Studi Komparasi Eksperimental Emisi Gas Buang Lscs Piston Chamber dan Flat Piston Chamber Four Stroke Small Marine Diesel Engine pada Beban Konstan 1000 Watt

Performa pembakaran dan karakteristik emisi gas buang dari motor diesel dipengaruhi oleh pembentukan campuran bahan bakar/udara. Oleh karena itu, campuran bahan bakar/udara yang homogen dalam ruang bakar dan peningkatan daerah campuran bahan bakar/udara secara signifikan dapat meningkatkan pemanfaatan udara dan membatasi pembentukan jelaga dalam motor diesel. Saat ini, rasio udara berlebih dari motor diesel pada umumnya adalah sekitar 1,8-2,2 dan rasio udara berlebih dari motor diesel yang digunakan untuk alat alat berat seperti marine diesel engine adalah sekitar 1,6-1,8. Dengan demikian, perlu untuk mengusulkan sistem pembakaran baru untuk mengurangi beban pada sistem turbocharger dan sistem intake/exhaust dan menunjukkan kinerja yang sangat baik di bawah rasio udara berlebih yang rendah. Dalam penelitian ini, penulis mengusulkan sistem motor diesel pembakaran baru, yang memiliki nilai ekonomi yang sangat tinggi dan kinerja emisi gas buang pada rasio udara lebih dari 1/3. Beban dari sistem turbocharger dan sistem intake/exhaust berkurang. Densitas daya dan Efisiensi termal ditingkatkan, dan konsumsi bahan bakar berkurang secara cukup signifikan. Selain itu, sistem pembakaran baru ini menunjukkan kinerja emisi yang sangat baik di bawah kondisi udara tipis/berkurang. Sistem pembakaran baru ini kita kenal dengan nama Lateral swirl combustion system (LSCS). Dan pada penelitian ini kita membandingkan emisi gas buang yang dihasilkan dari dua buah bentuk Piston Chamber yaitu LSCS Piston Chamber dan Flat Piston Chamber. Untuk mengetahui kelayakan penggunaan LSCS Piston Chamber, maka dilakukanlah pengujian kandungan gas buang pada sebuah motor diesel. Gas buang yang dihasilkan motor diesel diukur dengan menggunakan alat GreenLine 4000 Gas Analyser. Gas yang diukur terdiri atas CO2, SO2, NOx, CO, dan HC. Hasil pengukuran tersebut nantinya akan dibandingkan dengan hasil pengukuran yang didapatkan pada penggunaan Flat Piston Chamber. Dari analisa dapat ditarik kesimpulan bahwa pada pergantian Flat Piston ke LSCS Piston pada beban 1000 Wattt pada variasi putaran engine mengalami penurunan konsentrasi emisi gas buang rata – rata CO2, SO2, CO, NOx, HC dan (NOx+HC) sebesar 1,46 %, 1,56 %, 0,13 %, 0,31 %, 0,51 % dan 0,38 % . Hasil pengukuran emisi gas buang CO2, SO2, NOx, CO, dan HC pada beban konstan 1000 Watt dan variasi putaran engine dapat diperoleh kesimpulan bahwa LSCS Piston Chamber yang mempunyai konsentrasi emisi gas buang paling rendah dibandingkan dengan Flat Piston Chamber. Kata kunci - Motor diesel, emisi gas buang, LSCS Piston Chamber, Flat Piston Chamber

The Influence of Piston Bowl Geometries on In-Cylinder Air Flow in a Direct-Injection (DI) Diesel Engine for Biodiesel Operation / S. Jaichandar, E. James Gunasekaran and A. Gunabalan

