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Particulate Matter Deposition Regularity in Air Conditioning Ventilation Ducts

Author: ZhangCanFeng
Tutor: YuanShuJie
School: Anhui University of Technology
Course: Safety Technology and Engineering
Keywords: Gas-Solid Two-Phase Flow Particle migration regularity HVACducts Numerical simulation
CLC: TU834
Type: Master's thesis
Year: 2013
Downloads: 35
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Abstract

The particulate matter in the air is a class of important pollutant that endanger human health because of its toxic and the harmful substances that it carry. Especially the emergence of the large number of cities in the persistent haze weather, take people’s attention to the particle pollution again. Because the particulate matter pollution has a direct and significant impact to people’s work and live environment. So the particulate matter pollution, motion in the central air conditioning system should be paid more attention. Through analyzing the numerical simulation result, we can know the airflows’movement regularity and the particles’subsidence, sedimentary regularity in the central air conditioning ducts. Through the reasonable referencing and practical applying the simulation result, we can take corresponding control measures to reduce dust pollution and maintain piping clean, though it is very meaningful to personnel healthy and safety.At first, this paper has an overview of the current research status of the pollution control and particle movement in the air conditioning ventilation system. The types and characteristics of particulate matter, the seriousness of the particulate matter pollution in air conditioning system and the affect to human health have been theoretical analyzed. After analyzing the force and the factors influencing the particle deposition, using Reynolds stress model (RSM) and the discrete phase model (DPM), the particulate matter migration regularity in air conditioning duct system is studied. The differences of the air flow field and the particle migration regularity are discussed in rectangular and circular curved pipe. Last, the paper mainly discussed the influence of the particles size, air velocity and the elbow bent curvature to particles’concentration, sedimentation and the deposition.The numerical simulation and analysis results for particles in pipe are as follows: When the diameters of the particles range from1μm to10μm, the particles’behavior are mainly affected by the influence of turbulent diffusion and the particles’deposition rate in the square-shaped pipe higher than in the circular curved pipe when in the same air velocity. When particle size is becoming larger, the particle is affected by gravity, the greater of the particle size, the faster of the particles’deposition.The difference of the deposition rate in the square-shaped pipe and in the circular curved pipe becoming smaller. The numerical simulation and analysis results for particles in bend are as follows: With particle size increased, particle deposition rate increased.particle deposition distribution are offset to the outside of the elbow, particle concentration inside of the elbow is small. even it occur that some districts without particles; when the particles’ diameter is20μm, with the increase of wind speed, the particles in the pipe distribution becoming more uniform. The deposition rate in the pipe at the bottom is becoming smaller. But the increase in the number of deposited particles are on the inside wall of the pipe and bend, with the increase of the elbow bend curvature the particles’ deposition rate is increased, and the bend curvature can produce greater impact to the large size particles’ deposition rate.

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CLC: > Industrial Technology > Building Science > Housing construction equipment > Air-conditioning, heating, ventilation,and its equipment > Ventilation, dust,air purification,dehumidification
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