특성곡선법을 이용한 디젤엔진 가스유동 1차원 수치해석의 타당성 평가

김경현,공경주 한국수산해양기술학회 2020 수산해양기술연구 Vol.56 No.3

In order to design a diesel engine system and predict its performance, it is necessary to analyze the gas flow of the intake and exhaust system. A gas flow analysis in three-dimensional (3D) format needs a high-resolution workstation and enormous time for analysis. Therefore, the method of characteristics (MOC) was used for a gas flow analysis with a fast calculation time and a low-resolution workstation. An experiment was conducted on a single cylinder diesel engine to measure pressure in cylinder, intake pipe and exhaust pipe. The one-dimensional (1D) gas flow was analyzed under the same conditions as the experiment. The engine speed, valve timing and compression ratio were the same conditions and the intake pressure was inputted as the experimental results. Bent pipe such as an exhaust port that cannot be realized in 1D was omitted. As results of validation, the cylinder pressure showed accuracy, but the exhaust pipe pressure exhibited inaccuracy. This is considered as an error caused by the failure to implement a bent pipe such as an exhaust port. When analyzed in 3D, calculation time required 61 hours more based on a model of this study. In the future, we intend to implement a bent pipe that cannot be realized in 1D using 3D and prepare a method to supplement reliability by using 1D-3D coupling. 디젤엔진 시스템을 설계하고 성능을 예측하기 위해 흡·배기 시스템의 가스유동 해석이 필요하다. 3D로 가스유동해석 한다면 초고사양의 워크스테이션과 많은 계산 시간이 필요하다. 그러므로, 빠른 계산시간과 낮은 사양의 워크스테이션으로 계산을 하기 위해 특성곡선법을 사용하여 가스유동 해석을 하였다. 단기통 디젤엔진을 대상으로 실험을 하였고 실린더 압력과 흡 배기관 압력을 측정하였다. 실험과 동일한 조건으로 1D 가스유동 해석을 하기위해 흡기 압력은 실험 결과를 입력하였다. 1D로 구현하지 못하는 곡관 형상의 배기포트는 생략하여 1D 가스유동 해석을 하였다. 신뢰성 평가를 해본 결과, 실린더 압력은 정확성을 보였지만, 배기관 압력은 정확하지 않았다. 배기관 압력이 정확하지 않은 이유는 곡관 형상의 배기포트를 구현하지 못하여 발생한 오차라 생각한다. 추후 1D로 구현하지 못하는 곡관을 3D로 구현하고 1D-3D 결합을 이용하여 신뢰성을 보완할 방안을 마련하고자 한다.

단기통엔진에서의 GTL(Gas to Liquid) 연료특성 연구

金銅熙,李海喆,車京玉 明知大學校 産業技術硏究所 2006 産業技術硏究所論文集 Vol.25 No.-

Recently, alternative fuels are drawing more attentions due to the increasing need for lower emission characteristics and fuel consumption rate in automotive engine. The GTL(gas to luquid) is the one of most favored candidates. GTL is a synthetic liquified fuel made from natural gas or charcoal with Fischer-Tropsch mechanism. It has higher cetane number(more than 75) and almost negligible sulphur and aromatic contents. Therefore, enhanced emission characteristics are expected even in the application in diesel engines without any modification. In this study, the engine performances and emission characteristics are compared between diesel and GTL fuel in the single cylinder diesel engine. Also the various blendings between Diesel and GTL(30%, 50% in volume) are also tested to investigate optimal blending ratio in the respect of emission characteristics. Noticeable reduction in soot, THC and CO emission are observed without the loss of engine power due to low sulphur and aromatic contents in GTL. Also, the ignition delay creased due to higher cetane number of GTL, which slightly decreased the amount of NOx emissions.

