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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,189 records · Page 66

All sources NASA NTRS DOE OSTI

NASA NTRS1985

Practical aspects of photovoltaic technology, applications and cost (revised)

The purpose of this text is to provide the reader with the background, understanding, and computational tools needed to master the practical aspects of photovoltaic (PV) technology, application, and cost. The focus is on stand-alone, silicon solar cell, flat-plate systems in the range of 1 to 25 kWh/day output. Technology topics covered include operation and performance of each of the major system components (e.g., modules, array, battery, regulators, controls, and instrumentation), safety, installation, operation and maintenance, and electrical loads. Application experience and trends are presented. Indices of electrical service performance - reliability, availability, and voltage control - are discussed, and the known service performance of central station electric grid, diesel-generator, and PV stand-alone systems are compared. PV system sizing methods are reviewed and compared, and a procedure for rapid sizing is described and illustrated by the use of several sample cases. The rapid sizing procedure yields an array and battery size that corresponds to a minimum cost system for a given load requirement, insulation condition, and desired level of service performance. PV system capital cost and levelized energy cost are derived as functions of service performance and insulation. Estimates of future trends in PV system costs are made.

Rosenblum, L.↗

NASA NTRS1984

Measured effects of wind turbine generation at the Block Island Power Company

Data measurements made on the NASA MOD-OA 200-kw wind-turbine generator (WTG) installed on a utility grid form the basis for an overall performance analysis. Fuel displacement/-savings, dynamic interactions, and WTG excitation (reactive-power) control effects are studied. Continuous recording of a large number of electrical and mechanical variables on FM magnetic tape permit evaluation and correlation of phenomena over a bandwidth of at least 20 Hz. Because the wind-power penetration reached peaks of 60 percent, the impact of wind fluctuation and wind-turbine/diesel-utility interaction is evaluated in a worst-case scenario. The speed-governor dynamics of the diesel units exhibited an underdamped response, and the utility operation procedures were not altered to optimize overall WTG/utility performance. Primary findings over the data collection period are: a calculated 6.7-percent reduction in fuel consumption while generating 11 percent of the total electrical energy; acceptable system voltage and frequency fluctuations with WTG connected; and applicability of WTG excitation schemes using voltage, power, or VARS as the controlled variable.

Wilreker, V. F.↗

NASA NTRS1985

Effect of accuracy of wind power prediction on power system operator

This research project proposed a modified unit commitment that schedules connection and disconnection of generating units in response to load. A modified generation control is also proposed that controls steam units under automatic generation control, fast responding diesels, gas turbines and hydro units under a feedforward control, and wind turbine array output under a closed loop array control. This modified generation control and unit commitment require prediction of trend wind power variation one hour ahead and the prediction of error in this trend wind power prediction one half hour ahead. An improved meter for predicting trend wind speed variation is developed. Methods for accurately simulating the wind array power from a limited number of wind speed prediction records was developed. Finally, two methods for predicting the error in the trend wind power prediction were developed. This research provides a foundation for testing and evaluating the modified unit commitment and generation control that was developed to maintain operating reliability at a greatly reduced overall production cost for utilities with wind generation capacity.

Schlueter, R. A.↗

NASA NTRS1985

CELCAP: A Computer Model for Cogeneration System Analysis

A description of the CELCAP cogeneration analysis program is presented. A detailed description of the methodology used by the Naval Civil Engineering Laboratory in developing the CELCAP code and the procedures for analyzing cogeneration systems for a given user are given. The four engines modeled in CELCAP are: gas turbine with exhaust heat boiler, diesel engine with waste heat boiler, single automatic-extraction steam turbine, and back-pressure steam turbine. Both the design point and part-load performances are taken into account in the engine models. The load model describes how the hourly electric and steam demand of the user is represented by 24 hourly profiles. The economic model describes how the annual and life-cycle operating costs that include the costs of fuel, purchased electricity, and operation and maintenance of engines and boilers are calculated. The CELCAP code structure and principal functions of the code are described to how the various components of the code are related to each other. Three examples of the application of the CELCAP code are given to illustrate the versatility of the code. The examples shown represent cases of system selection, system modification, and system optimization.

Source record↗

NASA NTRS1985

Future heavy duty trucking engine requirements

Developers of advanced heavy duty diesel engines are engaged in probing the opportunities presented by new materials and techniques. This process is technology driven, but there is neither assurance that the eventual users of the engines so developed will be comfortable with them nor, indeed, that those consumers will continue to exist in either the same form, or numbers as they do today. To ensure maximum payoff of research dollars, the equipment development process must consider user needs. This study defines motor carrier concerns, cost tolerances, and the engine parameters which match the future projected industry needs. The approach taken to do that is to be explained and the results presented. The material to be given comes basically from a survey of motor carrier fleets. It provides indications of the role of heavy duty vehicles in the 1998 period and their desired maintenance and engine performance parameters.

