• Title, Summary, Keyword: Specific fuel consumption

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FE Simulation of Axial Crushing Test for AZ31 Tube Considering Tension-Compression Asymmetry (압축-인장 비대칭을 고려한 AZ31 튜브의 압괴해석)

  • Yoon, Jong-Hun;Lee, Jung-Hwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.9
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    • pp.997-1002
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    • 2012
  • With the increasing demand for lightweight materials to reduce fuel consumption, especially in the transportation industry, magnesium alloys are being widely studied. However, there are several limitations to the large-scale application of magnesium alloys in a structure because of their low formability and strong anisotropy. In order to take into account both the strong anisotropy and tension-compression asymmetry of AZ31 sheet alloy, the Cazacu-Plunkett-Barlat yield criterion (Cazacu, 2006) was adopted in material modeling. The variation of the anisotropic coefficients that describe the yield surface evolution of AZ31 is optimized using an interpolation function based on specific calibration results. It generates continuous yield surfaces, which makes it possible to describe different hardening rates in tension and compression as well as the tension-compression asymmetry of magnesium alloys. The performance of the CPB06 yield criterion for simulating an axial crushing test was tested and compared with that of the Hill (1948) yield criterion.

Optimization of Diesel Engine Performance with Dual Loop EGR considering Boost Pressure, Back Pressure, Start of Injection and Injection Mass (과급압력, 배압, 분사 시기 및 분사량에 따른 복합 방식 배기 재순환 시스템 적용 디젤 엔진의 최적화에 대한 연구)

  • Park, Jung-Soo;Lee, Kyo-Seung;Song, Soon-Ho;Chun, Kwang-Min
    • Transactions of the Korean Society of Automotive Engineers
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    • v.18 no.5
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    • pp.136-144
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    • 2010
  • Exhaust gas recirculation (EGR) is an emission control technology allowing significant NOx emission reduction from light-and heavy duty diesel engines. The future EGR type, dual loop EGR, combining features of high pressure loop EGR and low pressure loop EGR, was developed and optimized by using a commercial engine simulation program, GT-POWER. Some variables were selected to control dual loop EGR system such as VGT (Variable Geometry Turbocharger)performance, especially turbo speed, flap valve opening diameter at the exhaust tail pipe, and EGR valve opening diameter. Applying the dual loop EGR system in the light-duty diesel engine might cause some problems, such as decrease of engine performance and increase of brake specific fuel consumption (BSFC). So proper EGR rate (or mass flow) control would be needed because there are trade-offs of two types of the EGR (HPL and LPL) features. In this study, a diesel engine under dual loop EGR system was optimized by using design of experiment (DoE). Some dominant variables were determined which had effects on torque, BSFC, NOx, and EGR rate. As a result, optimization was performed to compensate the torque and BSFC by controlling start of injection (SOI), injection mass and EGR valves, etc.

Performance Trend of Korean-made Agricultural Tractors (국산 트랙터의 성능 변화)

  • Kim K. U.
    • Journal of Biosystems Engineering
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    • v.30 no.6
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    • pp.321-326
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    • 2005
  • Tractor performance was analyzed using the data from 226 Korean-made and 107 imported tractors tested at the National Institute of Agricultural Engineering for the 25-year period from 1980 through 2004. The performance analysis included the specific volumetric fuel consumption (svfc), power per unit weight and traction coefficient evaluated from the viewpoint of PTO power level. No significant performance improvement has been made for the Korean-made tractors over the last 25 years. The average svfc for the maximum PTO power has increased by only $2.1\%$ from 1980 to 2004, resulting in 2.86 kW${\cdot}$h/L in 2004. The average maximum PTO and drawbar power per unit weight of ballasted tractors were 1.38 and 1.19 kW/kN in 2000-2004, indicating $14.0\%$ and $5.9\%$ decreases respectively from 1980 to 2004. The traction coefficient has increased by $23.1\%$ over the 25 years, resulting in 0.68 in the 2000-2004 period. Poor performance improvement was also observed from the imported tractors. In the 2000-2004 period, average svfc for the maximum PTO power, PTO power per unit ballasted weight, drawbar power per unit ballasted weight and traction coefficient of the imported tractors were respectively 3.0 kW${\cdot}$h/L, 1.34 kW/kN, 1.13 kW/kN and 0.68. PTO and drawbar power per unit weight were lower in imported tractors than the Korean-made tractors. Comparing the test results with those of tractors less than 37 kW tested at the Nebraska Tractor Test Laboratory from 1981 to 2002, the Korean-made tractors have exhibited better performance in terms of power per unit weight. However, poor performance in the svfc and traction coefficient was observed. The average svfc and traction coefficient of the Korean-made tractors were respectively $86.4\%$ and $83.7\%$ of the tractors tested at the NTTL over the same period.

