• Title/Summary/Keyword: IMEP (Indicated Mean Effective pressure)

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A Study on the Performance Characteristics According to the Compression Ratio of Spark Ignition Engine Fuelled with Coal Oil (Coal Oil을 사용한 스파크 점화기관의 압축비 변화에 따른 엔진 성능에 관한 연구)

  • HAN, SUNG BIN;CHUNG, YON JONG
    • Transactions of the Korean hydrogen and new energy society
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    • v.28 no.2
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    • pp.225-230
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    • 2017
  • Coal oil is widely used as a home heating fuel for portable and installed coal oil heaters. Today, Coal oil is widely used as fuel for jet engines and some rocket engines in several grades. This paper describes the performance characteristics according to the compression ratio of spark ignition engine fuelled with coal oil. As a result, the following knowledge is obtained: As the compression ratio is decreased, there is an increase in torque, indicated mean effective pressure (IMEP), heat release rate, and brake thermal efficiency. Higher compression ratio of the engine decreases the ignition delay period, combustion period, and cooling loss.

The Effect of Fuel Injection Timing on the Combustion and Emission Characteristics of a Natural Gas Fueled Engine at Part Loads

  • Cho, Haeng-Muk
    • Journal of Advanced Marine Engineering and Technology
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    • v.32 no.7
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    • pp.1013-1018
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    • 2008
  • For a sequential port fuel injection natural gas engine, its combustion and emission characteristics at low loads are crucial to meet light duty vehicle emission regulations. Fuel injection timing is an important parameter related to the mixture formation in the cylinder. Its effect on the combustion and emission characteristics of a natural gas engine were investigated at 0.2 MPa brake mean effective pressure (BMEP)/2000 rpm and 0.26 MPa BMEP/1500 rpm. The results show that early fuel injection timing is beneficial to the reduction of the coefficient of variation (COV) of indicated mean effective pressure (IMEP) under lean burn conditions and to extending the lean burn limits at the given loads. When relative air/fuel ratio is over 1.3, fuel injection timing has a relatively large effect on engine.out emissions. The levels of NOx emissions are more sensitive to the fuel injection timing at 0.26 MPa BMEP/1500 rpm. An early fuel injection timing under lean burn conditions can be used to control engine out NOx emissions.

Performance Prediction according to Equivalence Ratio Change in Simulated-EGR Compression Ignition Engine Containing CO2 (CO2를 포함한 Simulated-EGR 압축착화엔진에서 당량비 변화에 따른 성능 예측)

  • Suh, Hyun Kyu
    • Journal of ILASS-Korea
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    • v.25 no.1
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    • pp.21-26
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    • 2020
  • The objective of this work is to numerically reveal the effect of equivalence ratio change on the simultaneous reduction of NOX and soot emissions from the simulated-EGR compression ignition engine containing CO2. An experiment was conducted by using a single-cylinder common-rail injection system engine, an intake control system, and exhaust emissions analyzers. The numerical analysis results were validated under the same experimental conditions. To investigate the effect of equivalence ratio by simulated-EGR containing CO2, the O2, N2, and CO2 mole fraction were changed in the initial air conditions to the cylinder. The results were analyzed in terms of peak cylinder pressure, indicated mean effective pressure, indicated specific nitrogen oxide, and indicated specific soot. It was revealed that ignition delay characteristics and heat release rate (ROHR) characteristics were not significantly different according to the equivalence ratio. However, as the equivalence ratio increased from 0.68 to 0.83, the maximum combustion pressure and IMEP decreased by about 6.5% and 9.4%, respectively. In the case of ISFC, as is well known, the trend is opposite of IMEP. In the case of ISNO, as the equivalence ratio increased, less NO was generated, and as the equivalence ratio increased by 0.05, the ISSoot value of about 10% increased.

