sizes, air speeds and duct surface orientations. Deposition rates at all locations were found to increase with an increase in particle size or air speed. High deposition rates at S-connectors resulted from impaction and these rates were nearly independent of the orientation of the S-connector. Deposition rates in the two 90{sup o} bends differed by more than an order of magnitude in some cases, probably because of the difference in turbulence conditions at the bend inlets. In straight steel ducts where the turbulent flow profile was developing, the deposition enhancement relative to fully developed turbulence generally increased with air speed and decreased with downstream distance from the duct inlet. This enhancement was greater at the duct ceiling and wall than at the duct floor. In insulated ducts, deposition enhancement was less pronounced overall than in steel ducts. Trends that were observed in steel ducts were present, but weaker, in insulated ducts.
Author : Mark Raymond Sippola
Publisher :
ISBN 13 :
Total Pages : 490 pages
Book Rating : 4.:/5 (34 download)
Download or read book Particle Deposition in Ventilation Ducts written by Mark Raymond Sippola and published by . This book was released on 2002 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 28 pages
Book Rating : 4.:/5 (871 download)
Download or read book Experiments Measuring Particle Deposition from Fully Developed Turbulent Flow in Ventilation Ducts written by and published by . This book was released on 2003 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Particle deposition in ventilation ducts influences particle exposures of building occupants and may lead to a variety of indoor air quality concerns. Experiments have been performed in a laboratory to study the effects of particle size and air speed on deposition rates of particles from turbulent air flows in galvanized steel and internally insulated ducts with hydraulic diameters of 15.2 cm. The duct systems were constructed of materials typically found in commercial heating, ventilating and air conditioning (HVAC) systems. In the steel duct system, experiments with nominal particle sizes of 1, 3, 5, 9 and 16 [mu]m were conducted at each of three nominal air speeds: 2.2, 5.3 and 9.0 m/s. In the insulated duct system, deposition rates of particles with nominal sizes of 1, 3, 5, 8 and 13 [mu]m were measured at nominal air speeds of 2.2, 5.3 and 8.8 m/s. Fluorescent techniques were used to directly measure the deposition velocities of monodisperse fluorescent particles to duct surfaces (floor, wall and ceiling) at two straight duct sections where the turbulent flow profile was fully developed. In steel ducts, deposition rates were higher to the duct floor than to the wall, which were, in turn, greater than to the ceiling. In insulated ducts, deposition was nearly the same to the duct floor, wall and ceiling for a given particle size and air speed. Deposition to duct walls and ceilings was greatly enhanced in insulated ducts compared to steel ducts. Deposition velocities to each of the three duct surface orientations in both systems were found to increase with increasing particle size or air velocity over the ranges studied. Deposition rates measured in the current experiments were in general agreement with the limited observations of similar systems by previous researchers.
Author :
Publisher :
ISBN 13 :
Total Pages : 166 pages
Book Rating : 4.:/5 (684 download)
Download or read book Particle Deposition from Turbulent Flow written by and published by . This book was released on 2002 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report reviews published experimental and theoretical investigations of particle deposition from turbulent flows and considers the applicability of this body of work to the specific case of particle deposition from flows in the ducts of heating, ventilating and air conditioning (HVAC) systems. Particle deposition can detrimentally affect the performance of HVAC systems and it influences the exposure of building occupants to a variety of air pollutants. The first section of this report describes the types of HVAC systems under consideration and discusses the components, materials and operating parameters commonly found in these systems. The second section reviews published experimental investigations of particle deposition rates from turbulent flows and considers the ramifications of the experimental evidence with respect to HVAC ducts. The third section considers the structure of turbulent airflows in ventilation ducts with a particular emphasis on turbulence investigations that have been used as a basis for particle deposition models. The final section reviews published literature on predicting particle deposition rates from turbulent flows.
Author :
Publisher :
ISBN 13 :
Total Pages : 21 pages
Book Rating : 4.3/5 (91 download)
Download or read book Deposition of Submicron-size Particles in Ventilation Ducts written by and published by . This book was released on 1963 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Mark Raymond Sippola
Publisher :
ISBN 13 :
Total Pages : 606 pages
Book Rating : 4.:/5 (34 download)
Download or read book Particle Deposition in Ventilation Ducts written by Mark Raymond Sippola and published by . This book was released on 2002 with total page 606 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 702 pages
Book Rating : 4.:/5 (31 download)
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
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ISBN 13 :
Total Pages : 5 pages
Book Rating : 4.:/5 (873 download)
Download or read book The Use of Large Surface Area for Particle and Power Deposition written by and published by . This book was released on 1993 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling Particle Loss in Ventilation Ducts written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Empirical equations were developed and applied to predict losses of 0.01-100 [mu]m airborne particles making a single pass through 120 different ventilation duct runs typical of those found in mid-sized office buildings. For all duct runs, losses were negligible for submicron particles and nearly complete for particles larger than 50 [mu]m. The 50th percentile cut-point diameters were 15 [mu]m in supply runs and 25 [mu]m in return runs. Losses in supply duct runs were higher than in return duct runs, mostly because internal insulation was present in portions of supply duct runs, but absent from return duct runs. Single-pass equations for particle loss in duct runs were combined with models for predicting ventilation system filtration efficiency and particle deposition to indoor surfaces to evaluate the fates of particles of indoor and outdoor origin in an archetypal mechanically ventilated building. Results suggest that duct losses are a minor influence for determining indoor concentrations for most particle sizes. Losses in ducts were of a comparable magnitude to indoor surface losses for most particle sizes. For outdoor air drawn into an unfiltered ventilation system, most particles smaller than 1 [mu]m are exhausted from the building. Large particles deposit within the building, mostly in supply ducts or on indoor surfaces. When filters are present, most particles are either filtered or exhausted. The fates of particles generated indoors follow similar trends as outdoor particles drawn into the building.
