• Title/Summary/Keyword: Real Gas

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Analysis of Cold Gas Flow in Puffer Type GCB Considering the Real Gas Property of $SF_6$ ($SF_6$ 가스의 실제 기체특성을 고려한 파퍼식 가스차단기 내의 냉가스 유동해석)

  • 김홍규;정진교;박경엽
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.53 no.3
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    • pp.129-134
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    • 2004
  • To analyze the performance of the gas circuit breaker(GCB), the flow field variables such as temperature, pressure and density should be evaluated accurately In the puffer chamber of puffer type GCB, the pressure rise may Exceed 20 bar and in this range of high pressure, $SF_6$ gas deviates the ideal gas property. Therefore, the real gas property of $SF_6$ should be taken into consideration for the accurate analysis of flow field. This paper presents the analysis technique of cold gas flow in GCB employing the real gas state equation of SF6. The FVFLIC method is Employed to solve the axisymmetric Euler equation. To reduce the computational effort of real gas state equation, the relationship between density and pressure is approximated by the polynomial at the temperature of 300K. The proposed method is applied to the test GCB model and simulation results show good agreement with the experimental ones.

Computational Study of Hypersonic Real Gas Flows Over Cylinder Using Energy Relaxation Method (에너지 완화법을 이용한 실린더 주위의 극초음속 실제기체 유동에 관한 수치해석적 연구)

  • Nagdewe, Suryakant;Kim, H.D.
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03b
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    • pp.216-217
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    • 2008
  • In recent years, scientific community has found renewed interest in hypersonic flight research. These hypersonic vehicles undergo severe aero-thermal environment during their flight regimes. During reentry and hypersonic flight of these vehicles through atmosphere real gas effects come into play. The analysis of such hypersonic flows is critical for proper aero-thermal design of these vehicles. The numerical simulation of hypersonic real gas flows is a very challenging task. The present work emphasizes numerical simulation of hypersonic flows with thermal non-equilibrium. Hyperbolic system of equations with stiff relaxation method are identified in recent literature as a novel method of predicting long time behaviour of systems such as gas at high temperature. In present work, Energy Relaxation Method (ERM) has been considered to simulate the real gas flows. Navier-Stokes equations A numerical scheme Advection Upstream Splitting Method (AUSM) has been selected. Navier-Stokes solver along with relaxation method has been used for the simulation of real flow over a circular cylinder. Pressure distribution and heat flux over the surface of cylinder has been compared with experiment results of Hannemann. Present heat flux results over the cylinder compared well with experiment. Thus, real gas effects in hypersonic flows can be modeled through energy relaxation method.

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Performance Analysis of a Reciprocating Compressor Using a Real Gas Equation of State (실제기체 상태방정식을 이용한 왕복동압축기의 성능해석)

  • Kim, J.W.;Kim, H.J.;Pak, H.Y.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.4 no.4
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    • pp.306-315
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    • 1992
  • This paper addresses performance analysis of a reciprocating compressor. A computer simulation model has been developed to predict and estimate the compressor performance. Instead of using ideal gas equations, real gas equations are used in describing the state of gas. The compressor simulation model consists of a cylinder control volume, suction system and discharge system. Conservation laws of mass and energy are applied to the cylinder section only, The suction and discharge system are described by the Helmholtz resonator modeling. Some of input data required for the simulation have been obtained from experiments. These experimentally obtained input data are effective flow area, effective force area and dynamic characteristics of valves. Simulation results of real gas equations have been compared with those of ideal gas equations. It has been found that the simulation with real gas equations yields lower cylinder temperature and heat transfer compared with those of ideal gas equations. Differences in pressure, mass flowrates, valve motions and gas pulsations are found quite small.

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The Study on Characteristic of Vehicle Greenhouse Gas Emission Applying Real Road Driving (실도로 주행을 반영한 자동차 온실가스 배출 특성 연구)

  • Lee, Jung-Ki;Yong, Geejoong;Kim, Cha-Ryung;Eom, Seong-Bok
    • Journal of Auto-vehicle Safety Association
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    • v.10 no.3
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    • pp.45-54
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    • 2018
  • Greenhouse gas is the big issue of the whole world. So foreign countries, EU, USA, Japan, China and Korea made the policy for reducing greenhouse gas. For calculation of reduction, it is necessary to know the quantity of current greenhouse emission per year in Korea. It is not reflected real driving condition for measuring the Fuel economy and greenhouse gas. The subject of this study is to figure out the characteristics which influence on greenhouse gas in real driving condition. And final goal is applying the policy greenhouse emission reduction.

Numerical Analysis of Hypersonic Shock-Shock Interaction using AUSMPW+ Scheme and Gas Reaction Models (AUSMPW+ 수치기법과 반응기체 모델을 이용한 극초음속 충격파-충격파 상호작용 수치해석)

  • Lee Joon-Ho;Kim Chongam;Rho Oh-Hyun
    • 한국전산유체공학회:학술대회논문집
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    • 1999.05a
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    • pp.29-34
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    • 1999
  • A two-dimensional Navier-Stokes code based on AUSMPW+ scheme has been developed to simulate the hypersonic flowfield of hypersonic shock-shock interaction. AUSMPW+ scheme is a new hybrid flux splitting scheme, which is improved by introducing pressure-based weight functions to eliminate the typical drawbacks of AUSM-type schemes, such as non-monotone pressure solutions. To study the real gas effects, three different gas models are taken into account in this paper: perfect gas, equilibrium flow and nonequilibrium flow. It has been investigated how each gas model influences on the peak surface loading, such as wall pressure and wall heat transfer, and unsteady flowfield structure in the region of shock-shock interaction. With the results, the value of peak pressure is not sensitive to the real gas effects nor to the wall catalyticity. However, the value of peak heat transfer rates is affected by the real gas effects and the wall catalyticity. The structure of the flowfield also changes drastically in the presence of real gas effects.

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A Computational Work of Critical Nozzle Flow for High-Pressure Hydrogen Gas Mass Flow Measurement (고압수소 유량계측용 임계노즐 유동의 수치해석적 연구)

  • Lee, Jun-Hee;Kim, Heuy-Dong;Park, Kyung-Am
    • 유체기계공업학회:학술대회논문집
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    • 2006.08a
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    • pp.227-230
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    • 2006
  • The method of mass flow rate measurement using a critical nozzle is well established in the flow satisfying ideal gas law. However, in the case of measuring high-pressure gas flow, the current method shows invalid discharge coefficient because the flow does not follow ideal gas law. Therefore an appropriate equation of state considering real gas effects should be applied into the method. The present computational study has been performed to give an understanding of the physics of a critical nozzle flow for high-pressure hydrogen gas and find a way for the exact mass flow prediction. The two-dimensional, axisymmetric, compressible Navier-Stokes equations are computed using a fully implicit finite volume method. The real gas effects are considered in the calculation of discharge coefficient as well as in the computation. The computational results are compared with the previous experimental data and predict well the measured mass flow rates. It has been found that the discharge coefficient for high-pressure hydrogen gas can be corrected properly adopting the real gas effects.

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A REAL GAS SOLUTION ALGORITHMS FOR MULTI-PHASE FLOW ANALYSIS (다상 유동 해석을 위한 압축성 실제기체 해법)

  • Han S.H.;Choi J.Y.
    • 한국전산유체공학회:학술대회논문집
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    • 2005.10a
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    • pp.187-194
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    • 2005
  • For the analysis of compressible multi-phase and real gas flows, characteristic form of Roe's Riemann solver was derived using real gas equation of state. It was extended to multi component reactive system considering variable specific heat. From this study, it is known that some correction should be made for the use of existing numerical algorithm. 1) Sonic speed and characteristic variable should be corrected with real gas effect. 2) Roe's average was applicable only with the assumption of constant properties. 3) Artificial damping term and characteristic variables should be corrected but their influences may not be significant.

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A Study on the Effect of Gas Composition at Gas Supply Point on the Pressures in Gas Pipe Networks (가스 배관망에서 인입가스의 조성이 배관망 내 압력에 미치는 영향에 관한 연구)

  • Chang, Seung-Yong
    • Journal of the Korean Institute of Gas
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    • v.11 no.2 s.35
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    • pp.1-4
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    • 2007
  • Natural gas has different gas composition according to imported gas region, and the difference of gas composition affects pressure loss value occurred in pipe networks, Therefore, using real gas composition instead of averaged gas composition can obtain more reliable results for pipe network analysis. In this study, the effect of real gas composition at gas supply points on the demand pressure has been analyzed. To compare the results, the calculated pressure values for averaged gas composition at all the supply points have been used. From the results, we found that the effect of real gas composition consideration on demand pressure was considerable, and the real gas composition has to be considered for reliable pipe network analysis in gas industry.

