• Title/Summary/Keyword: Cyclone model

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Development of prediction model for pressure loss and cut-size of cyclone separator depend on wall curvature (사이클론 집진기의 벽면구배에 따른 압력손실과 컷-사이즈 변화 예측 모델 개발)

  • Heo, Kwang-Su;Seol, Seoung-Yun
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.2676-2681
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    • 2008
  • In previous studies, Convex cyclone are proposed to reduce pressure loss which are design cyclone wall with a single continuous curve. Studies about a prediction model for pressure loss and cut-size has focused on conventional cylinder-on-con cyclone. Therefore, the models do not perform well for uncommon design. In this study, a predict model for pressure loss and cut-size depend on cyclone wall curvature are developed. The tangential velocity below vortex-finder is obtained with consideration about friction area and momentum loss on the cyclone wall, and with this the variation of vortex-core and core velocity is obtained. Pressure loss is predicted using a Rankine vortex hypothesis. The prediction results are well agreed with experiments and CFD results.

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Performance of cyclone separator for syngas production in downdraft gasifier

  • Kumara, Sunil;Shukla, S.K.
    • Advances in Energy Research
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    • v.4 no.3
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    • pp.223-237
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    • 2016
  • The excess use of conventional sources of energy by the industries and power sector result in acute shortage of energy produced by fossil fuel. To overcome this energy crisis, biomass feedstock is used to produce syngas or producer gas. For cleaning the dust particle present in the producer gas cyclone separators are largely used. In this paper we investigate the performance parameters of cyclone separator mainly efficiency and pressure drop for different feedstock. Cyclone performance has been evaluated based on experimentation and empirical approach using Leith and Licht model. The same has also been calculated by using turbulent RSM in Ansys Fluent for Wood and Coconut shell feedstock. Experimental results show that using feed stock with 10 % Calcium oxide (CaO) by weight, the efficiency of cyclone got reduced from 71.87% to 70.75% for wood feed stock, whereas in case of coconut shell, the cyclone efficiency got reduced from 78% to 73.44%. It is also seen that Leith and Licht model and Reynolds stress model (RMS) predicts very close to the particle collection efficiency evaluated by using experimental data.

Study of Convex Cyclone with Continuous Curve (연속적인 곡선으로 정의 되는 볼록한 형상의 사이클론에 대한 연구)

  • Heo, Kwang-Su;Seol, Seoung-Yun;Li, Zhen-Zhe
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2757-2762
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    • 2007
  • A cyclone design concept named Convex cyclone was developed to reduce pressure losses. Contrary to conventional cylinder-on-con type cyclone, inner wall of Convex cyclone are defined with a continuous curve and it has convex shape body. The discontinuity of inner diameter variation rate of cylinder-on-con type cyclone cause additional pressure loss. Continuous wall of Convex cyclone prevent additional pressure loss. In order to verify Convex cyclone design concept, we make a comparative experiments between Stairmand HE and Convex cyclone. Experimental Convex cyclone designed based on Stairmand HE model, and inner wall are defined with circular arch. The experimental result clearly shows that Convex cyclone can achieve maximum 50% pressure loss reduction with a few percent of collection efficiency drop. In addition, the experimental results indicated the existence of optimum convexity, minimum pressure loss, of cyclone wall.

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A Study on Flow Characteristics of Ejector for Cyclone Air Drying Machine (사이클론 건조기용 이젝터 유동 특성에 관한 연구)

  • Kim, Bong-Hwan
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.11 no.6
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    • pp.189-194
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    • 2012
  • The purpose of this study is to predict the performance of a cyclone drying machine and air ejector used in drying applications. This paper deals with optimization of the geometry of the ejector for sludge drying using computational fluid dynamics. To facilitate the design of a jet ejector for air drying machines, a numerical model of simultaneous mass and heat transfers between the liquid(sludge) and gas(air) phases in the jet ejector was developed. The steady-state model was based on unidimensional balance equations of mass, energy and momentum for the liquid and gas phases. It was shown that the optimum condition to minimize pressure and momentum loss of air in the ejector was d=220mm. It was found that sludge particles inside the cyclone was smoothly discharged by the conical wedge installed on the bottom of the cyclone.

Geostrophic Response of the Yellow Sea to Cyclone Passage

  • Oh, Im-Sang;Subbotina, Marina M.
    • Journal of the korean society of oceanography
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    • v.31 no.4
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    • pp.183-195
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    • 1996
  • A barotropic non-linear numerical model is used to study the response of the Yellow Sea to winter cyclone passage. Cyclones normally come from the outside of the western boundary, China, and pass the region eastward. The cyclone parameters used for the present study are the following: the intensity, i.e., the maximum wind speed of the cyclone; the effective radius corresponding to this maximum; and the translation speed. The equations of motion are integrated over the depth which is supposed to be a constant. The Gaussian function is used to define the stream function of the wind. The following results have been found. A northward current is generated by the frontal part of the cyclone near the western boundary. After the cyclone leaves the sea area, a southward current is generated by the rear part of the cyclone. After that, a northward current is generated once again due to the westward propagating Rossby waves. The response of the sea to the cyclone passage is strongly influenced by a steady current when the steady current and the current due to the cyclone wind are of the same order. The steady current diminishes the sea response and reduces the speed of the southward current, and enhances the northward current speed. The intensity and the translation speed of a cyclone also influence the flow pattern significantly.

