Honeycomb Type Research Articles

Mechanical and structural characterization of ceramic spacers with a high aspect ratio for 5.2 in. field emission displays

Ceramic spacers with a high aspect ratio (80 μm/1.1 mm) were fabricated and laid out in a high voltage 5.2 in. field emission display (FED) panel. Alumina was chosen as spacer material and sintered at 1600 °C for high mechanical strength and suitable electric resistivity. Three different types of spacers, single-trench type, double-trench type, and honey-comb types, were considered in this study. We optimized the structure and the layout of spacers in terms of stress distributions, build up profiles of glass, carrier gas flows inside a panel. Among the three different types of spacers, the double-trench structure spacer provided the most uniform gas flow and the highest mechanical strength. The optimal number of spacers with 80 μm width and 1.1 mm height was found to be 7 for an uniform stress distribution in a 5.2 in. FED panel by experiments and computer simulations.

Evaluating the effective diffusivity of methane in the washcoat of a honeycomb monolith

The effective diffusion coefficient of methane in nitrogen is investigated in the washcoat of a honeycomb type monolith reactor. A flow cell operating at atmospheric pressure is used. The effective diffusivity of methane in the alumina based washcoat is found to lie in the range 0.6–4.2×10−7m2/s, whilst the value in the cordierite support is 9.2 (±3.8)×10−7m2/s. The experimental values are compared to those obtained from the random pore model, and are found to be significantly smaller. So, the random pore model is not appropriate for this alumina washcoat. The parallel pore model could be used to model the results. The tortuosity factor required to model the results using the parallel pore model was found to be 8.5 and 8.1 for the cordierite and washcoat, respectively.

Sorption Characteristics of Honeycomb Type Sorption Element Composed of Organic Sorbent.

This paper has dealt with the sorption characteristics of honeycomb shape type sorbent element composed of new organic sorbent which was composed of the bridged complex of sodium polya-crylate. The transient experiments in which the moist air was passed into the honeycomb type sorbent element were conducted under various conditions of air velocity, temperature, relative-humidity and honeycomb length. As a result, the effective mass transfer coefficjent of the organic sorbent sorbing the water-vapor was non-dimensionalized as a function of Reynolds number, modified Stefan number and non-dimensional honeycomb length.

省エクセルギー型高温空気燃焼

An exergy saving type combustion technique has been developed by introducing high temperature air burner which has a regenerative heat recovery with honeycomb type ceramics and frequent switching device to keep a level of 1000 deg. C and over. However, NOx emission will be increased by this high temperature air combustion and has to be decreased by some technique which is held by low oxygen combustion method. The low oxygen combustion can be obtained by well mixing of fresh air and combustion gas. In this paper, we can realize that the exergy value is decreased by combustion process and increased by heat recovery process. Therefore, the exergy saving process in combustion may be achieved by heat recovery from exhaust gas to fresh air. Recently, we have many application of exergy saving type high temperature air combustion for some industrial furnaces. When we introduce the above high temperature air combustion, it may be possible to reduce about 30% ener-gy for comparing with existing type of furnace. Furthermore, it is clear that the steam boiler or chemical reactor furnace may be constructed by radiation part only. So, we have many advantages of energy and resource saving results which are derived from high temperature air combustion.

Water Vapor Desorption Characteristics of Honeycomb Type Sorption Element Composed of Organic Sorbent

Water Vapor Desorption Characteristics of Honeycomb Type Sorption Element Composed of Organic Sorbent

Solid oxide fuel cell stacks using extruded honeycomb type elements

Abstract A solid oxide fuel cell (SOFC) stack concept is described which comprises “condensed-tubes” like extruded honeycomb sections of ceramic electrolyte (ZrO2-based) and interconnectors of nickel sheet as key elements. According to this concept, well known and extensively tested construction principles can be realised in a low-cost production. The cells are self-supported with in-plane conduction. A demonstrator model stack of five honeycomb elements and six nickel sheet seals/interconnectors was built and operated for 860 h at 1000°C. Volumetric power densities of 160 kW/m3 were obtained with H2 vs. air, of close to 200 kW/m3 with H2 vs. O2.

Development of an Electrostatic Generator that Harnesses the Motion of a Living Body. Use of a Honeycomb-Type Variable Capacitor.

