Stack Module Research Articles

Fracturing of industrial diamond plates

Indentation hardness and three-point bend tests were performed on perforated synthetic diamond substrates designed for use in a three-dimensional cube computer architecture based on interconnected stacking of multichip modules. The fracture strengths in bending of two substrate materials, with and without laser drilled interconnect “via holes”, were correlated with optical and scanning electron microscope (SEM) observations of the fracture surfaces, thus providing for matching of fracture strengths with different growth microstructures within the plates and, also, with the extent of weakening produced by the via holes. The relatively high strength levels, characteristic of diamond material, were found to be lowered somewhat either by a filamentary pattern of growth fissures in one material or less so by apparent cleavage fracturing among textured grains in a second material. In the latter case, the technique of fracture surface topography analysis (FRASTA) provided evidence of plastic flow having occurred during fracturing.

97/00455 Multi-pathway health risk assessment of power plant water discharges

Since the last paper presented at the Second Grove Fuel Cell Symposium, the Energy Research Corporation (ERC) has established two commercial subsidiaries, become a publically-held firm, expanded its facilities and has moved the direct fuel cell (DFC) technology and systems significantly closer to commercial readiness. The subsidiaries, the Fuel Cell Engineering Corporation (FCE) and Fuel Cell Manufacturing Corporation (FCMC) are perfecting their respective roles in the company's strategy to commercialize its DFC technology. FCE is the prime contractor for the Santa Clara Demonstration and is establishing the needed marketing, sales, engineering, and servicing functions. FCMC in addition to producing the stacks and stack modules for the Santa Clara demonstration plant is now upgrading its production capability and product yields, and retooling for the final stack scale-up for the commercial unit. ERC has built and operated the tallest and largest capacities-to-date carbonate fuel cell stacks as well as numerous short stacks. While most of these units were tested at ERC's Danbury, Connecticut (USA) R&D Center, others have been evaluated at other domestic and overseas facilities using a variety of fuels. ERC has supplied stacks to Elkraft and MTU for tests with natural gas, and RWE in Germany where coal-derived gas were used. Additional stack test activities have been performed by MELCO and Sanyo in Japan. Information from some of these activities is protected by ERC's license arrangements with these firms. However, permission for limited data releases will be requested to provide the Grove Conference with up-to-date results. Arguably the most dramatic demonstration of carbonate fuel cells in the utility-scale, 2 MW power plant demonstration unit, located in the City of Santa Clara, California. Construction of the unit's balance-of-plant (BOP) has been completed and the installed equipment has been operationally checked. Two of the four DFC stack sub-modules, each rated at 500 kW, are on-site and will be installed to the BOP upon completion of the BOP pretests now in the final stages. Full operation and commencement of the formal demonstration is to begin late this year. Now five years old, the Fuel Cell Commercialization Group (FCCG) has grown to include over 30 buyers. The Group's Committees have been actively working with FCE personnel to hone the plant's performance, configuration and cost/benefit trade-offs to assure a market-responsive unit results from the collaboration. A standard contract has been developed for use with the FCCG buyers to streamline the purchase agreement negotiations for the early units. These are essential steps to support a market entry for the 2.8 MW power plant in 1999. The paper details the program's progress and provides additional information on the current demonstration and stack test efforts, with comparisons to earlier test data. Recent accomplishments and planned efforts to affect market entry of the first production units is reviewed as well.

Direct fuel cell power plants: the final steps to commercialization

Since the last paper presented at the Second Grove Fuel Cell Symposium, the Energy Research Corporation (ERC) has established two commercial subsidiaries, become a publically-held firm, expanded its facilities and has moved the direct fuel cell (DFC) technology and systems significantly closer to commercial readiness. The subsidiaries, the Fuel Cell Engineering Corporation (FCE) and Fuel Cell Manufacturing Corporation (FCMC) are perfecting their respective roles in the company's strategy to commercialize its DFC technology. FCE is the prime contractor for the Santa Clara Demonstration and is establishing the needed marketing, sales, engineering, and servicing functions. FCMC in addition to producing the stacks and stack modules for the Santa Clara demonstration plant is now upgrading its production capability and product yields, and retooling for the final stack scale-up for the commercial unit. ERC has built and operated the tallest and largest capacities-to-date carbonate fuel cell stacks as well as numerous short stacks. While most of these units were tested at ERC's Danbury, Connecticut (USA) R&D Center, others have been evaluated at other domestic and overseas facilities using a variety of fuels. ERC has supplied stacks to Elkraft and MTU for tests with natural gas, and RWE in Germany where coal-derived gas were used. Additional stack test activities have been performed by MELCO and Sanyo in Japan. Information from some of these activities is protected by ERC's license arrangements with these firms. However, permission for limited data releases will be requested to provide the Grove Conference with up-to-date results. Arguably the most dramatic demonstration of carbonate fuel cells in the utility-scale, 2 MW power plant demonstration unit, located in the City of Santa Clara, California. Construction of the unit's balance-of-plant (BOP) has been completed and the installed equipment has been operationally checked. Two of the four DFC stack sub-modules, each rated at 500 kW, are on-site and will be installed to the BOP upon completion of the BOP pretests now in the final stages. Full operation and commencement of the formal demonstration is to begin late this year. Now five years old, the Fuel Cell Commercialization Group (FCCG) has grown to include over 30 buyers. The Group's Committees have been actively working with FCE personnel to hone the plant's performance, configuration and cost/benefit trade-offs to assure a market-responsive unit results from the collaboration. A standard contract has been developed for use with the FCCG buyers to streamline the purchase agreement negotiations for the early units. These are essential steps to support a market entry for the 2.8 MW power plant in 1999. The paper details the program's progress and provides additional information on the current demonstration and stack test efforts, with comparisons to earlier test data. Recent accomplishments and planned efforts to affect market entry of the first production units is reviewed as well.

