저온디젤연소에서 파일럿 분사가 연소특성에 미치는 영향

김기현(Kihyun Kim),한상욱(Sangwook Han),배충식(Choongsik Bae) 한국연소학회 2011 KOSCOSYMPOSIUM논문집 Vol.- No.42

This experimental study investigated the effect of pilot injection on combustion characteristics ; specifically combustion noise and soot emission in the low temperature diesel combustion. Preliminary experiments under wide range of exhaust gas recirculation rate and injection timing were performed to find experimental condition which shows near zero nitrogen oxides emission and maximum indicated mean effective pressure. In the pilot injection experiment, pilot injection ratio and timing were varied. with fixed pilot injection quantity, more retarded pilot injection timing caused vigorous heat release prior to start of the main injection. It accelerated combustion start of the fuel injected at main injection timing while decreased peak of heat release rate. Soot emission was increased as pilot injection quantity and timing was increased and retarded, respectively. Maximum pressure rise rate was decreased when the small pilot injection quantity was injected. However, when pilot injection quantity and timing were increased and retarded respectively, maximum pressure rise rate increased even higher than single injection case.

디젤 연료 온도에 따른 분무 발달 특성

이진우(Lee, Jin-Woo) 한국산학기술학회 2016 한국산학기술학회논문지 Vol.17 No.3

본 연구에서는 디젤 연료 온도에 따른 실제 분사되는 연료량, 분사율 그리고 거시적 분무 발달 과정에 대한 특성을 파악하고자 하였다. 시험 결과 동일한 분사 시작 신호 및 분사 기간 신호를 입력하였음에도 불구하고, 연료 온도가 낮아짐에 따라 실제 연료 분사량이 감소하는 경향을 보였다. 분사율 측정 결과를 통해 연료 온도가 낮은 조건에서 실제 분사 시작 시점이 지연되며, 실제 분사가 유지되는 기간이 짧아지는 것을 확인하였으며, 이를 통해 실제 분사되는 연료량 저감에 대한 근거를 찾을 수 있었다. 거시적 분무 이미지 촬영 결과를 연료 온도 별 분무 도달 거리로 표현하여 비교 하였으며, 낮은 연료 온도 조건에서 분무 미립화 성능 악화로 인해 분무 도달 거리가 길어지는 것을 확인하였다. 저온 조건에서의 연소 개선을 위해 향후 시도할 선행 평가로서 피스톤 타켓팅 평가를 수행하였으며, 이른 시기에 분사되는 파일럿 연료가 크레비스 영역으로 유입되는 것을 확인하였으며, 이를 통해 파일럿 분사 방식 적용 시 연료량 분배 및 분사 시기 선정이 매우 중요한 인자가 됨을 파악하였다. The characteristics of the fuel quantity, injection rate and macro spray development was investigated under a range of diesel fuel temperatures. The actual injection quantity decreased despite the same signal of the injection start and injection duration as the fuel temperature decreased. The injection rate measurements confirmed that the actual injection commencement was delayed and the actual injection duration was shortened under lower fuel temperature conditions, which explains why the injection quantity decreased. Spray tip penetration with a lower fuel temperature was longer than that with a higher fuel temperature due to the deteriorated atomization. As a pre-test for the combustion experiment under low temperature conditions, piston targeting with pilot injection was accomplished, which showed that the fuel droplet from pilot injection was introduced into the crevice area. This suggests that the pilot injection quantity and timing should be chosen with careful consideration for actual applications.

다단분사를 사용한 경량 DME 엔진의 연소제어에 관한 연구

정수진(Soo-Jin Jeong),오세두(Se-Doo Oh),박정권(Jeong-Kwon Park) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5

Dimethyl-ether(DME) is one of the most promising alternative fuels for IC engines. In this study, the compression ignition combustion fueled with dimethyl-ether was investigated. Three-point split injection strategy was applied and evaluated its availability and performance in terms of emission(CO, HC, NOx, PM), fuel economy and power. Experiments were carried out in 4-cylinder 2.9 liter direct-injection diesel engine equipped with common-rail injection system, and the engine performance and emission characteristics were tested the various pre and pilot injection timings and quantities. Experiments were performed under the engine condition ranging from 1200rpm, 2bar to 3000rpm,4 bar. From the results of this study, three-point split injection strategy showed the possibility to overcome the disadvantages of DME engine such as high NOx and HC emissions due to long injection duration for attaining diesel equilibrium performance. By optimizing pre and pilot injection timing and quantities NOx emission could be reduced by maximum 68.5% for low speed and load conditions. Additional NOx reduction of could be obtain by retarding main injection timing. Torque could be improved by reducing injection dwell timing between pilot and main injection. In the range of medium and high load and speed conditions, main injection timing was retarded for reducing NOx emission with sacrificing torque. However, this torque reduction could be compensated by reducing pilot injection quantity and increasing the quantity of main injection.

