Abstract. The stricter on emission legislation and growing demands for lower fuel consumption require significant efforts to improve combustion efficiency while satisfying the demand of emission quality. Gasoline blend with ethanol provided advantages due to its self-sustaining concept and high octane number which can be influenced to the combustion process. The purpose of this study is to investigate the effect on the emission and flame propagation of gasoline under the different blending ratio of ethanol fuel in a constant volume chamber. In this paper, the flame propagation of ethanol blends with gasoline in a constant volume chamber has been carried out. The real image is observed by schlieren optical visualization technique and image processing technique. The parameters in this study also included different types of injection pressure, characteristics of flame propagation and different blending ratio of ethanol in gasoline fuels. As a result, the burn rate increases when the content of ethanol percentage in gasoline increased. Therefore, the higher flame propagation area for 0.2 MPa, 0.3 MPa, 0.4 MPa were headed by E15 followed by E10, E5 and gasoline fuels respectively. It is subjected that the increasing of ethanol percentage blends with gasoline could lead to the reduction of CO, HC and NOX emissions. However, the CO2 emission is higher due to the combustion process was enhanced.
Schlieren optical visualization technique system is the unique technique due to the ability in producing a neutral image easily-interpretable image of refractive-index-gradient areas. The Schlieren system provides a method for viewing the flow through the transparent media and the most using this technique is to photograph the flow. This paper presents the review of the application of the Schlieren optical visualization system external and internal combustion engine in order to observe the fuel-air mixing and flame development during the burning process. The basic technique of Schlieren system, especially for Z-type and two mirror Schlieren system provide a powerful and clearly image to visualize the changes of the density in a transparent medium. This method can capture spray evaporation, spray interference and mixture formation clearly with real images. Analysis of optical image visualization observations reveals that the mixture formation of fuel and air exhibits the influence of the ignition and flame development. Thus, the observation of systematic control of the creation of a mixture of experimental apparatus allows us to achieve significant progress in the combustion process and will present the information to understanding the basic terms of reduced fuel consumption and exhaust emissions. IntroductionThe first Schlieren system was invented by Robert Hook in the 17th century and Schlieren technique developed in the 19th century by Toepler [1]. The Schlieren technique is an optical technique that detects density gradients occurring in a fluid flow in its simplest from light a slit is collimated by a lens and focused onto a knife-edge by a second lens, the flow pattern is placed between these two lenses and the diffraction pattern that results on a screen or photographic film placed behind the knife-edge is observed. The schlieren technique is often used to investigate heat and mass transfer process in gases and liquid [1][2][3]. Referable to the three dimensionality of the investigated processes, it's virtually inconceivable to get quantitative result about the density gradient from the schlieren image [1,2].The primary reasons why Schlieren technique difficult to produce quantitative results because when the geometry is known or simple like sphere, cylinder or other it is possible to calculate the density gradient. Thither are many types of Schlieren technique, setup, but all the setup are based using the same principle [3][4][5][6].
The use of energy and natural resources being increase due to the growth of economy and world population. One of the natural resources is being consumed heavily is diesel for transportation and burner combustion. However, the major product results from the combustions of diesel are NOx and PM emissions. This review paper focuses on the influences of the emulsified renewable biodiesel fuel such as crude palm oil and waste cooking oil with the concept fuel-air-water internally rapid mixing injector for the open burner system. Water is introduced directly into the combustion field. The concept of rapid mixing from biodiesel and water are controlling of the combustion process in order to minimize the emissions. The water content in the emulsified biodiesel fuels effectively in the reduction of NOx emissions especially the high blending biodiesel. Moreover, emulsion technology significantly reduced particulate matter (PM) emissions as compared to the standard biodiesel fuel combustion. The parameters include equivalent ratio, water content in biodiesel-water, and spray characteristics such as spray penetration, spray angle and spray area. IntroductionAs the environment pollution and diminishing supply of fossil fuels are the key factors the search of alternative sources of energy. Biodiesel now is the best choice for consumers and can occupy a great volume of the world's fuel sector. Biodiesel, as an alternative fuel of diesel, is described as fatty acid methyl or ethyl esters from vegetable oils or animal fats. It is renewable, biodegradable and oxygenated. Many researches had been concluded that biodiesel can reduce greenhouse gas emission [1]. In addition, the properties of biodiesel are similar to diesel fuels, but variation in fuel viscosity of biodiesel will cause poor atomization of the diesel engine as well as causing the clogging of the injector [6][7][8]. Some method had been used to decrease the viscosity of biodiesel like preheating the biodiesel and blending with lighter fuels such as diesel [13][14][15][16][17][18]. The researchers had studied that the performance of internal combustion engine fuel with preheated biodiesel like palm oil and the result is better because produce a better combustion and less deposits [2].