We aimed for permanently supplying the electrical energy to an apparatus for in vivo use such as a cardiac pacemaker and proposed a totally implantable electrostatic generator that harnesses the motion of a living body. The generating system consists of a battery for supplying electric charge, a variable capacitor for energy conversion, a capacitor of energy storage and two rectifiers. We made a honeycomb type variable capacitor whose capacitance is varied from 44 to 220 [nF]. It was possible to generate maximum electrical energy of about [μJ/cycle]. We found that the electrical energy for driving a cadinc pacemaker can be generated by using the honeycomb-type capacitor with higher capacitance.

Effects of base metal promoters in VOC catalysts for chlorocarbons and n-Hexane Oxidation

The oxidation reactions of dichloromethane, dichloroethane and n-hexane were carried out over honey-comb type platinum basic VOC catalyst (BVC) containing vanadium, chromium, manganese, cobalt, copper or barium. In dichloromethane and dichloroethane catalytic oxidation up to 450 °C, chromium was found as the most active component. Although vanadium was also effective initially, it was deactivated after treatment in the furnace at 800 °C for 120 hours. Chromium, cobalt, vanadium and barium promoted catalysts showed higher activities than BVC in the reaction of n-hexane.

Influence of rhodium- and ceria-promotion of automotive palladium catalyst on its catalytic behaviour under steady-state and dynamic operation

The dynamic behaviour of honeycomb type, unpromoted, and rhodium (Rh) and ceria (CeO 2) promoted palladium/alumina ( PdAl 2O 3 ) automotive catalysts has been tested under constant air/fuel ratios as well as under symmetric and asymmetric cycling of simulated exhaust feed gas. Combined use of FTIR spectroscopy and mass spectrometry allowed simultaneous monitoring of the exhaust components. Light-off tests carried out in the range 150–500°C indicated drastic differences in the conversion of the main target species NO x , CO and hydrocarbons during warm up, depending on the presence of ceria and/or Rh. Best performance with regard to NO conversion under steady feed conditions was observed with the Rh promoted Pd, whereas under cycling, addition of ceria resulted in a further improvement of NO x conversion and lowering of undesirable NH 3 formation. CO conversion was substantially enhanced by ceria addition as well as cycling operation. As concerns the behaviour in hydrocarbon conversion, Rh had a much more pronounced influence than ceria, significantly enhancing the average conversion during light-off. The benefits of λ-cycling were generally lower light-off temperatures for NO, CO and C 3H 8 conversion and an improved catalytic behaviour of the ceria-containing catalysts, especially for higher amplitudes and frequencies.

WATER VAPOR ADSORPTION-DESORPTION CHARACTERISTICS OF A MIXED ADSORBENT

Air conditioning systems that are incorporating desiccant based dehumidifiers are finding increased applications over traditional vapor compression refrigeration systems due to their efficient handling of latent heat loads. Generally, silica gel, molecular sieves, or activated alumina coaled on a rotating honeycomb type desiccant matrix is used as a dehumidifier in these systems. However, shapes of the isotherm for water vapor adsorption on these materials are not favorable for optimal performance of desiccant cooling systems. Theoretical studies have shown that a material having a type I isotherm for water vapor, whose shape lies between that on molecular sieve 13X and silica gel would lower installation and operating costs of desiccant based air-conditioning systems. An adsorbent was prepared by mixing a silica gel, molecular sieve 13X, and a hydrophobic molecular sieve. The mixed adsorbent was mixed with a binder and was further coated on both sides of a 0.0014“ thick aluminum foil. Both plain and corrugated foils were used in preparing a desiccant matrix. A plain sheet was inserted in between two corrugated sheets and then they were rolled into a cylinder. The shape of water adsorption isotherm and equilibrium water adsorption capacity were obtained for this desiccant matrix. The shape of the water isotherm in the temperature range of 288-308 K was found to be more favorable than that on silica gel or molecular sieve 13X. However, the total water adsorption capacity of the new mixed adsorbent was significantly lower than these materials. The water adsorption data on the mixed adsorbent could be correlated according to Polyani's potential theory

Adiabatic UT-3 thermochemical process for hydrogen production

The UT-3 thermochemical hydrogen producing cycle is a four step process developed at the University of Tokyo. In the process, only solid and gas reactants/products are used and the maximum temperature is 1033 K. In this paper, a new UT-3 process has been developed in which all four reactions are carried out adiabatically using a heat carrier vector (steam or an inert gas). The new process has been evaluated using the ASPEN-PLUS process code. The first law efficiency of the cycle has been determined as 48.9% and the second law efficiency as 53.2%. The process can be realized using conventional materials for the reactors, which can be packed bed, honeycomb or fluidized bed type. In the latter case, it is found that the flow rate of the heat carrier fluid is sufficient to fluidize all four reactors. For a plant producing 30,000 Nm 3 per hour or 2.68 × 10 6 GJ H 2 per year, the plant sizing has been carried out, its operation is discussed and its advantages are presented.

