Applied Mechanics and Materials Vols. 592-594

Abstract: Fuel injection pressures in diesel engines play an important role to distribute the fuel jet quickly and to form a uniform gas mixture after fuel injection in order to reduce fuel consumption and emissions. In this study, an attempt has been made to study the effect of injection pressure on a single cylinder direct injection diesel engine fueled with diesel, diesel – bael biodiesel blend (B20) and methyl ester of bael (Aegle marmelos) seed oil with injection pressures of 220,230,240 and 250 bar. Increasing the injector opening pressure has been found to increase brake thermal efficiency and reduce CO, HC and smoke emissions significantly. The optimum injection pressure was found to be 240 bar for bael seed biodiesel.

Abstract: Diesel plays a very important role in rapid depletion of conventional energy sources along with increasing demand and also major contributors of air pollutants. Diesel is used in the present days for engines and the invention of an alternative or a blend to the conventional diesel seems very essential to the energy crisis. Major portion of today's energy demand in India is with fossil fuels. Hence it is high time that alternate fuels for engines should be derived from indigenous sources. As India is an agricultural country, there is a wide scope for the production of corn oil from the germ of corn (maize). In this experiment, an attempt has been made to investigate four types of fuels are considered 100% Diesel, 90% Diesel+10% Corn oil Methyl Ester, 80% Diesel+20% Corn oil Methyl Ester, 70% Diesel+30% Corn oil Methyl Ester and 60% Diesel+40% Corn oil Methyl Ester. The various performance parameters like, brake thermal efficiency, Mechanical efficiency and brake specific fuel consumption were measured and analyzed. In the experiment it found the biodiesel blends gives comparable performance to diesel.

Abstract: Jatropha bio diesel blended with mineral diesel in proportion 2:1 by volume is used to conduct performance test and emission characteristics of a single cylinder direct injection diesel engine. Jatropha-diesel blend is used to perform engine performance and emission tests at variable loads & throttle settings (25%, 50%, 75% and 100%). Observed data were utilized to obtain various performance parameters such as brake power, brake specific fuel consumption, brake thermal efficiency at various loads and throttle settings. Simultaneously observations were also made to obtain exhaust gas temperatures and exhaust emissions (CO, CO₂, HC and NO_x). In existing engine diesel provides higher and economic power generating capacity for entire operating ranges but effect of varying load /throttle on performance behavior were fantastically similar. Reduced HC and NOx emission with the blend also better, highlights some positive aspects of combustion and allowance for higher compression ratio with the blend.

Abstract: The geometrical and flow parameters are governing the performance of the Proton Exchange Membrane Fuel Cell (PEMFC). The flow channels are used for distributing the reactants uniformly throughout the active area of fuel cell. Among different flow field designs, the serpentine flow field can give better performance to the PEM fuel cell. This paper numerically investigates the effects of the serpentine flow field with different number of passes. The 2 pass, 3 pass and 4 pass serpentine flow field designs of same rib size and channel size were modelled and analyzed using commercially available software package. From the polarization curves and performance curves drawn using the numerical results, the performance of three flow channel designs were compared and the maximum power densities of each design were found

Abstract: An extensive measurement using 2-D Particle Image Velocimetry (PIV) technique has been carried out during natural convection with a heating sources protruded on the non-heated lower surface of a rectangular enclosure. A time-resolved data series have been captured to analyse the effect of different Rayleigh number on flow fields for fluid of Prandtl number 0.71. A fast and efficient data analysis tool based on the Proper Orthogonal Decomposition (POD) technique has been used to create low dimensional approximations of high dimensional systems for predicting the dominant flow structures. This includes interpolating results at off-design parameters, along with knowledge about contours of different higher modes as well as obtaining information about the energy content in each specific mode. The mean non fluctuating mode showed maximum energy and the same decreased with increasing mode number. This allowed a clear detailed understanding about the complex non-linearities in the problem using a linear decomposition technique

