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A requirement for thermophysical property data of diesel fuels at conditions removed from ambient was identified. A series of measurements of the pressure-volume-temperature relations of diesel fuels was undertaken using a Micro-PVT apparatus at pressures to 300MPa in the temperature range 25 to 75°C. A new calibration procedure for this instrument was devised to enable measurements of high accuracy to be made. Viscosity measurements of diesel fuels over a range of temperature and pressure were made using the National Engineering Laboratory high pressure viscometer to pressures of 460MPa in the temperature range 25 to 100°C.Corresponding states theory was applied for compressed liquid density prediction. Improvement in density prediction in this region was found through use of iso-octane and heptadecane as reference fluids. Compressibility factors of these were represented by Tait-style equations. An iterative solution technique was developed to allow the corresponding states method to be applied to diesel fuelsusing limited density measurement and a guess value of boiling point as inputs. Densities predicted from this method agreed well with measurements made using the Micro-PVT apparatus. Hard sphere theory was applied as a method for viscosity prediction. Despite the complexity of the diesel fuel mixture, reasonable estimates of viscosity were made with limited measurement input at higher temperatures. At lower temperatures, an additional simple empirical correction term was required. A method of viscosity estimation of complex hydrocarbon mixtures based upon composition is presented. Further development of this would require additional measurements and greater characterisation of the fuel.

MBA Professional Report / Approved for public release; distribution is unlimited. / The purpose of this MBA project was to complete a cost-benefit analysis of refueling via pipeline versus refueling via barge at Pearl Harbor, Hawaii. The alternatives are (1) refueling via a combination of pipeline and barge (status quo), (2) refueling via a single pipeline, and (3) refueling via barge only. The objective was to compare the three alternatives, choosing that alternative that provides the greater net benefit and most efficient use of resources. The analysis involved data collection of labor costs, pipeline operations (flow rates data, costs of repairs, and operational costs), barge operational costs, and environmental protection costs. This Cost Benefit Analysis (CBA) will be valuable to personnel with approval authority who make decisions on the merits of future pipeline projects. This CBA can be used to evaluate other Navy bases' refueling operations worldwide. / Lieutenant Commander, United States Navy

Thesis (M. Tech. Engineering: Electrical--Vaal University of Technology) / The air-breathing Direct Methanol Fuel Cell (DMFC) and Zinc Air Fuel Cell (ZAFC)were experimentally studied in a climate chamber in order to investigate the impact of climatic environmental parameters such as varying temperature and relative humidity conditions on their performance. The experimental results presented in the form of polarization curves and discharge characteristic curves indicated that these parameters have a significant effect on the performance of these fuel cells. The results showed that temperature levels below 0ºc are not suitable for the operation of these fuel cells. Instead, it was found that air-breathing DMFC is favored by high temperature conditions while both positive and negative effects were noticed for the air-breathing ZAFC. The results of the varying humidity conditions showed a negative impact on the air-breathing DMFC at a lower temperature level but a performance increase was noticed at a higher temperature level. For air-breathing ZAFC, the effect of humidity on the performance was also found to be influence by the operating temperature. Furthermore, common atmospheric air pollutants such as N20, S02, CO and N02 were experimentally investigated on the air-breathing DMFC and ZAFC. At the concentration of 20 ppm, these air contaminants showed to have a negative effect on the performance of both air-breathing DMFC and ZAFC. For both air-breathing DMFC and ZAFC, performance degradations were found to be irreversible. It is therefore evident from this research that the performance of the air-breathing fuel cell will be affected in an application situated in a highly air-polluted area such as Vaal Triangle or Southern Durban. It is recommended the air-breathing fuel cell design include air filters to counter the day-to-day variations in concentration of air pollutants.

Thesis advisor: Udayan Mohanty / Solar fuel synthesis via photoelectrochemistry represents a promising strategy to achieve solar energy conversion and storage. The improvement of photoelectrochemical water splitting performance lies in choosing suitable photoelectrode materials, followed by strategic optimization of their properties. Among those properties, the interface between the semiconductors and electrolyte is of paramount importance, yet it is still not well understood. In my dissertation, I will mainly focus on understanding and controlling those interfaces, with two study platforms. The first study platform is tantalum nitride (Ta3N5), which is an attractive photoanode material with good optoelectronic properties. However, it suffers from low photovoltage despite of the high theoretical expectation and rapid performance decay when it is used for water oxidation. With the help of various characterization methods, it was found that water or hydroxyl group adsorption on the surface as well as the self-limited surface oxidation during water oxidation led to the positive shift of band edge positions and Fermi level, accompanied with increase of charge transfer resistance on the surface. In consequence, decrease of photovoltage and photocurrent was observed. Two different strategies were developed. The first was to fully isolate Ta3N5 from water with the deposition of uniform protection layer through atomic layer deposition. The second strategy utilized the reaction between Ta¬3N5 and co-catalyst instead of water, which led to the formation of a photo-induced interface that favored the desired chemistry instead of side reactions. The second study platform is a Si buried junction protected by GaN. By tuning the loading amount of Pt nanoparticles on GaN surface, both the photocurrent density and photovoltage of the photocathode was improved. With detailed spectroscopic study, it was implied that both charge transfer kinetics and interfacial energetics could be influenced by the loading of Pt on the surface. / Thesis (PhD) — Boston College, 2019. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

"This thesis investigates the effect of temperature, methanol concentration, and oxidant type on the performance of a Direct Methanol Fuel Cell (DMFC) using two versions of a commercially available polybenzimidazole (PBI)-based membrane electrode assembly (MEA): the Celtec®-P 1000 MEA of original thickness and double thickness. The PBI-based MEA’s were tested under the vapor-phase methanol concentrations of 1M, 2M, 3M, 5M, 7.5M, and 10M, temperatures of 160-180°C, and oxidants of oxygen and air. It was found that performance increased with temperature and that oxygen outperformed air as methanol concentrations increased. The double thickness PBI-based MEA, was more resistant to methanol crossover and performed better with increasing methanol concentrations. Thus, these commercial MEAs may be suitable for developing higher temperature DMFCs."

Fuel cell, as an alternative green power source for automobiles and portable electronics, has attracted worldwide attention due to its desirable properties such as high energy density and low greenhouse gas emission. Despite great progress in the past decades, several challenges still remain as obstacles for the large-scale commercialization. Among them, the high cost of Pt-based electrode material is considered as a major barrier, while the life span or stability of electrode catalysts is another concern since the electrocatalysts can be easily poisoned during the fuel cell operation. In order to overcome these issues, nanostructured carbon materials, especially carbon nanotubes (CNTs), are studied as catalyst support. In addition, recent research also suggests that the coupling of a second metal element with Pt can effectively protect the electrocatalysts from being poisoned and thus improve their long-term durability. The objective of the present work was to demonstrate an efficient synthetic method for the preparation of CNTs supported binary PtM (M=Ru, Sn) electrocatalysts. In this project, a polymer wrapping technique along with an in-situ polyol reduction strategy was adopted to decorate well-dispersed binary PtM nanoparticles on the surface of modified-CNTs. The unique nanostructures as well as the excellent catalytic activities of the as-prepared nanohybirds were investigated through a diversity of physiochemical and electrochemical characterization techniques. This fabrication method provided a simple and convenient route to assemble Pt-based catalyst on carbon substrates, which is useful for the further development of high-performance fuel cell catalysts.

Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Ocean Engineering. / Microfiche copy available in Archives and Engineering. / Includes bibliographical references. / M.S.

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