Fuel cell powered aircraft have been of long term interest to the aviation community because of their potential for improved performance and environmental compatibility. Only recently have improvements in the technological readiness of fuel cell powerplants enabled the first aviation applications of fuel cell technology. Based on the results of conceptual design studies and a few technology demonstration projects, there has emerged a widespread understanding of the importance of fuel cell powerplants for near-term and future aviation applications. Despite this, many aspects of the performance, design and construction of robust and optimized fuel cell powered aircraft have not been fully explored. This goal of this research then is to develop an improved understanding of the performance, design characteristics, design tradeoffs and viability of fuel cell powerplants for aviation applications. To accomplish these goals, new modeling, design, and experimental tools are developed, validated and applied to the design of fuel cell powered unmanned aerial vehicles. First, a general sub-system model of fuel cell powerplant performance, mass and geometry is derived from experimental and theoretical investigations of a fuel cell powerplant that is developed in hardware. These validated fuel cell subsystem models are then incorporated into a computer-based, application-integrated, parametric, and optimizeable design environment that allows for the concurrent design of the aircraft and fuel cell powerplant. These tools and methods are then applied to the analysis and design of fuel cell powered aircraft in a series of case studies and design experiments. Based on the results of the integrated fuel cell system and aircraft analyses, we gain a new understanding of the interaction between powerplant and application for fuel cell aircraft. Specifically, the system-level design criteria of fuel cell powerplants for aircraft can be derived. Optimal sub-system configurations of the fuel cell powerplant specific to the aircraft application are determined. Finally, optimal energy management strategies and flight paths for fuel cell and battery hybridized fuel cell aircraft are derived. The results of a series of design studies are validated using hardware in the loop testing of fuel cell propulsion systems and field testing of a series of fuel cell powered demonstrator aircraft.

The disturbing current situation regarding the world climate has initiated a major wave of urgent developments towards decreasing the overall impact of human activities on the living environment. A major role player in this development is the automobile industry that is inherently connected to pollution of various types, be it air, water or noise pollution. There have been drastic changes not only in the technologies employed in producing vehicles and components, but also in the construction and technologies built into modern automobiles to lessen the overall environmental impact of the industry. Noxious emissions have been decreased, overall efficiencies increased and vehicles are becoming more economical with each new generation. Stricter laws dictate that the level of acceptable vehicle emissions is to be decreased ever further and all manufacturers are developing various possibilities to achieve this. With the emergence of hybrid vehicle technology, there was also a sudden development of different electrical systems that were made viable by the higher onboard voltage systems employed in hybrid vehicles. One of these developments was the electrical air conditioning compressor for use in automobile applications. Although it is designed to operate with a higher voltage than the traditional 12V onboard vehicle systems, it is theoretically possible to incorporate it into a 12V system by making use of a DC-DC converter to step up the supply voltage of the electrical compressor sufficiently to allow for its successful operation. The question therefore arises whether it would be feasible and sensible to employ an electrical air conditioning system in conventional combustion engine vehicles from an overall fuel consumption and vehicle emissions point of view. A modelling approach was taken where an overall vehicle driving simulation was created to represent an average modern production vehicle. The simulation was then extended to include the options of incorporating models for both mechanically and electrically driven air conditioning systems. This provides insight into the influences of the air conditioning system on the vehicle’s overall fuel consumption and an opportunity to compare the influences from the two different systems. This study attempted to provide answers to some of the viability questions regarding the incorporation of electrically driven air conditioning systems into vehicles that use standard 12V onboard voltage systems. It was found that the electrical system has definite potential as a viable replacement option for the conventional system should it be combined with an appropriate alternator and equipped with an efficient control system.

No description available.

