Reactivity controlled compression ignition (RCCI) engine give advantages over conventional diesel engine with the promising engine power and good control on NOx and soot emission. The trend of the RCCI concept is still new and Is very important to control the ignition in order to control the combustion progress and emission. The objective of this study is to provide data on the combustion characteristics and emission of diesel as high reactive, and ethanol as the low reactive fuel in the RCCI engine. The engine speed and injection timing were varied. Simulation work was conducted by using the Converge CFD software based on the Yanmar TF90 diesel engine parameter. Results show that operating the engine at low speed resulting in better engine performance and low carbon emissions due to the sufficient oxygen contents. For the high-speed engine, advancing the injection timing improves the fuel and air reactivity and steeper the equivalence ratio gradient, which result in a complete combustion process.
Biodiesel is a renewable fuel known to produce more environmentally friendly emissions compared to diesel fuel. However, at times it has been reported as exhibiting a much lower engine performance compared to standard diesel fuel. Biodiesel fuel has the potential to achieve similar performance as compared to diesel fuel when the optimum percentage of biodiesel blend is used. In this study, an experiment was conducted to determine the performance and opacity of emissions collected from soybean biodiesel and canola biodiesel fuel by using a YANMAR TF90 single cylinder direct injection diesel engine. The objective of this study is to determine the best percentage of dieselsoybean and diesel-canola fuel mixture that would result in the best performance of an engine. The experiment investigated the brake specific fuel consumption (BSFC), brake thermal efficiency (BTE), brake power (BP), and torque generated by the engine using different biodiesel fuel percentages at varying engine speeds. Additionally, the emission opacity was investigated to identify the most favourable fuel percentage for optimised biodiesel compared to the quality obtained from soybean and canola soybean biodiesel. The results from the experiment clearly show that the engine using biodiesel fuel has a slightly lower performance as compared to the engine that only used diesel fuel for all percentages used. However, at low speeds, a BTE of 40% canola biodiesel was higher compared to diesel and soybean biodiesel. The BSFC for all biodiesel fuel was found to be slightly higher than diesel, except for BC40, which was greater for BSFC compared to other blends used at much lower engine speeds. Engine emission opacity of biodiesel was recorded to be less than diesel fuel at all engine speeds, but slightly higher for BC5, BS5 and BS20 due to the insufficient air intake to the engine. Engine performance and emission opacity of all biodiesel fuels were found to be similar to diesel fuel. From the results relating to engine performance and emission, canola biodiesel was found to be an excellent biodiesel product to be used in a diesel engine since it had a higher BTE, lower BSFC and a lower opacity which was greater than those of soybean biodiesel blends. Therefore, biodiesel can be blended in a diesel engine at a higher percentage while maintaining engine performance and reducing engine emission.
Blending biodiesel in the diesel would increase the tendency of having a high viscosity fuel. For this reason, the addition of a small amount of additives into the blends may improve the engine performance and lead to better fuel consumption. The purpose of this paper is to experimentally investigate the performance and emissions generated by various mixtures of biodiesel and diesel with palm oil based additive in the compression ignition direct injection diesel engine of Yanmar TF90. Experiments were also conducted to identify the ideal biodiesel, diesel and the additive mixture that produces the optimum engine emission and performance. The experiment was conducted by using mixtures that consisted of 10%, 20% and 30% of biodiesel with and without the additives. From the results of the experiments, PB10 with 0.8 ml additives produced the highest braking power and lowest fuel consumption as compared to the diesel and the rest of the biodiesel blends. The presence of biodiesel and additives were found to not only improve the engine performance, but also led to the reduction of carbon emission. Although all the diesel, biodiesel and additive demonstrated low smoke emission with a complete combustion, a slight increase however, was observed in the NOx emission. In conclusion, PB10 is seen as the most ideal blend for diesel engine in terms of providing the most optimum engine emission and performance.
Abstract. Diesel engine is known as the most efficient engine with high efficiency and power but always reported as high fuel emission. Malaysia National Automotive Policy (NAP) was targeting to improve competitive regional focusing on green technology development in reducing the emission of the engine. Therefore, ethanol was introduced to reduce the emission of the engine and while increasing its performance, Palm methyl ester was introduced as blend enhancer to improve engine performance and improve diesel-ethanol blends stability. This paper aimed to study the characteristics of the blends and to prove the ability of palm-methyl-ester as co-solvent in ethanol-diesel blends. Stability and thermophysical test were carried out for different fuel compositions. The stability of dieselethanol blended was proved to be improved with the addition of PME at the longer period and the stability of the blends changed depending on temperature and ethanol content. Density and viscosity of diesel-ethanol-PME blends also give higher result than diesel-ethanol blends and it's proved that PME is able to increase density and viscosity of blends. Besides, heating value of the blends also increases with the increasing PME in diesel-ethanol blends.
The elimination of NOx emissions for hydrogen combustion in the compression ignition (CI) engine is the primary concern, therefore replacing nitrogen with noble gas is one of the solutions to the eliminated the NOx emission. Current research trend focuses on oxygen-argon as the most suitable working. When using argon, external heating for intake is required for low compression ratio (CR) engines. Hence, neon is another potential solution because it has a high specific heat ratio that is as high as other noble gasses with the specific heat capacity, Cp, which is almost identical to nitrogen. This advantage pointed to neon as the best nitrogen replacement option. This paper aims to study neon-oxygen as the working gas for stabilization of the hydrogen ignition with the standard ambient intake condition. In addition, the optimum intake temperature and suitable CR was also determined from the analysis of the combustion properties. A computational analysis was performed using Converge CFD software with specific initial temperature and CR conditions base on Yanmar NF19SK engine. The study showed that the mean initial hydrogen temperature in the neon-oxygen atmosphere was lower than that of oxygen-argon. However, the initial minimum temperature needed for compression ratio 10:1 is 310 K, with a slightly unstable ignition and potential of knock. Hence, the most suitable initial temperature is at 340K. For higher CR, external heating on intake gas is no longer required; hence the engine output was increased. Neon-oxygen is available in CI engine hydrogen combustion at a higher compression ratio with no modification. Analysis of the injection parameters and control of heat loss in the neon-oxygen atmosphere is needed for hydrogen combustion strategies for this type of engine.
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