AMTEC: High efficiency static conversion for space power

Future manned and unmanned space missions will require reliable, high efficiency energy conversion systems. For a manned Mars mission, power levels in the range of 10 to 100 kWe will be needed. The Alkali Metal Thermoelectric Converter (AMTEC) is a direct energy conversion technology with the potential to meet these needs. The AMTEC is a thermally regenerative electrochemical device that derives its operation from the sodium ion conducting properties of beta-alumina solid electrolyte (BASE). To date, an efficiency of 19%, area power density of 1 W/sq cm, and a lifetime of 10,000 hours at high temperature were demonstrated in laboratory devices. Systems studies show that projected AMTEC systems equal or surpass the performance of other static or dynamic systems in applications of 1 kWe-1 MWe. Thus, the laboratory experiments and applications studies conducted to date have shown that the AMTEC posseses great potential. In order to bring this technology to the stage where prototype units can be built and operated, several technical issues must be addressed. These include the need for long life, high power electrodes, minimization of radiative parasitic losses, and high temperature seals. In summary, the evidence shows that if AMTEC is developed, it can play a significant role in future space power applications

A computer program to process data from a direct current plasma emission spectrometer

This program processes data from a Spectraspan IIB spectrometer retrofitted with a Spectrajet III plasma excitation source (Spectrametrics, Inc ., Andover, MA). The spectrometer is operated manually and can determine only one element at a time. Accordingly, the program treats data for each element individually. Two of the spectrometer's performance characteristics tend to change gradually during normal operation: average blank count and analytical sensitivity. The program compensates for these variations. For the program to process data from the spectrometer, a reagent blank and a high standard (in this order) should be aspirated first; then the high standard and blank (in this order) should be run again after every six or fewer samples . The program, moreover, causes all data to be converted to logarithmic form before being used in computation. This makes possible the calculation of statistically valid confidence limits about predicted analyte concentrations. The program consists of a main section, DCPEOES, and three external sub-routines: BASELINE, SENSITIV, and XLNSQFT. BASELINE compensates for any change in the average blank count, and SENSITIV corrects for any variation in analytical sensitivity. XLNSQFT governs all correlation and prediction functions and has two interchangeable versions: one for first-order; the other for second-order, correlation.Prepared for the United States Department of Energy under Contract DE A102-81EV10694 and for the National Science Foundation under Grant OCE 81-19056

Metal chloride cathode for a battery

A method of fabricating a rechargeable battery is disclosed which includes a positive electrode which contains a chloride of a selected metal when the electrode is in its active state. The improvement comprises fabricating the positive electrode by: providing a porous matrix composed of a metal; providing a solution of the chloride of the selected metal; and impregnating the matrix with the chloride from the solution

Nondestructive testing of bond integrity in foam insulation/aluminum composites

Nondestructive test methods are used for evaluating bond integrity of low-density polyurethane spray-on foam used as cryogenic insulation on aluminum alloy surfaces

Advanced rechargeable sodium batteries with novel cathodes

Various high energy density rechargeable batteries are being considered for future space applications. Of these, the sodium sulfur battery is one of the leading candidates. The primary advantage is the high energy density (760 Wh/kg theoretical). Energy densities in excess of 180 Wh/kg have been realized in practical batteries. More recently, cathodes other than sulfur are being evaluated. Researchers at JPL are evaluating various new cathode materials for use in high energy density sodium batteries for advanced space applications. The approach is to carry out basic electrochemical studies of these materials in a sodium cell configuration in order to understand their fundamental behaviors. Thus far studies have focused on alternate metal chlorides such as CuCl2 and organic cathode materials such as tetracyanoethylene (TCNE)

Investigation of spray dispersion and particulate formation in diesel fuel flames