Thermal efficiency improvement, fuel consumption and pollutant emissions reduction from biodiesel fueled engines are critical requirements in engine research. In order to achieve these, a rapid and better air-fuel mixing condition is desired. The mixing quality of biodiesel with air can be improved by selecting the best engine design particularly combustion chamber design and injection system parameters. The present work investigates the effect of varying the piston bowl geometry on the air flow characteristics such as swirl velocity, Swirl Ratio (SR), and Turbulent Kinetic Energy (TKE) inside the engine cylinder. The piston’s bowl geometry was modified into several configurations that include Shallow depth combustion chamber (SCC), Toroidal combustion chamber (TCC), Shallow depth reentrant combustion chamber (SRCC) and Toroidal re-entrant combustion chamber (TRCC) from the standard Hemispherical combustion chamber (HCC), without altering the compression ratio of the engine. A commercially available CFD code STAR-CD was used to analyze the in-cylinder flow at different conditions. Flow conditions inside the cylinder were predicted by solving momentum, continuity and energy equations. The results confirmed that the piston bowl geometry had little influence on the in-cylinder flow during the intake stroke and the first part of compression stroke i.e. up to 300oafter suction TDC. However, the piston bowl geometry plays a significant role in the latter stage of the compression stroke i.e. beyond 300oafter suction TDC to compression TDC. The intensity of maximum swirl velocity at the end of compression stroke for TRCC was observed higher as 18.95 m/s and a strong recirculation was observed due to the geometry. Compared to baseline HCC the TRCC had higher, maximum swirl ratio and turbulent kinetic energy by about 28% and 2.14 times respectively. From the analysis of results, it was found that TRCC configuration gives better in-cylinder flows

STUDI KOMPARASI EKSPERIMENTAL EMISI GAS BUANG LSCS PISTON CHAMBER DAN FLAT PISTON CHAMBER FOUR STROKE SMALL MARINE DIESEL ENGINE PADA BEBAN KONSTAN 1000 WATT

Performa pembakaran dan karakteristik emisi gas buang dari motor diesel dipengaruhi oleh pembentukan campuran bahan bakar/udara. Oleh karena itu, campuran bahan bakar/udara yang homogen dalam ruang bakar dan peningkatan daerah campuran bahan bakar/udara secara signifikan dapat meningkatkan pemanfaatan udara dan membatasi pembentukan jelaga dalam motor diesel. Saat ini, rasio udara berlebih dari motor diesel pada umumnya adalah sekitar 1,8-2,2 dan rasio udara berlebih dari motor diesel yang digunakan untuk alat alat berat seperti marine diesel engine adalah sekitar 1,6-1,8. Dengan demikian, perlu untuk mengusulkan sistem pembakaran baru untuk mengurangi beban pada sistem turbocharger dan sistem intake/exhaust dan menunjukkan kinerja yang sangat baik di bawah rasio udara berlebih yang rendah. Dalam penelitian ini, penulis mengusulkan sistem motor diesel pembakaran baru, yang memiliki nilai ekonomi yang sangat tinggi dan kinerja emisi gas buang pada rasio udara lebih dari 1/3. Beban dari sistem turbocharger dan sistem intake/exhaust berkurang. Densitas daya dan Efisiensi termal ditingkatkan, dan konsumsi bahan bakar berkurang secara cukup signifikan. Selain itu, sistem pembakaran baru ini menunjukkan kinerja emisi yang sangat baik di bawah kondisi udara tipis/berkurang. Sistem pembakaran baru ini kita kenal dengan nama Lateral swirl combustion system (LSCS). Dan pada penelitian ini kita membandingkan emisi gas buang yang dihasilkan dari dua buah bentuk Piston Chamber yaitu LSCS Piston Chamber dan Flat Piston Chamber. Untuk mengetahui kelayakan penggunaan LSCS Piston Chamber, maka dilakukanlah pengujian kandungan gas buang pada sebuah motor diesel. Gas buang yang dihasilkan motor diesel diukur dengan menggunakan alat GreenLine 4000 Gas Analyser. Gas yang diukur terdiri atas CO2, SO2, NOx, CO, dan HC. Hasil pengukuran tersebut nantinya akan dibandingkan dengan hasil pengukuran yang didapatkan pada penggunaan Flat Piston Chamber. Dari analisa dapat ditarik kesimpulan bahwa pada pergantian Flat Piston ke LSCS Piston pada beban 1000 Wattt pada variasi putaran engine mengalami penurunan konsentrasi emisi gas buang rata – rata CO2, SO2, CO, NOx, HC dan (NOx+HC) sebesar 1,46 %, 1,56 %, 0,13 %, 0,31 %, 0,51 % dan 0,38 % . Hasil pengukuran emisi gas buang CO2, SO2, NOx, CO, dan HC pada beban konstan 1000 Watt dan variasi putaran engine dapat diperoleh kesimpulan bahwa LSCS Piston Chamber yang mempunyai konsentrasi emisi gas buang paling rendah dibandingkan dengan Flat Piston Chamber. Kata kunci - Motor diesel, emisi gas buang, LSCS Piston Chamber, Flat Piston Chamber