The shell DENOX system for low temperature NO x removal

Shell has developed a low temperature DENOX system which consists of a high activity granular SCR catalyst and a low pressure drop lateral flow reactor. The Shell DENOX system achieves more than 95% NO x reduction with minimal ammonia slip. The Shell DENOX system can be installed at the low temperature end of the flue gas stream and, therefore, represents a more economical solution compared to retrofitting of honeycomb type catalysts in the high temperature window.

Calculation of lateral interactions of adsorbed molecules on planar lattices

Methods of calculating lateral interactions in systems of adsorbed molecules are considered which allow determination of stable orientational structures of polar molecules as well as the parameters of the vibrational and electronic spectra of an adsorbate. A number of new results on determination of the ground state for dipoles on a planar hexagonal lattice (of honeycomb type) are presented. Dipoles in this state are shown to form a complex vortex antiferroelectric structure. In these structures dipole orientations are inclined relative to the lattice plane, because of the adsorption potentials, resulting in Davydov splitting of spectral lines in two perpendicular polarizations.

Reduction of NO x in diesel exhaust with methanol over alumina catalyst

NO x reduction in diesel exhaust using selective catalytic reduction by methanol over alumina catalyst was investigated. Although a slight decrease in catalytic activity took place at the initial stage of the catalyst evaluation, more than 40% NO x conversion was obtained at 400°C and a space velocity of 10 000 h −1 by using a ball type alumina catalyst and methanol ( CH 3OH/NO x mole ratio = 2) as a reducing agent. The experimental results using synthetic exhaust gases containing SO 2 indicated that the initial catalytic deactivation is ascribed to the formation of Al 2(SO 4) 3-like species on alumina surface through reaction with SO 2. However, the formation stopped at a certain point in time. The stable activity following the initial deactivation did not depend on SO 2 concentration. A durability test of a honeycomb type alumina was also conducted, and more than 70% of NO x conversion maintained for more than 4000 h at a CH 3OH/NO x mole ratio of 6. In this case a gradual decrease in the activity of alumina occurred due to catalyst sintering.

Optical and thermal testing of a new 1.12X CPC solar collector

A new CPC collector is described and tested, both optically and thermally, in different configurations. This CPC has a receiver shaped as an inverted “V”, which was conceived to accommodate a large gap between itself and the reflector, without optical losses, a novelty which distinguishes this device from others previously proposed. Its acceptance angle was chosen to be large (56.4°, before truncation, and 76° after truncation) in order to allow for both fully stationary E.W. and N.S. possible orientations for the collector to be used. Collector height was chosen to allow for the inclusion of convection suppression mechanisms, to enhance the thermal performance of the collector at high temperature. Measurements of instantaneous efficiency are presented, for the collector in E.W. and N.S. orientation. Measurements are also presented for the instantaneous efficiency when a double cover configuration achieved with a Teflon film and a transparent insulation material of the honeycomb type are included. It is shown that the collector's low heat losses are reduced by roughly 30% trough the addition of such convection suppression devices. Based on these results, the average yearly performance is calculated and compared with the energy delivered by other collector types (flat pates, evacuated tubular collectors). It is shown that, up to 100°C, the present collector outperforms the others, and has a cost which is comparable, if not potentially lower than conventional flat plates.

An ion-exchange method for selective separation of palladium, platinum and rhodium from solutions obtained by leaching automotive catalytic converters

An ion-exchange method has been developed for the separation of palladium, platinum and rhodium from a solution that is highly acidic and contains a considerable amount of lead, aluminum, iron and cerium, obtained by leaching a used honeycomb type automotive catalytic converter. A column of Amberlite IRA-93 anion-exchange resin was found appropriate to recover platinum metals from the pregnant solution. Selective stripping of these metals from the resin was achieved by eluting rhodium first with 6.0 M hydrochloric acid, then palladium with a 1% ammonia solution at ambient temperature, and platinum with 5% of the reagent at elevated temperatures. Optimum conditions for leaching these metals from the catalyst were 5.0 M hydrochloric acid and 0.4 M sodium chlorate at 70°C. This method can be applied to both analytical as well as large scale operations. It is simple, economical, and relatively safe for human exposure and the environment.

