• 제목/요약/키워드: Mixing-Efficiency

검색결과 913건 처리시간 0.028초

Optimization of Passive Mixer for Enhanced Mixing in a Micro-channel by Using Lattice Bloltzmann Method (격자 볼츠만 방법을 이용한 미소 채널에서의 혼합효율 증가를 위한 수동형 믹서의 최적화)

  • Han Gyu suk;Byun Sung Joon;Yoon Joon Yong
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • 제29권5호
    • /
    • pp.707-715
    • /
    • 2005
  • In this work, Scalar Passive code in Lattice Boltzmann Method is employed to simulate two-phase flow of low Reynolds number in a micro-channel. The mixing characteristics in a micro-channel is a function of Peclet number. The mixing length increases with the Peclet number. It is found that with the inclusion of static elements at the channel, rapid mixing of two liquids can be achieved, as shown by the results of computer simulations. The enhancement in mixing performance is thought to be caused by the generation of eddies and by lateral velocity component when the mixture flows past static elements. The results indicate that the size of static element has more effect on the mixing than the number of static element.

Field performance analysis of a card cleaner type separating system for a self-propelled pepper harvester

  • Shin, Seo-Yong;Cho, Yongjin;Kim, Su-Bin;Kim, Dae-Cheol
    • Korean Journal of Agricultural Science
    • /
    • 제47권4호
    • /
    • pp.921-931
    • /
    • 2020
  • This study was carried out to determine the factor of a separating system according to the pepper varieties and the absence of a card cleaner system. The pepper varieties of Jeokyoung and AR-Legend were transplanted on November 20, 2019 and tested on March 18, 2020 with a harvesting speed of 0.2 m·s-1 for 10 pepper plants. The performance evaluation was determined by analyzing the separation efficiency of the peppers and the foreign matter mixing rate. The pepper harvester with a card cleaner showed a higher separation efficiency of the peppers compared to the pepper harvester without a card cleaner. The average separation efficiency of peppers on the pepper harvester with a card cleaner was higher at 13.5% for Jeokyoung and 1.9% for AR-Legend than that without a card cleaner. The mixing ratio of foreign materials on the pepper harvester with a card cleaner was lower at 8.7% and 2.5% for Jeokyoung and AR-Legend than that without a card cleaner, respectively. For the two-way ANOVA results according to the variety and the card cleaner, there was no effect on the separation efficiency of the peppers, but there was an effect on the foreign matter mixing rate.

Optical Design of Light Guide Plate Material for Slim Liquid Crystal Display (박형 디스플레이를 위한 도광판의 광학설계)

  • Gong, Taewon;Choi, Gyu Jin;Kwon, Jin Hyuk;Park, In Shik;Lee, Sunmook;Woo, DongJin;Gwag, Jin Seog
    • Journal of the Korean institute of surface engineering
    • /
    • 제47권5호
    • /
    • pp.233-238
    • /
    • 2014
  • In this paper, in order to achieve slim and light liquid crystal display, we examine the optical conditions that can obtain uniform light with higher optical efficiency over whole light guide plate (LGP) through simulation. Furthermore, to overcome the issues of hot spot in front of red, green, and blue light emitting diodes (RGB LEDs) source and non-uniform color mixing, we propose four shaped color mixing bars tied up with the LGP and check the optical characteristics of the LGP with them by simulation. Consequently, we could know the optical conditions of improving optical efficiency and optical uniformity in the LGP through the optical design. Also we confirmed that the issues of the hot spot and non-uniform color mixing in edge type LED could be solved by using the ${\bigwedge}$-shaped window color mixing bar.

Gas dischage Simulation for Color Plasma Display Panel and Measurement of VUV (Vacuum UltraViolet) (칼라 플라즈마 디스플레이 패널용 혼합 가스 최적화 시뮬레이션 및 진공 자외선 측정)

  • Park, Hun-Gun;Lee, Seok-Hyun
    • Proceedings of the KIEE Conference
    • /
    • 대한전기학회 1997년도 하계학술대회 논문집 E
    • /
    • pp.1666-1668
    • /
    • 1997
  • This paper reports the optimal gas mixing ratio for color plasma display panel to improve luminous efficiency using gas dischage simulation which contains energy equation. We verified a simulation by measuring vacuum ultraviolet. The luminous efficiency has improved considerably(about 30%) by adding Ar (0.5%), compared with Ne-Xe(4%) mixing gas.