Numerical Investigation of Exhaust Gas Recirculation Effect under Boost Pressure Condition on Homogeneous Charge Compression Autoignition (HCCI엔진의 과급조건에서 EGR영향에 대한 수치해석적 연구)

  • Oh, Chung Hwan;Jamsran, Narankhuu;Lim, Ock Tack
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.38 no.6
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    • pp.451-464
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    • 2014
  • This study used numerical methods to investigates investigate the exhaust gas recirculation (EGR) effect under the condition of boost pressure condition on a homogeneous charge compression ignition (HCCI) combustion engine using numerical methods. The detailed chemical-kinetic mechanisms and thermodynamic parameters for n-heptane, iso-octane, and PRF50 from the Lawrence Livermore National Laboratory (LLNL) are were used for this study. The combustion phase affects the efficiency and power. To exclude these effects, this study decided to maintain a 50 burn point (CA50) at 5 CA after top dead center aTDC. The results showed that the EGR increased, but the low temperature heat release (LTHR), negative temperature coefficient (NTC), and high temperature heat release (HTHR) were weakened due by theto effect of the O2 reduction. The combined EGR and boost pressure enhanced the autoignition reactivity, Hhence, the LTHR, NTC, and HTHR were enhanced, and the heat-release rate was increased. also In addition, EGR decraeased the indicated mean effective pressure (IMEP), but the combined EGR and boost pressure increased the IMEP. As a results, combining the ed EGR and boost pressure was effective to at increase increasing the IMEP and maintaining the a low PRR.

Combustion Characteristics Using a S.I. Optically Acessible Engine with SCV (SCV를 장착학 가솔린 가시화엔진에서의 연소특성)

  • 정구섭;김형준;전충환;장영준
    • Journal of Advanced Marine Engineering and Technology
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    • v.25 no.1
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    • pp.115-123
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    • 2001
  • This study describes the combustion characteristics under various condition of air excess ratio and ignition timing in a 2-valve gasoline optically accessible engine with swirl control valve(SCV). It adapted three different types of SCA(open ration 72.5%, 78%, 89%) to strengthen a swirl flow. Pressure data were acquired using pressure sensor to investigate the effect of swirl flow on combustion, and from these pressure data, IMEP(indicated mean effective pressure) and MFB(mass fraction burnt)were calculated to explain burn rate and flame speed. From acquired flame images, inspected the flame propagation direction, flame area, and flame centroid, Flame propagation direction was shown different tendency between with/without SCV, and flame area with SCV was faster and larger than that of conventional engine. Finally, the representative flame image at each crank angle were acquired by PDF method to verify flame growth process. It is found that strengthened swirl flow is more beneficial for faster and stable combustion.

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Analysis of performance and combustion characteristics of D.O./butanol blended fuels in a diesel engine (디젤기관에서 경유/부탄올 혼합연료의 기관성능 및 연소특성 해석)

  • KIM, Sang-Am;WANG, Woo-Gyeong
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.55 no.4
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    • pp.411-418
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    • 2019
  • In this study, to investigate the effect of physical and chemical properties of butanol on the engine performance and combustion characteristics, the coefficient of variations of IMEP (indicated mean effective pressure) and fuel conversion efficiency were obtained by measuring the combustion pressure and the fuel consumption quantity according to the engine load and the mixing ratio of diesel oil and butanol. In addition, the combustion pressure was analyzed to obtain the pressure increasing rate and heat release rate, and then the combustion temperature was calculated using a single zone combustion model. The experimental and analysis results of butanol blending oil were compared with the those of diesel oil under the similar operation conditions to determine the performance of the engine and combustion characteristics. As a result, the combustion stabilities of D.O. and butanol blending oil were good in this experimental range, and the indicated fuel conversion efficiency of butanol blending oil was slightly higher at low load but that of D.O. was higher above medium load. The premixed combustion period of D.O. was almost constant regardless of the load. As the load was lower and the butanol blending ratio was higher, the premixed combustion period of butanol blending oil was longer and the premixed combustion period was almost constant at high load regardless of butanol blending ratio. The average heat release rate was higher with increasing loads; especially as butanol blending ratio was increased at high load, the average heat release rate of butanol blending oil was higher than that of D.O. In addition, the calculated maximum. combustion temperature of butanol blending oil was higher than that of D.O. at all loads.

