• Journal of Biosystems Engineering
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• v.24 no.6
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• pp.487-492
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• 1999

One of effective utilization method of rice husk is to utilize it as culture material by carbonizing the rice husk. As a second part of a series to investigate the effective and continuous production of carbonized rice husk by a cyclone combustor, a non-slagging vertical cyclone combustor without vortex collector pocket was introduced. Isothermal and mixed firing with LPG and rice husk were undertaken in order to characterize the system. Inert rice husk was used during the isothermal test to find mass of rice husk collected. It was impossible to ignite rice husk itself over the experimental conditions considered in this experiment. Cyclone combustor was operated at temperatures of 1,273~1,473K. Detailed combustion data were obtained from a pilot unit with the air flow rate of 70m$^3$/h and rice husk feed of 2kg. The equivalence ratio ranged from 0.66 to 3.48. The auxiliary gas flow rate was varied from 3.22 to 12.86$\ell$/min. The weight reduction, pH and particle size distribution of carbonized rice husk were measured to evaluate the quality of carbonized rice husk. An analysis of exhaust gas emission was conducted to characterize the combustor. The required carbonized rice husk could be obtained at equivalence ratio of 1.68~2.17, combustor temperature of 1,273~1,373K and auxiliary gas flow rate of 3.22~6.43$\ell$/min. A method to reduce CO emissions should be employed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.2
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• pp.144-153
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• 2008

A numerical analysis has been carried out to examine the flow characteristics and the collection efficiency for fine particles in a cyclone using Computational Fluid Dynamics (CFD) technique. The cyclone with the cylinder diameter of 60 mm has been considered for the investigation of the particle collection in a relatively smaller cyclone with somewhat higher inlet air velocities. Fundamental air flow patterns for different inlet velocities have been calculated and then the motions of particles of different sizes have been obtained. The calculated collection efficiencies for fine particles are compared with the experimental results, which shows a good agreement. The current result can be used for the design of cyclones with high collection efficiency.

• Journal of Energy Engineering
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• v.13 no.2
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• pp.112-117
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• 2004

Volatile organic compounds (VOCs) are low calorific value gases (LCVG) emitted from chemical processes such as painting booth, dye works and drying processes etc. Characteristics of VOCs are low calorific values less than 150kcal/㎥, high activation energy for ignition and low energy output. These characteristics usually make combustion unstable and its treatment processes needs high-energy consumption. The cyclone combustion system is suitable for LCVG burning because it can recirculate energy through a high swirling flow to supply the activation energy for ignition, increases energy density In make a combustion temperature higher than usual swirl combustor and also increases mixing intensity. This research was conducted to develop optimized cyclone combustion system for thermal oxidation of VOCs. This research was executed to establish the effect of swirl number with respect to the combustion temperature and composition of exhausted gas in the specific combustor design.

• Particle and aerosol research
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• v.11 no.2
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• pp.47-55
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• 2015

This study compares the results of collection efficiency of difference gas temperature in cyclone 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 $20^{\circ}C$, $100^{\circ}C$, $200^{\circ}C$, $300^{\circ}C$, $600^{\circ}C$ and $1000^{\circ}C$. As the temperature decreases, the average velocity of outer vortex and collection efficiency is increased, showed the highest collection efficiency at $20^{\circ}C$. It can be inferred smooth flow in cyclone dust collector is difficult because air viscosity increases as temperature increases. The power required at $1000^{\circ}C$ is almost 18 times greater than that of $20^{\circ}C$ to get the similar collection efficiency.

• Journal of Biosystems Engineering
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• v.36 no.3
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• pp.204-210
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• 2011

This study developed the cyclone conveying system using roughage cutter for the round bale reported in the previous papers. Performance tests were conducted whether it can easily separate dust from roughage such as rice straws and it can transport roughages from cutter to TMR mixer. In addition, the airflow patterns in the cyclone conveying system were investigated using CFD code (FLUENT 6.2) for various velocities of dust collection fan. The cyclone conveying system was designed based on dried rice straws with a diameter of 1,340 mm, a cylinder length of 1,220 mm, a cone length of 850 mm and the current velocity of the dust collection fan was 15~20 m/s. It was found that transporting of roughage from cutter to TMR mixer and the separation of dust were satisfactory, and the dust removal rate of rice straws was around 31.9%. CFD analysis showed that, at the blowing fan velocity of 11.6 m/s, the airflow velocity inside the dust collector increased as velocity of the dust collection fan increased, but the airflow patterns inside the dust collector were all much the same.

