Power Conference Research Articles

Beacon Power demos Smart Power M5

Massachusetts-based Beacon Power Corporation unveiled its newly engineered Smart Power M5 power conversion system at the recent UPEx Solar Electric Power Conference & Technology Exhibition in Scottsdale, Arizona. The company also demonstrated its new Smart Power Monitor PC-based software, which monitors, analyzes and reports on the performance of an M5-based solar power system. Visit www.re-focus.net for the latest renewable energy industry news

E-Junk explosion.

e-Junk explosion.

Thermoeconomic analysis of mixed gas–steam cycles

In this paper the direct thermoeconomic analysis approach developed by the authors [ASME Paper 95-CTP-38; ASME Cogen Turbo Power Conference, Wien, 23/25 August, 1995] is applied to the assessment of the thermoeconomic performance of mixed gas–steam cycles such as the steam injected cycle (steam injected gas turbine, STIG), regenerated water injected (RWI) cycle, and humid air turbine (HAT) or evaporative cycle. All the simulations were carried using the thermo-economic modular program (TEMP) code developed at the University of Genoa [ASME Trans., J. Engng. Gas Turbine Power 119 (1997) 885; Thermo-economic and environmental optimisation of energy systems, Tesi di Dottorato, Università di Genova (DIMSET), 1997] and carefully tested here, mainly for the HAT cycle and saturator, using the experimental data provided by the HAT pilot-plant operating at the Lund University, Sweden [Theoretical and experimental evaluation of the EvGT-process, Thesis for Degree of Licentiate in Engineering, Lund Institute of Technology, Sweden, 1999; Evaporative cycles – in theory and in practice, Doctoral Thesis, Lund Institute of Technology, Sweden, 2000]. Three different mixed cycles (STIG, RWI, and HAT) are analysed in detail together with an additional fourth layout proposed by the authors [Thermoeconomic analysis of STIG, RWI and HAT cycles with carbon dioxide (CO 2) emissions penalty, Tesi di laurea, Università di Genova (DIMSET), 2000], named HAWIT, humid air water injection turbine, that appears to be the most attractive solution. The thermoeconomic results of mixed cycles are presented here for the first time in open literature. These results are compared to the data of a conventional two-pressure level combined cycle considered as representative of the state of the art of high efficiency conversion systems. A new representation proposed by the authors [ASME Trans., J. Engng. Gas Turbine Power 122 (2000)], such as cost of electricity versus cycle efficiency or internal rate of return versus electric efficiency, is used to demonstrate the main features of these types of innovative energy plants.

Trends in plasma conditions inferred from an analysis of x-ray data from high wire-number, Z-pinch load implosions

An analysis of x-ray data from two series of Z-pinch shots taken on the short current-risetime Saturn accelerator at Sandia National Laboratories [Proceedings of 6th International IEEE Pulsed Power Conference, Arlington, VA, edited by P. J. Turchi and B. H. Bernstein (IEEE, New York, 1987), p. 310] is presented. In one series, the array radius was held constant and the array mass was varied; in the other series, the array mass was held constant and its radius varied. In both sets of experiments, large wire-number loads (N⩾93) of aluminum were used in contrast to earlier small wire-number aluminum array experiments on Saturn where N⩽42. Average electron temperatures and ion densities were inferred from the data. In addition, from the measured size of the emission region of K-shell x rays and from the inferred ion density, a fraction of the total array mass that participated in the K-shell emission was inferred and found to be directly correlated to the K-shell yields that were measured. This paper also demonstrates that the yields varied as a function of array mass and radius in much closer agreement with predictions [J. Appl. Phys. 67, 1725 (1990)] than had been observed in the earlier small wire-number experiments. Thus, a serious misperception that the reason for the early disagreement was in the calculations and not in the experiments is corrected. These predictions were made using one-dimensional (1D) magnetohydrodynamics calculations. The density and temperature trends inferred from the data analysis are well-behaved and consistent with the 1D calculations. This data analysis confirms the importance of achieving uniform plasma initial conditions and implosion symmetry when comparing computer code calculations with experiment. When the wire number of an array load is increased, a more uniform shell of plasma is calculated initially as the wires explode and, as the plasma stagnates on axis, the x-ray powers and yields are found experimentally to approach the powers and yields predicted by 1D calculations.