Performance and emissions analysis on diesel engine fuelled with cashew nut shell biodiesel and pentanol blends

  • Devarajan, Yuvarajan;Nagappan, Beem Kumar;Munuswamy, Dinesh Babu
    • Korean Journal of Chemical Engineering
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    • v.34 no.4
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    • pp.1021-1026
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    • 2017
  • We studied the impact of blending pentanol, a next generation biofuel, with cashew nut shell biodiesel on its performance and emissions characteristics in a constant speed compression ignition engine. Our main objective was to reduce CO, HC, $NO_X$ and smoke emission when fueled with neat cashew nut shell biodiesel and the pentanol blends. Cashew nut shell oil is a byproduct from cashew nut industry. Since it is nonedible, it can be used as a promising alternative. Conventional transesterification process was used to convert the cashew nut shell oil into cashew nut shell biodiesel. Pentanol with 98.4% purity was used as an oxygenated additive. The experiment involved three test fuels: neat cashew nut shell biodiesel (C100), Pentanol blended with cashew nut shell biodiesel by 10% volume (C90P10) and Pentanol blended with cashew nut shell biodiesel by 20% volume (C80P20). The feasibility of using neat biofuel (without adding diesel) was also investigated. Experimental work concluded that the test fuels used in this study does not require any modification in engines. In addition, the combustion of fuels was smooth and there was no physical and visible damage in the engine components when fueled with cashew nut shell biodiesel and the pentanol blends. By adding 10% and 20% of pentanol to cashew nut shell biodiesel, significant reduction in CO, HC, $NO_X$ and smoke emission was observed. In addition, brake thermal efficiency increased marginally with slight reduction in brake specific fuel consumption.

Effect of the Cone Index on the Work Load of the Agricultural Tractor (원추 지수가 트랙터 작업 부하에 미치는 영향)

  • Kim, Wan Soo;Kim, Yong Joo;Baek, Seung Min;Baek, Seung Yun;Moon, Seok Pyo;Lee, Nam Gyu;Kim, Taek Jin;Siddique, Md Abu Ayub;Jeon, Hyeon Ho;Kim, Yeon Soo
    • Journal of Drive and Control
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    • v.17 no.2
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    • pp.9-18
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    • 2020
  • The purpose of this study was to analyze the effect of the soil cone index (CI) on the tractor work load. A load measurement system was constructed for measuring the field data. The field sites were divided into grids (3×3 m), and the cone index was measured at the center of each grid. The work load measured through the plow tillage was matched with the soil cone index. The matched data were grouped at 600 kPa intervals based on the cone index. The work load according to the cone index was analyzed for engine, axle, and traction load, respectively. The results showed that when the cone index increased, engine torque decreased by up to 9%, and the engine rotational speed and brake-specific fuel consumption increased by up to 5% and 3%, respectively. As the cone index increased, the traction and tillage depth were inversely proportional to the cone index, decreasing 7% and 18%, respectively and the traction and tillage depth were directly proportional to the cone index, increasing 13% and 12%, respectively. Thus, it was found that the cone index had a major influence on the engine, axle, and traction loads of the tractor.

