Ftwi Yohaness Hagos

Current Trends in Water-in-Diesel Emulsion as a Fuel

Water-in-diesel emulsion (WiDE) is an alternative fuel for CI engines that can be employed with the existing engine setup with no additional engine retrofitting. It has benefits of simultaneous reduction of both NOx and particulate matters in addition to its impact in the combustion efficiency improvement, although this needs further investigation. This review paper addresses the type of emulsion, the microexplosion phenomenon, emulsion stability and physiochemical improvement, and effect of water content on the combustion and emissions of WiDE fuel. The review also covers the recent experimental methodologies used in the investigation of WiDE for both transport and stationary engine applications. In this review, the fuel injection pump and spray nozzle arrangement has been found to be the most critical components as far as the secondary atomization is concerned and further investigation of the effect of these components in the microexplosion of the emulsion is suggested to be center of focus.

Experimental study on the effect of varying syngas composition on the emissions of dual fuel CI engine operating at various engine speeds

Using syngas as a supplement fuel of diesel in dual fuel mode is a proposed solution in the effort to protect the environment and control the serious threats posed by greenhouse gas emissions from compression ignition engines. The objective of this study was to experimentally examine the effect of syngas composition on the exhaust emission of dual fuel compression ignition (CI) engine at various engine speeds, and to compare the operating ranges of imitated syngas versus pure diesel. The study was conducted using a naturally aspirated, two strokes, single cylinder 3.7 kW diesel engine operated at speeds of 1200, 2000 and 3000 rpm. The engine was tested with three different syngas compositions. Diesel fuel was partially substituted by syngas through the air inlet. The test results disclose the impact of using syngas in CI engines on emission of CO2, NOx, unburned hydrocarbons and carbon monoxide. The experimental measurements confirmed that all syngas compositions are capable of reducing the emissions of CO2 and NOX compared with diesel fuel. Wide range of diesel replacement ratios (up to 72%) was attained without any penalty. Syngas with composition of 49% N2, 12% CO2, 25% CO, 10% H2, and 4% CH4 reduced the emissions of CO2 and NOx at engine speed of 1200 rpm up to 1% and 108 ppm, respectively. The lowest emission of UHC and NOx was emitted when the engine was operating at speed of 2000 rpm and 3000 rpm, respectively with composition of 38% N2, 8% Co2, 29% CO, 19% H2, and 6% CH4. Therefore, syngas could be a promising technique for controlling NOx emissions in CI engines. However, hydrogen content in syngas is important parameter that needs to be further investigation for its effect.

Effect of injection timing on combustion, performance and emissions of lean-burn syngas (H2/CO) in spark-ignition direct-injection engine

This article is aimed at exploring syngas as an alternative fuel for the modern gas engines. It presents the experimental results on the effect of start of injection on combustion, performance and emissions of a direct-injection spark-ignition engine powered by syngas of H2/CO composition. The engine was operated with wide open throttle at minimum advance to achieve maximum brake torque. Two different start of injections were selected to represent before and after inlet valve closing and the excess air ratio (λ) was set at 2.3. The engine operation at start of injection = 120° before top dead center was found to be best for combustion and performance at speed up to 2100 r/min. At engine speed higher than 2100 r/min, this start of injection does not permit maximum performance due to injection duration limitation. Hence, early injection at start of injection = 180° before top dead center was adopted at higher speed with better combustion and performance. Therefore, best performance of syngas in direct-injection spark-ignition engine could be attained by setting start of injection at 120° before top dead center for lower speeds and at 180° before top dead center for speed greater than 2100 r/min. Even though fast combustion of syngas suggested late injection for better combustion, performance and emissions, its lower calorific value resulted in operational limitations for direct-injection system particularly at higher speeds maintaining air–fuel ratio close to the stoichiometry.

Impact of oxygenated additives to diesel-biodiesel blends in the context of performance and emissions characteristics of a CI engine

Butanol is receiving huge interest in the area of alternative fuel in the compression ignition (CI) engines. In this work, butanol is used as an oxygenated additive to diesel and biodiesel blend fuels to evaluate the performance and emission of CI engine. The commercially available pure diesel fuel (D100) and 80% commercially available diesel- biodiesel bled (5% biodiesel and 95% by volume) and 20% butanol (BU20) fuels were investigated to evaluate the effects of the fuel blends on the performance and exhaust emissions of a single cylinder diesel engine. The experiment was conducted at fixed load of 75% with the five engine speeds (from 1200-2400 rpm with an interval of 300 rpm). The engine performance parameters such as power, torque, fuel consumption and thermal efficiency and exhaust gas emissions such as nitrogen oxides, carbon monoxide, and exhaust gas temperature were analysed from the experimental data. The results shows that although butanol addition has caused a slight reduction in power and torque values (11.1% and 3.5%, respectively), the emission values of the engine were improved. With respect to the exhaust gas temperature, CO and NOx emissions, of BU20 is reported to have reduction by 17.7%, 20% and 3%, respectively than the B100. Therefore, butanol can be used as a fuel additive to diesel-biodiesel blends.