An Experimental Study of the Effects of Water Vapor in Intake Air on Comvustion and knock Characteristics in a Spark Ignition Engine (흡기중 수증기 함량이 스파크 점화기관의 연소 및 노킹에 미치는 영향에 관한 실험적 연구)

  • 이택헌;전광민
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.1
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    • pp.205-212
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    • 1998
  • In this study, the effects of water vapor in inlet air on combustion efficiency, general performance, knock characteristics and emission gas concentration were investig- ated through the experiments of combustion and vibration analyses, emission gas analysis by changing water vapor quantity in inlet air with temperature and humidity auto control unit. With partial vapor pressure increase, the brake torque at wide open throttle status decreased and the average ignition delay angle increased, IMEP (indicated mean effective pressured using the integral and 3rd derivatives of filtered cylinder pressure as knock intensity, which matched well with the method of frequency power spectrum of block vibration signal. Water vapor in intake air had influence on the spark knock sensitivity. With the increase of water vapor content in intake air NOx emission was decreased and HC emission was increased.

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EXPERIMENTAL STUDY ON HOMOGENEOUS CHARGE COMPRESSION IGNITION ENGINE OPERATION WITH EXHAUST GAS RECIRCULATION

  • Choi, G.H.;Han, S.B.;Dibble, R.W.
    • International Journal of Automotive Technology
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    • v.5 no.3
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    • pp.195-200
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    • 2004
  • This paper is concerned with the Homogeneous Charge Compression Ignition (HCCI) engine as a new concept in engines and a power source for future automotive applications. Essentially a combination of spark ignition and compression ignition engines, the HCCI engine exhibits low NOx and Particulate Matter (PM) emissions as well as high efficiency under part load. The objective of this research is to determine the effects of Exhaust Gas Recirculation (EGR) rate on the combustion processes of HCCI. For this purpose, a 4-cylinder, compression ignition engine was converted into a HCCI engine, and a heating device was installed to raise the temperature of the intake air and also to make it more consistent. In addition, a pressure sensor was inserted into each of the cylinders to investigate the differences in characteristics among the cylinders.

A Basic Experimental Study on Potential Operating Range in Gasoline Direct-Injection Compression Ignition (GDICI) Engine (가솔린 직접분사식 압축착화 엔진의 가능한 운전영역에 관한 기초실험 연구)

  • Cha, Junepyo;Yoon, Sungjun;Lee, Seokhwon;Park, Sungwook
    • 한국연소학회:학술대회논문집
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    • 2013.06a
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    • pp.33-35
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    • 2013
  • The present work is an experimental investigation on potential operating range using directly injected gasoline fuel in a single-cylinder compression ignition (CI) engine. The objectives of present study were to apply auto-ignited combustion to gasoline fuel and to evaluate potential operating range. In order to auto-ignite gasoline fuel in CI engine, the fuel direct-injection system and the intake air system were modified that a flow rate and temperature of intake air were regulated. The heat-release rate (HRR), net indicated mean effective pressure (IMEP), start of combustion (SOC), and combustion duration were derived from in-cylinder pressure data in a test engine, which has 373.33cc displacement volume and 17.8 compression ratio. The exhaust emission characteristics were obtained emission gas analyzer and smoke meter on the exhaust line system.

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Analysis of Cylinder Compression Pressure Uniformity and Valve Timing by Start Motor Current and Cylinder Pressure during Cranking (기동 모터의 전류 파형과 실린더 압력 분석을 통한 기관의 압축 압력 균일도 및 밸브 개폐 시점 이상 여부 분석)

  • Kim, In-Tae;Park, Kyoung-Suk;Shim, Beom-Joo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.1
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    • pp.133-138
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    • 2011
  • Compression pressure of individual cylinder and valve timing have big influence on combustion pressure, indicated mean effective pressure (IMEP), emission, vibration, combustion noise and many other combustion parameters. Therefore, uniformity of compression pressure and valve timing became one of most important engine design and production standard. Conventional method to evaluate compression pressure uniformity is to measure each cylinder pressure by mechanical pressure gage during cranking. This conventional method causes inaccuracy of cylinder pressure measurement because of different cranking speed results from battery status and also causes high manhour and cost. To check valve timing, related FEAD parts should be disassembled and timing mark should be checked manually. This study describes and suggests new methodology to measure compression pressure by analysis of start motor current and to check valve timing by cylinder pressure with high accuracy. With this new methodology, possibility to detect leaky cylinder and wrong valve timing was observed.