Effects of Binder-Sheaf Size on Threshing Performance and Load Characteristics of an Auto Feed Thresher (바인더 볏단의 크기가 자동탈곡기(自動脱糓機)의 탈곡성능(脱糓性能) 및 부하특성(負荷特性)에 미치는 영향(影響))

  • Yoo, Soo Nam;Ryu, Kwan Hee
    • Journal of Biosystems Engineering
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    • v.6 no.1
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    • pp.60-72
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    • 1981
  • This study was carried out to find out the effects of the sheaf size of paddy harvested by the binders on the threshing performance, load characteristics and power requirement of an auto-feed thresher. The results of the study are summarized as follows: 1. The seperating performance of the thresher appeared to be satisfactory for all the sheaf sizes although the amount of rubbishes and empty grains slightly increased with the sheaf size of paddy. 2. There was no significant difference in grain output quality of the thresher among the three sheaf sizes. However, the amount of grains left unthreshed increased with the sheaf size. In the case of the largest sheaf size with the feed rate of 780kg/h, it exceeded the limit set by the national inspection regulations. 3. The position of the feed-chain rail gave a significant effect on the power requirement of the thresher. At the feed rate of 780kg/h, the net power required to convey sheafs through the feed chain was in the range of 0.37 to 0.50 PS for the middle and lowest position of feed-chain rail, and there was no significant difference among the sheaf sizes. At the highest position, however, it appeared that the smallest sheaf required more power than the others. The net power requirements at this position were 1.03, 0.59. 0.65 PS for the smallest, medium and largest sheafs respectively. 4. The torques of both the thresher and the engine shaft increased with the feed rate and were not affected by the sheaf size for the lower two feed rates of 520 and 780kg/h. At the highest feed rate of 1,040 kg/h, however, they were affected by the sheaf size. In this case, the medium sheaf size gave lower values than the others. 5. The variations in the thresher and the engine torque increased with the feed rate and were not affected by the sheaf size for the feed rate of 520kg/h. At the feed rate of 780kg/h, however, they increased with sheaf size. And at the feed rate of 1,040 kg/h, the torque variations increased greatly for all the sheaf sizes due to an over-load operating condition. 6. It appeared that the average and maximum power requirements of the thresher increased with the feed rate. But, there was no significant difference in power requirement among the sheaf sizes for the lower two feed rates. 7. The threshing efficiency of the thresher was in the range of 214-249 kg/ps.h with the feed rates of 520 and 780 kg/h, and it was not affected by both the sheaf size and the feed rate. At the feed rate of 1,040 kg/h, however, it decreased to as low as 171-174 kg/ps.h because of a sudden increase in power requirement. 8. The average power requirements of the engine were slightly higher than those of the thresher due to the slippage of flat belt between the thresher and engine. It appeared that power transmission from the engine to the thresher was maintained properly since slippages were moderately low with the range of 2.78 to 6.51% throughout the tests. 9. The specific fuel consumption of the engine (diesel 8PS) decreased as the feed rate increased. However, there was no significant reduction in specific fuel consumption as the feed rate increased above 780 kg/h.

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Comparison of Combustion Characteristics On the Basis of the Dilution Ratio in Diesel Engines with LPL EGR (저압 EGR을 적용한 디젤엔진의 희석비에 따른 연소 특성 비교)

  • Lim, Gi-Hun;Park, Jun-Hyuk;Choi, Young;Lee, Sun-Youp;Kim, Yong-Min
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.5
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    • pp.525-531
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    • 2011
  • Exhaust gas recirculation (EGR) is more effective than selective catalytic reduction (SCR) or lean $NO_x$ trap (LNT) for the reduction of $NO_x$ emissions in diesel engines. A large amount of EGR gas is necessary to satisfy the stringent regulations on $NO_x$ emissions. Low pressure loop (LPL) EGR is almost independent of the variable geometry turbocharger (VGT) at a specific boost pressure, so LPL EGR is better than conventional high pressure loop (HPL) EGR in terms of EGR supply. We compare the influence of HPL EGR and LPL EGR on the combustion characteristics at a constant boost pressure in a diesel engine. The dilution ratio was employed as an independent parameter to analyze the effect of the dilution of the intake charge for each EGR loop. At the same level of $NO_x$ emissions, the fuel consumption and smoke opacity were slightly lower for LPL EGR than for HPL EGR.