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Effects of Two Stage Vortex Finder on the Particulate Collection Efficiency of Cyclone Separator (2단 선회류 약화기가 원심력집진기의 집진효율에 미치는 영향)

  • 강순국;유경선
    • Journal of Korean Society for Atmospheric Environment
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    • v.16 no.6
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    • pp.633-640
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    • 2000
  • The effects of structure modification of the vortex finder on the collection efficiency and pressure drop have been investigated. The pressure drop in a cyclone having the two stage vortex finder is higher than that in a conventional cyclone and increases proportionally with the increase of square of gas inlet velocity in both cases. The pressure drop of both conventional cyclone of friction resistance at the boundary layer. The collection efficiency of fine dust has been enhanced by addition of vortex finder in a conventional cyclone and gas inlet velocity showing maximum dust removal efficiency increase to 17 m/s(1.7 times of saltation velocity). Optimum size of two stage vortex finder has been induced to 13 cm I.D$\times$2.6cm Length from the results of overall dust collection efficiency. Previous models were tested for the simulation of collection efficiency of cyclone having two stage vortex finder and the Dietz model predict the similar value with experimental results of the present study.

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Seasonal Prediction of Tropical Cyclone Frequency in the Western North Pacific using GDAPS Ensemble Prediction System (GDAPS 앙상블 예보 시스템을 이용한 북서태평양에서의 태풍 발생 계절 예측)

  • Kim, Ji-Sun;Kwon, H. Joe
    • Atmosphere
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    • v.17 no.3
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    • pp.269-279
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    • 2007
  • This study investigates the possibility of seasonal prediction for tropical cyclone activity in the western North Pacific by using a dynamical modeling approach. We use data from the SMIP/HFP (Seasonal Prediction Model Inter-comparison Project/Historical Forecast Project) experiment with the Korea Meteorological Administration's GDAPS (Global Data Assimilation and Prediction System) T106 model, focusing our analysis on model-generated tropical cyclones. It is found that the prediction depends primarily on the tropical cyclone (TC) detecting criteria. Additionally, a scaling factor and a different weighting to each ensemble member are found to be essential for the best predictions of summertime TC activity. This approach indeed shows a certain skill not only in the category forecast but in the standard verifications such as Brier score and relative operating characteristics (ROC).

Numerical Study on the Effect of the Internal Temperature Distribution in the Cyclone Dust Collector (사이클론 집진장치의 내부 온도 변화에 따른 집진효율에 관한 전산해석적 연구)

  • Hyun, Daegeun;Cha, Hyuksang
    • Particle and aerosol research
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    • v.10 no.4
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    • pp.155-162
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    • 2014
  • The internal temperature will change depending on operation conditions and material of cyclone dust collector. This study compares the results of collection efficiency and temperature distribution on the different heat flux at wall of dust collector. The previous researcher's experiment results were used to confirm the reliability of CFD(Computational Fluid Dynamics) model. Based on this verified CFD model, we extended the analysis on the cyclone dust collectors. In CFD study, we used RNG k-epsilon model for analysis of turbulence flow, fluid is air, the velocity at inlet is 10 m/s, the temperature of air is $600^{\circ}C$. Because of the difference of outer vortex and inner vortex temperature, the collection efficiency will reduce with the increase of heat flux, showed the highest collection efficiency at heat insulation.

Improvement of a High-volume Aerosol Particle Sampler for Collecting Submicron Particles through the Combined Use of a Cyclone with a Smoothened Inner Wall and a Circular Cone Attachment

  • Okuda, Tomoaki;Isobe, Ryoma
    • Asian Journal of Atmospheric Environment
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    • v.11 no.2
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    • pp.131-137
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    • 2017
  • A cyclone is an effective tool to facilitate the collection of aerosol particles without using filters, and in cell exposure studies is able to collect a sufficient amount of aerosol particles to evaluate their adverse health effect. In this study, we examined two different methods to improve the aerosol particle collection efficiency of a cyclone. The individual and combined effects of reducing the surface roughness of the inner wall of the cyclone and of using a circular cone attachment were tested. The collection efficiency of particles of diameter $0.2{\mu}m$ was improved by approximately 10% when using a cyclone with a smoothened inner wall (average roughness $Ra=0.08{\mu}m$) compared with the original cyclone ($Ra=5.1{\mu}m$). A circular cone attachment placed between the bottom section of the cyclone and the top section of a collection bottle, resulted in improved collection of smaller particles without the attachment. The 50% cutoff diameter of the modified cyclone (combined use of smoothened inner wall and attachment) was $0.23{\mu}m$ compared to $0.28{\mu}m$ in the original model. The combined use of these two techniques resulted in improved collection efficiency of aerosol particles.

Numerical Study for the Design of Biogas-fired Low Emission Cyclone Incinerator (바이오 가스 소각용 저공해 사이클론 소각기 개발을 위한 수치 해석적 연구)

  • 전영남;김시욱;백원석
    • Journal of Korean Society for Atmospheric Environment
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    • v.18 no.5
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    • pp.401-410
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    • 2002
  • Concerns for energy conservation, environmental pollution, and the fact that organic wastes account for a major portion of our waste materials, have created the interest of biogas, which usually contains about 60 to 70 percent methane, 30 to 40 percent carbon dioxide, and other gases, including ammonia, hydrogen sulfide, mercaptans and other noxious gases. Cyclone combustors are used for homing a wide range of fuels such as low calorific value gas, waste water, sludge. coal, etc. The 3-dimensional swirling flow, combustion and emission in a tangential inlet cyclone incinerator under different inlet conditions are simulated using a standard k-s turbulence model and ESCRS (Extended Simple Chemically-Reacting System) model. The commercial code Phoenics Ver.3.4 was used for the present work. The main parameters considered in this work are inlet velocity and air to fuel ratio. The results showed that the change of operating conditions had an influence on the shape and size of recirculation zones, mixture fraction and axial velocity which are important factors for combustion efficiency and emission behavior. The application of this kind of computer program seams to be promising as a potential tool for the optimum design of a cyclone combustor with low emission.