• Journal of Power System Engineering
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• v.17 no.5
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• pp.52-57
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• 2013

In this paper, an analysis on exergy efficiency of high-efficiency R717 OTEC power system for the efficiency and pressure drop in main components were investigated theoretically in order to optimize the design for the operating parameters of this system. The operating parameters considered in this study include turbine and pump efficiency, and pressure drop in a condenser and evaporator, respectively. As the turbine efficiency of R717 OTEC power system increases, the exergy efficiency of this system increases. But pressure drop in the evaporator of R717 OTEC power system increases, the exergy efficiency of this system decreases, respectively. And, in case of exergy efficiency of this OTEC system, the turbine efficiency and pressure drop in a condenser on R717 OTEC power system is the largest and the lowest among operation parameters, respectively.

• Journal of the Korean Society of Visualization
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• v.18 no.3
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• pp.77-83
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• 2020

A uniflow cyclone has simple structure with a single channel in one direction. The one directional particle removal enables the uniflow cyclone to have compact size and low pressure drop. However, it has low collection efficiency compared to conventional cyclones. In this study, the effect of primary geometry on the performance of a uniflow cyclone with swirl vane is numerically investigated for the design of high performance uniflow cyclone. It is found that as the vortex finder diameter is increased, the pressure drop and the collection efficiency are decreased. Also, the same trend is predicted when the vortex finder height is increased. The best collection efficiency is predicted to be obtained when the vortex finder height is equal to the diameter of a cyclone. Reducing the body height by half will increase the pressure drop by 41%. When the body height is decreased, the collection efficiency is first increased and then decreased. The best collection efficiency is obtained when the body height is 4~5 times the cyclone diameter. Overall, the particle collection efficiency is highest when the Dν/D is equal to 0.3. But, the pressure drop is as high as 1592 Pa. Considering both collection efficiency and pressure drop, the best design is when Dν/D, Hν/D, and Hb/D are equal to 0.5, 1, and 5, respectively.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2227-2232
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• 2003

For a reasonable analysis of grade efficiency of cyclone separator, in-line measurements of particle size and particle concentration are needed. The purpose of this study is to define the correlation of measurement data and to measure grade efficiency and pressure drop. The authors adapted that the grade efficiency could be calculated directly from the counted particle numbers. The problem of collection efficiency calculation was different from counting rate of aerosol counters under the same conditions. It is important factor to use the rate of the particle counters to obtain reliable results. Therefore, the authors should use and calculate compensation factor considering sensitivity of aerosol counters, gas velocity and concentration affect higher 30% than originally measured grade efficiency. As the pressure drop and grade efficiency increase, as flow rate increase and then also pressure drop and grade efficiency increase.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.347-354
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• 2009

Plate Heat Exchnager(PHE) has recently become widely adopted for cogeneration systems owing to its small installation space and high thermal efficiency. The gap between plates can be changed depending on its assemble type, i.e. gasket or blazing. The gap is known to affect thermal efficiency and working pressure drop in PHE with complicated geometrical features. Numerical simulation techniques have been developed to deal with PHE with complex configuration of chevron plates. The present study is aiming at identifying the gap effect on pressure drop and thermal efficiency of the PHE. The numerical simulation results show that the gap has relatively large effects on working pressure drop than thermal efficiency in performance of PHE.

• Advances in Computational Design
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• v.5 no.3
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• pp.261-276
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• 2020

The reasonable layout of vacuum cleaner can effectively improve the collection efficiency of iron filings generated in the process of steel production. Therefore, in this study, the CFD-DEM coupling model and two-fluid model are used to calculate the iron filings collection efficiency of vacuum cleaner with different inclination/cross-sectional area, pressure drop and inlet angle. The results are as follows: The CFD-DEM coupling method can truly reflect the motion mode of iron filings in pneumatic conveying. Considering the instability and the decline of the growth rate of iron filings collection efficiency caused by high pressure drop, the layout of 75° inclination is suggested, and the optimal pressure drop is 100Pa. The optimal simulation results based on two-fluid model show that when the inlet angle and pressure drop are in the range of 45°~65° and 70Pa~100Pa, larger mass flow rate of iron filings can be obtained. It is hoped that the simulation results can offer some suggestion to the layout of vacuum cleaner in the rolling mill.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.2
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• pp.179-190
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• 2000

The main object of this study was to investigate experimentally the characteristics of electrostatic cyclone-bag filter with upper tangential inlet in order to overcome the low collection efficiency for the submicron particle and high pressure drop which were main problems of general fabric bag filters. The experiment was carried out for the analysis of collection efficiency and pressure drop of electrostatic cyclone-bag filter comparing to those of fabric bag filter with various experimental parameters such as the inlet velocity(filtration velocity) and applied voltage etc. In the results the upper tangential inlet type showed higher collection efficiency for submicron particles below 2 ${\mu}{\textrm}{m}$ in diameter than that of center inlet and over 99.9% for overall collection efficiency. Pressure drop reduction ratios were shown as 40-50% for the applied voltage 0kV by centrifugal force and 70-90% for 20k V by the centrifuga and electrostatic force with the tangential inlet velocity (12-21m/s)

• Journal of Mechanical Science and Technology
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• v.18 no.6
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• pp.979-989
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• 2004

Numerical simulations have been performed to investigate tip clearance effect on through-flow and performance of a centrifugal compressor which has the same configuration of impeller with six different tip clearances. Secondary flow and loss distribution have been surveyed to understand the flow mechanism due to the tip clearance. Tip leakage flow strongly interacts with mainstream flow and considerably changes the secondary flow and the loss distribution inside the impeller passage. A method has been described to quantitatively estimate the tip clearance effect on the performance drop and the efficiency drop. The tip clearance has caused specific work reduction and additional entropy generation. The former, which is called inviscid loss, is independent of any internal loss and the latter, which is called viscous loss, is dependent on every loss in the flow passage. Two components equally affected the performance drop as the tip clearances were small, while the efficiency drop was influenced by the viscous component alone. The additional entropy generation was modeled with all the kinetic energy of the tip leakage flow. Therefore, the present paper can provide how to quantitatively estimate the tip clearance effect on the performance and efficiency.

• Particle and aerosol research
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• v.5 no.1
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• pp.9-16
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• 2009

Pressure drop and particle removal efficiency of two commercial fibrous medium filters were measured with 20~1,000 nm sized aerosolized KCl particles. Pressure drop and particle removal efficiency were also theoretically predicted and the results qualitatively agreed with the experimental data. For this given particle removal efficiency, a filter design method for obtaining minimum pressure drop (and therefore minimum fan power) was suggested in this study by selecting solidity and fiber diameter as parameters. Therefore, by carrying out theoretical and experimental approaches together, this paper introduced a way of finding conditions for low pressure drop and high performance of a fibrous filter, especially if the filter would be used in mechanical ventilation system.

• 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.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.3
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• pp.279-287
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• 1996

Pressure drop and fractional collection efficiency of automotive cabin air filters were examined to obtain the basic data for the development of high performance domestic cabin air filters. Pressure drop of MA-V100 was higher than that of VF-V100, and it increased with the air flow rate. VF-V100 had longer time to rise the critical pressure drop than that MA-V100 had. Total collection efficiency of MA-V100 for initial and dust loaded conditions was higher than that of VF-V100. Also, fractional collection efficiency of MA-V100 for the fine particles was higher than that of VF-V100. Particla size distribution for the minimum collection efficiency ranged from 0.02 $\mu$m to 0.04 $\mu$m for MA-V100 and it ranged from 0.02 $\mu$m to 0.15 $\mu$m for VF-V100.