Using the Debye-Huckle approximation, the effects of Coulomb interactions on the equilibrium, frozen, and nonequilibrium flow of an ionized gas have been investigated. The gas is assumed to be monatomic, electrically neutral, and thermal equilibrium (i.e., a one temperature fluid); but the composition of the gas is arbitrary, that is, multiple ionization of any degree is allowed. The thermodynamic variables are derived starting from the appropriate expression for the Helmholtz free energy. Using Boltzmann statistics and assuming that the velocity distribution functions are given by their Maxwellian values, the rate of ionization is derived for atom-atom, atom-ion, and atom-electron collisions. The resulting expressions are then employed in solving the quasi-one-dimensional flow in a converging-diverging nozzle for the equilibrium, frozen, and nonequilibrium cases. Numerical examples, using argon as the working substance, are discussed and the results presented graphically. The results of these calculations indicate that, for single ionization, the effect of Coulomb interactions on the performance of rocket engines is negligible; but that data obtained from hypersonic arc jet wind-tunnels can be significantly influenced by the presence of the interactions. / Ph. D.

A high compression type engine operates far more satisfactorily on gasoline than on kerosene. Frequent oil changes are necessary when kerosene is used. When burning gasoline the engine operated on fuel-air mixtures varying from 1 - 17.5 to 1 - 7.48 by weight. The most economical ratio was 1 - 15.2, with the intake air at 135° F. The most powerful mixture was a ratio of 1 - 12.3*, and intake air at 86.2° F. Kerosene mixtures varied. from 1 - 7.41 to 1 - 16.75. Greatest economy was secured on a mixture of 1 - 15.62, air intake at 134° F. The most power was developed from kerosene on a mixture of 1 - 13.3*, and an air temperature of 80° F. The efficiency of the engine on the most powerful mixtures was 19.75% for gasoline at 23.05 H.P.,and 25.7% for kerosene at 22.85 H.P. The engine developed as much power from a pound of kerosene as from a pound of gasoline. Gasoline and kerosene require practically the same external conditions for optimum operation. Kerosene does not deposit a great deal more carbon than gasoline. Heat added to the intake air gives greater engine economy, but at the same time decreases its capacity. 135° F. gave the most economy in both fuels. Hot air and lean mixtures makes the engine knock on gasoline. The engine knocked with kerosene at all heats on practically all mixtures. Speed above 1350 R.P.M.,and low water temperatures *Average of three mixtures used on power curve. minimize the “pinging” The outlet water must be kept above 180° F when burning kerosene. Oil “stands up” better while burning gasoline. Nine gallons of kerosene produce power equivalent to that produced by ten gallons of gasoline. / M.S.

The analysis and redesign of a centrifugal impeller for a rocket pump is presented in this thesis. A baseline impeller was designed by Rocketdyne for the NASA Marshall Pump Consortium. Initially, the objective was to reduce the circumferential exit flow distortion of the baseline impeller. Later in the study, the objective became raising the head coefficient of the impeller. The study presented in this thesis was also undertaken to demonstrate current CFD capabilities for impeller design. A literature review includes an overview of centrifugal impeller geometries and configurations. Centrifugal impeller performance and secondary flows are discussed, and a summary of studies on the effects of impeller exit and diffuser inlet velocity distortion on diffuser performance is also presented. The flow calculation details and the results of the baseline impeller flow calculations are described. Fourteen redesigned impeller geometries were analyzed using the Moore Elliptic Flow Program, and the results were compared to the baseline geometry in terms of head rise, losses, and exit flow distortions. A final geometry was chosen; this geometry will be built and tested by Rocketdyne. The results show that backward blade lean can be effective in red using the exit flow distortion of the impeller. Tip slots or holes were not beneficial because of the large inlet boundary layer. Also, it appears possible to raise the head coefficient of the baseline impeller without creating excessive flow distortion. The planned testing is necessary to verify the predictions of the flow code. / Master of Science

No / Since the beginning of time, energy has pervaded our earth. We rely on it to advance in any development. As the energy sources become scarcer, it is important to learn how to save and economize energy. A perfect energy should be cheap and efficient. Bi-Fuel system is such a concept, which combines the best of Diesel and Gas driven engines. Diesel driven engines though provide high power density but own the drawback of high cost and high on-site fuel storage. Gas driven engines provide low cost but own the drawback of low power density. A Bi-Fuel system is Compression ignited engine, which runs on the simultaneous combustion of Diesel and Natural gas. It works by introducing gas to the engine via various technologies and then electronically controlling flow dependent on output. This greatly extends the runtimes and limits the amount of diesel fuel that must be stored on site.

