M. Jaat

CFD Analysis of Circle Grid Fractal Plate Thickness on Turbulent Swirling Flow

In this paper, steady state, incompressible, swirling turbulent flow through circle grid fractal plate has been simulated. The aim of the simulation is to investigate an effect of the circle grid fractal plate thickness in order to reduce swirling due to swirl disturbance in pipe flow. The simulation and analysis were carried out using finite volume CFD solver ANSYS CFX. Three different thickness of fractal plate were used in the simulation work with the thickness of 1 mm, 3 mm and 6 mm. The simulation results were compared with the pressure drop correlation of BS EN ISO 5167-2:2003 and turbulent model used, standard k-ε model gave the best agreement with the ISO pressure drop correlation. The effects of circle grid fractal plate thickness on the flow characteristics which are swirl angle and tangential velocity have been investigated as well.

An Experimental Study on the Performance and Emissions of Diesel Engine Fuelled with Biodiesel Derived from Palm Oil

The use of biodiesel as an alternative fuels in the diesel engine is very effective due to less of emissions and high performance. This study investigated the effect of palm oil blending and engine speed on performance and emission in diesel engine. The performance of biodiesel blends were investigated in terms of brake power, fuel consumption rate, flywheel torque, while emissions parameter was tested in terms of smoke opacity, hydrocarbon (HC), nitrogen oxide (NOx), carbon oxide (CO), carbon dioxide (CO2) and oxygen (O2) at various engine speed 1500, 2000, 2500 and 3000 revolution per minute (rpm). Biodiesel was blended with ordinary diesel fuel in various proportions. The engine was tested up to 50% load conditions by using Ordinary Diesel (OD), B5, B10 and B15 fuels. The properties of biodiesel fuel were tested including density, kinematic viscosity, water content and flash points test. Experimental results indicated that biodiesel blend shows the flywheel torque obtained is higher compared to the OD but fuel consumption rate and the brake power are quite similar when tested at ambient temperature. All biodiesel blends released good emissions compared to the OD. The CO2, CO, HC and O2 content released from the biodiesel fuels were clearly lower than the normal fuel except for NOX contents. Biodiesel released higher smoke opacity compared to OD at all range of engine speeds under 50% load condition. In conclusion, biodiesel fuels are found to offer better performances and emissions and are suitable to be used in unmodified diesel engine.

Effects of Biodiesel Derived by Waste Cooking Oil on Fuel Consumption and Performance of Diesel Engine

Biodiesel is the alternate fuel which is derived from renewable sources either is vegetable oils or animal fats. For that reason, the vehicle run by Bio-diesel Fuel (BDF) has been a potential option and the alternative sources of fuel are receiving a lot attention in the automotive industry. The use waste cooking oil (WCO) biodiesel as an alternative fuel in engines has advantages from both economic and the emissions of carbon monoxide (CO) and hydrocarbons (HC) in the exhaust gas. Purpose of this study is to investigate the effects of waste cooking oil blended fuel, engine speed and test load conditions on the fuel properties, combustion characteristics and engine performance. The engine speed was varied from 1500 to 3000 rpm, load test condition varied by dynapack chassis dynamometer in 0, 50 and 100% and blends of 5(WCO5), 10(WCO10) and 15vol%(WCO15) waste cooking oil with the diesel fuel. The results showed that the use of WCO as biodiesel results in a higher fuel consumption rate, especially at low engine speed and full load condition.

Dynamic Behavior of Rapeseed Oil Spray in Diesel Engine

Fuel-air mixing is important process in diesel combustion which significantly affects the combustion and emission of diesel engine. Due to the nature of biomass fuel that has high viscosity and high distillation temperature, the condition and furthermore the improvement of atomization process is very important. This study investigates the atomization characteristics and droplet dynamic behaviors of diesel engine spray fueled by rapeseed oil (RO). Optical observation of RO spray was carried out using shadowgraph photography technique. Single nanospark photography technique was used to study the characteristics of the rapeseed oil spray while dual nanospark shadowgraph technique was used to study the spray droplet behavior. Using in-house image processing algorithm, the images were processed and the boundary condition of RO spray also was studied. The results show that RO has very poor atomization due to the high viscosity nature of the fuel. This is in agreement with the results from spray droplet dynamic behavior studies that shows due to the high viscosity, the droplets are large in size and travel downward, with very little influence of entrainment effect due to its large kinematic energy.

Study on Spray Characteristics of Biodiesel using a Rapid Compression Machine

Diesel engine is an internal combustion engine that uses the high compression pressure to ignite the combustible mixture due to high temperature in the combustion chamber. There were many studies on the fuel-air premixing that resulting from air entrainment which linked to the improvement of exhaust emissions [1][2][3]. The most important issue in diesel combustion is achieving sufficient rapid mixing between the injected fuel and the air in cylinder prior to ignition. The oxidation reactions at the end of endothermic period depend on the physical process such as air entrainment, the breakup of the jet spray, and droplets evaporation.

