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Song, Jingeun,Choi, Minhu,Park, Sungwook Elsevier 2017 Applied thermal engineering Vol.121 No.-
<P><B>Abstract</B></P> <P>In the present study, the volumetric efficiency and combustion characteristics of compressed natural gas (CNG) direct injection (DI) and port fuel injection (PFI) were compared. In a single-cylinder engine, various fuel injection timings were tested for each fuel injection position, and the volumetric efficiency of each test condition was calculated from the intake flow rate. The one-dimensional simulation program AMESim was also used to further investigate the intake process. Experimental and numerical results showed that the volumetric efficiency was not influenced by the position of the injector. For the early fuel injection, before the intake valve close (IVC), the volumetric efficiencies of the DI and PFI were similar to each other; the averaged volumetric efficiencies were both about 38.62% and the standard deviations of volumetric efficiency were less than 0.2%. However, as the fuel injection timing was retarded after the IVC, the volumetric efficiency of DI increased while the volumetric efficiency of PFI was kept constant or slightly decreased. The increase in the volumetric efficiency was due to the fact that the fuel volume did not occupy the cylinder volume during the intake stroke. Combustion was stable for all the test conditions. The coefficient of variation of the indicated mean effective pressure (COV<SUB>IMEP</SUB>) was lower than 1.5%. The highest fuel conversion efficiency was observed for late fuel direct injection, after the IVC, due to the fastest combustion. Thus, by applying the late fuel injection timing after IVC, the CNG-DI could have a higher volumetric efficiency and fuel conversion efficiency than the CNG-PFI.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Volumetric efficiencies of DI and PFI were similar for early injection conditions. </LI> <LI> 1D simulation code (AMESim) was used to investigate the intake process in detail. </LI> <LI> For various injection timings, the volumetric efficiency of PFI was kept constant. </LI> <LI> Late fuel DI increased volumetric efficiency and fuel conversion efficiency. </LI> <LI> DI after IVC was the best injection strategy for high engine power and efficiency. </LI> </UL> </P>
이상득(S. D. Lee),강희영(H. Y. Kang),고대권(D. K. Koh),안수길(S. K. Ahn) 한국동력기계공학회 2005 한국동력기계공학회 학술대회 논문집 Vol.- No.-
The pressure fluctuation in the intake and exhaust pipe of 4 stroke-cycle diesel engine is caused by reciprocating motion of piston for suction of fresh air and exhaust of burned gas. this gas dynamic effect can be utilized for increase the volumetric efficiency. Many empirical studies have been carried out to investigate the effects of intake pulsating flow on the volumetric efficiency. However, when the gas dynamic effects are utilized for the variable speed engine to increase its performance, The speed range in which the volumetric efficiency is maximum is limited and there occurs some difficulties in lay-out of intake system because it become too long. During induction process, as waves travel both directions, they are reflected and interacted each other and pressure waves are transmitted through it. Hence, the flow becomes more complex and unsteady flow. These pressure waves act upon intake pulsating flow and affects on the volumetric efficiency. In this paper the effects of pulsating flow of intake and exhaust pipes on volumetric efficiency were examined and evaluated. It was found that volumetric efficiency was affected by pulsating flow of intake and exhaust pipes.
가변밸브 작동기구를 적용한 가솔린 기관의 잔류가스분율, 체적효율, 펌핑손실 예측을 위한 해석적 연구
조용석(Yong-Seok Cho),이성욱(Seang-Wock Lee),장익규(Ik-Kyoo Jang),박정권(Jung-kwon Park),윤여빈(Yu-bin Yoon),박영준(Young-Joon Park),김현철(Hyunchul Kim),나병철(Byungchul Na) 한국자동차공학회 2010 한국 자동차공학회논문집 Vol.18 No.2
To satisfy the needs on fuel economy and engine performance, continuous variable valve lift systems are applying to engines. In the CVVL system, fuel economy can be improved by reducing pumping loss during the induction process, and engine performance can be also improved by controlling volumetric efficiency and the residual gas fraction. Because the residual gas fraction directly affects volumetric efficiency, engine performance, combustion efficiency and emissions in SI engines, controlling residual gas fraction is one of the important things in engine development process. This analysis investigates the residual gas fraction and volumetric efficiency with changes of intake valve lifts and intake valve timings. In this study, unsteady state solutions were solved during exhaust and induction processes. Results show variation of the residual gas fraction and volumetric efficiency by changing intake valve timing and lift. Decreasing intake valve lift leads to increase the residual gas fraction and to decrease volumetric efficiency.
가변 헬름홀츠 공진기가 다기통 디젤기관의 체적효율에 미치는 영향
강희영(H. Y. Kang),고대권(D. K. Koh),장세호(S. H. Jang),안수길(S. K. Ahn) 한국동력기계공학회 2005 한국동력기계공학회 학술대회 논문집 Vol.- No.-
The volumetric efficiency is significantly affected by the behavior of pressure wave in induction system and exhaust pipe. By the motion of the piston, there exist pressure fluctuation in induction system which produce waves. Waves are propagated along a pipe bi-directional as they propagated through it, making compression wave and rare-faction(expansion) wave. These can affect to the volumetric efficiency. As a method of improvement of the volumetric efficiency and pollutant emission reduction particularly in transient engine speeds, a side-branch additional tunable helmholtz resonator on the secondary pipe of intake system is proposed by use of their acoustic vibrations. Some of results are presented which deal with their physical phenomena for the wave action of intake system in a four-stroke three cylinders diesel engine.