단기통 디젤엔진에서 흡기온도변화에 따른 연소 및 배기특성

신달호(Dalho Shin),박수한(Suhan Park) 한국자동차공학회 2017 한국 자동차공학회논문집 Vol.25 No.3

Intake air conditions, such as air temperature, pressure, and humidity, are very important parameters that influence engine performance including combustion and emissions characteristics. The purpose of this study is to investigate the effects of intake air temperature on combustion and exhaust emissions characteristics in a single cylinder diesel engine. In this experiment, an air cooler and a heater were installed on the intake air line and a gas flow controller was installed to maintain the flow rate. It was found that intake air temperature induced the evaporation characteristics of the fuel, and it affects the maximum in-cylinder pressure, IMEP(indicated mean effective pressure), and fuel consumption. As the temperature of intake air decreases, the fuel evaporation characteristics deteriorate even as the fuel temperature has reached the auto-ignition temperature, so that ignition delay is prolonged and the maximum pressure of cylinder is also reduced. Based on the increase in intake air temperature, nitrogen oxides(NOx) increased. In addition, the carbon monoxide(CO) and unburned hydrocarbons(UHC) increased due to incomplete fuel combustion at low intake air temperatures.

저온디젤연소엔진에서 미연탄화수소 생성에 관한 연구

오승묵(Seungmook Oh),Wiil F. Colban,Paul C. Miles 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

The cycle-to-cycle variability and potential sources of unburned hydrocarbon (UHC) emissions are examined in a single-cylinder, light-duty diesel test engine operating in low-temperature combustion regimes. A fast flame ionization detector (FID) was employed to examine both cycle-to-cycle emissions behavior. A standard suite of emissions measurements, including CO, CO₂, NOx and soot, was also obtained. Measurements were made spanning a broad range of intake O₂ concentrations-to examine the UHC behavior of dilution-controlled combustion regimes-and spanning a broad range of injection timings-to clarify the behavior of increased UHC emissions in late-injection combustion regimes. Both low- and moderate-loads were investigated. The cycle-resolved UHC data showed that the coefficient of variation of single-cycle UHC did not increase with increases in UHC emissions as either O₂ concentration or injection timing was varied. Additionally, the crank-angle-resolved UHC measurements were coupled with a I-D engine model to examine the variation of exhaust mass flow rate of UHC within each cycle. The results showed that most of the UHC mass exited the cylinder during the latter part of the exhaust process, and that UHCs originating from cylinder wall and piston top quench layers are likely of greater importance than UHCs emitted from quench layers along the head.

대형 디젤 엔진에서 연소 가시화를 통한 항공유와 디젤의 배기 특성 분석

이진우(Jinwoo Lee),배충식(Choongsik Bae) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11

Combustion process with JP-8 and diesel was analyzed in an optically-accessible single-cylinder heavy-duty diesel engine equipped with a high pressure common-rail injection system. Direct imaging and two-color thermometry were applied to verify the emission trend for both fuels. The combustion process was characterized by means of image analysis focusing on the luminosity. The results from the two-color thermometry were analyzed by flame temperature and KL factor distribution. From the combustion process analysis of direct imaging, it was verified that JP-8 had a longer ignition delay compared to diesel, while flame was vanished more rapidly. Analysis of flame luminosity intensity showed that diesel combustion had higher intensity and lasted for longer duration. Two-color thermometry results showed that higher temperature region was distributed more with JP-8 combustion, which means that more NOx was formed with JP-8 combustion. Also, relatively homogeneous and low level of KL factor distribution was shown with JP-8 combustion, which implied that JP-8 combustion produced less smoke emission.

코먼레일 單汽筒 디젤엔진에서 GTL 熱料의 噴射時期 變化에 따른 排出物 特性에 關한 硏究

金秉儁,崔源鶴,柳鍾植,李海喆,車京玉 명지대학교 산업기술연구소 2008 産業技術硏究所論文集 Vol.27 No.-

Recently, alternative fuels are drawing more attentions due to the increasing need for lower emission characteristics and fuel consumption rate in automotive engines. The GTL(gas to luquid) is the one of most favored candidates. It has higher cetane number(more than 75) and almost negligible sulphur and aromatic contents. Therefore, enhanced emission characteristics are expected even in the application in diesel engines without any modification. In this study, the cylinder pressure and heat release, emission characteristics with fuel injection timings are compared between diesel and GTL fuel in the single cylinder diesel engine. Noticeable reduction in PM, THC and CO emission are observed due to lower sulphur and aromatic contents in GTL. Also, the ignition delay decreased due to higher cetane number of GTL , which slightly decreased the amount of NOx emissions. With the retards of main injection timing. NOx decreases more for the case of GTL, while the level of THC and CO emissions still remains lower than the case of diesel. Therefore, there is much room for the control of injection timiing for NOx reduction without sacrificing THC and CO emissions. With the retards of main injection timing, Small size distribution of PM became lager and there amount increased. But from all conditions, size distribution of PM for the case GTL was lower than Diesel.