Strawhorn, L. W.↗

NASA NTRS1986

Tribolgy of selected ceramics at temperatures to 900 deg C

Results of fundamental and focused research on the tribological properties of ceramics are discussed. The basic friction and wear characteristics are given for ceramics of interest for use in gas trubine, adiabatic diesel, and Stirling engine applications. The importance of metal oxides in ceramic/metal sliding combinations is illustrated. The formulation and tribological additives are described. Friction and wear date are given for carbide and oxide-based composite coatings for temperatures to at least 900 C.

Sliney, H. E.↗

NASA NTRS1986

Sliding Seal Materials for Adiabatic Engines, Phase 2

An essential task in the development of the heavy-duty adiabatic diesel engine is identification and improvements of reliable, low-friction piston seal materials. In the present study, the sliding friction coefficients and wear rates of promising carbide, oxide, and nitride materials were measured under temperature, environmental, velocity, and loading conditions that are representative of the adiabatic engine environment. In addition, silicon nitride and partially stabilized zirconia disks were ion implanted with TiNi, Ni, Co, and Cr, and subsequently run against carbide pins, with the objective of producing reduced friction via solid lubrication at elevated temperature. In order to provide guidance needed to improve materials for this application, the program stressed fundamental understanding of the mechanisms involved in friction and wear. Electron microscopy was used to elucidate the micromechanisms of wear following wear testing, and Auger electron spectroscopy was used to evaluate interface/environment interactions which seemed to be important in the friction and wear process. Unmodified ceramic sliding couples were characterized at all temperatures by friction coefficients of 0.24 and above. The coefficient at 800 C in an oxidizing environment was reduced to below 0.1, for certain material combinations, by the ion implanation of TiNi or Co. This beneficial effect was found to derive from lubricious Ti, Ni, and Co oxides.

Lankford, J.↗

NASA NTRS1985

Traction forces at solid-lubricated rolling/sliding contacts

A single-element traction rig was used to measure the traction forces at a solid-lubricated contact of a ball against a flat disk at room temperature under combine rolling and sliding. The load and speed conditions were selected to match those anticipated for bearing applications in adiabatic diesel engines. Traction vs slide/roll ratio curves were similar to those for liquid lubricants but the traction forces were an order of magnitude higher. The test data were used to derive equations to predict traction force as a function of contact stress and rolling speed. The data showed that the magnitude of traction forces were almost the same for all the lubricants tested. The lubricants, should, therefore, be selected on the basis of their ability to limit the wear of contact surfaces.

Aggarwal, B. B.↗

NASA NTRS1984

Hydrogen fueled-hydrogen transport rail system - A NASA proposal

The technical possibility of fueling motive power equipment with hydrogen as an alternative to petroleum is studied, and the economics of operating hydrogen-fueled systems are evaluated. Technical considerations include the areas of fuel storage and distribution systems, engine design changes, and a test and evaluation program. A conversion methodology, which conforms to the scheme of high-pressure injection of hydrogen directly into the cylinder late in the compresssion stroke and injection of pilot diesel fuel for ignition, is illustrated with detailed diagrams.

Bain, A. L.↗

NASA NTRS1986

Effect of elevated temperature and pressure on sprays from simplex swirl atomizers

An examination is made of the effects of air temperature and pressure on the spray quality of a moderately high capacity pressure swirl atomizer spraying jet-A and No. 2 diesel fuel. Drop size distributions, in terms of both Sauter mean diameter (SMD) and the width of the distribution given by the Rosin-Rammler N parameter, are determined over a variety of air conditions. Close to the nozzle, limited data suggest that the SMDs were a strong function of air density, but independent of air temperature. Trends of SMD and N are shown as a function of distance from the nozzle at all conditions, indicating some of the evaporation characteristics of fuel sprays.

Dodge, L. G.↗

NASA NTRS1986

Life cycle cost assessment of future low heat rejection engines

The Adiabatic Diesel Engine Component Development (ADECD) represents a project which has the objective to accelerate the development of highway truck engines with advanced technology aimed at reduced fuel consumption. The project comprises three steps, including the synthesis of a number of engine candidate designs, the coupling of each with a number of systems for utilizing exhaust gas energy, and the evaluation of each combination in terms of desirability. Particular attention is given to the employed evaluation method and the development of this method. The objective of Life Cycle Cost (LCC) evaluation in the ADECD program was to select the best from among 42 different low heat rejection engine (LHRE)/exhaust energy recovery system configurations. The LCC model is discussed along with a maintenance cost model, the evaluation strategy, the selection of parameter ranges, and a full factorial analysis.

Petersen, D. R.↗

NASA NTRS1987

Carbide/Fluoride/Silver Self-Lubricating Composite

Bearing coatings survive at operating temperatures up to 870 degrees C. PS200 composite self-lubricating coating for bearing applications operating at temperatures above failure points of traditional solid lubricants. Excellent friction and wear performance in oxidizing atmospheres up to 1,600 degrees F and reducing atmospheres up to 1,400 degrees F. Performance needed for development of advanced heat engines as adiabatic diesel and Stirling engine.