Abstract: Soot, NO_x paradox in compression ignition engines is an extremely challenging issue. Low temperature combustion followed by Homogeneous charge compression ignition (HCCI) type of combustion is capable of reducing nitrogen oxides and soot simultaneously. Homogeneous charge compression ignition (HCCI) has a potential for high fuel conversion efficiency and extremely low emissions of particulate matter and oxides of nitrogen (NO_x). However, feasibility of HCCI is also posing certain issues .In this paper, three zone extended coherent flame combustion model of STAR-CD package has been used to study the CI engine in both conventional and HCCI mode. A comparison of important parameters like in-cylinder pressure, temperatures, CO, NO_x emissions, in conventional and HCCI mode are predicted. Relatively Low in-cylinder pressures and temperatures are realized in HCCI mode when compared to conventional mode of combustion. Uniform mixing of fuel-air, turbulent kinetic energy and velocity contours are obtained in HCCI mode. Key Words: HCCI, ECFM-3Z, Phi-T charts, Piston Work, Turbulent Kinetic energy.

Abstract: This article considers a radiative transport problem coupled with conduction in the one dimensional slab in the presence of participating media. The finite volume method of computation is presented to discretize the radiative transfer equation over the control volume and by using the error function, conduction term is being computed. In the mathematical derivation the RTE is integrated with respect to control volume and control angles with the freedom in choosing number of angular nodes. The results reveals that the proposed method is a promising alternative to the well-established practices like the discrete ordinates method (DOM), discrete transfer method (DTM), monte-carlo method and many more.

Abstract: Increased demand and production in all segments of the automotive industry has driven the nation to impose stringent emission norms for automobile engines. At this juncture, bio-diesel has sufficient attraction as vehicular fuel. But the properties of bio-diesels are not the same as diesel fuels, including high viscosity and low volatility. Due to this inherent problem it exhibits poor atomization, which results in incomplete combustion and increased exhaust emissions. This naturally implies that automotive designers have to focus their research more on engine emissions while at the same time not compromising on power development. This has put enormous pressure on automotive industry to design the engine efficiently and economically to compete with the global market. This paper relates the modification of engine combustion chamber design, for inducing turbulence to improve the combustibility of combustible mixture of karanja bio-diesel and to reduce the exhaust emissions. The modification includes the tri-chambered piston and twisting blade pistons. In the present work the emission characteristics of modified piston engine are compared with the standard piston engine. It was observed that the CO and UBHC emissions can be effectively reduced with tri-chambered piston engine.

Abstract: Mining industry in India currently occupies a coveted position in the world league table. Large scale mechanization has made major breakthroughs in this industry. Mechanization trends have introduced sophisticated off-road dumpers as the main ore/rock transporting equipment in opencast mines. To achieve targeted production and to survive intense competition in the mining industry, it is imperative that the dumper as an equipment and its different operating units should be reliable and maintained effectively to ensure its maximum availability. The diesel engine is the most critical operating unit of a dumper. To improve the performance and to reduce frequency of downtime, the engines need overhauling time to time. The engine after overhauling should be able to perform its desired function under stated condition for a specified period of time. The present study investigates reliability of overhauled engines in a fleet of dumpers used in an opencast mine. In this paper the operational reliability of overhauled engines, mean time to overhaul (MTO) and time between inspection (TBI) are examined. MTO and TBI values predicts the next time to overhaul and inspection respectively, which will aid in reducing the downtime of dumpers and thereby increasing their availability.

Abstract: Use of latent heat storage system using Phase Change Materials (PCM) is an effective way of storing thermal energy and has several advantages like high storage density, isothermal nature of the energy storage etc. Solar cooking is one of the solutions to overcome increasing demand of fossil fuels in country like India. However it suffers from problems like low solar intensity, fluctuations during cloudy environment, limited availability (only during few hours of the day), and fluctuations with time. Use of latent heat storage system in solar cooking, can overcome some of the problems listed above. In this paper, efforts were made to gather the information on previous works on solar cooking system using PCM, use of Phase Change Materials (PCMs) for evening / night cooking and conceptual design of solar cooker using PCM. This review will be important for further research in this field. Heat storage system enables cooking food during cloudy sky or in the evening. Hence, solar cooker with PCM storage will increase the utility and reliability of the solar cookers. As the source temperature raises, the chemical bonds within the PCM breaks which changes phase from solid to liquid. The phase change is a heat-seeking (endothermic) process and therefore, the PCM absorbs heat on melting. Upon storing heat in the storage material, the material begins to melt when the phase change temperature is reached. The temperature then stays constant until the melting process is completed. The solar energy stored during day time can be used directly for cooking or can be stored in PCM and used during night/evening time.