Author :
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ISBN 13 :
Total Pages : 11 pages
Book Rating : 4.:/5 (925 download)
Download or read book Experimental Study on the Particles Deposition in the Sampling Duct written by and published by . This book was released on 1995 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: A high standard of protection against the harmful effects of radioactive aerosol dissemination requires a measurement, as representative as possible, of their concentration. This measurement depends on the techniques used for aerosol sampling and transfer to the detector, as well as on the location of the latter with respect to the potential sources. The aeraulic design of the apparatus is also an important factor. Once collected the aerosol particles often have to travel through a variably shaped duct to the measurement apparatus. This transport is responsible for losses due to the particles deposition on the walls, leading to a distortion on the concentration measurements and a change in the particle size distribution. To estimate and minimize measurement errors it is important to determine the optimal transport conditions when designing a duct; its diameter and material, the radius of curvature of the bends and the flow conditions must be defined in particular. This paper presents an experimental study in order to determine, for each deposition mechanism, the retained fraction, or the deposition velocity for different flow regimes. This study has pointed out that it exists a favourable flow regime for the particle transport through the sampling ducts (2 500
Author :
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ISBN 13 :
Total Pages : 696 pages
Book Rating : 4.F/5 ( download)
Download or read book Heat Transfer & Fluid Flow Digest written by and published by . This book was released on 1983 with total page 696 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Mark Herring
Publisher :
ISBN 13 :
Total Pages : 86 pages
Book Rating : 4.:/5 (811 download)
Download or read book Deposition of Small Particles in Oscillatory Flows written by Mark Herring and published by . This book was released on 1996 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Jonathan Frederick William Adams
Publisher :
ISBN 13 :
Total Pages : 558 pages
Book Rating : 4.:/5 (89 download)
Download or read book Particle Deposition, Dispersion and Re-suspension Behaviour in Turbulent Square Duct and Circular Pipes Flows written by Jonathan Frederick William Adams and published by . This book was released on 2011 with total page 558 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study is concerned with the modelling of single-phase and two-phase turbulent flows in a square duct over a range of Reynolds numbers with attention focused on the deposition, dispersion and re-suspension of particles. Reynolds averaged Navier Stokes (RANS) modelling is used in conjunction with a Lagrangian particle tracker (LPT). Modelling and simulation of single- and two-phase turbulent flows in circular pipes with the presences of stationary flat beds are also considered using the previously stated methodologies, as well as large eddy simulation (LES). The performance of the RANS modelling technique is evaluated against available experimental, simulation and empirical data. The RANS modelling technique is seen to perform with qualitative accuracy across all of the test cases considered within this thesis, and it can be said that this approach is capable of reproducing many of the key feature' associated with these flows. In almost all cases, qualitative agreement is seen between the RANS modelling results and the available experimental data, simulation results and empirical correlations. A key failing of the RANS modelling technique is the inaccurate representation of the magnitude of the secondary velocities found in square ducts and pipes with variable bed height. The RANS modelling technique with a Reynolds stress model (RSM) for turbulence, coupled with a LPT, can be usefully used in modelling particle-laden duct and pipe flow. across a range of conditions. Important qualitative information can be gained from this technique in terms of particle deposition, dispersion and re-suspension. For more detailed studies on the physics of these flows, the preferred methodologies are the more advanced simulation techniques of LES and direct numerical simulation CDNS), while there is also a clear need for further experimental investigations of such particle- laden flows.
Author : Olle Wallin
Publisher :
ISBN 13 :
Total Pages : 162 pages
Book Rating : 4.:/5 (186 download)
Download or read book Computer Simulation of Particle Deposition in Ventilating Duct Systems written by Olle Wallin and published by . This book was released on 1994 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : G. A. Sehmel
Publisher :
ISBN 13 :
Total Pages : 16 pages
Book Rating : 4.:/5 (245 download)
Download or read book Particle Deposition from Turbulent Air Flow written by G. A. Sehmel and published by . This book was released on 1969 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : United States. Environmental Protection Agency
Publisher :
ISBN 13 :
Total Pages : 1068 pages
Book Rating : 4.0/5 ( download)
Download or read book N.A.P.C.A. Abstract Bulletin written by United States. Environmental Protection Agency and published by . This book was released on 1971 with total page 1068 pages. Available in PDF, EPUB and Kindle. Book excerpt:
