• 설비공학논문집
• /
• 제15권1호
• /
• pp.50-58
• /
• 2003

An analytical study was carried out to investigate the performance of an oil pumping system of a variable speed compressor using a commercial CFD program. The simulations for the oil supplying system with the oil and air mixture were performed by varying compressor speed from 40 Hz to 90 Hz. Comparing the predicted with the measured data on the modified scroll compressor validated the simulation model. The predicted results were consistent with the test data with a maximum deviation of 12.8%. The oil flow rate significantly increased with a rise of compressor speed due to a higher oil flow rate from the swing pump and a greater centrifugal force on oil gallery.

• 동력기계공학회지
• /
• 제16권5호
• /
• pp.26-31
• /
• 2012

A numerical study has been carried out to investigate the heat and mass transfer of an oil pumping system with a variable shape of the housing using the CFD method. Especially, the electric motor and the pump combined together, accomplishes a research about the oil supplying system. In this study, the temperature and velocity distribution of the oil pumping system by varying the flow rate of supplying oil have been investigated. The temperature changes with each five conditions(flow rate of supply oil : 2, 4, 8, 12, and 16 liter/min) have also been studied. The numerical results show that the exhaust temperature decreases as the flow rate of the supplying oil increases. It also reveals that the temperatures change differently with the housing shape.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 1999년도 제29회 춘계학술대회
• /
• pp.359-365
• /
• 1999

We have evaluated the performance and some physical properties of 25 automotive engine oils (21 domestic and 5 imported products) which are purchased on the market to verify the API(American Petroleum Institute) or ILSAC(International Lubricant Standardization and Approval Committee) certification marks attached on the products and to determine the necessity of the quality control of the engine oils on the market. 12 test items are chosen according to API engine oil specification, which are flash point, pour point, cold cranking simulator apparent viscosity, pumping viscosity, gelation index, HTHS(High Temperature High Shear viscosity), foam, high temperature foam, filterability, volatility, high temperature deposit(TEOST), phosphorus content. We have found one product which did not meet the API specification on gelation index, one on HTHS, four on foam, and one on volatility, which implies that the quality control system is in need to check the fidelity of the certification marks attached on the engine oils being marketed. In addition, this works raises the necessity of the upgrade of the present Korean engine oil specification.

• 전기학회논문지
• /
• 제57권10호
• /
• pp.1812-1817
• /
• 2008

A cooling system for microelectronics is becoming more important as its surface heat density is projected to reach that of the sun surface. The existing technologies using natural and forced convection are limited to solve the problems. Recently, an electrohydrodynamic driven flow is studied as one of the means to cope with this problems. A new method, utilizing a needle-centered nozzle electrode, has been proposed and investigated. The I-V characteristics of the nozzle electrode for deionized water and silicone oil were significantly different from that of without liquid, which might be due to the liquid drop covered on the nozzle tip by the EHD force acting near the needle tip. Results showed that the liquid pumping rate and flow efficiency of the nozzle electrode were very high, especially for the silicone oil. Theoretical analysis also showed the effectiveness of the needle electrode centered in the ceramic nozzle, which, however, can be a means as a liquid pump.

• 한국유체기계학회 논문집
• /
• 제3권4호
• /
• pp.52-58
• /
• 2000

The numerical study on the waterhammer was carried out for the intake pumping station of the metropolitan water supply 6th stage project. Because the waterhammer problems as a result of the pump power failure were the most important, these situations were carefully investigated. The surge tank and the stand pipes effectively protected the tunnels md the downstream region of pipeline from the pressure surge. In case the moment of inertia of the pump and motor was above $5080\;kg{\cdot}m^2$, the column separation did not occur in the pipeline between the pumping station and the inlet of 1st tunnel. As the moment of inertia increased, the pressure surges decreased in the pipeline conveying raw water. The pump control valve was chosen as the main surge suppression device for the intake pumping station. After power failure, the valve disc should be rapidly closed in 2.5 seconds and controlled the final closure to 15 seconds by the oil dashpot. If the slamming happened to the pump control valve, there was some danger of this system damaging. As the reverse flow through the valve increased, the upsurge extremely increased.