Numerical Methodology for Optimization of Compression-Ignited Engines Considering Combustion Noise Control

[EN] It is challenging to develop highly efficient and clean engines while meeting user expectations in terms of performance, comfort and drivability. One of the critical aspects in this regard is combustion noise control. Combustion noise accounts for about 40 percent of the overall engine noise in typical turbocharged diesel engines. The experimental investigation of noise generation is difficult due to its inherent complexity and measurement limitations. Therefore, it is important to develop efficient numerical strategies in order to gain a better understanding of the combustion noise mechanisms. In this work, a novel methodology was developed, combining computational fluid dynamics (CFD) modeling and genetic algorithm (GA) technique to optimize the combustion system hardware design of a high-speed direct injection (HSDI) diesel engine, with respect to various emissions and performance targets including combustion noise. The CFD model was specifically set up to reproduce the unsteady pressure field inside the combustion chamber, thereby allowing an accurate prediction of the acoustic response of the combustion phenomena. The model was validated by simulating several steady operating conditions and comparing the numerical results against experimental data, in both temporal and frequency domains. Thereafter, a GA optimization was performed with the goal of minimizing indicated specific fuel consumption (ISFC) and combustion noise, while restricting pollutant (soot and NOx) emissions to their respective baseline values. Eight design variables were selected pertaining to piston bowl geometry, nozzle inclusion angle, number of injector nozzle holes and in-cylinder swirl. An objective merit function based on the emissions, ISFC and combustion noise, was constructed to quantify the strength of the engine designs, and was determined using the CFD model as the function evaluator. The in-cylinder noise level was characterized by the total resonance energy of local pressure oscillations. The optimum engine configuration thus obtained, showed a significant improvement in terms of efficiency and combustion noise compared to the baseline system, along with both soot and NOx emissions within their respective constraints. This optimum configuration included a deeper and tighter bowl geometry with higher swirl and larger number of nozzle holes. Subsequently, a more detailed acoustics analysis based on proper orthogonal decomposition (POD) technique was carried out to further explore the combustion noise benefits achieved by the GA optimum. This computational study is a first of its kind (to the best of the authors¿ knowledge), which demonstrates a comprehensive framework to incorporate combustion noise into a numerical optimization strategy for engine design.The equipment used in this work was partially supported by FEDER and the Spanish Government through grant no. DPI2015-70464-R and by Fondo Europeo de Desarrollo Regional (FEDER) project funds "Dotacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica y Medioambiental de Sistemas de Transporte (CiMeT), (FEDER-ICTS-2012-06)," framed in the operational program of unique scientific and technical infrastructure of the Spanish Ministerio de Economia y Competitividad. J. Gomez-Soriano was partially supported through contract FPI-S2-2016-1353 of the "Programa de Apoyo para la Investigacion y Desarrollo (PAID-01-16)" of Universitat Politecnica de Valencia. The submitted manuscript was created partly by UChicago Argonne, LLC, Operator of Argonne National Laboratory. Argonne, a US Department of Energy (DOE) Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. This research was partly funded by the US DOE Office of Vehicle Technologies, Office of Energy Efficiency and Renewable Energy under Contract No. DE-AC02-06CH11357. The authors wish to thank Gurpreet Singh and Leo Breton, program managers at DOE, for their support.Broatch, A.; Novella Rosa, R.; Gómez-Soriano, J.; Pinaki, P.; Som, S. (2018). Numerical Methodology for Optimization of Compression-Ignited Engines Considering Combustion Noise Control. SAE International Journal of Engines. 11(6):625-642. https://doi.org/10.4271/2018-01-0193S62564211

Effect of nozzle and combustion chamber geometry on the performance of a diesel engine operated on dual fuel mode using renewable fuels

