• Title/Summary/Keyword: Mixing Degree

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Evaluation of Pressurized Water Mixing of Big Pipe with CFD at Water Treatment Process (CFD를 활용한 수처리공정 대형관에서 압력수 혼합공정 평가)

  • Cho, Young-Man;Yu, Hyun-chul;Jang, Gyeong-Hyuk;Jung, Yong-Jun
    • Journal of Korean Society on Water Environment
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    • v.37 no.3
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    • pp.168-174
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    • 2021
  • Mixing is a very important unit in water treatment process. A mechanical stirring method is generally used for mixing, but recently, the use of pressurized water mixing method (pump diffusion flash mixer) has gained interest because it is more advantageous in terms of mixing time, noise, energy consumption, and maintenance. The following conclusions were obtained from the study of pressurized water mixing method by Computational Fluid Dynamics. Firstly, the mixing degree in the pipe increased as the density of water increased. Secondly, even if the relative velocity between flow rate in the pipe and the pressurized water was constant, the mixing degree decreased as the flow velocity in the pipe increased. Thirdly, the stronger the injection energy the higher the mixing degree. It was also found that the mixing degree was greatly affected by the injection velocity as compared to the injection flow amount. Finally, the required energy to achieve 95% mixing degree at the distance of 10 times diameter in big pipes of 500 mm to 3000 mm was 0.3 to 4.5 kJ. The result of this study could be used in the process design of injection with water purification chemicals, such as, ozone, chlorine, and coagulant.

Prediction of Degree of Mixing for Insoluble Solution with Vortex Index in a Passive Micromixer (마이크로 믹서에서 와도 지수에 의한 비용해성 물질의 혼합 예측)

  • Cho Il-dae;Kim Bum-joong;Maeng Joo-sung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.2 s.233
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    • pp.232-238
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    • 2005
  • The 'Mixing Index($D_I$)' is used as a conventional guidance measuring the degree of mixing for multiphase flows. For the case when insoluble solutions flow in a passive micromixer, a new method to calculate $D_I$ is proposed. The 'Vortex Index(${\Omega}_I$)' is suggested and formulated. We infer that ${\Omega}_I$ relates to the degree of chaotic advection. Various arbitrary shaped microchannels were tested to calculate the $D_I\;and\;{\Omega}_I$, and then a simple algebraic equation, $D_I=Aexp(B{\Omega}_I)$, is obtained. This equation may be used instead of the conventional partial differential equation, concentration equation, to estimate the degree of mixing.

Flame Structure and NOx Emission Characteristics in Laminar Partially Premixed $CH_4$/Air Flames;Effect of Premixing Degree (메탄/공기 층류 부분 예혼합화염의 화염구조와 NOx 배출특성;예혼합 인자의 영향)

  • Oh, Jeong-Seog;Jeong, Yong-Ki;Jeon, Chung-Hwan;Chang, Young-June
    • 한국연소학회:학술대회논문집
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    • 2003.12a
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    • pp.75-81
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    • 2003
  • In this paper, the study of effects of flow variables on flame structure and NOx emission concentration was performed in co-axial laminar partially premixed methane/air flames. the objectives are to reveal its effect as parameters were varied and to understand the correlation between flame structure and NOx emission characteristics in the reaction zone. equivalence ratio(${\Phi}$), fuel split degree(${\sigma}$), and mixing distance(x/D) were defined as a premixing degree and varied within $1.36{\sim}3.17$(equivalence ratio), $50{\sim}100$(fuel split degree), and $5{\sim}20$(mixing distance). the image of $OH{\ast}$ and $CH{\ast}$, and NOx concentration were obtained with an ICCD camera and a NOx analyzer. additionally the maximum intensity location of $OH{\ast}$ chemiluminescence and $CH{\ast}$ chemiluminescence were measured to compare each flame structures. In conclusion flame structure and NOx emission characteristics were changed from diffused to premixed flame when mixing degree was on the increase. the main effect on flame structure and NOx production was at first equivalence ratio(${\Phi}$), and next fuel split degree(${\sigma}$), and finally mixing distance(x/D).

