April Covington

Bio: April Covington is an academic researcher from Georgia Southern University. The author has contributed to research in topics: Diesel engine & Diesel fuel. The author has an hindex of 3, co-authored 6 publications receiving 37 citations.

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

Performance of a Direct Injection Diesel Engine Fueled by a Heavy Oil With the Addition of Low Density Polyethylene (LDPE) Polymer

Abstract: Considering the escalating cost of fossil fuels in correlation with the growing influence of sustainability, the need to seek new alternative fuels is increasing rapidly. This movement has lead researchers to look beyond the usual alternative fuels and focus on plastics as an energy resource in the form of a low density polyethylene (LDPE) used throughout the global community. The authors investigated the injection and combustion of a new class of polymer fuel containing 5% LDPE by weight in a heavy fuel oil (AHFO) in a direct injection diesel engine, in order to evaluate its effectiveness for application as a new alternative fuel. The analysis occurred at 1200 rpm, under loads that ranged from BMEP 1.4-6.04 bar. In order to maintain the fuel’s viscosity around 20 cSt the fuel was heated at 130-150 °C. The smoke (bosch) and emission analysis were also performed and provided promising results in terms of engine performance. This suggests that the feedstock of LDPE may be a viable substitute for AHFO for application in a diesel engine with the addressing of the technical challenges associated with the injection system operation.

Recent advances on catalysts for improving hydrocarbon compounds in bio-oil of biomass catalytic pyrolysis

Abstract: This paper reports the progress of catalysts for improving the hydrocarbon compounds in bio-oil obtained from catalytic pyrolysis of biomass. In addition, the effects of the other operating conditions, such as temperature, type of biomass, heating rate, vapors residence time, carrier gas, and hydrogen donor on the yield and properties of bio-oil have been briefly explored. Temperature and catalysts type were found to have major impact on the bio-oil yield and quality. TGA-DTA analysis of biomass revealed that major biomasses pyrolysis zone for high bio-oil yield is in the range of 400–600 °C. Pilot, semi-pilot and large-scale units reported an average temperature of 500 °C for pyrolysis of biomass. The development of advanced catalysts such as zeolite-based catalysts, supported transition and noble metal catalysts, and metal oxide catalysts have been designed to remove the undesired compounds and to increase the hydrocarbon yield in bio-oil. Noble metal supported catalysts produced bio-oil with a low content of oxygenated compounds compared to non-noble metal catalysts; however, their cost and accessibility favor the utilization of non-noble metal supported catalysts.

Tribological Effects of Mineral-Oil Lubricant Contamination with Biofuels: A Pin-on-Disk Tribometry and Wear Study

Abstract: Use of biodiesel produces engine oil dilution because of unburned biodiesel impinging on cold walls of the combustion chamber, being scrapped to the oil pan, and leading to changes of oil friction, wear and lubricity properties. In this paper, mixtures of SAE 15W-40 oil, which were contaminated by known percentages of the biodiesels from canola oil, peanut oil, soybean oil, and chicken fat, were tested in a pin-on-disk tribometer. A contact was employed of AISI 1018 steel disk and AISI 316 stainless-steel ball for pin material, and friction force and specific wear were measured. Wear on the disk surfaces showed that any degree of mineral-oil dilution by the tested biodiesels reduces the wear protection of engine oil even at small mixture percentages. However, these reductions were not substantially different than those observed for same percentages of dilution of mineral oil by fossil diesel. The tested mixture of oil contaminated with animal fat feedstock (e.g., chicken fat) biodiesel showed the best wear behavior as compared to those for the other tested mixtures (of mineral oil with vegetable feedstock biodiesel dilutions). Obtained results are discussed as baseline for further studies in a renewable energy multidisciplinary approach on biofuels and biolubes.