Specific Hydrocarbon Emissions Research Articles

Optimization of the parameters influencing the fuel efficiency of SI engine using taguchi method

In this study, Taguchi’s method is used to optimize the fuel efficiency of Spark Ignition (SI) engine and also to reduce the emissions from the engine. For this purpose, four control variables are considered, viz Engine speed (rpm), Compression ratio, Air-Fuel ratio (A: F) and Ignition timing (degrees). Brake thermal efficiency (BTE), Brake Specific Hydro-Carbon emissions (BSHC) and Brake Specific NOx emissions (BSNO) are considered as response variables. The efficiency of optimized engine was calculated and compared with the efficiency of a Baseline engine. Signal to Noise (S/N) ratio and Analysis of Variance (ANOVA) are used in analyzing the response variables. From the results, after general optimization the optimum engine speed, compression ratio, air-fuel ratio and ignition timing were found to be 2400 rpm, 9, 15:1 and 26 degrees respectively. The results obtained from optimized engine was found to have improved brake thermal efficiency as well as reduced emissions when compared to baseline engine.

Experimentally tested performance and emissions advantages of using natural-gas and hydrogen fuel mixture with diesel and rapeseed methyl ester as pilot fuels

Higher unburned hydrocarbon emissions are attributed to the relatively low temperature combustion of natural gas in compression ignition engines whereas the combustion of hydrogen in compression ignition environment results in higher NOX. These emissions characteristics are explained on the basis of different physio-chemical properties of the two gaseous fuel: higher Cp value in case of natural gas and higher diffusion coefficient, wider flammability limits and shorter quenching gaps for hydrogen are held responsible for these trends. This study assesses the potential of hydrogen being used in combination with natural gas with diesel and rapeseed methyl ester (RME) as pilot fuels. This type of fueling can be referred as ‘triple fueling of the compression ignition engines’ and has the potential to achieve a better trade-off between the higher NOX associated with hydrogen and higher hydrocarbon emissions associated with natural gas based dual fueling of compression ignition engines. The present study has investigated the potential of the triple fueling of the compression ignition engines so far the attainment of a better trade-off between NOX and hydrocarbon emissions are concerned. Comparing the specific NOX and hydrocarbon emissions in different cases reveals that a significant drop in specific hydrocarbon emissions can be achieved at the cost of a small increment in specific NOX. At both speeds (1000 rev/min and 1500 rev/min), the reduction in hydrocarbon emissions is more prominent at relatively lower loads, which can be a potential solution of reducing specific hydrocarbon emissions at lower loads in diesel engine operations. The stoichiometric equation for the triple fueling (Diesel or RME piloted mixture of natural gas and hydrogen) is also presented.

Impact of edible and non-edible biodiesel fuel properties and engine operation condition on the performance and emission characteristics of unmodified DI diesel engine

ABSTRACTThe purpose of this work is to test the feasibility of biodiesel as a substitute for diesel used in a direct injection (DI) diesel engine. The biodiesel was produced by an esterification and transesterification process. Experiments were conducted with diesel–biodiesel blends containing 10 and 20% biodiesel with the diesel fuel. The results of the biodiesel blends are compared with baseline diesel which was assessed at constant speed in a single cylinder diesel engine at various loading conditions. The physicochemical properties of palm and Calophyllum inophyllum biodiesel and their blends meet the standard specification ASTM D6751 and EN 14214 standards. The maximum brake thermal efficiency was attained with diesel fuel, 10% palm biodiesel (PB10) and 10% C. inophyllum biodiesel (CI10) at all load condition except low load condition. Engine emission results showed that the 20% C. inophyllum with 80% diesel blend exhibited 6.35% lower amount of brake specific carbon monoxide, and the PB20 blend and CI20 blend reduced brake specific hydrocarbon emission by 7.93 and 9.5%, respectively. NOx emission from palm and C. inophyllum biodiesel blends are found to be 0.29–4.84% higher than diesel fuel. The lowest smoke intensity is found at 27.5% for PB10 and CI10 biodiesel blends compared with diesel fuel.