사출성형공정 모니터링용 엣지 디바이스 개발 및 평가

김종선,이준한,Kim, Jong-Sun,Lee, Jun-Han 한국금형공학회 2020 한국금형공학회지 Vol.14 No.4

In this study, an edge device that monitors the injection molding process by measuring the mold vibration(acceleration) signal and the mold surface temperature was developed and evaluated its performance. During injection molding, signals of the injection start, V/P switchover, and packing end sections were obtained through the measurement of the mold vibration and the injection time and packing time were calculated by using the difference between the times of the sections. Then, the mold closed and mold open signals were obtained using a magnetic hall sensor, and cycle time was calculated by using the time difference between the mold closed time each process. As a result of evaluating the performance by comparing the process data monitored by the edge device with the shot data recorded on the injection molding machine, the cycle time, injection time, and packing time showed very small error of 0.70±0.38%, 1.40±1.17%, and 0.69±0.82%, respectively, and the values close to the actual were monitored and the accuracy and reliability of the edge device were confirmed. In addition, it was confirmed that the mold surface temperature measured by the edge device was similar to the actual mold surface temperature.

Effect of Heat Injection through a Vertical Drain on Clay Consolidation

김범준,우상인,윤찬영 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.9

Temperature change affects the consolidation behavior of soft clay. An increase in temperature in soft clay leads to the dissipation of excess pore water pressure and the decrease of volume. This temperature-induced consolidation can be utilized as a novel approach to improve soft ground. In this study, in order to investigate the effect of heat injection through a vertical drain on soft ground consolidation, a test device was designed to install different-sized sand drains that enabled heat injection and temperature control of a vertical drain. Using the device, a series of consolidation tests was performed with varying heat injection and varying diameter of the vertical drain. During consolidation, vertical settlement and temperature at various locations in the ground were measured. After each consolidation test, the spatial distribution of void ratio in the ground was estimated. Test results showed that heat injection increased the radial temperature of the ground, and the increasing diameter of sand drain with an internal heat source also expanded the heating area in the ground. Furthermore, the larger diameter sand drain led to greater final settlement and lower void ratio.

엔지니어링 플라스틱 材料의 再活用 混合比가 成形品 收縮에 미치는 영향

김인관 한국자원리싸이클링학회 2004 資源 리싸이클링 Vol.13 No.3

플라스틱 재료는 재생이 가능한 열가소성 플라스틱과 재생이 거의 불가능한 열경화성 플라스틱으로 분류 할 수 있고, 본 연구에서는 재생이 가능한 열가소성 플라스틱 중 산업 및 생활 전반에 널리 사용되고 있는 PP, PA6, PC 및 PBT 재료의 재생 방안에 대한 기초 연구로서 재생 재료의 혼합비가 증가함에 따라 치수 정밀도에 미치는 영향을 고찰 하였다. In this study, an experimental work was performed to mold tensile specimens by using the injection molding machine. Melt temperature, mold temperature and the mixed ratio of recycled resin were selected as processing parameters for studying the effect of those conditions on the shrinkage and weight of molded parts. As a result, the shrinkage was increased with the higher mold and melt temperature and it was more sensitive to the change of mold temperature. On the other hand, the weight of molded parts was decreased with the increment of mold and melt temperature.

사출성형품의 리브 설계에 따른 휨의 연구

이민,류민영,Lee, Min,Lyu, Min-Young 한국금형공학회 2008 한국금형공학회지 Vol.2 No.4

Warpage, which is one of the molding trouble, acts as possible factor which results in defect in assembly. In this study, a mold was designed to produce specimens with rib parallel to flow direction, specimens with rib perpendicular to flow direction and specimens without rib. This work researched change of warpage according to injection molding condition such as injection pressure, packing pressure, packing time, resin temperature, mold temperature in non-crystalline resins(PC, ABS), crystalline resins(PP, PA66), and 30% glass fiber reinforced-resins(PC, ABS, PP, PA66).Specimens with rib and Crystalline resins show more warpage than specimens without rib and non-crystalline resins, respectively. Glass fiber reinforced-resins and specimens with rib parallel to flow direction show smaller warpage than conventional resins and specimens with rib perpendicular to flow, respectively. Specimens with rib and specimens without rib show reduced warpage as packing time increases. In addition, warpage increase as resin temperature increases. It is found that CAE shows similar tendency with experiment as packing time, resin temperature. when the rib is caused, warpage will reduce and prevent the transformation. product of a irregular form occurs warpage. In the study It'll be basic data that product occurs warpage, preferablity.