• Particle and aerosol research
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• v.17 no.3
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• pp.71-79
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• 2021

Ultrafine dust, which is emitted from industrial factories or all kinds of vehicles, threatens the human's respiratory system and our environment. In this regard, separating airborne particles is essential to mitigate the severe problem. In this work, an axial cyclone for the effective technology of eliminating harmful dust is investigated by numerical simulation using Ansys 2020, Fluent R2. In addition, the optimized structure of the cyclone is constructed by means of multi objective optimization based on the response surface method which is a representative method to analyze the effect of design parameter on response variables. Among several design parameters, the modified length of the vortex finder and dust collector is a main point in promoting the performance of the axial cyclone. As a result, the optimized cyclone exhibits remarkable performance when compared to the original model, resulting in pressure drop of 307 Pa and separator efficiency of 98.5%.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.11
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• pp.17-23
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• 2021

A cyclone is a dust-separating mechanism that works on the principle of centrifugal force. The performance of a cyclone is evaluated using pressure loss and collection efficiency. A multi-cyclone arrangement is used to improve the collection efficiency within a limited area. In this study, experiments and numerical analyses were conducted on a dual arrangement of mini-hydrocyclone separators, which was fabricated using 3D printing. The experiment was performed at an inlet flow rate of 0.7 m/s, and alumina powder with a particle size of 0.5, 15, and 50 ㎛. ANSYS FLUENT, was used for the numerical analysis. The reliability of the numerical analysis was verified through a comparison with the experimental results. The errors in the experiment and numerical analysis were confirmed to be 2% at the outlet flow rate.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.407-408
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• 2001

This paper describes the effects of varying the minor flow on particle collection efficiency and particle concentration in small cyclones. A cyclone haying a minor flow pumped out from its dust outlet is referred to as a virtual cyclone in this study although the terminology has been used for other types of devices (Torczynski and Rader, 1997). The virtual cyclones tested here have a rectangular inlet and circular outlet similar to the conventional cyclone. (omitted)

• Ocean Systems Engineering
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• v.10 no.2
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• pp.181-199
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• 2020

Cyclone Heat Potential (CHP) is an essential parameter for accurate prediction of the intensity of tropical cyclones. The variability of the heat storage in the near-surface layers and the vertical stratification near the surface due to large fresh water inputs create challenges in predicting the intraseasonal and interannual evolution of monsoons and tropical cyclones in the Bay of Bengal. This paper for the first time presents the D26- referenced cyclone heat potential observed in the Bay of Bengal during the period 2012-17 based on the in-situ data collected from 5.5 million demanding offshore instrument-hours of operation in the Ocean Moored Buoy Network for Northern Indian Ocean (OMNI) buoy network by the National Institute of Ocean Technology. It is observed that the CHP in the Bay of Bengal varied from 0-220 kJ/㎠ during various seasons. From the moored buoy observations, a CHP of ~ 90 kJ/㎠ with the D26 isotherm of minimum 100m is favorable for the intensification of the post-monsoon tropical cyclones. The responses of the D26 thermal structure during major tropical cyclone events in the Bay of Bengal are also presented.

• Journal of Ocean Engineering and Technology
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• v.28 no.4
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• pp.280-287
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• 2014

In this paper, the numerical simulation of the gas-liquid flow in a cylinder cyclone separator is performed to investigate the flow characteristics using a commercial software, FLUENT, which solves the Reynolds-averaged Navier-Stokes(RaNS) equations. First, a single-phase flow with water in a gas-liquid cylinder cyclone(GLCC) separator is simulated and compared with the experiments(Farchi, 1990) and numerical simulations(Erdal, 1997). Then, the characteristics of the multi-phase flow for water-air, mud-only, and mud-air cases are discussed in the view point of the feasibilities for a mud handling system.