  • PDF

CYLINDRICAL MIXING LAYER MODEL IN STELLAR JET (항성 제트의 원통형 혼합층 모델)

  • Choe, Seung-Eon;Yu, Gyeong-Hui
    • Publications of The Korean Astronomical Society
    • /
    • 제9권1호
    • /
    • pp.21-38
    • /
    • 1994
  • We have developed a cylindrical mixing layer model of a stellar jet including cooling effect in order to understand an optical emission mechanism along collimated high velocity stellar jets associated with young stellar objects. The cylindrical results have been calculated to be the same as the 2D ones presented by Canto & Raga(1991) because the entrainment efficiency in our cylindrical model has been obtained to be the same value as the 2D model has given. We have discussed the morphological and physical characteristics of the mixing layers by the cooling effect. As the jet Mach number increases, the initial temperature of the mixing layer goes high because the kinetic energy of the jet partly converts to the thermal energy of the mixing layer. The initial cooling of the mixing layer is very severe, changing its outer boundary radius. A subsequent change becomes adiabatic. The number of the Mach disks in the stellar jet and the total radiative luminosity of the mixing layer, based on our cylindrical calculation, have quite agreed with the observations.

  • PDF

Removal Characteristics of Nitrogen and Phosphorus in swine wastewater by Using Acetic acid on the SBR Process (SBR에서 아세트산을 이용한 양돈폐수의 질소·인 제거 특성)

  • Huh, Mock;Kang, Jin-Young
    • Journal of the Korea Organic Resources Recycling Association
    • /
    • 제12권1호
    • /
    • pp.84-93
    • /
    • 2004
  • This study was performed : 1) to find the suitable HRT(hydralic retention time), 2) to evaluate the effects of the ratio of mixing/aeration time and injection time of external carbon source, for the removal of organics, nitrogen and phosphorus in swine wastewater by SBR(sequencing batch reactor process), which is one of the biological treatment process. The result of this study were summarized as follows : (1) As the ratio of mixing/aeration time was higher, $NH_4{^+}-N$ removal efficiency was increased and it was increased with increasing injection time of external carbon source because nitrification was affected by denitrification microbes propagation when injection time of external carbon soruce was shorted. T-N removal efficiency was increased with increasing the ratio of mixing/aeration time and injection time of external carbon source. (2) The T-P removal efficiency showed a great difference in each operating condition, and it was increased with increasing the ratio of mixing/aeration time increased and when the injection time of external carbon source was shorted because denitrification was done with effect by denitrification microbes propagation. (3) The highest removal efficiency of organic and nitrogen were obtained by the operating condition of Run 4-1(the ratio of mixing/aeration time : 16.5/5.5, injection time of external carbon source : 15hours) and T-P were obtained by the operation condition of Run 4-2(the ratio of mixing/aeration time : 16.5/5.5, injection time of external carbon source : 3hours), and efficiency(effluent concentration)of $BOD_5$, $COD_{Mn}$, $COD_{Cr}$, T-N and T-P in the treated water was 96.1%, 87.7%, 90.6%, 86.6% and 84.5%, respectively.

  • PDF

The Effect of Karman Vortex for Mixing in a Micro-channel with an Oscillating Micro-stirrer (진동 교반기가 있는 미소채널에서 혼합에 대한 Karman 와의 영향)

  • An, Sang-Joon;Maeng, Joo-Sung;Kim, Yong-Dae
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • 제30권2호
    • /
    • pp.144-152
    • /
    • 2006
  • In order to consider the effect of Karman vortex for mixing, mixing indices are calculated for 4 models of micro channel flows driven from the combinations of a circular cylinder and a oscillating stirrer. And their results are compared to that of a simple straight micro channel flow(model I). The mixing rate is improved 5.5 times by Karman vortex (model II) and 11.0 times by the stirrer(model III) respectively. In case of successive mixing by the cylinder and the stirrer(model IV), $27\%$ of shortening the channel length for the complete mixing as well as 1.37 times improvement of mixing efficiency then model III. And then, variation of mixing indices are much stable comparing with the others. Thus, it is found that the Karman vortex plays a good role as a pre-mixing method. The D2Q9 Lattice Boltzmann methods are used.