Thesis (MScEng (Process Engineering))--Stellenbosch University, 2008. / This report covers the development of a biofuels engine testing facility at Stellenbosch University. The motivation for the project was three fold: a) a desire to establish biofuels and engine testing know-how; b) to test the performance characteristics of biodiesel; and c) make a facility available for future research. The two main conclusions drawn from the initial test results are: 1) the test cell is fully operational and 2) biodiesel can be substituted for mineral diesel. To the author’s knowledge this is the first biofuel specific engine testing facility in South Africa. After a literature study the test cell was realised in three phases. • Firstly, the hardware layout was designed and the necessary equipment was sourced from respectable suppliers including the judicious use of good qaulity second hand components to minimize capital cost. • The test cell was then instrumented with new sensors. Key components among these are the K-type thermocouples, barometric pressure, humidity, oil pressure and an Allen-Bradley programmable controller to serve as a data acquisition card. Two software programs were chosen, ETA for the control of the test cell and RSLogix to program the programmable logic controller (PLC). • The complete system was then integrated, debugged and validated. The design methods and procedures have been documented throughout the project along with user manuals to facilitate further research. To determine the difference in combustion parameters between biodiesel and mineral diesel an autonomous power curve test was conducted. This revealed little difference in terms of performance between the two fuels, although biodiesel had on average a marginal 0.4% decrease in power over mineral diesel. The fuel consumption for pure biodiesel was found to be higher, which is as expected as it is has a lower calorific value than mineral diesel. As a final validation, an energy balance was conducted. Here the calculated calorific value of biodiesel was compared to the results from a calorie bomb test, and the two results were found to be within 2% of each of other. / Centre for Renewable and Sustainable Energy Studies