엄홍선(Hong Sun Eom),윤천식(Cheon Seog Yoon),김영민(Young Min Kim) 대한설비공학회 2013 설비공학 논문집 Vol.25 No.4
An experimental study of an ORC (Organic Rankine Cycle) system has been performed for small-scale applications in the range of a few kW for low-grade-recovery heat sources. The ORC system was equipped with a scroll expander. Experimental tests were carried out using this system, and showed good performance and reliability for the small-scale system. The effects of various operating conditions were selected as the main parameters for the performance of ORC system, such as the expander speeds and mass flow rates of R-134a for expander inlet temperatures ranging from 100℃ to 190℃, as well as the thermal power, thermal efficiency, expansion efficiency, and volumetric efficiency.
A. J. TORREGROSA,J. GALINDO,C. GUARDIOLA,O. VARNIER 한국자동차공학회 2011 International journal of automotive technology Vol.12 No.3
This paper presents a methodology for diesel engine intake line analysis that combines specific element tests and modeling. The purpose of this methodology is to determine the impact of intake lines, or newly designed intake elements, on the volumetric efficiency of internal combustion engines while avoiding expensive on-engine tests. For this research, the intake system is divided into several elements which are individually characterized using flow and impulse test rigs. Next, individual systems are modeled using a one-dimensional code. Finally, these component models are coordinated to provide an evaluation of the volumetric efficiency. Intake lines coming from two turbocharged diesel engines are used to illustrate the method. The model is validated by comparing the model results with the actual system performance evaluated in engine test cells. Discussions of the feasibility of the technique and on the impact of element model inaccuracies on the overall system model are provided.
성진우(Jin-woo Seong),조권회(Kwon-hae Cho),최재성(Jae-sung Choi) 한국마린엔지니어링학회 2006 한국마린엔지니어링학회 학술대회 논문집 Vol.2006 No.-
Compressed air has been used widely for the actual life as well as the industrial purpose. The majority of air compressor is a reciprocating type in spite of its demerits. In this paper, it was reported about a simulation program for performance of reciprocating air compressor and the results of simulation by influenced parameters for volumetric efficiency. Compression ratio, flow coefficient and heat loss were selected as the influenced parameters.
전산해석을 이용한 산업용 오일펌프 성능개선에 관한 연구
김진우,이현준,공석환,이성원,정원지 한국산업융합학회 2022 한국산업융합학회 논문집 Vol.25 No.6
Recently, interest in the circular economy has emerged in the industry. As a result, interest in Re-manufacturing, which makes old equipment similar to new products, is growing. In the machine tool industry with many aging equipment, the Re-manufacturing industry is essential, and among them, research on the performance improvement of gear type oil pumps was conducted. The purpose was to achieve the target performance of flow rate and volume efficiency by changing the shape of the gear pump housing clearance and inlet/outlet, and Computational Fluid Analysis and Central Composite Design were conducted using ANSYS CFX 2022 R2 and MINITAB®. The level of each determined factor was determined. 20 design points were derived, and the Flow Rate at each design point was calculated, and the Theoretical Flow Rate was calculated to obtain Volumetric Efficiency. The optimal design point was obtained when the Flow Rate was 140 lpm and the Volumetric Efficiency was maximum, the optimal design point was obtained when both were maximum, and the Surface Plot for each factor was obtained to identify the tendency.
연속 접촉 헬리컬 기어펌프의 수치해석 연구: 모델 개발 및 적용
장호성(H. S. Jang),박민규(M. G. Park),성준영(J. Y. Seong),양경욱(K. U. Yang),최세령(S. R. Choi),지상원(S. W. Ji) 유공압건설기계학회 2022 유공압건설기계학회 학술대회논문집 Vol.2022 No.06
External gear pump(EGP) has a simple structure and excellent durability among hydraulic pumps, so they are generally used in hydraulic control system and fuel transfer system. However, in an involute tooth type pump, a volume trapped between the gear teeth is formed during two-point contact, and as a result pressure pulsation, vibration, and noise are generated, thereby deteriorating volumetric efficiency. To compensate for these shortcomings, a continuous contact helical gear pump(CCHGP) has been proposed and has been commercialized recently. Advantages have proven to be of great benefit in terms of reduced flow and pressure pulsations, as well as noise reduction due to the absence of entrapped volumes. However, unbalanced thrust occurs and manufacturing is difficult, so related research is insufficient. In this paper, continuous contact gear teeth were designed, and flow analysis was performed using a commercial program (SimericsMP+) to shape continuous contact helical gear teeth. We present a numerical approach to predict flow and pressure pulsations and pump performance by applying cavitation and turbulence.
운전조건 변화에 따른 전기자동차 냉방시스템 성능특성에 관한 해석적 연구
김두식(Doosik Kim),김현우(Hyunwoo Kim),이길초(Gilcho Lee),박차식(Chasik Park),박경우(Kyoungwoo Park),이호성(Hoseong Lee) 대한설비공학회 2019 대한설비공학회 학술발표대회논문집 Vol.2019 No.-
This paper presents numerical study on the cooling performance of a heat pump system for an electric vehicle. The system modeling was carried out using Simemens PLM software Amesim. The modeling of the compressor was based on the volumetric, the isentropic and the mechanical efficiency. The expansion device considered a short tube orifice as the isenthalpic process. The detailed modeling of fins and tubes for the condenser and evaporator was implemented. The results of simulation were compared with experimental results for reliability verification. The present modeling yielded satisfactory predictions upon comparison with the experimental data within a relative deviation of 7.9%.