Foam Absorber Research Articles

Analysis of the conditions of experiments on the compression of capsules with a foam absorber at Iskra V facility

The compression conditions are analyzed and the capsules are discussed for the energy of ∼2 kJ and pulse duration of ∼0.5 ns at the second harmonic of an iodine laser (λ = 0.66 μm) under irradiation by a small number of beams at Iskra V facility (the facility has 12 beams, which are focused in a certain way onto the capsule). The authors consider different capsules filled with DT gas: the glass capsules (the inner radius is 260 μm; the thickness, 1.2-1.3 μm; the aspect ratio A = 200) experimentally examined with Iskra V; the capsules made of polystyrene (R = 140-170 μm; δ = 5-10 μm; A = 14-34), and the capsules made of polystyrene and covered by a foam absorber (R = 140-170 μm; δ = 5-10 μm; A = 14-34, foam absorber δ = 150 μm) - ‘Laser Greenhouse’ [4].

Improvements on calibration measurements with a Martin–Puplett interferometer

We describe a simple and efficient improvement to the Martin–Puplett interferometer, built at the Max-Planck Institute for Radioastronomy in Bonn. Interferograms with its corresponding spectra taken with the interferometer operating in the vacuum mode, have confirmed that the detector’s signal increases up to ∼10% when the microwave foam absorbers used as radiation sources are replaced by blackbody cavities.

Diffraction of sound by a poroelastic cylindrical absorber near an impedance plane

Acoustic scattering from an infinitely long fluid-saturated porous elastic circular cylinder located near a planar boundary with locally varying surface impedance is studied. The formulation utilizes the novel features of Biot dynamic theory of poroelasticity, the appropriate wave field expansions, the classical method of images and the translational addition theorem for cylindrical wave functions along with a simple local surface reaction model involving a complex amplitude wave reflection coefficient applied to develop a closed-form solution in the form of infinite series. The analytical results are illustrated with a numerical example in which a cylindrical plastic foam absorber is located near a layer of foam material set on an impervious rigid wall. The numerical results reveal the important effects of incident wave frequency, angle of incidence, interface local surface reaction, cylinder poroelasticity and position on the acoustic field quantities. The proposed model can lead to a better understanding of acoustic scattering from two-dimensional near-interface porous absorbers or targets which are commonly encountered problems in outdoor acoustics, noise control engineering, and ocean engineering. The presented solution could eventually be used to validate those found by numerical approximation techniques.

Ru ∕ Ni - Mg - O Catalyzed SiC-Foam Absorber for Solar Reforming Receiver-Reactor

High-temperature solar reforming of methane with CO2 is investigated using a directly solar-irradiated absorber subjected to a solar mean flux level above 400kWm−2 (the peak flux of about 700kWm−2). The new type of catalytically activated ceramic foam absorber—a Ru∕Ni-Mg-O catalyzed SiC-foam absorber—was prepared, and its activity was tested in a laboratory-scale volumetric receiver-reactor with a transparent (quartz) window by using a sun-simulator. Compared to conventional Rh∕Al2O3 catalyzed SiC-foam absorber, this new catalytic absorber is more cost effective and is found to exhibit a superior reaction performance at the high solar flux or at high temperatures, especially above 950°C. This new absorber will be applied in solar receiver-reactor systems for converting concentrated high solar fluxes to chemical fuels via endothermic natural-gas reforming at high temperatures.

An investigation of Columbia College Chicago reverberation chamber

The Audio Arts and Acoustics department at Columbia College in Chicago acquired a new building in 2003. The facility, a former bank, contained an old steel and concrete vault that was converted to a reverberation chamber. The acoustic properties of the space, including reverberation time, modal density, and early reflection maps were analyzed and compared to a computer model. Reflectograms were predicted at various locations and compared to test data acquired with Time Delay Spectrometry (TDS). Polar Energy Time (PET) techniques were also used to identify the location of a single 4×4 sample of foam absorber and the results of the test were compared to the predicted value from the computer model. The results of the tests show that, under its current configuration, the room is usable as a reverberation chamber down to 300 Hz, and that the computer model was able to accurately predict the results from the PET methodology.

4-11.触媒担持発泡受光体によるメタンのソーラー改質((3)太陽水素,Session 4 新エネルギー)

4-11.触媒担持発泡受光体によるメタンのソーラー改質((3)太陽水素,Session 4 新エネルギー)

Solar Methane Reforming Using a New Type of Catalytically-Activated Metallic Foam Absorber

The solar reforming of methane with CO2 is investigated using a direct irradiated absorber subjected to solar flux levels in the range 180-250 kWm−2. This solar thermochemical process can upgrade the calorific value of the methane feed by 17% to produce hydrogen via the water-gas shift reaction. The volumetric receiver-reactor is best suited for this application because of its compactness and low thermal capacity. The new type of catalytically-activated “metallic foam” absorber–an Ni-Cr-Al-foam absorber applied with Ru/Al2O3–was found to have a superior thermal performance at relatively low solar fluxes when compared to conventional ceramic foam absorbers.