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Numerical Analysis of Hypersonic Shock-Shock Interaction using AUSMPW+ Scheme and Gas Reaction Models

  • Lee, Joon Ho;Kim, Chongam;Rho, Oh-Hyun
    • International Journal of Aeronautical and Space Sciences
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    • v.1 no.1
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    • pp.21-28
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    • 2000
  • The flowfield of hypersonic shock-shock interaction has been simulated using a two-dimensional Navier-Stokes code based on AUSMPW+ scheme. AUSMPW+ scheme is a new hybrid flux splitting scheme, which is improved by introducing pressure-based weight functions to eliminate the typical drawbacks of AUSM-type schemes, such as non-monotone pressure solutions. To study the real gas effects, three different gas models are taken into account in the present paper: perfect gas, equilibrium flow and non equilibrium flow. It has been investigated how each gas model influences on the peak surface loading, such as wall pressure and wall heat transfer, and unsteady structure of flowfield in the region of shock-shock interaction. With the results, the value of peak pressure is not sensitive to the real gas effects nor to the wall catalyticity. However, the value of peak heat transfer rates is affected by the real gas effects and the wall catalyticity. Also, the structure of the flowfield changes drastically in the presence of real gas effects.

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Anaerobic treatment of red-bean processing wastewater in a sludge bed reactor (슬러지반응기에서 팥가공폐수의 철기성 처리)

  • 안재동;금재우;홍종향
    • Journal of environmental and Sanitary engineering
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    • v.9 no.1
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    • pp.29-37
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    • 1994
  • Anaerobic treatment of wastewater of the red- bean processing industry was carried out and discussed an anaerobic sludge bed reactor( ASBR) as a preliminary study to evaluate applicability of given processes. The dimension of reactor were same as 0.09m- ID$\times $1.5m- height. The type of substrate and the hydraulic retention time( HRT) were considered as experimental variables. The synthetic wastewater with glucose in the laboratory, the wastewater from the red bean processing industry mixed with synthetic wastewater with variation of mixing percent were fed as substrate. The hydraulic retention time was changed from one day to five days. The gas production, the methane content in produced gas, efficiencies of COD removal and 55 removal were evaluated as principal characteristics. With synthetic wastewater as a substrate and at a hydraulic retention time of one day, characteristics of ASBR was the gas production(12$\ell$/day ), the methane content of produced gas(60%), the efficiency of COD removal(92%) and 55 removal(30%). With the real wastewater and at a hydraulic retention time of one day, the gas production and the efficiency of COD removal of the ASBR decreased with the proportion of real wastewater. The gas production and the efficiency of COD removal with real wastewater only was decreased to 70% and 87% of those with synthetic wastewater only, respectively. However, the methane content in produced gas and the efficiency of 55 removal with real wastewater only was increased significantly by 1.25 times and two times of those with synthetic wastewater only, respectively. However, the methane content in produced gas and the efficiency of 55 removal with real wastewater only was increased significantly by 1.25 times and two times of those with synthetic wastewater only, respectively. With real wastewater only as a substrate in the ASBR, the gas production was decreased with an increase of HRT, but the efficiency of COD removal increased with HRTI like the usual trend reported. As a conclusion, the wastewater of the red- bean Processing industry could be treated by anaerobic digestion successfully in the ASBR.Anaerobic treatment of wastewater of the red- bean processing industry was carried out and discussed an anaerobic sludge bed reactor( ASBR) as a preliminary study to evaluate applicability of given processes. The dimension of reactor were same as 0.09m- ID$\times $1.5m- height. The type of substrate and the hydraulic retention time( HRT) were considered as experimental variables. The synthetic wastewater with glucose in the laboratory, the wastewater from the red bean processing industry mixed with synthetic wastewater with variation of mixing percent were fed as substrate. The hydraulic retention time was changed from one day to five days. The gas production, the methane content in produced gas, efficiencies of COD removal and 55 removal were evaluated as principal characteristics. With synthetic wastewater as a substrate and at a hydraulic retention time of one day, characteristics of ASBR was the gas production(12$\ell$/day ), the methane content of produced gas(60%), the efficiency of COD removal(92%) and 55 removal(30%). With the real wastewater and at a hydraulic retention time of one day, the gas production and the efficiency of COD removal of the ASBR decreased with the proportion of real wastewater. The gas production and the efficiency of COD removal with real wastewater only was decreased to 70% and 87% of those with synthetic wastewater only, respectively. However, the methane content in produced gas and the efficiency of 55 removal with real wastewater only was increased significantly by 1.25 times and two times of those with synthetic wastewater only, respectively. However, the methane content in produced gas and the efficiency of 55 removal with real wastewater only was increased significantly by 1.25 times and two times of those with synthetic wastewater only, respectively. With real wastewater only as a substrate in the ASBR, the gas production was decreased with an increase of HRT, but the efficiency of COD removal increased with HRTI like the usual trend reported. As a conclusion, the wastewater of the red- bean Processing industry could be treated by anaerobic digestion successfully in the ASBR.

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