• 지질공학
• /
• 제20권2호
• /
• pp.169-181
• /
• 2010

지질구조 요소 중 산성 암맥은 K-1 유류비축기지에서 지하수 유동에 직접적인 영향을 미칠 수 있다. 산성 암맥의 산출 특성과 기지 주변의 수리지질학적 조건을 토대로 지하수 모델링을 수행하였으며, 자연적 또는 인위적으로 가능한 시나리오를 구성하여 기지 인근 지역의 지하수위 변화 스트레스에 대한 반응을 모의하였다. 기지 주변에서 24개의 가상적인 우물들을 활성화하고 4단계 양수량 변화에 따른 수위 영향반경의 변화를 고려함으로써, 비축기지 내 안정적 수위 유지를 위해 다음과 같이 5개의 구획을 구분하여 양수량 제한 구역 설정을 제안하였다; zone I (기지에서 300 m 이내 범위), 50 $m^3/day$ 이하; zone II (기지에서 300~600 m 범위), 75 $m^3/day$ 이하; zone III (기지에서 600~900 m 범위), 150 $m^3/day$ 이하; zone IV (기지에서 900~1,200 m 범위), 300 $m^3/day$ 이하; zone V (산성암맥 주변). 산성 암맥을 따른 zone V에서는 맥암으로부터 70~100 m 거리까지 양수의 영향이 나타날 수 있으므로 다른 지점들에 비해 특별히 지하수 사용에 대한 제한과 주의가 요구된다.

• International Journal of Fluid Machinery and Systems
• /
• 제6권1호
• /
• pp.1-10
• /
• 2013

Jet pump is one type of artificial lifts and is used when depth and deviation of producing wells increases and pressure depletion occurs. In the present study, numerical analysis has been carried out to analyze the flow behavior and find the performance of the jet pump. Reynolds-averaged Navier Stokes equations were solved and k-${\varepsilon}$ turbulence model was used for simulations. Water and light oil as primary fluids were used to pump water, light oil and heavy oil. The ratios of area and length to diameter of the mixing tube were considered as design parameters. The pump efficiency was considered to maximize for the downhole conditions. It was found that the increase in viscosity and density of the secondary fluid reduced efficiency of the system. Water as primary fluid produced better efficiency than the light oil. It was also found that the longer throat length increased efficiency upto 40% if light oil was used as primary fluid and secondary fluid viscosity was 350 cSt.

• 한국자동차공학회논문집
• /
• 제14권3호
• /
• pp.119-124
• /
• 2006

This paper deals with energy-saving effort in the hydraulic power steering system. Commonly, the hydraulic power steering systems are used for passenger cars and the reduction of pumping loss under non-steering condition is important to improve fuel economy. Experiments and simulations are performed simultaneously to examine the main factors to reduce the pumping loss-pressure loss and flow rate of the power steering systems. Fuel economy effect of the optimal design of power steering system is verified by vehicle test - more than 1% fuel consuming reduction is attained.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2006년도 하계학술발표대회 논문집
• /
• pp.1186-1190
• /
• 2006

Rising in important of alternative energy due to the recenfly high oil price and environment problem. Application of alternative energy has become higher than before. In this study, facility test of Geothermal energy to bankfiltration was examined appliying changwon pumping well. Initial installation cost was efficiently saved by connecting a heat pump system to pumping well in changwon bankfiltration site. A falling-off in efficiency of heat pump was free due to the bankfiltration that is rare for the temperature fluctuation. Therefore, Heat soure as bankfiltration system solve the existing facilities problems of geothermal heat pump system.

• 설비공학논문집
• /
• 제29권3호
• /
• pp.127-133
• /
• 2017

Performance analysis has been carried out on a high side scroll compressor that had a fixed scroll equipped with a circular oil groove on its thrust surface. Oil was supplied to the oil groove through an intermittent opening from a high pressure oil reservoir formed inside the orbiting scroll hub. Oil in the groove was then delivered to both suction and back pressure chambers by pressure differentials and viscous pumping action of the orbiting scroll base plate. Mathematical modeling of this oil groove system was incorporated into a main compressor performance simulation program for an optimum oil groove design. The study findings were as follows. Pressure in the oil groove can be controlled by changing its configuration and the oil passage area. With an enlarged oil passage, the pressure in the oil groove heightens due to an increased flow rate, but the pressure elevation in the back pressure chamber is small, resulting in reduced friction loss at the thrust surface between the two scrolls. On the other hand, by increasing the oil passage area, the oil content in the refrigerant flow increases. Considering all these factors, the energy efficiency ratio could be improved by about 3.6% under the ARI condition by an optimal oil groove design.