Quantization of Contact Manifolds

We show the existence of the stack of micro-differential modules on an arbitrary contact manifold, although we cannot expect the global existence of the ring of micro-differential operators.

Prediction of Solid Oxide Fuel Cell Power System Performance Through Multi-Level Modeling

This paper presents an integrated multi-level model of a solid oxide fuel cell system, which accounts for the effects of concentration, activation, and ohmic polarizations on single-cell performance, as well as the cell-to-cell interactions in a cell stack module. Furthermore, this model extends the work of Lu and Mahoney (1988) and Harvey and Richter (1994) by including the performance of a cell stack operating with a fuel reformer, heat exchangers, and a steam generator over a range of design parameters. This paper also demonstrates the procedure by which a single-cell model is scaled to a system model.

The H 1 liquid argon calorimeter system

The liquid argon calorimeter of the H 1 detector presently taking data at the HERA ep collider at DESY, Hamburg, is described. The main physics requirements and the most salient design features relevant to this calorimeter are given. The aim to have smooth and hermetic calorimetric coverage over the polar angular range 4° ≤ θ ≤ 154° is achieved by a single liquid argon cryostat containing calorimeter stacks structured in wheels and octants for easy handling. The absorber materials used are lead in the electromagnetic part and stainless steel in the hadronic part. The read-out system is pipelined to reduce the dead time induced by the high trigger rate expected at the HERA collider where consecutive bunches are separated in time by 96 ns. The main elements of the calorimeter, such as the cryostat, with its associated cryogenics, the stack modules, the read-out, calibration and trigger electronics as well as the data acquisition system are described. Performance results from data taken in calibration runs with full size H 1 calorimeter stacks at a CERN test beam, as well as results from data collected with the complete H 1 detector using cosmic rays during the initial phase of ep operations are presented. The observed energy resolutions and linearities are well in agreement with the requirements.

A portable spark-chamber range spectrometer and data acquisition system

A portable spark-chamber range spectrometer and electronic data acquisition system is described for acquiring spectral data on energetic charged particles. The instrument system consists of a uni-directional spark-chamber range telescope with pulse-height analysis of the specific energy loss ( dE dx of a charged particle that passes through a triggering telescope. The range telescope consists of a stack of sealed double-gap spark-discharge modules with absorbers sandwiched between them. A Cherenkov counter discriminates against electrons and muons. Cherenkov and dE dx signals are gated by the coincidence circuit. Data, either telemetered or recorded in situ, include the number of coincidences, a clock signal, system voltage levels, and the dE dx , Cherenkov, and spark-discharge module signals. Power consumption of the self-contained system is about 10 W at an event rate of 20 per second and 17 W at an event rate of 100 per second. The standby power is about 8 W. This instrument system can measure primary protons and alphas at balloon altitudes and secondary protons at lower altitudes. A particular configuration with a geometric factor of about 1 cm 2 sr has been assembled for measuring atmospheric proton intensities and spectra in the range from MeV to 300 MeV and at altitudes ranging from the altitude of high-flying aircraft to balloon altitudes near the top of the atmosphere.

Flat packaged thyristor assembly for high-voltage application

Applications for high-power thyristors continue to increase at an accelerated pace. The circuit designer (user) and device designer (producer) have attained a high degree of maturity in their respective areas of interest and in the joint effort of mating the device to this application for optimum performance. It is the purpose of this paper to describe and analyze recent developments in the device encapsulation design area which are directed to tailoring thyristors for high-power, multikilovolt service. The use of conventional thyristors in an application requiring, e.g., 100 kilovolts holdoff capability, presents a number of problems. The physical layout alone is quite extensive, considering perhaps 100 devices plus balancing networks, anode reactors, firing circuitry, etc. Also, one must properly cool the aggregate of units which may be dissipating on the order of 25 kilowatts. A thyristor encapsulation and stack module specifically designed to fulfill the requirements of high-power multikilovolt applications are described. Compression bonded encapsulation and integral heat sink design principles are employed. Stack modules for forced air cooling and oil cooling applications are reviewed. Particular note is made of a radar modulator application and, more recently, the projected use in high-voltage dc transmission line converter stations. Mechanical and thermal design features are emphasized in the review. Potential application of the devices in conventional bridge-type arrays is explored.

A note on the ductility of beryllium single crystals oriented for basal slip and tested in tension

A portable spark-chamber range spectrometer and electronic data acquisition system is described for acquiring spectral data on energetic charged particles. The instrument system consists of a uni-directional spark-chamber range telescope with pulse-height analysis of the specific energy loss (dEdx of a charged particle that passes through a triggering telescope. The range telescope consists of a stack of sealed double-gap spark-discharge modules with absorbers sandwiched between them. A Cherenkov counter discriminates against electrons and muons. Cherenkov and dEdx signals are gated by the coincidence circuit. Data, either telemetered or recorded in situ, include the number of coincidences, a clock signal, system voltage levels, and the dEdx, Cherenkov, and spark-discharge module signals. Power consumption of the self-contained system is about 10 W at an event rate of 20 per second and 17 W at an event rate of 100 per second. The standby power is about 8 W. This instrument system can measure primary protons and alphas at balloon altitudes and secondary protons at lower altitudes. A particular configuration with a geometric factor of about 1 cm2 sr has been assembled for measuring atmospheric proton intensities and spectra in the range from MeV to 300 MeV and at altitudes ranging from the altitude of high-flying aircraft to balloon altitudes near the top of the atmosphere.