舶用ディーゼル機関の脱硝システムに関する研究

In this paper, we describe the influence of the particulate matter and in the exhaust gas on the structure of the honeycomb type catalysts in developing the shipboard NOx reduction plant.We set the cordierite honeycomb support in the small size test equipment, flowed the exhaust gas from marine diesel engine into the test equipment and investigated the influence of the particulate matter and the pressure loss.The test results are as follows.(1) As the test time becomes longer, the amount of the particulate matter increases. But the rate of the increase per time gets lower.(2) As the exhaust gas velocity becames higher, the amount of the particulate matter increases. But the amount of the particulate matter per gas volume decreases.(3) In case of the honeycomb with equal opening-ratio, the amount of the particulate matter increase as opening of honeycomb becames smaller.(4) As the exhaust gas temperature becames lower, the amount of the particulate matter in-creases.

Refractory concrete lining for a hot-blast valve

This paper gives a brief description of the composition, technology and main properties of a high-alumina concrete that has been used for making the lining of the disk and rings of a hot-blast valve. The tenon and honeycomb types of concrete reinforcement have been tested in the linings of experimental valves. The results of the tests of the experimental valves in the blast-furnace shop of the Azovstal' Integrated Works have demonstrated that the lining with the tenon-type reinforcement is in fairly good condition. Due to the use of the concrete lining, the heat losses through a valve have been decreased by a factor of 1.5 – 2, the hot-blast temperature increased by 10 – 12°C, and the average service life of valves, by a factor of two.

Decomposition of chlorinated dioxins, odourous compounds and NO x from MSW incineraton plant by oxidizing catalyst

An experiment was carried out to decompose chlorinated dioxins (PCDDs, PCDFs) Chlorobenzenes, NOx and odourous compounds (H 2S, CH 4S, C 2H 6S 2, C 8H 8, C 2H 6S, C 2H 4O, NH 3) simultaneously using a catalyst in the MSW incineration plant. The experiments were conducted at temperatures from 200°C to 400°C and from 3000h −1 to 6000h −1 at space velocity. A catalyst containing V 2O 5 and WO 3 on the basis of TiO 2 is used, an oxidizing catalyst of the honeycomb type. The average decomposition efficiencis were 95%, 98%, 92% for PCDDs(4∼8CDDs), PCDFs(4∼8CDFs) and Chlorobenzenes(3∼6CLBs) at a reaction temperature of 350°C and a space velocity of 3000h −1, more than 90% for NOx at a reactiont temperature of 300°C and more than 80% for odourous compounds at the reaction temperature of 300°C and a space velocity of 6000h −1. All those compounds were decomposed successfully with increasing contact time and surface. The rate-determing step was the chemical reaction of catalyst surface.

High‐Order Behavior of Sandwich Beams with Flexible Core and Transverse Diaphragms

The bending behavior of a sandwich beam with transversely “soft” core and transverse diaphragms is analytically investigated using variational principles. The beam consists of one or two skins, upper and lower, interconnected at discrete locations through transverse diaphragms, metallic or composite laminated, with a symmetric lay‐up and a fully or partially bonded (delaminated) transverse flexible core made of foam or low‐strength honeycomb type. The diaphragm is rigidly connected to the skins but may be bonded or unbonded with the adjacent core through its entire height. The analysis considers the discrete diaphragm as a concentrated interference that affects the beam's behavior through particular boundary and continuity conditions. The behavior of the beam is determined with the aid of a high‐order theory that uses a two‐dimensional elasticity formulation for the core, in the longitudinal and the transverse directions, combined with a beam theory for the skins and the diaphragms. The core‐diaphragm interaction is determined explicitly for the bonded and the unbonded cases and the equivalent conditions in terms of the solution unknowns are derived. The presence of a discrete diaphragm yields concentrated effects that affect the beam's behavior globally and locally. These localized effects are significantly important for the safety of the structure and are explicitly determined by the analysis for the entire structure as well as in the vicinity of the diaphragm. A study that investigates the effects of the existence of a reinforcing diaphragm and its interaction with the adjacent core in a vertical cut‐off end connection between a sandwich panel and its supporting members is presented, including the level of stress concentration involved.