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A Study of Effects with Using After Mixing Ample and Permanent Solvent During Permanent Wave Operating, of Dyod Hairs (염색모발에서 퍼머시술시 퍼머 1제와 앰플의 혼합사용에 대한 효과)

  • Lee, Eun-Kyeung;Choi, Jeung-Sook
    • Journal of the Korean Society of Fashion and Beauty
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    • v.3 no.3 s.3
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    • pp.56-63
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    • 2005
  • In the study of permanent waving method after mixing ample and permanent wave solvent in permanent wave the dyed humans hair are as follows; First, Permanent waving method after mixing ample and permanent wave solvent is that the better effective way in permanent wave the dyed humans hair because permanent waving cycle is constant and hair cuticle is glossy. Second, This study is not interpret in permanent wave dyed humans hair that tensile strength is effect of permanent waving method after mixing ample and permanent wave solvent. A extension degree is effect of permanent waving method after mixing ample and permanent wave solvent use indifferent ample treatment method. Third, Hair cuticle damages are a little permanent waving method after mixing ample and permanent wave solvent in permanent wave dyed humans hair.

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Performance Evaluation of Multi-Degree-of-Freedom Robotic Mixer using Discrete Element Mixing Simulations (이산요소법 교반 시뮬레이션을 이용한 다자유도 로봇 믹서 성능 평가)

  • Son, Kwon Joong
    • Journal of the Korea Convergence Society
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    • v.11 no.10
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    • pp.219-224
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    • 2020
  • Industrial mixers to homogeneously blend particulate materials have been developed and widely used in various industries. However, most industrial mixers have at most two-degree-of-freedom for the operation, which limits the range of operation parameter selection for optimal blending. This paper proposes a multi-degree-of-freedom robotic mixer designed by converging a conventional drum blender and a robotic manipulator and evaluated its performance in a virtual operating environment. Discrete element simulations were conducted for mixing performance evaluation. The numerical results showed that the proposed mixer design exhibits a better mixing performance than conventional ones.

The Relation between Vortex Index and Mixing Index in Micromixer;Insoluble Solution;Insoluble Solution (마이크로 믹서에서 와도 지수와 혼합 지수의 관계;비용해성 물질)

  • Maeng, Joo-Sung;Kim, Bum-Joong;Cho, Il-dae
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1841-1844
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    • 2004
  • 'Mixing Index($D_I$)'s generally used to measure the degree of mixing. A new method to calculate $D_I$ was proposed, when insoluble solution flows in micromixer. 'Vortex Index (${\Omega}_I$)'which indicate the degree of chaotic advection, is defined and formulated. A lots of arbitrary shaped microchannels were tested to calculate the $D_I$ and ${\Omega}_I$. And then a simple algebraic equation, $D_I=A{\Omega}_I+B$, was obtained. This equation may be used instead of partial differential equation, concentration equation.

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Effect of the Degree of Fuel-Air Mixing and Equivalence Ratio on the NOx Emission and Heat Release in a Dump Combustor (모형연소기에서 연료-공기의 혼합정도 및 당량비가 NOx 배출과 열 방출량에 미치는 영향에 대한 연구)

  • Cho, Bong-Kug;Choi, Do-Wook;Kim, Gyu-Bo;Chang, Young-June;Song, Ju-Hun;Jeon, Chung-Hwan
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.9
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    • pp.658-665
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    • 2009
  • Lean premixed combustors are used for significant NOx reduction which one of issues in current gas turbine combustor. This study was investigated to estimate the effects of the unmixedness of fuel-air, equivalence ratio on the instability mechanism, NOx emission and combustion oscillation in a lean premixed combustor. The experiments were conducted in a dump combustor at atmospheric pressure conditions using methane as fuel. The swirler angle was $45^{\circ}$, the degrees of fuel-air mixing were 0, 50 and 100 and inlet temperature was 650K. The equivalence ratio was ranging from 0.5 to 0.8. This paper shows that NOx emission was increased when the degree of fuel-air mixing is increased in same equivalence ratio and when equivalence ratio is increased. And the range of the combustion instability was enlarged as a function of increasing of the degree of fuel-air mixing.