Optical Technique Using Nano-Spark Lightsource for Macro and Microscale Image Acquisition to Study Diesel Spray Atomization

Atomization and fuel-air mixing is an important process in diesel combustion. It directly affects the combustion and emission of diesel engine. Optical technique has the advantage of being unobtrusive in nature when compared to other technique. nanospark unit that has spark duration of 30ns was used as a lightsource to capture high resolution spray image using still film camera. The very short duration of the spark freeze the fast movement of the spray droplet, and sharp image of fuel droplet to be successfully captured by the camera, and then analyzed for sizing and spatial distribution. In addition, by using a more elaborate optical setup, dual image of the same spray can be captured, with a very short time interval between each of them. This provides the means to study dynamic behaviors of the diesel spray and also the droplets, as the progression of the spray and trajectory and velocity of the droplet can be analyze from these images. With the proposed optical technique and optical arrangement, microscopic detail of the diesel engine spray can be captured. Critical data such as droplet sizing can be extracted from this high resolution image. Furthermore, by introducing a more sophisticated optical arrangement coined dual-nano spark photography method, the droplet dynamic behaviors such as flying angle and velocity can be study.

Modeling of Common Rail System and Constant Volume Chamber in Biodiesel Combustion: A Review

Among the challenges faced by diesel engines combustion nowadays are to reduce emission especially Nitrogen Oxide (NOx) and Particular Matter (PM) while enhancing fuel efficiency and power. The purpose of this review is to explore the mixture formation of biodiesel combustion using constant volume chamber and optical visualization. This paper will review the development of a single-shot combustion system and constant volume chamber. An overview of the relation of mixture formation and combustion process in diesel combustion is provided first. This review has shown that the application of Rapid compression Machine (RCM) is used to simulate actual condition especially the injection pressure and air motion. The review also found that the mixing between fuel and air is unavoidable and very important during ignition delay period thus predominantly influences the exhaust emission. The detailed behaviour of injection characteristic that strongly effects the mixture formation especially the spray evaporation and spray interference are discussed.Keywords: Rapid Compression Machine; Ignition Delay; Nozzle; Injection System; Air Motion; Ambient

Effects of Ambient Temperature Condition on Biodiesel Properties Derived from Palm Oil

Crude palm oil (CPO) is currently the most preferable feedstock to be converting into biodiesel via transesterification process in this region. Though the commercial projections for biodiesel have grown, there remains some concerns with respect to its resistance to degradation during storage that possibly will compromise the fuel quality. The purpose of this study is to investigate the influences of ambient temperature condition on properties of biodiesel characteristics and emission. The biodiesel samples were stored and monitored in glass container at the temperature 6°C, 25°C and 30°C, and blending of biodiesel was varied from 5vol% (B5) - 45vol% (B45). The changes of density, kinematic viscosity, flash point, water content, acid value, and as well as emission of CO2 and CO were observed. The result show storage under ambient temperatures properties of CPO biodiesel were found to have higher value compare to the other temperature storage and also have significant effect on the CO emission.

Influences of Cylinder Wall Temperature on Heat Release during Compression Period

Compression period in a diesel engine is generally seen as initial characteristics before injection into combustion chamber. A free-piston type rapid compression machine (RCM) has been designed simulate the combustion phenomena in order to observe the chemical and physical kinetics studies at elevated pressures and temperatures. Purpose of this study is to clarify the effects of wall cylinder temperature on air heat release, especially during compression period. This method can a light piston is pneumatically shot and gets hammered in stopper at compression end. Measurements were made on a light piston compress in a rapid compression machine (RCM) with intended to simulate the actual compression period related phenomena. During this phenomena, the ambient temperature influences from the cylinder wall temperature has appear beneficial for the biodiesel fuel premixing and achieving best mixture preparation There are three tests will used to investigate the effects of the variant temperature of wall cylinder during compression period. Results show high temperature on cylinder wall will be effects decrease during temperature drop after compression stroke. The new characteristics rapid compression machine (RCM) is to develop and analyse before combustion process.

Effects of Biodiesel on Performance and Emissions Characteristics in Diesel Engine

Biodiesel is the alternate fuel which is derived from renewable sources either is vegetable oils or animal fats. Biodiesel is non-toxic, have higher biodegradability, free of sulphur, no aromatics and its oxygen content of about 10-11% which is usually not contained in diesel fuel. These characteristics thus predominantly influences to the emissions of carbon monoxide (CO) and hydrocarbons (HC) in the exhaust gas. Purpose of this study is to investigate the effects of oil palm blended fuel, engine speed and test load conditions on the fuel properties, combustion process, combustion characteristics, exhaust emissions and engine performance. The engine speed was varied from 1500 to 3000 rpm, load test condition varied by dynapack chassis dynamometer in 0% ,50% and 100% and blends of 5 (B5), 10 (B10) and 15 vol% (B15) palm oil with the diesel fuel. Increased of blends ratio can improve the combustion process and give less HC and CO emission and almost nearly engine performance. However, this condition tends to produce high NOx production due to higher oxygenated fuel in biodiesel content.