none6siRenewable and alternative fuels have numerous advantages compared to fossil fuels as they are biodegradable, providing energy security and foreign exchange saving and addressing environmental concerns, and socio-economic issues as well. Therefore renewable fuels can be predominantly used as fuel for transportation and power generation applications. In view of this background, effect of nozzle and combustion chamber geometry on the performance, combustion and emission characteristics have been investigated in a single cylinder, four stroke water cooled direct injection (DI) compression ignition (CI) engine operated on dual fuel mode using Honge methyl ester (HOME) and producer gas induction. In the present experimental investigation, an effort has been made to enhance the performance of a dual fuel engine utilizing different nozzle orifice and combustion chamber configurations. In the first phase of the work, injector nozzle (3, 4 and 5 hole injector nozzle, each having 0.2, 0.25 and 0.3 mm hole diameter and injection pressure (varied from 210 to 240 bar in steps of 10 bar) was optimized. Subsequently in the next phase of the work, combustion chamber for optimum performance was investigated. In order to match proper combustion chamber for optimum nozzle geometry, two types of combustion chambers such as hemispherical and re-entrant configurations were used. Re-entrant type combustion chamber and 230 bar injection pressure, 4 hole and 0.25 mm nozzle orifice have shown maximum performance. Results of investigation on HOME-producer gas operation showed 4-5% increased brake thermal efficiency with reduced emission levels. However, more research and development of technology should be devoted to this field to further enhance the performance and feasibility of these fuels for dual fuel operation and future exploitations.openYaliwal, V.S.; Banapurmath, N.R.; Gireesh, N.M.; Hosmath, R.S.; Donateo, Teresa; Tewari, P.G.Yaliwal, V. S.; Banapurmath, N. R.; Gireesh, N. M.; Hosmath, R. S.; Donateo, Teresa; Tewari, P. G

Keberkesanan manual pembelajaran kendiri (MPK) Kemahiran berfikir aras tinggi (KBAT) dalam proses pengajaran dan pembelajaran dalam kalangan pelajar politeknik

Kemahiran Berfikir Aras Tinggi (KBAT) adalah aspek penting dalam pengajaran dan pembelajaran. Pemikiran seseorang boleh memberi kesan kepada keupayaan pembelajaran, kepantasan dan keberkesanan pembelajaran. Tujuan kajian ini adalah untuk menilai keberkesanan MPK KBA T dalam proses pengajaran dan Pembelajaran dalam kalangan pelajar politeknik. Kajian ini menggunakan pendekatan kuantitatif dan reka bentuk Kuasi Experimental yang terdiri daripada kumpulan rawatan (KR) dan kumpulan kawalan (KK) yang melibatkan 78 orang pelajar. Rubrik penilaian tugasan kerja kursus dimodifikasikan untuk menilai aras pencapaian tugasan kerja kursus pelajar. Hasil dapatan kajian menunjukkan bahawa pencapaian tugasan kerja kursus pra bagi KR dan KK berada di tahap yang baik dan memuaskan. Selain itu, terdapat perbezaan yang signifikan min markah tugasan kerja kursus pos individu antara KR dan KK secara keseluruhan. Hasil dapatan kajian juga menunjukkan bahawa terdapat perbezaan yang signifikan min markah antara tugasan kerja kursus pra dan pos individu secara keseluruhan bagi KR. Secara kesimpulan, terdapat keberkesanan yang signifikan KBA T menerusi penggunaan manual pembelajaran kendiri KBAT terhadap pencapaian tugasan kerja kursus pelajar politeknik

Methodology to develop heuristic for re-entrant flow shop with two potential dominant machines using bottleneck approach

This paper presents a bottleneck-based methodology to solve scheduling problem of M1,M2,M3,M4,M3,M4 re-entrant flow shop where M1 and M4 have high tendency of being the dominant machines. Two generalised makespan algorithms using bottleneck approach were developed for the identified bottleneck. Each algorithm has specific correction factor which was used to ensure the accuracy of the makespan computation. Using these correction factors, a constructive heuristic was developed to solve for near-optimal scheduling sequence. For small size problems, the heuristic results were compared with the optimum makespan generated from complete enumeration. For medium and large size problems, the heuristic performance was measured by comparing its makespan with the solutions generated by the NEH and lowerbound. At weak and strong dominance level, the heuristic shows good performance against the lowerbound and better results compared to the NEH for large and medium size problems