Exhaust Emission Reduction of Diesel Engine Fueled with Emulsified Palm Oil Methyl Esters

An emulsion fuels is one of an alternative method that have been used to reduce exhaust emission from diesel engine. However, there were still not properly explored on the emulsified biodiesel. In this work, the effects of water concentration in palm oil diesel emulsions (POD) [POD is palm oil Methyl esters] on exhaust emissions of a 4-cylinder diesel engine were investigated. The engine speed was set at 2500 rpm and loads at 20, 40 and 60 %. Emulsions were prepared using ultrasound method by mixing POD fuel with 5, 10 and 20 % of water by volume. Results of exhaust emissions for POD and their emulsion were compared with OD fuel. The experimental results show that, the increasing water concentration in POD decrease the NOx and PM simultaneously. POD emulsions is a promising alternative fuels for reducing emissions from diesel engines without any engine modifications.

Low and Medium Calorific Value Gasification Gas Combustion in IC Engines

Higher hydrogen to carbon ratio of gasification gases produced from solid fuels has been utilized in internal combustion engines (ICE) since long ago. Advancements in the conversion technologies and the abundant availability of solid fuels added with advancements in the technology of gas engines and their fuelling system have renewed the interest and are believed to be transition fuels from carbon based to hydrogen based. Over the past 30 years, there were many trials to bring back the gasification gas technology in ICE. This study is mainly focused on the investigation of technical challenges with lower and medium calorific value gasification gases in IC engines The range of operation of these fuels is found to be influenced by available injection duration and injector pulse width in direct-injection spark-ignition engines. The lower calorific value of these gases also make them less competitive to CNG and H2 in the dual fueling in CI engine even though they have better advantage in the emissions. Furthermore, red glow color deposit was spotted on the surface of the combustion chamber after short running on all fuels that was resulted from decomposition of iron pentacarbonyl (Fe(CO)5) contaminants.

Tri-fuel (diesel-biodiesel-ethanol) emulsion characterization, stability and the corrosion effect

This paper presents the result of experimenting emulsified tri-fuel in term of stability, physico-chemical properties and corrosion effect on three common metals. The results were interpreted in terms of the impact of five minutes emulsification approach. Tri-fuel emulsions were varied in proportion ratio consist of biodiesel; 0%, 5%, 10%, and ethanol; 5%, 10%, 15%. Fuel characterization includes density, calorific value, flash point, and kinematic viscosity. Flash point of tri-fuel emulsion came with range catalog. Calorific value of tri-fuel emulsion appeared in declining pattern as more ethanol and biodiesel were added. Biodiesel promoted flow resistance while ethanol with opposite effect. 15% ethanol content in tri-fuel emulsion separated faster than 10% ethanol content but ethanol content with 5% yield no phase separation at all. Close cap under static immersion with various ratio of tri-fuel emulsions for over a month, corrosiveness attack was detected via weight loss technique on aluminum, stainless steel and mild steel.

Experimental investigation of the impact of using alcohol- biodiesel-diesel blending fuel on combustion of single cylinder CI engine

The effect of alcohol addition has been experimentally in vestgated in the current study by blending it with diesel and palm based biodiesel on the combustion of a compression ignition engine. The experiment was run by single-cylinder, naturally aspirated, direct injection, four-stroke diesel engine. Based on the pressure-crank angle data collected from the pressure transducer and crank angle encoder, the combustion analysis such as incylinder pressure, incylinder temperature, energy release rate, cumulative energy release and ignition delay are analysed. In this comparative study, the effects of alcohols namely butanol BU20 (20% butanol addition on the commercially available diesel biodiesel emulsion) is compared and evaluated with pure diesel (D100). The results revealed that the the ignition delay for BU20 is longer as compared to that of D100 in all engine speeds and loads compared. Besides, the incylinder temperatures were rudecued with the butanol addition. The energy release rate for BU20 was higher than that for diesel, whereas the peak positions concerning the energy release rate for BU20 was discovered at 2400 rpm. Therefore addition of butanol will have positive role on the NOx emissions and stability of the engine due to its higher latent heat of vaporization.

Early flame development image comparison of low calorific value syngas and CNG in DI SI gas engine

The early flame development stage of syngas and CNG are analysed and compared from the flame images taken over 20° CA from the start of ignition. An imitated syngas with a composition of 19.2% H2, 29.6% CO, 5.3% CH4 and balance with nitrogen and carbon dioxide, which resembles the typical product of wood biomass gasification, was used in the study. A CCD camera triggered externally through the signals from the camshaft and crank angle sensors was used in capturing of the images. The engine was accessed through an endoscope access and a self-illumination inside the chamber. The results of the image analysis are further compared with the mass fraction burn curve of both syngas and CNG analysed from the pressure data. The analysis result of the flame image of syngas validates the double rapid burning stage of the mass fraction burn of syngas analysed from in-cylinder pressure data.