커먼레일 단기통 엔진에서 GTL 연료의 분사시기 변화에 따른 배출물 특성

김병준(Byoungjun Kim),이용규(Yonggyu Lee),최교남(Kyonam Choi),정동수(Dongsoo Jeong),차경옥(Kyungok Cha) 한국자동차공학회 2008 한국 자동차공학회논문집 Vol.16 No.1

Recently, alternative fuels are drawing more attentions due to the increasing need for lower emission characteristics and fuel consumption rate in automotive engines. The GTL(gas to luquid) is the one of most favored candidates. It has higher cetane number(more than 75) and almost negligible sulphur and aromatic contents. Therefore, enhanced emission characteristics are expected even in the application in diesel engines without any modification. In this study, the cylinder pressure and heat release, emission characteristics with fuel injection timings are compared between diesel and GTL fuel in the single cylinder diesel engine. Noticeable reduction in PM, THC and CO emission are observed due to lower sulphur and aromatic contents in GTL. Also, the ignition delay decreased due to higher cetane number of GTL , which slightly decreased the amount of NOx emissions. With the retards of main injection timing, NOx decreases more for the case of GTL, while the level of THC and CO emissions still remains lower than the case of diesel. Therefore, there is much room for the control of injection timing for NOx reduction without sacrificing THC and CO emissions. With the retards of main injection timing, Small size distribution of PM became lager and there amount increased. But from all conditions, size distribution of PM for the case GTL was lower than Diesel.

흡기조건 변화에 따른 바이오디젤의 연소 및 배기특성

신달호 ( Dal Ho Shin ),박수한 ( Su Han Park ) 한국액체미립화학회 2016 한국액체미립화학회 학술강연회 논문집 Vol.2016 No.-

The combustion and exhaust emissions characteristics of biodiesel were studied in a single-cylinder diesel engine with about 498 cc of displacement volume under various intake air conditions. Biodiesel used in this work was derived from soybean oil, and it has high viscosity, surface tension, and density compared to a conventional diesel. In addition, biodiesel has an oxygen as 11 %, and it has the influence on the high nitrogen oxides (NOx) and a low soot emission. The single-cylinder diesel engine was operated by AC dynamometer, and its oil temperature and coolant temperature were set to 80 ℃. The emissions, such as NOx, CO, and HC, were measured by the emission analyzer (MEXA-9100DER, Horiba). The test was conducted under 1800 rpm of engine speed, 14 mg of injection quantity, and BTDC 3 º ~BTDC 30 º of injection timings. The temperature of intake air was changed from 30℃ to 60℃. From results, we could analyze the IMEP (indicated mean effective pressure), combustion pressure, emissions (NOx, HC, CO). The increase of intake air temperature induced the increase of NOx and decrease of HC and CO emissions.

예혼합 압축 착화 엔진용 산하 촉매의 정화 특성

정길성(Gil Sung Jung),정종우(Jong-Woo Jeong),성용하(Yongha Sung),김화남(Hwanam Kim),최병철(Byungchul Choi),임명택(Myung Taeck Lim) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

HCCI engines are expected to offer the high efficiency of DI diesel engines with low level of NOx and particulate emissions. Experimental HCCI engines are however reported to exhaust THC and CO at a level comparable to the gasoline engines. Because the exhaust gas temperature of HCCI engines is lower than that of the diesel engines, development of exhaust treatment devices like DOC's with high conversion efficiency especially at low temperature is crucial to commercialization of HCCI engines. Experimental DOC's are designed and fabricated in this study using various level of platinum loading and 600 cpsi ceramic monolith coated with two different type of wash coat. Performance test result of these DOC's show that the low-temperature type washcoat effectively lowers the 50% light-of f temperature by 30℃. L90, the catalyst with this type of wash coat and an intermediate level of level of platinum loading, demonstrates the lowest light-of f temperature in the model gas tests.

피에조 인젝터의 구동방식별 CRDi 단기통 디젤엔진의 연소 성능 해석

정명철(Myungchul Chung),성기수(Gisu Sung),김상명(Sangmyung Kim),이진욱(Jinwook Lee) 한국자동차공학회 2013 한국자동차공학회 학술대회 및 전시회 Vol.2013 No.11