The Study on Flame Structure and NOx Emissions by Swirl Numbers and Fuel-Air Mixing Length in a Dump Combustor Gas Turbine (모형 가스터빈 연소기에서의 스월수와 혼합길이에 따른 화염구조와 NOx배출에 관한 실험적 연구)

  • Choi, Do-Wook;Kim, Gyu-Bo;Jeon, Chung-Hwan;Song, Ju-Hun;Chang, Young-June
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.11
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    • pp.849-857
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    • 2009
  • The experimental study was performed to investigate the effects of partial premixing, varying the equivalence ratio, mixing degree, swirl intensity, mixing length on the characteristics of flame structure and NOx emission. Experiments were conducted in a dump combustor at 1 bar using methane as fuel. Inlet air temperature was 570K. OH chemiluminescence images were acquired with an ICCD camera. As a result of the experimental investigation of characteristics of flame and NOx emission in partial premixed combustor, we can conclude the results as below. With the increase of swirl number, The flame length decreases and the flame width increases and it helps flame stabilization. It means that lean flammability limit is extended. With the increase of mixing of fuel-air length ratio, Flame goes to be stabilized and NOx emission and $OH^{\ast}$ intensity decrease. Through the comparison of preceding results, It is possible that the exhausted NOx emission from a gas turbine combustor will be able to predict through the $OH^{\ast}$ intensity.

Evaluations of Coagulation Process for Membrane Pre-treatment using Floc Growth Rate Analyzer (응집 플록 성장률 측정기를 이용한 멤브레인 공정의 전처리 응집공정 평가)

  • Son, Hee-Jong;Kim, Sang-Goo;Kim, Do-Hwan;Kang, So-Won;Choi, Young-Ik
    • Journal of Environmental Science International
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    • v.25 no.2
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    • pp.231-238
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    • 2016
  • In this study, we have investigated to find optimal pre-treatment flocculation condition by analyzing the floc growth rate with mixing conditions and the membrane permeation flux for pre-treatment step of the membrane process. The higher mixing intensity showed a constant floc size index (FSI) values, and lower mixing intensity increased the degree of dispersion of the FSI values. Results of comparing the distribution characteristics of the FSI value and the permeation flux were more effective in increasing flux when the FSI values were 0.2 or higher. The degree of dispersion of FSI was relatively large in 40 rpm mixing condition compared to 120 rpm. In 40 rpm mixing condition, it decreased the permeation flux compared to 120 rpm because various sizes of flocs were distributed. Coagulation-UF membrane process enhanced 30%~40% of the flux rate compare to UF alone process, and the coagulation-MF process increased up to 5% of the flux rate compare to MF alone process. Pre-treatment, that is, coagulation process, has been found to be less effects on relatively larger pore size for MF membrane. For UF membrane, the flux was a little bit same when applying only the rapid mixing process or rapid mixing with slow mixing processes together. In case of MF membrane, the flux was improved when rapid mixing process applied with slow mixing process together.

A Study on Flow and Mixing Caracteristics according to Hot Water Extraction (온수 추출에 따른 유동 및 혼합 특성에 관한 연구)

  • 장영근;박이동;김철주;황영규
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 1995.05a
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    • pp.53-59
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    • 1995
  • In a hot water extraction process, the flow pattern of upper region in a storage tank is a major reason of mixing between hot water and cold water. In this study, the temperature distribution in a storage tank was measured to predict the flow pattern of upper region, and the degree of stratification was analysed to the variables dominating a extraction process. And also, it was found that the degree of stratification improved expecially in a low flow rate in case of using modified distributor I(DMI) as a outlet port type.

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