Jeffery Lewis

Bio: Jeffery Lewis is an academic researcher from Georgia Southern University. The author has contributed to research in topics: Diesel fuel & Diesel engine. The author has an hindex of 3, co-authored 4 publications receiving 55 citations.

Experimental and Numerical Investigations on Drag and Torque Characteristics of Three-Bladed Savonius Wind Turbine

Abstract: With the growing demand of energy worldwide, conventional energy is becoming more and more scarce and expensive. The United States is already facing an energy crunch as the fuel price soars. Therefore, there is an obvious need for alternative sources of energy—perhaps more than ever. Wind is among the most popular and fastest-growing forms of electricity generation in the world, which is pollution free and available almost at any time of the day, especially in the coastal regions. The main attraction of the vertical-axis wind turbine is its manufacturing simplicity compared to that of the horizontal-axis wind turbine. Among all different vertical axis wind turbines, Savonius wind turbine is the simplest one. Operation of the Savonius wind turbine is based on the difference of the drag force on its semi-spherical blades, depending on whether the wind is striking the convex or the concave part of the blades. The advantage of this type of wind turbine is its good self-starting and wind directional independence characteristic. It, however, has a relatively lower efficiency in comparison with the lift type vertical-axis wind turbines. Due to its simple design and low construction cost, Savonius rotors are primarily used for water pumping and wind power on a small scale. The main objective of this ongoing research work is to improve the aerodynamic performance of vertical axis Savonius wind turbine. Wind tunnel investigation has been performed on aerodynamic characteristics, such as drag coefficients, and static torque coefficient of three-bladed Savonius rotor model. Also the computational fluid dynamics (CFD) simulation has been performed using FLUENT software to analyze the static rotor aerodynamics such as drag coefficients and torque coefficient, and these results are compared with the corresponding experimental results for verification.Copyright © 2009 by ASME

JP-8 Combustion Characteristics in a Small Diesel Auxiliary Power Unit

Abstract: The US Army Single Fuel Forward policy mandates that deployed vehicles must be operable with aviation fuel JP-8. Therefore, an investigation into the influence of JP-8 on a diesel engine’s performance is currently in progress. The injection, combustion, and performance of JP-8, 20–50% by weight in diesel no.2 mixtures (J20-J50) produced at room temperature were investigated in a 77mm indirect injection, high compression ratio (23.5) diesel engine, in order to evaluate its effectiveness for application in Auxiliary Power Units (APUs) at 2000rpm continuous operation (100% load/BMEP 4.78 bar). Due to the viscosity requirements for proper injection the new fuel can contain as high as 100% JP-8 (J100). The blends had an ignition delay of 1.03ms regardless of the amount of JP-8 introduced. J50 and diesel no.2 exhibited similar characteristics of heat release, the premixed phase being combined with the diffusion combustion. The maximum combustion pressure remained relatively constant for all blends, 72.7bar for diesel and decreased slightly by 0.40bar for J50, with the peak pressure position being delayed by 0.5CAD for the J50. The instantaneous volume-averaged gas combustion temperature reached 2162K for diesel versus 2173K for J50; displaying a 1.2CAD delay in the position of the maximum temperature and retaining the higher temperature for a longer duration for J50. The heat flux in the engine cylinder exhibited comparable maximum values for all blends (diesel: 2.12MW/m2 , J50: 2.14MW/m2 ). The cylinder heat losses were at a minimum during combustion before TDC with increased convection losses at TDC for all fuels and the beginning of the power stroke. The heat losses associated with the system increased slightly with the addition of JP-8. The BSFC for diesel no.2 was 242(g/kW/hr) and increasing by only 0.7% for J50. The engine’s mechanical efficiency displayed similar values for all blends, 83% and decreasing by only 1% for J50. Taking into account each fuels’ corresponding density, the engine’s overall efficiency remained relatively constant at 29% with the addition of the JP-8. The engine investigation demonstrated that up to 50% JP-8 by weight in diesel can be injected and burnt in a small diesel engine with a combustion duration of approximately 5ms, while maintaining the engine overall efficiency. The study validates JP-8 as an excellent source for power generation in a diesel APU based on its combustion characteristics. The next stage of research shall be the full emissions investigation.Copyright © 2011 by ASME

The Influence of Peanut Fatty Acid Methyl Ester Blends on Combustion in an Indirect Injection Diesel Engine

Abstract: The project investigates the effects of peanut FAME on diesel engine combustion and thermal efficiency. The cold flow properties and viscosity were tested and were found that the cloud point (CP) and pour point (PP) of peanut FAME were 17°C and 8°C respectively, and was able to achieve CP of 0°C when blended 20:80 (wt%) with diesel No. 2 (P20). The dynamic viscosity of peanut FAME was 4.2cP (P100) and 2.85cP at 54°C (P20), both fuels are within the ASTM standard for biodiesel. The lower heating value (LHV) of peanut FAME was 37.10MJ/kg (P100) and 41.3MJ/kg (P20) compared to 41.7MJ/kg for diesel No.2 (D100), which supports the usage of peanut FAME in compression ignition engines. At residence time of 5ms from start of injection, P50 has shown positive combustion characteristics with ignition delay of 1.072ms at 2600rpm, 4.78 bmep (100% load). The P50 heat release displayed similar development compared with diesel No. 2, where premixed phase combined with diffusion combustion and reaching a maximum of 20.0J/CAD, which was higher than 17.5J/CAD for D100. Convection flux for both D100 and P50 had values of 1.4MW/m2 . The total heat flux, calculated by Annand model, produced maximum values of 2.1MW/m2 for D100 compared with 2.3MW/m2 for the P50. The mechanical efficiency was only a 4% loss when observing the transition from D100 to P50. These findings support peanut FAME as a viable option when blended and used with diesel engines in order to meet the standards set forth by the RSF-2 and EISA allowing the U.S. to decrease foreign energy dependency and benefiting society through a cleaner burning fuel than is currently in use.Copyright © 2011 by ASME

Review of propulsion systems on LNG carriers

Abstract: Vessel ozone depleting emission regulations are regulated in Annex VI of the MARPOL Convention, wherein the maximum levels of NOx, SOx and suspended particles are established These increasingly strict regulations, together with the increase in natural gas consumption and its price, have conditioned propulsion systems implemented on board vessels This article reviews the different propulsion systems used on board vessels for the transport of Liquefied Natural Gas (LNG) The study describes the main characteristics of the propulsion systems, and the advantages and drawbacks that come along with these, from its very beginnings up to the systems installed to date The described propulsion systems include both gas and steam turbines, combined cycles, 2 and 4 stroke internal combustion engines, as well as reliquefaction plants, while encompassing mechanical, electric and Dual Fuel (DF) technology systems The propulsion systems implemented have undergone continual alteration in order to adjust to market needs, which were always governed by both efficiency and the possibility of consuming boil-off gas (BOG), always in compliance with the strict antipollution regulations in force The current direction of LNG vessel propulsion systems is the installation of 2-stroke DF low pressure engines due to their high efficiency and their possibility of installing a BOG reliquefaction plant Another great advantage of this propulsion system is its compliance with the IMO TIER III emission regulations, without the need to install any supplementary gas treatment system