The present dissertation covers three research topics on catalytic environmental emissions control, including (1) aging and regeneration mechanisms of Rh- and Pd- model three-way catalysts (TWC) for gasoline automotive emission control, (2) catalytic methane emissions abatement from natural gas vehicles, and (3) scale-up of CO₂ capture and methanation using dual functional catalytic materials. The study resulted in two peer-reviewed publications, two future papers and one patent application which is currently under review. Modern TWC use supported two separate catalyst layers on a monolith containing one Pd and the other Rh for the emissions control of CO, HC and NOₓ. The rhodium (Rh) metallic component (active for NOₓ reduction) experiences the most severe oxidative thermal deactivation (forming inactive Rh³⁺) during fuel cutoff, an engine mode (e.g., at downhill coasting) used for enhancing fuel economy. In a subsequent switch to a slightly fuel rich condition, in situ catalyst regeneration is accomplished by the reduction of the Rh³⁺ with H₂ generated through steam reforming catalyzed by residual Rh⁰ sites. The present thesis reports the effects of the deactivation and regeneration processes on the activity, stability and structural properties of 0.5% Rh/Al₂O₃ and 0.5% Rh/Ce_xO_y-ZrO₂ (CZO) as model catalysts. Both materials are used to varying extents in modern TWC. A very brief introduction of three-way catalysis and system considerations will be presented. During simulated fuel cutoff, catalyst deactivation is accelerated with increasing aging temperature from 800 °C to 1050 °C. Rh on a CZO support experiences less deactivation and faster regeneration than Rh on Al₂O₃. Catalyst characterization techniques including BET surface area, CO chemisorption, temperature programmed reduction, and x-ray photoelectron spectroscopy, transmission electron microscopy, scanning-electron microscopy, and x-ray diffraction measurements were applied to examine the role of metal-support interactions in each catalyst system. For Rh/Al₂O₃, strong metal-support interactions leading to the formation of a stable rhodium aluminate (Rh(AlO₂)_y) complex dominates during fuel cutoff, resulting in more difficult catalyst regeneration (reduction). For Rh/CZO, Rh sites were partially oxidized to Rh₂O₃ and were relatively easy to be reduced to active Rh⁰ during regeneration. Moderate Pd and support sintering of Pd-Ce_xO_y is experienced upon aging, but with a minimal effect on the catalyst activity. Cooling in air, following aging, was not able to reverse the metallic Pd sintering by re-dispersing to PdO. Unlike the aged Rh-TWCs, reduction via in situ steam reforming (SR) of exhaust HCs was not effective in reversing the deactivation of aged Pd/Al₂O₃, but did show a slight recovery of the Pd activity when CZO was the carrier. The Pd⁺/Pd⁰ and Ce³⁺/Ce⁴⁺ couples in Pd/CZO are reported to promote the catalytic SR by improving the redox efficiency during the regeneration, while no such promoting effect was observed for Pd/Al₂O₃. A suggestion is made for improving the catalyst performance. The use of natural gas for vehicle applications is growing in popularity due to advanced fracking technology. Exhaust methane has been excluded from regulations since it does not participate in photochemical reactions. New vehicle environmental regulations are expected for controlling methane emissions given their contribution to the greenhouse gas effects. Methane is extremely resistant to oxidation when the natural gas-fueled engine operates in the stoichiometric mode with a supported Rh-Pd three-way catalyst (TWC). Furthermore, vehicles will still operate with fuel cutoff (for enhanced fuel economy), resulting in thermal oxidative deactivation (1050 °C) of the Rh metal in TWC to inactive Rh³⁺, resulting in a loss of both NOₓ and methane abatement activity. When the engine returns to the slightly rich mode, H₂ generated by methane steam reforming does not readily occur to reduce and regenerate the Rh. We report a solution to methane emissions abatement by catalytic reforming of an injected aqueous solution of ethanol into the simulated exhaust stream in TWC mode, which generates sufficient H₂ to regenerate especially Rh by reducing Rh³⁺ to its metallic active state. Conventional CO₂ capture and sequestration (CCS) in aqueous alkaline solutions is a very energy-intensive process with relative unstable performance and low efficiency especially for power plant effluents, and therefore there is a need for new approaches to control green house gas emissions of CO₂. Here we report on progress with an advanced technology involving CO₂ adsorption from flue gas and synthetic natural gas production, via methanation, both performed at the same temperature with the addition of renewable H₂ and by using a dual functional material (DFM). The stored H₂ used is produced by water electrolysis during those times when solar, wind, and other alternative energies generate excess power out of phase with the direct use of the electricity. The DFM is composed of nano-dispersed CaO (or Na₂CO₃) and Ru metal supported on γAl₂O₃ carrier, respectively functioning as the CO₂ adsorbent and methanation catalyst. The present paper focuses on a laboratory scale-up study by using a simulated flue gas and 5%Ru,10%CaO/Al₂O₃ and 5% Ru,10%Na₂CO₃/Al₂O₃ DFM samples. The effects of DFM preparation methods, Al₂O₃ carrier materials (with different shapes and properties), and adsorption and methanation conditions (feed compositions, flow rates, reaction temperatures) on the DFM performance were examined. Samples were prepared using chloride precursor salts and showed stable performance under pseudo scale-up conditions, with SASOL TH100 Al₂O₃ (with the highest BET surface area and pore volume/radius among the support materials) exhibiting the best performance. Compared to Ru-CaO, Ru-Na₂CO₃ based DFM materials showed improved CO₂ utilization and methanation production. Reaction conditions were explored to find optimized CO₂ adsorption and methanation.

Thesis (Elec.E)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Wing Hong Lee. / Elec.E