Optimum design of propulsion shafting system considering characteristics of a viscous damper applied with high-viscosity silicon oil (고점도 실리콘오일 적용 점성댐퍼 동특성을 고려한 추진축계 최적 설계)

  • Kim, Yang-Gon;Cho, Kwon-Hae;Kim, Ue-Kan
    • Journal of Advanced Marine Engineering and Technology
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    • v.41 no.3
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    • pp.202-208
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    • 2017
  • The recently developed marine engines for propulsion of ships have higher torsional exciting force than previous engines to improve the propulsion efficiency and to reduce specific fuel oil consumption. As a result, a viscous damper or viscous-spring damper is installed in front of marine engine to control the torsional vibration. In the case of viscous damper, it is supposed that there is no elastic connection in the silicon oil, which is filled between the damper housing and inertia ring. However, In reality, the silicon oil with high viscosity possesses torsional stiffness and has non-linear dynamic characteristics according to the operating temperature and frequency of the viscous damper. In this study, the damping characteristics of a viscous damper used to control the torsional vibration of the shafting system have been reviewed and the characteristics of torsional vibration of the shafting system equipped with a corresponding viscous damper have been examined. In addition, it is examined how to interpret the theoretically optimal dynamic characteristics of a viscous damper for this purpose, and the optimum design for the propulsion shafting system has been suggested considering the operating temperature and aging. when the torsional vibration of the shafting system is controlled by a viscous damper filled with highly viscous silicon oil.

Effect of Cooling Water Capacity on the Engine Performance for Small Diesel Engine (냉각수(冷却水) 용량(容量)이 소형(小型) 디젤기관(機關)의 성능(性能)에 미치는 영향(影響))

  • Myung, Byung Soo;Kim, Soung Rai
    • Korean Journal of Agricultural Science
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    • v.13 no.2
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    • pp.265-278
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    • 1986
  • This study was attempted to improve the thermal efficiency of 6 kW water-cooled diesel engine on power tiller. The engine performance tests were conducted to find out the effect of cooling water capacity of 2700cc, 2800cc, 2900cc, 3000cc, 3100cc on power, brake specific fuel consumption (BSFC), torque, temperature of cooling water and lubricating oil and friction losses of the engine with D. C. dynamometer. The results obtained in the study are summarized as follows: 1. The performance of the engine tested was adequated to Korea Industrial Standard but actual economy power was 10% higher than the labeled rated power of the engine. The BSFC of the engine tested 297.8g/kW-h which is belong a little higher level than hreign products. The temperature of cooling water was $101^{\circ}C$ which is higher than SAE standard ($88^{\circ}C$) 2. The friction losses of engine tested was 3.656 kW at 2200 rpm of rated rpm (piston speed 6.97m/sec) and is higher than those of foreign products. 3. When the cooling water capacity was increased from 2700cc to 3100cc the power output of the engine was increased from 6.7 kW to 7.13 kW at the rate of 6.4% and also the torque of the engine was increased from 28.85 N.m to 30.76 N.m at the rate of 6.39%. 4. When the cooling water capacity was increased from 2700cc to 3100cc, the BSFC was decreased 6.9g/kW-h from 310.9g/kW-h to 304.1g/kW-h, and after one half hour operation with full load, the temperature of cooling water was decreased $13^{\circ}C$ from $101^{\circ}C$ to $88^{\circ}C$ and also the temperature of lubricant oil was decreased $6.4^{\circ}C$ from $76.7^{\circ}C$ to $70.4^{\circ}C$. 5. The mechanical efficiency was increased from 70.08% to 71.08% when the cooling water capacity was increased from 2700cc to 3100cc.

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