Ni−Mg−O Catalyst Driven by Direct Light Irradiation for Catalytically-Activated Foam Absorber in a Solar Reforming Receiver-Reactor

A nickel−magnesia solid solution Ni−Mg−O was examined as a catalyst for solar CO2 reforming of methane. The activity was tested in a laboratory-scale transparent (quartz) reactor under direct irradiation of the catalyst by high-flux visible light from a sun-simulator. The 8−11 wt % Ni−Mg−O catalyst gave the high reforming activity or about 100% of chemical conversion, with little coking, under a high-flux irradiation of 890 kW m-2 and at a short residence time of about 0.15 s while passing a 1:1 CH4−CO2 gas mixture at 1 atm. The comparison of the activity data with those obtained in a light-irradiated, nontransparent (steel) reactor showed that the intensification of heat supply by the direct light irradiation of the Ni−Mg−O catalyst leads to considerable reaction rate enhancement. Applying this Ni−Mg−O catalyst, a new type of “catalytically activated” ceramic (alumina) foam absorber was prepared and tested on activity in a laboratory-scale volumetric receiver-reactor using the sun-simulator. This new absorber may be applied in solar receiver-reactor systems for converting concentrated solar high fluxes to chemical fuels via endothermic natural-gas reforming.

Catalytically Activated Metal Foam Absorber for Light-to-Chemical Energy Conversion via Solar Reforming of Methane

CO2 reforming of methane was examined under direct irradiation of the catalytically activated metal foam absorber by solar-simulated, concentrated visible light in the small receiver−reactor system with a transparent window. Rh, Ru, or Ni was applied as the active metal on the alumina-coated or noncoated Ni−Cr−Al metal foam disk for the preparation of the absorber. Rh showed the best activity on the noncoated metal foam while Ru was the best on the alumina-coated one. The most active and stable Ru/Al2O3/Ni−Cr−Al-foam absorber yielded a maximum methane conversion of 73% at a GHSV of 8500 h-1 and at ambient pressure, in which about 50% of the incident light energy reaching the absorber was stored as chemical enthalpy at a relatively low value of the average input-power density of radiation, ρ = 180 kW m-2 (the peak flux density of 274 kW m-2 at the center of the irradiated surface of the absorber). This catalytically activate metal foam absorber will be used in the receiver−reactor system for solar methane ...

Miscellaneous data on materials for millimetre and submillimetre optics

Several parameters of various materials, including solid and foam dielectrics, absorbers, and metals, are collected for use in optical design in the millimetre and submillimetre range. Although the list is not exhaustive it covers most of the important materials and parameters, and extensive references are given.

Deformation and energy absorption of polymer foams as a function of 2‐D indenter and absorber geometries

AbstractTwo‐dimensional indenters (flat plate and cylinder) were used to compress rectangular and trapezoidal foam energy absorbers as a function of polymer, foam density, and thickness. An increased deformation volume formed when the indenter contact area was less than the foam absorber area, resulting in both increased energy absorption and stress transmitted to the indenter (i.e., “load spreading”). The deformation volume was trapezoidal, not prismatic, and was characterized by the indenter geometry, dimensions, and foam thickness. Conservative energy absorber design can be achieved by using “energy absorption diagrams” that account for the indenter (i.e., product) and absorber geometry and degree of load spreading.

Pressure loaded volumetric ceramic receiver

Based on the experiences with the first and second generation of the volumetric ceramic receiver [1–5,7] with grid absorber design, a small pressure loaded volumetric ceramic receiver (PLVCR) with foam absorber for a power level of 5 kW was designed. This small PLVCR was tested at the solar furnace of Sandia (SNLA), Albuquerque, New Mexico, USA in summer 1989. While driving the experiment at 1050°C air outlet temperatures and a gauge pressure of 4.2 bar a power output of 2.5–3.7 kW was obtained. With these results a large PLVCR for a power output of 500 kW at air outlet temperatures of 1000°C and pressures up to 10 bar was designed. Showing the feasibility of a modular design for solar power plants a hexagonal compound parabolic concentrator (HCPC) for this windowed receiver was designed. Preliminary tests with PLVCR and HCPC were made on the SSPS-tower of the Plataforma Solar de Almeria to demonstrate the function of this system.