Study of fuel additives for residual fuel oil applicable to ships

최근 주요 해운회사 들은 연료비 절감을 목적으로, 선박용 연료 첨가제의 본선 적용에 많은 관심을 가지고 있다. 선박은 경제적이면서도 원하는 성능을 발휘할 수 있는 연료유가 에너지원으로 공급되어야 선박의 운항 안정성이나 경제성을 확보할 수 있다. 실제로 연료첨가제를 적용하는 사용자들이 첨가제 적용을 검토하는 배경으로는 유지보수 비용의 감소, 연료 절감 및 유해 배출가스 감소를 가장 대표적인 이유로 들고 있다. 선박에 설치된 대부분의 디젤엔진이 연료유 품질에 대한 민감성이 다소 떨어지긴 하나, 이 또한 초기 개발이나 설계 단계에서부터 매뉴얼에 명시된 최적의 연료유가 공급되는 조건에서 충분히 안정적으로 그리고 효율적으로 운전될 수 있도록 고려되었음은 부정할 수 없다. 기관의 설계 기준과 시장에서 구할 수 있는 연료유의 품질이 완벽히 일치할 수는 없다. 실제로 시장에는 다양한 종류의 연료가 존재하며 이들의 기본 물성이 천차만별 일 뿐 아니라, 화학적 성상도 다양하다. ISO에서 선박 기관에 적용할 수 있는 선박용 연료유의 품질 기준을 정하여 통용하고 있긴 하나, 실제 선박에서 수급 받거나 본선에서 자체 제조하여 사용하는 연료유의 성상은 ISO의 표준치 범위를 벗어나는 경우가 종종 발생하고 있다. 본 연구에서는 고급유로 간주할 수 있는 증류유를 배제하고, 실제 원양항해 선박이 주로 사용하고 있는 잔사유에 연료 첨가제가 미치는 영향에 대해 연구하였다. 잔사유용 연료첨가제를 실제 엔진에서 첨가하여 운전함으로써 객관적인 성능 검증을 시도하였으며, 분산 안정제와 연소 촉매의 반응 메커니즘에 대한 기계공학적인 측면에서의 반응 모델 제안을 시도하였다. 또한, 광학적 분석을 통한 반응 메커니즘 검증에 연구의 촛점을 맞췄다. 잔사유는 상압 증류, 감압 증류, 촉매 분해, 열 분해 등의 정제과정을 통해 고품질의 증류 연료유를 추출해 내고 남은 잔존 연료유를 의미한다. 잔사유의 품질은 아이러니하게도 정제 기술이 고도화 되어감에 따라 악화되어 가고 있다. 이유는 상품적 가치가 높은 연료유를 정제 과정에서 최대한 추출하기 위해 열분해, 촉매 분해 공정이 고도화 되면서 원유가 받게 되는 물리화학적 스트레스가 크게 증대되었기 때문이다. 또한, 촉매 분해의 반응 효율을 높이기 위해 사용한 최대 반응면적의 촉매는 잔사유에 미소 입자로 남아 엔진의 연료 및 연소시스템에 심각한 손상을 야기할 수 있다. 잔사유는 나프텐계 탄화수소 (CnH2n – 환형구조)로 알려져 있다. 이는, 파라핀계 보다도 더 안정한 구조이다. 주요 구성 물질은 아스팔텐이며, 아스팔텐은 연소시 반응속도가 느리고 연료 분사 시 액적의 크기가 미소화 되기 어려운 특성이 있다. 따라서, 연소 후 카본 누적층이 생성되거나 입자상 물질이 생성되기 쉬운 특성을 가지고 있다. 연료첨가제 기술은 인류가 기관을 개발한 이래로 함께 성장해 온 기술이다. 과거로부터, 옥탄가 향상제, 윤활성 향상제 등 다양한 형태로 활용되어 오고 있다. 다만, 대부분 자동차 산업을 위주로 함께 발전해 왔으며, 잔사유에 적용 가능한 첨가제의 개발이 이뤄진 건 역사가 오래되지 않았음에 주목할 필요가 있다. 현재 선박에 적용 가능한 대표적인 종류의 연료 첨가제로는 분산 안정제, 탄소 적층 방지제, 해유화제, 유동성 향상제, 윤활성 향상제, 연소 촉매, 부식 방지제 및 다기능 첨가제를 들 수 있겠다. 그 중에서도 시장에서 가장 많은 활용을 보이고 있는 첨가제는 분산 안정제가 있으며 그 뒤를 이어 연소 촉매가 또한 많이 사용되고 있다. 본 연구는 분산 안정제의 반응 메커니즘을 문헌 연구를 통하여 확인하고 그 메커니즘을 검증하였다. 또한 연소 촉매의 반응 메커니즘을 문헌 및 실험 결과에 주목하여 도출하고 이 또한 광 분석 기술로 검증하였다. 분산안정제를 잔사유 탱크에 첨가하게 되면, 분산 안정제가 연료유에 침윤하게 되는 과정이 있고, 침윤한 안정제는 응축 경향이 강한 아스팔텐 입자들을 분리시키게 된다. 침윤 과정 및 분리과정이 완료되면, 마지막은 침윤 및 분리 과정을 지속적으로 유지하는 메커니즘이 필요함을 확인 하였다. 분산성을 분석한 결과에 따르자면, 분산제의 3가지 반응 메커니즘 중 침윤 및 분리과정을 유지하는 성능 차이가 존재함이 실험에 의해 밝혀졌으며, 이에 대한 대응이 필요하다. 연소 촉매의 효과를 검증하고 메커니즘을 분석하기 위하여 엔진 연료 소모량 계측, 배출가스 계측, 정적 연소기 계측, 열 계측, 광 계측 등의 분석을 활용하였다. 연료 소모량 계측 결과는 첨가제가 연소 촉매이건 분산성 향상제 이건 간에 무관하게 연료 소모량 저감에 효과를 줄 수 있음을 확인하였다. 이는 잔사유의 특성으로부터 설명 할 수 있다. 잔사유 속에 다량 함유된 아스팔텐은 응집성향이 강하나 분산성 향상제가 응집을 방지하였고, 이는 결국 연료유내 가용 에너지 분율이 증가되었기 때문이다. 연소 촉매는 반응성이 좋은 금속이나 전이금속을 주요 구성성분으로 활용하고 있다. 이들은 연소 초기에 활성 래디컬 생성에 기여하여 활발한 연소 화학반응을 조장하게 되어 연소가 촉진되는 것으로 보인다. 또한, 연소 후에도 배출가스 온도가 충분히 높다면 촉매 활성을 유지하여 탄소 적층의 방지, 중질의 탄소분 감소 등의 효과가 있어 보이며, 결국 입자상 물질의 저감에도 효율적으로 작용할 수 있다. 배출가스 관점에서는 연소 활성화로 인하여 질소산화물 배출이 증가함이 관찰되었다. 더불어, 첨가제 불포함 연료에 비해 이산화탄소 배출 농도는 증가하였고 산소 배출 농도는 감소하였다. 이는 분자량이 큰 잔사유의 연소에 산소가 적극 개입할 수 있도록 자유래디컬이 충분히 효과적으로 작용했고, 그 결과로 많은 양의 이산화탄소가 생성되었음이다. 광 계측 결과에서는 연소촉매 첨가제들이 비정질의 탄소 구조를 배출하였고, 첨가제가 포함되어 있지 않거나 효과가 의문시되었던 첨가제에서 흑연(graphite)구조가 계측되었다. 이는 첨가제의 영향으로 인하여 유용한 탄소성분을 엔진의 연소과정 중에 다 소진하였기에 나타난 결과로 보인다. 본 연구를 통해 고찰한 결과를 종합함으로써, 선박 잔사유용 연료 첨가제의 메커니즘을 일부 규명할 수 있었다. 