• 한국가스학회지
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• 제13권5호
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• pp.7-14
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• 2009

본 연구는 석탄화력발전소 노의 연소효율 향상을 위하여 미분탄 수송배관의 공기-입자 유동장의 압력손실 특성을 분석하여 미분탄 수송장치 내에 설치되어 유량을 제어하는 오리피스의 설계에 적용하고자 하는 것이다. 통상의 미분탄 수송배관장치는 관의 형태에 따라 직선관, 곡선관 및 엘보우로 구성된다. 본 연구에서는 공기유동과 입자운동의 상호작용 해석을 통하여 직선관과 곡선관을 갖는 미분탄 수송배관장치 내의 압력손실을 분석하였다. 총 압력손실은 공기-미분탄 입자의 마찰 손실 증가와 배관의 길이, 곡선관 각도의 증가에 따라 증가하는 것으로 확인되었다. 연구결과로 압력손실과 유량제어를 위한 최적화된 오리피스 설계 프로그램이 개발되었으며 그 계산 결과를 기존의 실험결과와 비교, 분석하였다.

• 한국연초학회지
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• 제10권1호
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• pp.83-91
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• 1988

The effects of tipping paper permeability and plugwrap porosity on the ventilation and the pressure drop of cigarettes have been studied and the results obtained were as follows. 1. The single and the multiple regression equation to estimate tip ventilation were establised. In the equations, the observed values of the tip ventilation with the varieties the plugwrap porosity were content with them by the single regression equation. 2. As based on the statistical consideration of the above equation, the deviation of the observed tip ventilation versus the tipping paper permeability were higher than them to the plugwrap porosity. 3. The regression equations to calculate pressure drop ratio and the total ventilation rate in filter tip from the tea ventilation were obtained. According to the equation, the observed values of the pressure drop ratio were significantly similar to them calculated. 4. It was found that the equations could be applied to the calculation of the ventilation of cigarettes using the mechanical and micro laser perforation tipping paper as well as the electrically perforated tipping paper of this Study.

• 한국대기환경학회지
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• 제12권3호
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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.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.281-287
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• 2005

This study investigates the pressure drop and heat transfer characteristics of heat exchanger according to the combination of fin configuration and fin pitch of each row by the similitude experiments with the finned-tube geometry scaled as large as four times Finned-tube heat exchanger has 2 rows, and fin geometry consists of two cases, louver-louver and louver-slit. Fin pitch is varied with three types in each case, 6-6 mm, 8-8 mm and 8-6 mm. Results show that total heat transfer can be occurred evenly at each row by varying the fin pitch of 1st row and 2nd row. Heat transfer rate and pressure drop characteristics change according to the combination for fin geometry and fin pitch.

• 설비공학논문집
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• 제27권8호
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• pp.402-408
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• 2015

A series of numerical simulations have been carried out to study the performances of cyclone-type oil separators, which are designed for refrigeration-system compressors. The corresponding working fluid is R22, which is a typical refrigerant, whereby a mineral-oil droplet is supplied (Ed-highlight-My interpretation). The outlet-tube length in relation to the total chamber volume is considered a design parameter. Depending on the tube length, the separation efficiency varies from 98.7% to 99.3%, while the predicted pressure drop is between 5.1 kPa and 6.4 kPa. Considering both the pressure drop and separation efficiency, the length of the outlet-port tube of the separator is 152 mm.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.226-235
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• 2000

Two representative finite volume methods, i.e., the time marching method and the pressure correction method, were applied to 8 centrifugal compressor impeller flows, with low to very high level of pressure ratio, among which 7 impellers' experimental performance is given in the open literature. The present study is focused on the prediction differences from both methods, developed by the authors, in the pressure correction method's point of view. In all cases, the time marching method gives a satifactory solution, but the pressure correction method does not. Up to about $18\%$ less level of total-to-total pressure ratio is predicted by the pressure correction method as the level of the impeller pressure ratio increases up to about 10. The drop of total pressure ratio is caused by the underestimation of static pressure rise which seems to be attributed to inappropriate linearization and discretization of the pressure/density coupling terms in the pressure correction equation.

• 한국대기환경학회지
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• 제32권4호
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• pp.384-393
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• 2016

In this study, two kinds of industrial filter bags were tested for their filtration performance to apply the existing bag filter systems. Experimental variables were examined for pressure drop, cleaning interval, residual pressure drop, cleaning efficiency, fractional grade efficiency, total collection efficiency according to the filter bag structure. According to these results, the filter bags tested in this study demonstrated good performance in dust collection. This was also true for the double surface filter bag. The lifetime was longer than the round type filter bag because the filtration area was more than 1.6 times wider and the filter quality factor was much higher. Therefore, double surface filter bags are suggested to be used in order to increase filtration performance of the bag filter systems.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.191-198
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• 2001

A numerical analysis of the heat and mass transfer and pressure drop characteristics in modular shell and tube bundle heat exchanger was carried out. Finite Concept Method based on FVM and $k-\varepsilon$ turbulent model were used for this analysis. Condensation heat transfer enhanced total heat transfer rate $4\sim8%$ higher than that of dry heat exchanger. With increasing humid air inlet velocity, temperature and relative humidity, and with decreasing heat exchanger aspect ratio and cooling water velocity, total heat and mass transfer rate could be increased. Cooling water inlet velocity had little effect on total heat transfer.

• 설비공학논문집
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• 제17권12호
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• pp.1177-1184
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• 2005

A numerical analysis was carried out on the heat and mass transfer, and pressure drop characteristics of the modular tube bundle heat exchanger. The finite volume method with a $k-\varepsilon$ turbulence model was used for the analysis. Due to condensation, the total heat transfer rate is observed about $4\~8\%$ higher than that on dry surfaces. Total heat transfer rate increases with increase in the velocity, temperature and relative humidity of incoming air. It also increases with decreasing the aspect ratio of heat exchanger tube. The inlet velocity of cooling water has little effect on the total heat transfer when the other conditions are fixed.

• Journal of Mechanical Science and Technology
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• 제17권11호
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• pp.1801-1811
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• 2003

An experimental study was conducted to investigate the effects of air-side fouling and cleaning on the performances of various condenser coils used in unitary air-conditioning systems. A total of six condenser coils with different fin geometry and row number were tested. Performance tests were performed at three different conditions: clean-as-received, after fouling, and after cleaning. In all cases, it was observed that the fouling was mostly confined to the frontal face of the heat exchanger as reported in the previous investigations. The amount of deposited dust was more dependent on fin geometry for the single-row heat exchangers than for the double-row heat exchangers. The predominant effect of fouling was to cause a more significant increase in air-side pressure drop than a degradation in heat transfer performance. For the single-row heat exchangers, the pressure drop increased by 28 to 31%, while the heat transfer performance decreased by 7 to 12% at the standard air face velocity of 1.53 m/s depending on fin shape. For the double-row heat exchangers, the pressure drop increased by 22 to 37%, and heat transfer performance decreased by only 4-5% at the same air face velocity. Once the contaminated coils were cleaned according to the given cleaning procedure the original performance of the heat exchangers could almost be recovered completely. The pressure drop could be restored within 1 to 7% and the heat transfer performance could be recovered to within 1 to 5% of the originally clean heat exchangers. Therefore, it is concluded that a periodic application of the specified cleaning technique will be effective in maintaining the thermal performance of the condenser coils.