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This paper summarises some applications of advanced thermal techniques for the characterisation and preparation of catalysts using different sample controlled thermal analysis (SCTA) methods. The techniques are applied to temperat...
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This paper summarises some applications of advanced thermal techniques for the characterisation and preparation of catalysts using different sample controlled thermal analysis (SCTA) methods. The techniques are applied to temperature programmed decomposition (calcination), oxidation, reduction, dehydration, desorption and reaction. SCTA methods can produce significant enhancements in the resolution of complex reactions, provide a detailed insight into the energetics of surface and bulk processes and, when applied to catalyst preparation, give improvements in the pore structure and uniformity of the resulting materials. The advantages and limitations of SCTA methods, in which the sample temperature or concentration of reactant gas is altered as some function of the rate of a thermally induced physico-chemical process, are discussed.
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In the helium-cooled lead lithium (HCLL) blanket concept convective phenomena caused by nonuniform thermal conditions due to bulk neutron volumetric heating can occur. Buoyancy can become very important and modify the velocity dis...
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In the helium-cooled lead lithium (HCLL) blanket concept convective phenomena caused by nonuniform thermal conditions due to bulk neutron volumetric heating can occur. Buoyancy can become very important and modify the velocity distribution and related heat transfer performance of the blanket. A numerical study has been performed to investigate liquid metal flows driven by buoyant forces in a breeder unit (BU) of a HCLL test blanket module (TBM) under the influence of intense uniform magnetic fields. According to the last design review, two internal cooling plates subdivide the fluid domain into three slender flow regions, which are thermally and electrically coupled through common walls. First, a uniform volumetric heat source is considered to identify the basic convective patterns that establish in the liquid metal. Results are then compared with those obtained by applying a realistic radial distribution of the power density as obtained from a neutronic analysis. This paper summarizes the main effects of spatial gradients of a neutron thermal load on velocity and temperature distribution in magnetohydrodynamic flows in a BU of a HCLL TBM.
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This paper applies the advantage of isoconversional method to the new experimental arrangement of controlled rate thermal analysis (CRTA). The CRTA technique leads to a more effective control of heat and mass transfer phenomena su...
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This paper applies the advantage of isoconversional method to the new experimental arrangement of controlled rate thermal analysis (CRTA). The CRTA technique leads to a more effective control of heat and mass transfer phenomena such that much greater sensitivity can be achieved. (C) 1997 Elsevier Science B.V. [References: 14]
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Thermal analysis combined with mass spectrometry was applied to radiocarbon dating procedures (age determination of carbon containing samples) to determine the optimal temperature range for the reduction of CO_2 over metallic coba...
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Thermal analysis combined with mass spectrometry was applied to radiocarbon dating procedures (age determination of carbon containing samples) to determine the optimal temperature range for the reduction of CO_2 over metallic cobalt of various particle sizes. Experiments were carried out to show the different catalytic activities of cobalt of particle sizes 1, 1-45 and 44 μm. The morphology of the cobalt samples and the deposited carbon were investigated. The quantification of CH_4 and CO formed during the reduction of CO_2 was done by means of pulse thermal analysis.
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With the increasing pressures on electric motor manufacturers to develop smaller and more efficient electric motors, there is a trend to carry out more thermal analysis in parallel with the traditional electromagnetic design. It h...
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With the increasing pressures on electric motor manufacturers to develop smaller and more efficient electric motors, there is a trend to carry out more thermal analysis in parallel with the traditional electromagnetic design. It has been found that attention to thermal design can be rewarded by major improvements in the overall performance. Thus, there is a requirement for accurate and reliable thermal analysis models that can be easily incorporated into motor design software. In this paper, emphasis is given to thermal sensitivity analysis of totally enclosed fan-cooled induction motors. In particular, thermal parameters are modified and their effects on the temperature rise shown. The results are useful for identifying the most important thermal parameters and enable robust designs to be developed that are insensitive to manufacturing tolerances.
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Dynamic and controlled rate thermal analysis has been used to characterise synthesised jarosites of formula [M(Fe)_3(SO_4) _2(OH)_6] where M is Pb, Ag or Pb-Ag mixtures. Thermal decomposition occurs in a series of steps. (a) dehyd...