Development of a Barrier Embedded Chaotic Micromixer (배리어가 포함된 카오스 마이크로 믹서의 개발)

  • 김동성;이석우;권태헌;이승섭
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • 제28권1호
    • /
    • pp.63-69
    • /
    • 2004
  • It is of great interest to enhance mixing performance in a microchannel in which the flow is usually characterized as a low Reynolds number (Re) so that good mixing is quite difficult to be achieved in this laminar flow regime. In this regard, we present a new chaotic passive micromixer, named Barrier Embedded Micromixer (BEM), of which the mixing mechanism is based on chaotic flows. In BEM, chaotic flow is induced by periodic perturbation of the velocity field due to periodically inserted barriers along the channel wall while a helical type of flow is obtained by slanted grooves on the bottom surface of the channel in the pressure driven flow. To experimentally compare the mixing performance, a T-microchannel and a microchannel with only slanted grooves were also fabricated. All microchannels were made of PDMS (Polydimethylsiloxane) from SU-8 masters that were fabricated by conventional photolithography. Mixing performance was experimentally characterized with respect to an average mixing intensity by means of color change of phenolphthalein as pH indicator. It was found that mixing efficiency decreases as Re increases for all three micromixers. Experimental results obviously indicate that BEM has better mixing performance than the other two. Chaotic mixing mechanism, suggested in this study, can be easily applied to integrated microfluidic systems , such as Micro-Total-Analysis-System, Lab-on-a-chip and so on.

Trade-off Evaluation due to Application of Mixing Chamber for Hybrid Rocket-Propulsion System (하이브리드 로켓 추진 시스템의 혼합 연소실 적용에 따른 Trade-off 평가)

  • Kim, Hakchul;Moon, Keunhwan;Moon, Heejang;Kim, Jinkon
    • Journal of Aerospace System Engineering
    • /
    • 제10권3호
    • /
    • pp.23-31
    • /
    • 2016
  • The intermediate mixing chamber is one of various methods for improving the regression rate and combustion efficiency of the hybrid rocket. The mixing chamber with its non-combustible material makes the propulsion performance increase, but it leads to a low fuel-loading density in the combustion chamber; therefore, this performance-related trade-off between the mixing chamber and the low fuel-loading density was studied. In this study, the trade-off was conducted by comparing the intermediate-mixing-chamber case with a w/o-mixing-chamber case. The small hybrid-sounding rocket is designed with internal ballistics for comparing the rocket length to the weight. In addition, an external ballistic analysis was conducted for comparing the performances of the w/- and w/o-mixing-chamber cases. As a result, the intermediate-mixing-chamber case shows that the length and the weight were decreased to 12 % and 8 %, respectively; furthermore, when compared with the normal cases, the estimated altitude result of the w/-mixing-chamber case was increased to approximately 75 m.

Effect of the distance between the adjacent injectors on penetration and mixing characteristics of the jet in supersonic crossflow (수평 배치된 분사구의 배치 간격에 따른 초음속 유동장 내 분사 유동의 침투 및 혼합 특성)

  • Kim, Sei Hwan;Lee, Hyoung Jin
    • Journal of Aerospace System Engineering
    • /
    • 제12권4호
    • /
    • pp.81-89
    • /
    • 2018
  • In the present study, a numerical investigation was conducted to analyze the effect of the distance between the adjacent injectors on the characteristics of flow structure, fuel penetration, and air/fuel mixing. Numerical results were validated with experimental data using a single injection. Subsequently, the same injector geometry and properties were applied on a non-reacting flow simulation with multiple injectors. Total pressure loss, penetration height, and mixing efficiency were compared with the distance between the injectors. The results showed that each injected gas merged into a single stream, resulting in the 2D-like flow fields under the condition of short distance and lower mixing efficiency along with higher total pressure loss. When the distance between the injectors increased, total pressure loss reduced and mixing efficiency increased due to the weakening of interactions between the injected gases.