An experimental study of electrostatical atomized and dispersed diesel fuel jets was conducted at various back pressures to 40 atm. A new electrostatic injection technique was utilized to generate continuous, stable fuel sprays at charge densities of 1.5 to 2.0 C/m3 of fluid at one atm, and about 1.0 C/m3 at 40 atm. Flowrates were varied from 0.5 to 2.5 ml/s and electric potentials to -18 kV. Visual observations showed that significant enhanced dispersion of charged fuel jets occurred at high back pressures compared to aerodynamic breakup and dispersion. The average drop size was about the same as the spray triode orifice diameter, and was between the Kelly theory and the Rayleigh limit. The ignition tests, done only at one atm, indicated stable combustion of the electrostatically dispersed fuel jets

Dish stirling solar receiver combustor test program

The operational and energy transfer characteristics of the Dish Stirling Solar Receiver (DSSR) combustor/heat exchanger system was evaluated. The DSSR is designed to operate with fossil fuel augmentation utilizing a swirl combustor and cross flow heat exchanger consisting of a single row of 4 closely spaced tubes that are curved into a conical shape. The performance of the combustor/heat exchanger system without a Stirling engine was studied over a range of operating conditions and output levels using water as the working fluid. Results show that the combustor may be started under cold conditions, controlled safety, and operated at a constant air/fuel ratio (10 percent excess air) over the required range of firing rates. Furthermore, nondimensional heat transfer coefficients based on total heat transfer are plotted versus Reynolds number and compared with literature data taken for single rows of closely spaced tubes perpendicular to cross flow. The data show enhanced heat transfer for the present geometry and test conditions. Analysis of the results shows that the present system meets specified thermal requirements, thus verifying the feasibility of the DSSR combustor design for final prototype fabrication

University Student Shopping Patterns: Internet vs. Brick And Mortar

In today’s retail environment there are some who enjoy shopping and some who do not.  People have many options when it comes to where they shop; they can shop from home or venture out to the store.  Shopping has never been as fast and convenient as it is today. Technology is more advanced and internet usage is rapidly increasing.  Retailers are realizing internet shopping is a phenomenon that is not going to disappear.  It is a rare retailer who has no web presence.   In order to satisfy customers, managers need to examine how people shop.  College students have their own shopping behavior as this study examines

The accumulation of barium by marine phytoplankton grown in culture

Marine phytoplankton have been implicated as potentially important vectors for the vertical transport of barium in the oceans. To better assess the extent to which phytoplankton can influence the geochemical cycling of barium, its bioconcentration was studied in 21 clones of 19 species of marine phytoplankters belonging to 9 algal classes. Barium levels in the ash ranged from less than 2 μg g–1 for the coccolithophore Emiliania huxleyi and the red alga Porphyridium cruenturn to 589 μg g–1 for the flagellate Tetraselmis levis. Concentrations ≥4000 μg g–1, previously reported for certain samples of diatom ash were not encountered in this study. Concentration factors on a volume basis (VCF) ranged from 0 to 3.2 × 104; the geometric mean VCF for all species was 225. Diatoms and coccolithophores generally had lower VCFs (geometric means of 90 and 12, respectively) than did other species; dinoflagellates had a geometric mean VCF of 490. Experiments with the diatom Thalassiosira pseudonana indicated that Ba cell–1 increased linearly with ambient Ba concentration. Experiments to localize the site of Ba deposition in diatom cells indicated that most of the Ba was associated with the frustules rather than with the organic fraction. Dinoflagellates and several other algae not only concentrated Ba to relatively high levels, but also accumulated Si when grown in Si-enriched medium, although they grew at least as well without added Si as with it. Ba and Si accumulation were generally negatively correlated

Thin metal electrode for AMTEC

An electrode having higher power output is formed of a thin, porous film (less than 1 micrometer) applied to a beta-alumina solid electrolyte (BASE). The electrode includes an open grid, current collector such as a series of thin, parallel, grid lines applied to the thin film and a plurality of cross-members such as loop of metal wire surrounding the BASE tube. The loops are electrically connected by a bus wire. The overall impedance of the electrode considering both the contributions from the bulk BASE and the porous electrode BASE interface is low, about 0.5 OHM/cm.sup.2 and power densities of over 0.3 watt/cm.sup.2 for extended periods