Initial results for an argon Z pinch using a double-shell gas puff

Recent observations are given for an argon double-shell gas puff imploded with up to 4 MA in 200 ns on the Double Eagle generator [G. B. Frazier et al., Digest of Technical Papers, Fourth IEEE Pulsed Power Conference (IEEE, Piscataway, NJ, 1983), p. 583]. Good K-shell x-ray output with good pinch quality was observed. A novel experimental procedure was used to selectively seed the inner or outer gas plenums with a chlorine tracer. The tracer data provide the first direct experimental evidence that the mass initially closest to the axis is the dominant contributor to the hot core of the radiating pinch.

Systematic trends in x-ray emission characteristics of variable-wire-number, fixed-mass, aluminum-array, Z-pinch implosions

Increasing the number of wires an order of magnitude from 10 to almost 200 while simultaneously fixing the total wire mass in annular aluminum-wire-array Z-pinch implosions on the 20 TW Saturn generator [Proceedings of the 6th International IEEE Pulsed Power Conference (Institute of Electrical and Electronics Engineers, Piscataway, NJ, 1987), p. 310] demonstrates two separate power-law trends in the measured x-ray characteristics as a function of the initial interwire gap (g). These trends are approximately independent of the array radius. When g decreases from ∼6 to 0.4 mm, the peak total radiated power increases by a factor of 20 and the total energy by a factor of 2. There is a more rapid increase in peak power and energy radiated as g decreases for gaps greater than ∼2 mm. This increase is related to a measured decrease in precursor plasma and to a calculated decreased sensitivity of the implosion to azimuthal asymmetries that occurs when individual wire plasmas begin to merge following their vaporization. The substantial increase in power arises from an inferred increase in plasma compression and can be correlated with an almost linear reduction in the calculated effective thickness of the plasma annulus near stagnation as g decreases.

「電力・エネルギー部門大会」特集号によせて

「電力・エネルギー部門大会」特集号によせて

「電力・エネルギー部門大会」特集号によせて

「電力・エネルギー部門大会」特集号によせて

Ammonia–water power cycles for direct-fired cogeneration applications

There is a great interest in increasing the efficiency of power generation. In many applications it has been shown that using an ammonia–water mixture as working fluid increases the power output[1–3](1. Kalina, A., in Second Law Analysis—Industrial and Environmental Applications, ASME AES, 1991, 191, 41.; 2. Kalina, A., in Proceedings of the American Power Conference, Vol. 55-I, 55th Annual Meeting, Chicago, 1993, p. 191; 3. Olsson, E., Thorin, E., Deijors, C. and Svedberg, G., Flowers ’94, Florence, Italy, 6–8 July 1994.). The Kalina cycle is the best known power cycle that uses ammonia–water mixtures as working fluid.In Sweden, the new power plants being built are direct-fired biomass-fueled steam turbine cycles. They generate power and produce heat for district heating. The plants are quite small, around 100 MWfuel.The aim of the study reported here was to investigate whether there are any thermodynamic advantages of using ammonia–water mixture cycles in small direct-fired biomass fueled cogeneration plants. The main interest is to achieve a higher net power output. The fuel input rate has been assumed to correspond to 80 MW. The district heating network supply temperatures are 90, 100 and 110°C respectively and the return temperature is 50°C. Different configurations of the ammonia–water mixture cycle were compared to a Rankine steam cycle with a five-pressure turbine and three preheaters. Conventional condensing power applications were also studied.Of the three different supply temperatures to the district heating network, the Rankine steam cycle has the highest net power generation. The ammonia–water cycle approaches the Rankine steam cycle when a high supply temperature is desired. For a cogeneration plant without reheat, the difference in net power generation is between 4 and 11%. With condensing power application, the ammonia–water cycle reaches higher power generation than the Rankine steam cycle.