항공유의 온도에 따른 분사특성 변화연구

최호진(Hojin Choi),김일두(Ildoo Kim),진유인(Yuin Jin),이형주(Hyung Ju Lee),황기영(Ki-Young Hwang) 한국추진공학회 2013 한국추진공학회 학술대회논문집 Vol.2013 No.12

실제 항공유가 온도변화에 따라 분사특성이 변화하는 경향을 실험적으로 연구하였다. 스월 인젝터를 사용하여 연료의 비등점 이상까지 연료를 가열하면 인젝터 유량계수 변화를 살펴본 이전연구에 이어, 동일한 방법으로 ?30℃ 수준까지의 저온영역에서 유량계수가 변화하는 현상을 확인하였다. 또한 연료온도 변화에 따라 분사된 연료의 분무입경이 변화하는 경향을 살펴보기 위하여 레이저 광계측 기법을 이용하여 분무 입경 분포를 측정하였다. 유량계수는 상온 대비 저온과 고온에서 모두 감소하는 경향을 보였으며, 분무입경 분포에 있어 고온영역에서는 연료온도가 증가함에 따라 분무 입경 평균이 증가하는 경향을 보였으나 이는 작은 입경의 연료가 활발하게 기화하는 현상에 기인한 것으로 확인되었으며, 저온영역에서는 미소하게 분무 직경이 증가하는 결과를 보였다. An experimental study was conducted to investigate fuel injection characteristics with temperature change of aviation fuel. The change of flow coefficient through pressure swirl injector with low temperature fuel was studied by same analysis method with previous research on high temperature injection. Also, droplet size distribution with fuel injection temperature change is measured using laser diagnostics technique. The flow coefficient through swirl injector was decreased at higher and lower temperature conditions compared to standard temperature injection. When the fuel was heated to higher temperature, the averaged droplet size of spraty was increased and this was caused by rapid evaporation of smaller sized droplets. At lower temperature injection, droplet size distribution was slightly increased.

전류 주입 자기공명영상에 온도 변화가 미치는 영향

이수열,강현수,우응제,조민형 대한의용생체공학회 2001 의공학회지 Vol.22 No.3

It is well known that the electrical impedance of biological tissues is very sensitive to their temperature. In this paper, we have analyzed the effects of temperature change on the phase of magnetic resonance images obtained with external current injection. It has been found that the local phase in the current injected magnetic resonance image can be changed noticeably when local temperature change appears at a part of the tissue. At the experiments with a 0.3 Tesla MRI system, we observed the local phase changes at the phantom images when the phantom temperature was varied between 25 -45$^{\circ}C$. We think that the current injection MRI technique can be used for in-vivo monitoring of the temperature inside biiological tissues if the relation between the local temperature and phase can be quantified.

An Experimental Study on the Spray Characteristics of a Dual-Orifice Type Swirl Injector at Low Fuel Temperatures

Park, Byung-Sung,Kim, Ho-Young,Kim, Yongchan,Chung, Jin-Taek The Korean Society of Mechanical Engineers 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.7

The objective of this study is to investigate the effects of fuel temperature on the spray characteristics of a dual-orifice type swirl injector used in a gas turbine. The major parameters affecting spray characteristics are fuel temperature and injection pressure entering into the injector. In this study, the spray characteristics of a dual-orifice type swirl injector are investigated by varying fuel temperature from - 30$^{\circ}C$ to 120$^{\circ}C$ and injection pressure from 0.29 to 0.69 ㎫. Two kinds of fuel having different surface tension and viscosity are chosen as atomizing fluids. As a result, injection instability occurs in the low fuel temperature range due to icing phenomenon and fuel property change with a decrease of fuel temperature. As the injection pressure increases, the range of kinematic viscosity for stable atomization becomes wider. The properties controlling the SMD of spray is substantially different according to the fuel temperature range.