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41.
F. Bay V. Labbe Y. Favennec J. L. Chenot 《International journal for numerical methods in engineering》2003,58(6):839-867
This paper presents a mathematical and numerical model developed for coupling the various physical phenomena (electromagnetic, thermal and mechanical) taking place in axisymmetrical induction heating processes. All three electromagnetic, thermal and mechanical models are time dependent and take full account of the electromagnetic and thermal non‐linear effect especially with magnetic materials. The electromagnetic problem is discretized and solved in the workpiece, air and inductors. The heat transfer equation and the mechanical equilibrium equations are solved in the workpiece only, both using a finite element method. The mechanical model can take into account thermoelastic–plastic behaviour for the part. The model has been successfully applied to several cases of induction heating. Comparisons between numerical and experimental results show an excellent agreement. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
42.
43.
在分析了感应加热小半径弯管形变机理的基础上,提出了压缩弯曲的成型工艺,研制出了小半径中频弯管设备,并进行了大量的工艺实验和实验研究,取得了满意的结果。 相似文献
44.
DCS在采暖锅炉房中的应用 总被引:2,自引:1,他引:1
介绍了Jx—300X DCS系统的组成、功能、特点以及热水锅炉主要控制方案及其在锅炉测控方面的应用。 相似文献
45.
46.
就城市集中供热工程造价的控制问题,从对设计阶段的成本、施工过程,加强材料成本、工程结算的控制几方面对其进行了详细的阐述,最后对工料分析与检查方面进行了论述,以提高供热企业的投资效益。 相似文献
47.
The process of dispensing one-component heat-cure adhesives was investigated in order to understand current application processes and to guide new process development. Typical one-component adhesives exhibit non-Newtonian rheological behavior, and hence Newtonian fluid mechanics does not adequately describe the dispensing process. In the present study, the adhesives were modeled as Bingham fluids possessing a yield stress and a steady state viscosity. The model of the dispensing apparatus includes four major flow sections connected in a serial configuration. The fluid mechanics equations derived for Bingham fluids in the individual flow sections were solved by numerical methods in order to understand the interrelationships between the material variables (e.g. yield stress, viscosity, temperature dependencies) and process variables (e.g. pressure, flow geometry, temperature, output). The concept of the model is generic and the details of the model can be modified for any forced-flow adhesive application process.
The adhesive flow properties significantly influence the process output. Dispensing temperature, among the process variables, has the strongest effect on process output. A ± 1.0·C perturbation in the dispensing temperature can cause as much as a 14% variation in the bead size for the range of adhesives studied. Differences in flow characteristics result in differences in processability and non-linear temperature/pressure sensitivity. The non-linear sensitivity can be eliminated by operating the dispensing process isothermally. Finally, the process limits for one-component adhesives, which are susceptible to chemical instability induced by viscous heating during processing, are defined and discussed in terms of a modified Brinkman number that takes into account viscous dissipation, heat conduction and convection, and chemical stability of the material during processing. 相似文献
The adhesive flow properties significantly influence the process output. Dispensing temperature, among the process variables, has the strongest effect on process output. A ± 1.0·C perturbation in the dispensing temperature can cause as much as a 14% variation in the bead size for the range of adhesives studied. Differences in flow characteristics result in differences in processability and non-linear temperature/pressure sensitivity. The non-linear sensitivity can be eliminated by operating the dispensing process isothermally. Finally, the process limits for one-component adhesives, which are susceptible to chemical instability induced by viscous heating during processing, are defined and discussed in terms of a modified Brinkman number that takes into account viscous dissipation, heat conduction and convection, and chemical stability of the material during processing. 相似文献
48.
ABSTRACT: The thermal evolution behavior of the organic free radicals induced in irradiated black pepper was studied by electron spin resonance spectroscopy. To analyze the time-dependent evolution process, we used the theory of transient phenomena, that is, an ordinal differential equation, as well as the nonlinear least squares numerical method. We found that the radical evolution that occurred in the irradiated pepper obeys a single exponential function and yields a unique time constant. The evolution of the organic free radical undergoes a simple reaction process of a single radical species. 相似文献
49.
N. N. Man’kina A. V. Kirilina O. V. Ovechkina B. G. Lyudomirskii B. G. Rubanov Yu. G. Tikhomirov T. Sh. Zakirov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2006,40(5):307-315
Studies conducted on two power-generating units at the Kharanorskaya SAPP relative to the steam-water-oxygen passivation,
preservation, and partial cleaning of all boiler-heating surfaces, including the surfaces of the reheater, and passivation
of the surfaces of the high-pressure heaters on the steam and water sides by the steam-oxygen method, as well as partial passivation,
preservation, and cleaning of turbine blading are presented.
__________
Translated from élektricheskie Stantsii, No. 6, pp. 56–64, May, 2006. 相似文献
50.
C. Guesdon I. Alxneit H.R. Tschudi D. Wuillemin J. Petrasch Y. Brunner L. Winkel M. Sturzenegger 《Solar Energy》2006,80(10):1344-1348
A new experiment has been installed to conduct studies at temperatures as high as 2500 K on chemical reactions that involve solids or melts and the release of condensable gases. The sample is radiatively heated by a 1 kW xenon short arc lamp placed in the upper focus of a vertically oriented ellipsoid of revolution. The optimal optical configuration has been determined by a Monte-Carlo Ray tracing method. Several methods to machine the reflector have been evaluated by experimentally determining the optical quality of the surface of plane test pieces. In the imaging furnace the sample is placed on a water-cooled support and heated by the concentrated radiation. This arrangement allows for fast heating and impedes the reaction of the sample with crucible material. A remotely controlled hammer allows for freezing the high-temperature composition of the sample by a fast quench. Thus, the sample can be later analyzed by conventional methods such as XRD or TEM. To allow for measurements under defined atmospheres and to protect the ellipsoidal reflector from liberated condensable products, the entire sample stage is enclosed by a hemispherical glass dome. The dome itself is protected from condensable compounds by a laminar flow of inert gas. Experiments with an incense cone at the place of the sample to visualize the gas flow showed that a steady layer of inert gas protects the dome from smoke, if the inert gas flow is properly adjusted. Measured peak flux densities clearly exceed 500 W cm−2 required to access temperatures of at least 2500 K. Decomposition experiments on copper sulfides confirmed the operation of the furnace. In the near future flash assisted multi-wavelength pyrometry (FAMP) will be implemented to measure sample temperatures online. Though the imaging furnace was developed to study the decomposition of metal sulfides it is obviously suited to conduct high-temperature studies on most materials relevant for high-temperature solar technology. 相似文献