Performance and Emission Investigations of Jatropha and Karanja Biodiesels in a Single-Cylinder Compression-Ignition Engine Using Endoscopic Imaging

Biofuels produced from nonedible sources that are cultivated on marginal lands represent a viable source of renewable and carbon-neutral energy. In this context, biodiesel obtained from Jatropha and Karanja oil seeds have received significant interest, especially in South Asian subcontinent. Both of these fuels are produced from nonedible plant seeds with high oil content, which can be grown on marginal lands. In this research, we have investigated the performance and emission characteristics of Jatropha and Karanja methyl esters (biodiesel) and their blends with diesel. Another objective is to examine the effect of long-term storage on biodiesel's oxidative stability. The biodiesels were produced at Indian Institute of Technology Kanpur, (IIT Kanpur), India, and the engine experiments were performed in a single cylinder, four-stroke, compression ignition engine at Argonne National Laboratory (ANL), Chicago. An endoscope was used to visualize in-cylinder combustion events and examine the soot distribution. The effects of fuel and start of injection (SOI) on engine performance and emissions were investigated. Results indicated that ignition delay was shorter with biodiesel. Consequently, the cylinder pressure and premixed heat release were higher for diesel compared to biodiesel. Engine performance data for biodiesel (J100, K100) and biodiesel blends (J30, K30) showed an increase in brake thermal efficiency (BTE) (10.9%, 7.6% for biodiesel and blend, respectively), brake specific fuel consumption (BSFC) (13.1% and 5.6%), and nitrogen oxides (NOx) emission (9.8% and 12.9%), and a reduction in brake specific hydrocarbon emission (BSHC) (8.64% and 12.9%), and brake specific CO emission (BSCO) (15.56% and 4.0%). The soot analysis from optical images qualitatively showed that biodiesel and blends produced less soot compared to diesel. The temperature profiles obtained from optical imaging further supported higher NOx in biodiesels and their blends compared to diesel. Additionally, the data indicated that retarding the injection timing leads to higher BSFC, but lower flame temperatures and NOx levels along with higher soot formation for all test fuels. The physicochemical properties such as fatty acid profile, cetane number, and oxygen content in biodiesels support the observed combustion and emission characteristics of the fuels tested in this study. Finally, the effect of long-term storage is found to increase the glycerol content, acid value, and cetane number of the two biodiesels, indicating some oxidation of unsaturated fatty acids in the fuels.

Potential for using a tyre pyrolysis oil-biodiesel blend in a diesel engine at different compression ratios

This study is aimed at investigating effects of varying the compression ratio at optimum injection timing and nozzle opening pressure on the behaviour of a diesel engine, using a non-petroleum fuel, i.e. a blend of 80% biodiesel, and 20% oil obtained from pyrolysis of waste tyres. The engine was subjected to one lower (16.5) and one higher (18.5) compression ratio in addition to the standard compression ratio of 17.5. At the higher compression ratio of 18.5 and full load, shorter ignition delay, maximum cylinder pressure and higher heat release rate were found for the blend, compared to those of the original compression ratio. The increase in the compression ratio from 17.5 to 18.5 for the blend improved the brake thermal efficiency by about 8% compared to that of the original compression ratio at full load. The experimental results indicated that for the blend at a higher compression ratio of 18.5, the brake specific carbon monoxide (BSCO), brake specific hydrocarbon emission (BSHC) and smoke opacity were reduced by about 10.5%, 32%, and 17.4% respectively, than those of the original compression ratio at full load.

Performance and Emissions Characteristics of Diesel-Ignited Gasoline Dual Fuel Combustion in a Single-Cylinder Research Engine

Diesel-ignited gasoline dual fuel combustion experiments were performed in a single-cylinder research engine (SCRE), outfitted with a common-rail diesel injection system and a stand-alone engine controller. Gasoline was injected in the intake port using a port-fuel injector. The engine was operated at a constant speed of 1500 rev/min, a constant load of 5.2 bar indicated mean effective pressure (IMEP), and a constant gasoline energy substitution of 80%. Parameters such as diesel injection timing (SOI), diesel injection pressure, and boost pressure were varied to quantify their impact on engine performance and engine-out indicated specific nitrogen oxide emissions (ISNOx), indicated specific hydrocarbon emissions (ISHC), indicated specific carbon monoxide emissions (ISCO), and smoke emissions. Advancing SOI from 30 degrees before top dead center (DBTDC) to 60 DBTDC reduced ISNOx from 14 g/kW h to less than 0.1 g/kW h; further advancement of SOI did not yield significant ISNOx reduction. A fundamental change was observed from heterogeneous combustion at 30 DBTDC to “premixed enough” combustion at 50–80 DBTDC and finally to well-mixed diesel-assisted gasoline homogeneous charge compression ignition (HCCI)-like combustion at 170 DBTDC. Smoke emissions were less than 0.1 filter smoke number (FSN) at all SOIs, while ISHC and ISCO were in the range of 8–20 g/kW h, with the earliest SOIs yielding very high values. Indicated fuel conversion efficiencies were ∼ 40–42.5%. An injection pressure sweep from 200 to 1300 bar at 50 DBTDC SOI and 1.5 bar intake boost showed that very low injection pressures lead to more heterogeneous combustion and higher ISNOx and ISCO emissions, while smoke and ISHC emissions remained unaffected. A boost pressure sweep from 1.1 to 1.8 bar at 50 DBTDC SOI and 500 bar rail pressure showed very rapid combustion for the lowest boost conditions, leading to high pressure rise rates, higher ISNOx emissions, and lower ISCO emissions, while smoke and ISHC emissions remained unaffected by boost pressure variations.

