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1.
A. A. Minea 《实验传热》2013,26(3):175-184
Abstract The aim of this article is to present an experimental method to optimize the heating time in a furnace in order to show an example of the progression toward increasingly empirical solutions as the problems become progressively more unwieldy. During this experimental study, different cases are carefully chosen to compare and measure the effects of applying different enhancement methods of the heat transfer processes. It is found that changing the inner geometry by introducing radiant panels inside the heated chamber leads to important time savings in the heating process by increasing the convection rate in the furnace. 相似文献
2.
We have examined routes for the preparation of 2-pyrrolidinone-5S-carboxaldehyde which include oxidation of 5-hydroxymethyl-2-pyrrolidinone and reduction of 5-oxoproline ethyl ester. Only the oxidation route proved satisfactory. Moffatt oxidation was most efficient but PCC oxidation gave modest yields of the desired aldehyde. 相似文献
3.
Alina Adriana Minea 《Heat and Mass Transfer》2012,48(11):1837-1845
In this paper an investigation was conducted to study the suitability of inserting radiant panels for industrial heating. The study involved heat transfer enhancement in an oval and a classical semi-industrial furnace. The experiment suggests an optimal panel position at 10–15 degrees inclination. A maximum energy saving of 22.5?% for the oval furnace was noticed and the most suitable case is to use panels as thick as is possible. 相似文献
4.
Despite several reported procedures for coupling alkyl halides and 5-oxoproline esters (pyroglutamate derivatives), no general method has been described. The reaction of pyroglutamate with sodium hydride, in anhydrous THF in the presence of the halide, provides this general and practical alkylation method. Alkylation under phase transfer conditions is a useful, but less general, alternative. 相似文献
5.
Conventional fluids have poor heat transfer properties, but their vast applications in power generation, chemical processes, heating and cooling processes, electronics and other microsized applications make the reprocessing of those thermofluids to have better heat transfer properties quite essential. Recently, it has been shown that the addition of solid nanoparticles to various fluids can increase the thermal conductivity and can influence the viscosity of the suspensions by tens of percent. Thermophysical properties of nanofluids were shown dependent on the particle material, shape, size, concentration, the type of the base fluid, and other additives. In spite of some inconsistency in the reported results and insufficient understanding of the mechanism of the heat transfer in nanofluids, it has been emerged as a promising heat transfer fluid. In the continuation of nanofluids research, the researchers have also tried to use hybrid nanofluid recently, which is engineered by suspending dissimilar nanoparticles either in mixture or composite form. The idea of using hybrid nanofluids is to further improve the heat transfer and pressure drop characteristics by trade-off between advantages and disadvantages of individual suspension, attributed to good aspect ratio, better thermal network and synergistic effect of nanomaterials. As a conclusion, the hybrid nanofluids containing composite nanoparticles yield significant enhancement of thermal conductivity. However, the long-term stability, production process, selection of suitable nanomaterials combination to get synergistic effect and cost of nanofluids may be major challenges behind the practical applications. 相似文献
6.
7.
Wolfgang W. Breckner Tiberiu Trif Csaba Varga Воляфганг В. Брекнер Тибериу Триф Чаба Варга 《Analysis Mathematica》1999,25(1):15-32
RecentlyPrus-Wi?niowski [14] has proved that the continuous functions of Λ-bounded variation on [0, 1] form a set of the first category in the Banach space C[0, 1] and also in each Banach space CΓBV[0, 1] of continuous functions of Γ-bounded variation on [0, 1] provided that the sequence Γ is adequate. In the present paper these results are extended and completed by using a principle of the condensation of the singularities of a family of nonnegative functions that follows from the theorems given byBreckner [3]. It is shown that Baire category properties similar to those stated in [14] are valid for two very large classes of real-valued functions called functions of bounded λ-variation of orderp and functions of boundedmth variation of orderp, respectively. The benefit of considering these classes is that they comprise several classes of functions of bounded variation type which have occurred so far in Fourier analysis or real analysis; in particular, the functions investigated in [14]. Thus, by specializing the results derived in the present paper, they give at once Baire category information concerning a number of well-known sets of real-valued functions. 相似文献
8.
A. A. Minea 《Journal of Engineering Thermophysics》2010,19(3):184-191
Heat transfer simulation within heating furnaces is of great significance for prediction and control of the performance of
furnaces. In this paper, a set of models is proposed to solve heat transfer problems in a loaded furnace. Furthermore, a 2-dimensional
algorithm based on a finite difference method is presented. The heat transfer models are integrated with a furnace model to
simulate the heating process of workpieces. Temperature variation of the workpiece with time is predicted by the system. An
experiment is carried out for validation of the system. Themain objective of this work is to evaluate the behavior of a heated
enclosure, when variable radiant panels are introduced. Experimental investigation shows that their efficiency depends on
their position. 相似文献
9.
Electron-electron coincidence spectra of Ar-Kr clusters after photoionization have been measured. An electron with the kinetic energy range from 0 to approximately 1 eV is found in coincidence with the Ar 3s cluster photoelectron. The low kinetic energy electron can be attributed to an Ar + Kr+ + Kr+ final state which forms after electron transfer mediated decay. This autoionization mechanism results from a concerted transition involving three different atoms in a van der Waals cluster; it was predicted theoretically, but hitherto not observed. 相似文献
10.
A. A. Minea 《Journal of Engineering Thermophysics》2010,19(1):31-38
Heat transfer simulation is of great significance for the heating equipments control. In this paper, a set of models is proposed to solve heat transfer problems in a furnace, including radiation and convection. The heat transfer models are integrated with a furnace model to simulate the heating process. The heating rate is increased due to enhanced heat transfer at the surfaces by changing furnace chamber geometry. A fixed grid enthalpy formulation is applied to model heat transfer for an oval geometry. The heating temperature was found to increase linearly with curvature of the interior. 相似文献