궁극적으로 첨가제가 긍정적으로 작용하고 있으나, 본 연구는 4 행정 사이클(stroke cycle) 디젤엔진에서 수행되었고, 관련 문헌에 의하면 세탄가의 영향이 적거나 전혀 영향을 받지 않는 것으로 알려진 2 행정 사이클 엔진에 연소 활성 목적으로 첨가제 사용은 추가적인 연구가 필요할 것으로 보인다. 다만, 상용 엔진중에서 잔사유를 사용하되 행정이 짧아 평균 피스톤 속도가 상대적으로 높은 일부 4 행정 사이클 엔진에서는 연소 촉매 혹은 분산제가 사용 목적에 부합하게 사용될 수 있다. 미연 탄소의 배출 감소, 입자상 물질 감소 등의 연소 개선으로 인한 효과는 기대할 수 있으나, 질소산화물은 첨가제 제조사가 제시하고 있는 반응 메커니즘으론 저감할 수 없다고 판단된다.1. Introduction 1.1 Marine fuel 12 1.2 Basic properties of marine residual fuel oil 20 1.2.1 Viscosity 21 1.2.2 Density 21 1.2.3 Flash point 22 1.2.4 Pour point 22 1.2.5 Sulfur 22 1.2.6 Carbon residue 22 1.2.7 Water 23 1.2.8 Ash 23 1.2.9 Vanadium, magnesium and sodium 23 1.2.10 Aluminium and silicon 24 1.3 Additives 24 1.3.1 History of additives 24 1.3.2 Information and technical achievements of diesel additives from bibliography 27 2. Understanding additives and review of relevant literatures 2.1 Combustion with fuel additives 44 2.2 Chemistry of combustion 45 2.3 Additive effects on ignition delay 48 2.4 Additive effects on emissions 49 2.4.1 Reduction of NO to N2 by reaction with particles of Fe 49 2.4.2 Additive effects to the creation of Polycyclic Aromatic Hydrocarbon(PAH) 50 2.4.3 Additive effects to the emission reduction 53 2.4.4 Effects of an ignition-enhancing, diesel-fuel additive on diesel-spray evaporation, mixing, ignition, and combustion 54 3. Experimental setup and analyzers 3.1 Fuel oil samples 56 3.2 Fuel dispersability analysis 58 3.3 Fuel Ignition/Combustion Analysis (FIA/FCA) 60 3.4 Thermo Gravimetirc Analysis 65 3.5 Engine and auxiliary system 67 3.5.1 Low engine load test setup 67 3.5.2 Full engine load test setup 71 4. Results and Discussion 4.1 Dispersability 73 4.2 Investigation of fuel dispersant mechanism 76 4.2.1 Basic properties 76 4.2.2 Dispersants 84 4.2.3 Deposit control by dispersants 85 4.2.4 Dispersant structure 86 4.3 Fuel oil combustion characteristics by FIA/FCA 88 4.4 Thermogravimetric analysis 100 4.5 Fuel oil consumption 104 4.5.1 Fuel oil consumption at low engine load 104 4.5.2 Fuel oil consumption at fuel engine load 106 4.6 Investigation of fuel combustion improver effect to engine combustion 112 4.7 Emission characteristics 123 4.7.1 Emission characteristics at low engine load 123 4.7.2 Emission characteristics at full engine load 127 4.8 Optical analysis 130 4.8.1 Raman spectroscopy 131 4.8.2 Energy dispersive X-ray spectroscopy 133 5. Conclusions 5.1 Dispersability 138 5.2 Dispersant mechanism 139 5.3 Fuel oil combustion characteristics by FIA/FCA 139 5.4 Thermogravimetric Analysis 142 5.5 Fuel oil consumption evaluation 142 5.5.1 Fuel oil consumption at low engine load 143 5.5.2 Fuel oil consumption at full engine load 143 5.6 Investigation of fuel combustion improver effect to engine combustion 143 5.7 Emission characteristics 144 5.7.1 Emission characteristics at low engine load 144 5.7.2 Emission characteristics at full engine load 145 5.8 Optical analysis 145 5.8.1 Raman spectroscopy 145 5.8.2 Energy dispersive X-ray spectroscopy 145 References 14