Engine performance and exhaust emissions in stoichiometric combustion engines fuelled with dimethyl ether

This paper describes the effects of stoichiometric combustion on the engine performance and exhaust emissions in a single-cylinder compression ignition engine fuelled with dimethyl ether. In order to realize stoichiometric combustion in a direct-injection compression ignition engine, high exhaust gas recirculation was used to control air-to-fuel ratios based on a lambda meter. The combustion pressure, heat release rate, and indicated mean effective pressure, which are the main indicators of the engine performance, were derived from in-cylinder pressure data in a single-cylinder direct-injection compression ignition engine. The test engine had a displacement volume of 373.3 cm3, a compression ratio of 17.8, and a common-rail injection system. Exhaust emissions characteristics were obtained from emission gas analysers at the tailpipe. The experimental results show that increasing the equivalence ratio dramatically reduced the indicated specific nitrogen oxide emissions (i.e. by over 90 per cent) owing to the high exhaust gas recirculation in the conventional diesel combustion regime. Furthermore, soot emissions were negligible owing to the chemical properties of the dimethyl ether fuel in the operation range of the injection timings. For injection timings near top dead centre, the indicated specific carbon monoxide emission levels rise excessively as the equivalence ratio increases and the maximum value is 80.9 g/kW h. However, for advanced injection timing (i.e. near 25° crank angle before top dead centre), the indicated specific carbon monoxide emission level shows minimal variation as the equivalence ratio changes. In contrast, the levels of indicated specific hydrocarbon emissions vary according to the injection timing. Increasing the equivalence ratio causes the indicated mean effective pressure to deteriorate slightly (i.e. up to 10 per cent loss) owing to the intake conditions for high exhaust gas recirculation, which results in a low oxygen concentration and a high carbon dioxide concentration.

Performance and Emission Studies on a CI Engine Using Methyl Esters of Palm Oil and Waste Cooking Oil Mixture as Fuel

Palm oil (PO) is considered as one of the promising feed stocks for bio-diesel production due to its low cost and good production output. However, it is in solid form at ambient temperature. Mixing PO with waste-cooking oil (WCO) helps to reduce viscosity of PO significantly. This has the potential to reduce disposal of waste cooking oil. Making esterified fuel from this mixture of PO + WCO can be an effective method of preparing bio-diesel from waste which can be used as fuel in diesel engines. In this work refined palm oil was used as main fuel for preparing the methyl ester. Waste cooking oil was used as an inter esterification agent to reduce overall viscosity and cloud point of the blend and the ester. A single cylinder, direct injection, air cooled diesel engine was tested using neat diesel, neat PO and the methyl ester of the mixture (PO +WCO) as fuels under variable load operating conditions. Results showed increased specific fuel consumption with neat PO and methyl esters of PO+WCO mixture as compared to neat diesel. Specific hydrocarbon and carbon monoxide emissions were significantly reduced with the methyl esters of PO+WCO mixture as compared to neat PO. The specific hydrocarbon emission was found as 2 g/kW.hr. with the methyl esters of the mixture of PO+WCO and 5.2 g/kW.hr with neat PO at the maximum power output. Whereas it was 3.8 g/kW.hr. with neat diesel. The reduction in HC and CO emissions with the methyl esters of the mixture of PO+WCO was due to the better combustion of the ester as compared to neat PO. NO and NOx emissions were found higher with the methyl ester of PO+WCO as compared to neat PO due to increased cycle temperature as a result of improved combustion rate. On the whole it is concluded that methyl esters of the mixture of PO+WCO can be used as fuel in diesel engines without modification in engine design.