Sliney, Harold E.↗

NASA NTRS1987

Aviation fuel property effects on altitude relight

The major objective of this experimental program was to investigate the effects of fuel property variation on altitude relight characteristics. Four fuels with widely varying volatility properties (JP-4, Jet A, a blend of Jet A and 2040 Solvent, and Diesel 2) were tested in a five-swirl-cup-sector combustor at inlet temperatures and flows representative of windmilling conditions of turbofan engines. The effects of fuel physical properties on atomization were eliminated by using four sets of pressure-atomizing nozzles designed to give the same spray Sauter mean diameter (50 + or - 10 micron) for each fuel at the same design fuel flow. A second series of tests was run with a set of air-blast nozzles. With comparable atomization levels, fuel volatility assumes only a secondary role for first-swirl-cup lightoff and complete blowout. Full propagation first-cup blowout were independent of fuel volatility and depended only on the combustor operating conditions.

Venkataramani, K.↗

NASA NTRS1987

Environmental projects. Volume 2: Underground storage tanks compliance program

Six large parabolic dish antennas are located at the Goldstone Deep Space Communications Complex north of Barstow, California. As a large-scale facility located in a remote, isolated desert region, the GDSCC operations require numerous on-site storage facilities for gasoline, diesel and hydraulic oil. These essential fluids are stored in underground storage tanks (USTs). Because USTs may develop leaks with the resultant seepage of their hazardous contents into the surrounding soil, local, State and Federal authorities have adopted stringent regulations for the testing and maintenance of USTs. Under the supervision of JPL's Office of Telecommunications and Data Acquisition, a year-long program has brought 27 USTs at the Goldstone Complex into compliance with Federal, State of California and County of San Bernadino regulations. Of these 27 USTs, 15 are operating today, 11 have been temporary closed down, and 1 abandoned in place. In 1989, the 15 USTs now operating at the Goldstone DSCC will be replaced either by modern, double-walled USTs equipped with automatic sensors for leak detection, or by above ground storage tanks. The 11 inactivated USTs are to be excavated, removed and disposed of according to regulation.

Kushner, L.↗

NASA NTRS1987

Image analysis of particle field by means of computed tomography

In order to visualize and investigate spray structures, computed tomography technique is applied to analyze droplet information. From the transmitted light intensity through the spray and/or the data of particle size distribution obtained from a Fraunhofer diffraction principle, the quantitative volume of spray droplet or local particle size was calculated and the reconstruction of spray structures was made. The background of computed tomography is described along with some experimental results of the structure of intermittent spray such as diesel spray.

Nakayama, Mitsushige↗

NASA NTRS1986

Tribology of selected ceramics at temperatures to 900 C

Results of fundamental and focused research on the tribological properties of ceramics are discussed. The basic friction and wear characteristics are given for ceramics of interest for use in gas turbine, adiabatic diesel, and Stirling engine applications. The importance of metal oxides in ceramic/metal sliding combinations is illustrated. The formulation and tribological additives are described. Friction and wear data are given for carbide and oxide-based composite coatings for temperatures to at least 900 C.

Sliney, H. E.↗

NASA NTRS1987

Friction and wear behaviour of ion beam modified ceramics

In the present study, the sliding friction coefficients and wear rates of carbide, oxide, and nitride materials for potential use as sliding seals (ring/liner) were measured under temperature, environmental, velocity, and loading conditions representative of a diesel engine. In addition, silicon nitride and partially stabilized zirconia discs were modified by ion mixing with TiNi, nickel, cobalt and chromium, and subsequently run against carbide pins, with the objective of producing reduced friction via solid lubrication at elevated temperature. Unmodified ceramic sliding couples were characterized at all temperatures by friction coefficients of 0.24 and above. However, the coefficient at 800 C in an oxidizing environment was reduced to below 0.1, for certain material combinations, by the ion implantation of TiNi or cobalt. This beneficial effect was found to derive from lubricious titanium, nickel, and cobalt oxides.

Lankford, J.↗

NASA NTRS1987

Characterization of ion beam modified ceramic wear surfaces using Auger electron spectroscopy

An investigation of the surface chemistry and morphology of the wear surfaces of ceramic material surfaces modified by ion beam mixing has been conducted using Auger electron spectroscopy and secondary electron microscopy. Studies have been conducted on ceramic/ceramic friction and wear couples made up of TiC and NiMo-bonded TiC cermet pins run against Si3N4 and partially stabilized zirconia disc surfaces modified by the ion beam mixing of titanium and nickel, as well as ummodified ceramic/ceramic couples in order to determine the types of surface changes leading to the improved friction and wear behavior of the surface modified ceramics in simulated diesel environments. The results of the surface analyses indicate that the formation of a lubricating oxide layer of titanium and nickel, is responsible for the improvement in ceramic friction and wear behavior. The beneficial effect of this oxide layer depends on several factors, including the adherence of the surface modified layer or subsequently formed oxide layer to the disc substrate, the substrate materials, the conditions of ion beam mixing, and the environmental conditions.

Wei, W.↗