1997 Rural Electric Power Conference

1997 Rural Electric Power Conference

A new fault location technique for underground distribution circuits using artificial neural network : Glinkowski, M.T.; Wang, N.-C. Proceedings of the American Power Conference, Spons. Illinois Institute of Technology, Vol. 57-1, pp. 716–719 (1995) ISBN 0097-2126

A new fault location technique for underground distribution circuits using artificial neural network : Glinkowski, M.T.; Wang, N.-C. Proceedings of the American Power Conference, Spons. Illinois Institute of Technology, Vol. 57-1, pp. 716–719 (1995) ISBN 0097-2126

The use of artificial neural networks for the estimation and classification of vibration behaviour in power transformers : Booth, C.; McDonald, J.R.; Aresi, R. Proceedings of the American Power Conference, Spons. Illinois Institute of Technology, Vol. 57-II, pp. 1132–1137 (1995)

The use of artificial neural networks for the estimation and classification of vibration behaviour in power transformers : Booth, C.; McDonald, J.R.; Aresi, R. Proceedings of the American Power Conference, Spons. Illinois Institute of Technology, Vol. 57-II, pp. 1132–1137 (1995)

Dynamics of a high-power aluminum-wire array Z-pinch implosion

Annular Al-wire Z-pinch implosions on the Saturn accelerator [D. D. Bloomquist et al., Proceedings, 6th Pulsed Power Conference (Institute of Electrical and Electronics Engineers, New York, 1987), p. 310] that have high azimuthal symmetry exhibit both a strong first and weaker second x-ray burst that correlate with strong and weaker radial compressions, respectively. Measurements suggest that the observed magnetic Rayleigh–Taylor (RT) instability prior to the first compression seeds an m=0 instability observed later. Analyses of axially averaged spectral data imply that, during the first compression, the plasma is composed of a hot core surrounded by a cooler plasma halo. Two-dimensional (2-D) radiation magnetohydrodynamic computer simulations show that a RT instability grows to the classic bubble and spike structure during the course of the implosion. The main radiation pulse begins when the bubble reaches the axis and ends when the spike finishes stagnating on axis and the first compression ends. These simulations agree qualitatively with the measured characteristics of the first x-ray pulse and the overall energetics, and they provide a 2-D view into the plasma hydrodynamics of the implosion.

1996 Rural and Electric Power Conference

1996 Rural and Electric Power Conference

1997 American Power Conference Call for Papers

1997 American Power Conference Call for Papers

Two-dimensional modeling of x-ray output from switched foil implosions on Procyon

A series of two-dimensional radiation magnetohydrodynamic calculations are presented of a Z-pinch implosion using a plasma flow switch. Results from a recent experiment using the high explosive driven generator Procyon, which delivered 16.5 MA to a plasma flow switch and switched about 15 MA into a static load, are used to study the implosion of a 29 mg load foil [J. H. Goforth et al., ‘‘Review of the Procyon Explosive Pulsed Power System,’’ in Ninth IEEE Pulsed Power Conference, June 1993, Albuquerque, edited by K. R. Prestwich and W. L. Baker (Institute of Electrical and Electronics Engineers, Piscataway, NJ, 1993), p. 36]. The interaction of the switch with the load plasma and the effects of background plasma on the total radiation output is examined. Models which assume ideal switching are also included. Also included are the effects of perturbations in the load plasma which may be associated with initial vaporization of the load foil. If the background plasma density in the switch region and in the load region does not affect the dynamics, the pinch is predicted to produce a total radiation output of about 4 MJ. Including perturbations of the load plasma associated with switching and assuming a background plasma density after switching in excess of 10−7 g/cm3 results in a total output from the pinch of about 0.6 MJ.

Magnetohydrodynamic solution for a Z pinch showing the production of a hot spot

Two-dimensional LASNEX [National Technical Information Service Document No. DE 81026329 (Zimmerman, Report No. UCRL-74811, 1973)] calculations are made for a Z pinch on Saturn, the low-impedance, low-inductance electron accelerator at the Sandia National Laboratories [D. D. Bloomquist et al. Proceedings of the Sixth IEEE Pulsed Power Conference, Arlington, VA, edited by P. J. Turchi and B. H. Bernstein (Institute of Electronics and Electrical Engineers, New York, 1987), p. 310]. The experiment is characterized by a current of 6 MA with a tungsten wire load (4 mg) at 2 mm. Two-dimensional calculations show the evolution of the Rayleigh–Taylor instability to the bubble and spike phase, causing high-density islands to form in the pinch opposite the bubbles. The two-dimensional energy flow causes a ‘‘hot spot’’ to evolve, which is shown to agree in its size and brightness with pinhole camera measurements. This is the first explicit calculation of a hot spot in two dimensions employing the full magnetohydrodynamic equations.