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Dynamic and controlled rate thermal analysis has been used to characterise synthesised jarosites of formula [M(Fe)_3(SO_4) _2(OH)_6] where M is Pb, Ag or Pb-Ag mixtures. Thermal decomposition occurs in a series of steps. (a) dehydration, (b) well defined dehydroxylation and (c) desulphation. CRTA offers a better resolution and a more detailed interpretation of water formation processes via approaching equilibrium conditions of decomposition through the elimination of the slow transfer of heat to the sample as a controlling parameter on the process of decomposition. Constant-rate decomposition processes of water formation reveal the subtle nature of dehydration and dehydroxylation. CRTA offers a better resolution and a more detailed interpretation of the decomposition processes via approaching equilibrium conditions of decomposition through the elimination of the slow transfer of heat to the sample as a controlling parameter on the process of decomposition. Constant-rate decomposition processes of non-isothermal nature reveal separation of the dehydroxylation steps, since in these cases a higher energy (higher temperature) is needed to drive out gaseous decomposition products through a decreasing space at a constant, pre-set rate.
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Micro-thermal analysis (micro-TA) is a new subsurface thermal analysis technology. The average of the DC signal is a function of the thermal conductivity, and the response to the AC modulation signal is a function of the thermal d...
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Micro-thermal analysis (micro-TA) is a new subsurface thermal analysis technology. The average of the DC signal is a function of the thermal conductivity, and the response to the AC modulation signal is a function of the thermal diffusivity of the subsurface. Using this technique, three images based on topography, thermal conduc- tivity, and thermal diffusivity are obtained simultaneously. Specific areas and domains in these images can then be characterized by simply positioning the probe and per- forming a localized thermal analysis experiment. The technique has been used to study the phase separation process in a 50:50 (by weight) polystyrene (PS)-poly(vinyl methyl ether) (PVME) blend and natural rubber-nitrile rubber blends. For these polymer blends, considerable contrast between phases is obtained, based on thermal conductiv- ity, whereas optical and electron microscopy would show them as being very similar . For example, it is difficult to image the morphology of natural and nitrile rubber blends by means of transmission electron microscopy, because of their similar chemical struc- tures. Micro-'l'A gives an excellent image of the morphology of these natural-nitrile rubber blends. This opens a new way for rubber industries to study morphologies of rubber-rubber blends in general. In the 50:50 PS-PVME blend, annealed at 125degC, spinodal decomposition occurred. With increasing time, the domain size and the glass transition temperature ofPS-rich domains increased, indicating that the concentration ofPVME in the PS-rich phases decreases. The results imply that micro-TA can be used to image the composition in the near-surface or surface regions in multicomponent materials, if the resolution is high enough.
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We have developed a thermal microscope which has an InSb detector and optics optimized for the camera. Using this system, we evaluated maximum resolution of a 30×/numerical aperture 0.71 lens made of silicon and germanium, and ac...
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We have developed a thermal microscope which has an InSb detector and optics optimized for the camera. Using this system, we evaluated maximum resolution of a 30×/numerical aperture 0.71 lens made of silicon and germanium, and achieved the cutoff frequency of around 300 line pairs/mm, which is almost a diffraction-limited performance. The thermal microscope is installed on the THEMOS-1000, a product of Hamamatsu Photonics, for thermal emission analysis.
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We have developed a thermal microscope which has an InSb detector and optics optimized for the camera. Using this system, we evaluated maximum resolution of a 30x/numerical aperture 0.71 lens made of silicon and germanium, and ach...
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We have developed a thermal microscope which has an InSb detector and optics optimized for the camera. Using this system, we evaluated maximum resolution of a 30x/numerical aperture 0.71 lens made of silicon and germanium, and achieved the cutoff frequency of around 300 line pairs/mm, which is almost a diffraction-limited performance. The thermal microscope is installed on the THEMOS-1000, a product of Hamamatsu Photonics, for thermal emission analysis.
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Following the successful first-ever virtual NATAS Conference in 2021, we now hope that you are all dreaming of traveling again and that the 2022 NATAS Conference is on your list. The venue will be the historic Case Western Reserve...
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Following the successful first-ever virtual NATAS Conference in 2021, we now hope that you are all dreaming of traveling again and that the 2022 NATAS Conference is on your list. The venue will be the historic Case Western Reserve University (CSWU) campus in downtown Cleveland. We are looking forward to seeing you in person, beginning with a welcome reception on Monday, August 1st in the beautiful Havorka Auditorium along with our vendor exhibition. Then, the week will be full of concurrent lecture sessions plus the prestigious NATAS Short Course in thermal analysis. The room block will be at the Courtyard by Marriott University Circle at a rate of USD 165 per night. We thank them for their flexibility during the various stages of this pandemic.
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