The trade-off between NO x and PM is a main issue in the observation of combustion characteristics, NO x and PM are released from the combustion of biodiesel either in internal combustion engine or external burner system. Thus, the rapid mixing of biodiesel-water-air technique is one of the most significant approaches to the reduction of pollutant emissions from burner combustion. In this research, the relation between the mixture formation of biodiesel spray and the burning process was investigated in detail in order to understand the effects of the changes of fuel properties in fuel evaporation. In these experiments, different types of biodiesel fuel derived from the crude palm oil and waste cooking oil were used in the same nozzle characteristics of burner system. This study focuses on the observation of the real images of the spray characteristics together with equivalent ratio, water content, spray penetration length, spray angle and spray area. Water emulsion of percentage up to 15vol% and blending of biodiesel ratio was varied from 5vol%-15vol%. The diesel fuel has been compared with based analyzed of real spray images with the times change. The results show the percentage of biodiesel and shows the higher of water content due to the higher viscosity affects the higher penetration length and lower spray angle and influence the flame penetration. IntroductionIn the near future, the growth of economic and population have driven the use of energy and natural resources. However, natural resources such as fossil fuel, gasoline, coal and natural gas will exhaust toxic emissions when there are used as a fuel in the burner combustion. Diesel as one of the natural resources is being consumed heavily in the world demand. Diesel can be used in many applications such as automotive and burner system. These fuels will exhaust toxic emissions such as NOx, CO and particulate matters (PM) which causes environment problem[1], [8]. Therefore, in order to improve these emissions, a study in spray characteristic and formation is necessary before the combustion process started. The simplest method to control the emission is by adding water in diesel, which is diesel-water emulsion process [3][4][5]. It enhanced the air fuel mixing during the diffusion combustion phase, which allows combustion at lower global air fuel ratio while maintaining PM constant [10]. In addition, the water involves in the mixtures can reduce the flame temperature at the core region of the flame, hence the reduction of high temperature area will decrease the formation of NO x [1], [3], [8].
The prospects of fossil oil resources and strengthen of future emission regulation have raised keen attention together with the issue of renewable alternative fuel. As one of the different solutions to these problems, emulsion fuel technology in biodiesel has received close attention because it may provide better combustion efficiency and would contribute to a reduction in emissions, such as nitrogen oxides (NO x ) or particulate matter (PM).The solution of this issue is by using Biodiesel fuel as an alternative fuel from waste cooking oil (WCO), crude palm oil (CPO) and Jatropha Oil (JPO). In addition, Waste cooking oil is one of the most economical options for producing biodiesel due to the biodegradable properties and preserves energy. This study focuses on the observation of ignition and combustion characteristics of biodiesel-water-air rapid mixing of biodegradable fuel using internally rapid mixing injector in burner combustion. In this research, the relation of mixture formation, burning process and flame development of biodiesel were investigated in detail. The parameters include equivalent ratio, water content and mixture formation are studied. The flame development is analyzed in term of flame longest for testing. The result shows that equivalent ratio and water content affect the combustion. Increasingly of water content will reduce the flame length and increase the probability of misfire.
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