Combustion and emission characteristics of IC engines fueled by hydrogen and hydrogen/diesel mixtures and multi-objective optimization of operating parameters

“The present study considers combustion of hydrogen in IC engines. In general, the work focuses on simulating the engine performance and emissions at different operation parameters, and using optimization techniques. Task I work deals with the engine performance and emissions of a single cylinder spark-ignition (SI) engine fueled by hydrogen. The engine was simulated at different equivalence ratios, exhaust gas recirculation (EGR) and ignition timing. The results indicate that NOx emissions, engine power, and efficiency are reduced by increasing EGR level, and increased with increasing equivalence ratio and advanced ignition timing. The best operating conditions for hydrogen engines were obtained by solving the multi-objective problem of maximizing engine power and efficiency while minimizing the NOx. Task II deals with the engine performance and emissions of dual-fuel CI engines fueled by a hydrogen/diesel mixture. The engine was simulated under conditions of various hydrogen levels (%) by energy, diesel injection timing, and EGR levels (%). More hydrogen present inside the engine cylinder led to lower soot emissions, higher thermal efficiency, and higher NOx emissions. Ignition timing delayed as the hydrogen rate increased, due to a delay in OH radical formation. Exhaust gas recirculation (EGR) method and diesel injection timing were considered as well, due to their potential effects on the engine outputs. To obtain the best possible maximum efficiency along with lower NOx and soot emissions, optimization methods in (Task III) for the operating parameters were considered. Multi-objective problem with conflicting objectives was solved by using regression analysis, artificial neural networks, and genetic algorithms”--Abstract, page iv