Two-dimensional radiation-magnetohydrodynamic simulations of SATURN imploding Z pinches

Z-pinch implosions driven by the SATURN device [D. D. Bloomquist et al., Proceedings of the 6th Institute of Electrical and Electronics Engineers (IEEE) Pulsed Power Conference, Arlington, VA, edited by P. J. Turchi and B. H. Bernstein (IEEE, New York, 1987), p. 310] at Sandia National Laboratory are modeled with a two-dimensional radiation magnetohydrodynamic (MHD) code, showing strong growth of the magneto-Rayleigh–Taylor (MRT) instability. Modeling of the linear and nonlinear development of MRT modes predicts growth of bubble-spike structures that increase the time span of stagnation and the resulting x-ray pulse width. Radiation is important in the pinch dynamics, keeping the sheath relatively cool during the run-in and releasing most of the stagnation energy. The calculations give x-ray pulse widths and magnitudes in reasonable agreement with experiments, but predict a radiating region that is too dense and radially localized at stagnation. We also consider peaked initial density profiles with constant imploding sheath velocity that should reduce MRT instability and improve performance. Krypton simulations show an output x-ray power ≳80 TW for the peaked profile.

Simulation of charged-particle beam transport in a gas using a hybrid particle-fluid plasma model

The simulation of charged-particle beam transport in a ∼1 Torr gas requires accurate plasma-electron modeling. A simple resistive model, which assumes local energy deposition and a thermal plasma-electron distribution, is inadequate. A hybrid model has been implemented into the particle-in-cell simulation code, iprop (The iprop Three-Dimensional Beam Propagation Code, AMRC-R-966, available from D. Welch, Mission Research Corporation, 1720 Randolph Road SE, Albuquerque, NM 87106, September 1987), in which plasma electrons are divided into high-energy macroparticle and thermal-fluid components. This model, which includes ‘‘knock-on’’ bound-electron collision and runaway sources for high-energy electrons, is then used in the simulation of relativistic electron-beam and ion-beam experiments. Results are found to be in agreement with HERMES III [Performance of the HERMES III Gamma Ray Simulator, in Digest of Technical Papers, 7th IEEE Pulsed Power Conference, Monterey, CA, 11 June 1989 (Institute of Electrical and Electronic Engineers, New York, 1989), pp. 26–31] and GAMBLE II [Phys. Rev. Lett. 70, 2573 (1993)] experimental observables.

Very high-current propagation in the ion-focused to collision-dominated regime

Measurements and analysis show that the 13 TW, Hermes-III [J. J. Ramirez et al., Digest of Technical Papers, 6th IEEE Pulsed Power Conference (Institute of Electrical and Electronic Engineers, New York, 1987), p. 294], pulsed, electron beam has two windows of stable transport in long drift cells filled with N2 gas terminated by a bremsstrahlung producing target: a low-pressure window (between ∼1 and ∼100 mTorr) that is dominated by propagation in the semicollisionless ion-focused regime (IFR), and a high-pressure window (between ∼1 and ∼100 Torr) that is dominated by propagation in the resistive collisional regime. In the transition region between the two windows, beam plasma–electron instabilities significantly disrupt propagation. Propagation in both regimes (the IFR at early time and the collisional at later time) is observed from ∼5 to ∼100 mTorr, which produces two distinct bremsstrahlung pulses from the single injected beam pulse. As the pressure increases, two-stream instabilities terminate IFR propagation and the associated bremsstrahlung pulse earlier and earlier in time. Above 5 mTorr, the instability is sufficiently quenched by gas collisions that propagation in the collisional regime back in the beam body occurs, leading to a second propagation and associated bremsstrahlung pulse. Above 200 mTorr, the gas breaks down too rapidly for a significant IFR pulse to form, and for higher pressures only a single pulse in the collisional regime is propagated. Reasonable stability in the collisional regime is not achieved until pressures exceed 1 Torr.