102,445 research outputs found
Opusculum in quo una oratio, & duae questiones: altera de certitudine, & altera de medietate mathematicarum continentur
No full text[Francesco Barozzi]Exlibrisstempel: nicht entzifferbar 005213081_0001 Exemplar der ETH-BI
Enhanced visualisation of complex thermofluid data: Vertical and horizontal combined convection and microscale heat transfer cases
No full textCopyright @ 2000 UITIn general, convective heat transfer is an 'n-dimensional' problem where n is well in excess of 3 for steady flows. Traditionally, the method of dimensional analysis results in a small number of dimensionless groups. In the case of steady forced convection these can reduce to three, namely the Nusselt (Nu), Reynolds (Re) and Prandtl (Pr) numbers, for heat transfer, fluid flow regime and fluid properties respectively. Again, traditionally, data are presented on log-log graphs, say of Nu versus Re, with Pr being a possible third parameter. For natural convection, the Grashof number (Gr) expresses buoyancy effects in place of Re, while for combined (natural and forced) convection Gr becomes additional to, rather than replacing, Re. Using sets of data for: (a) vertical combined convection in nuclear safety, (b) horizontal combined convection review material, and (c) microchannel heat transfer, in the first part of this paper we survey this problem. We reach the following conclusions: that heat transfer data are presented in either 'holistic' or 'reductive' modes, and that other thermodynamic performance data are related to the generic scientific cases of (a) 3-dimensional space and (b) multi-dimensional space. In the second part of the paper we present a first attempt at applying design-type procedures to specifying this problem. Visualisation priorities are suggested from which particular solutions will be developed in future
Conjugated Heat Transfer in a Circular Duct with Uniform and non-Uniform Wall Thickness
No full textThe interaction between convection and axial heat conduction along a pipe is analysed assuming third kind boundary conditions at the outer face of the duct. Wall thickness is assumed to be either uniform or having periodic step variations in the axial direction. Axial heat conduction is found to have a definite influence on the heat flux and the Nusselt number distributions. However, the overall heat flux can accurately be predicted by ordinary methods disregarding axial conduction in the wall
Experimental Investigation of Coupled Conduction and Laminar Convection in a Circular Tube
No full textWall heat conduction effects on laminar flow heat transfer are experimentally investigated. The steady flow of water through a uniformly heated copper pipe is considered in the experiment, which covers a range of Reynolds numbers from 500 to 1900. The thermal behaviour of the test section is simulated numerically and the influence of conduction along the pipe wall is therefore accounted for in the reduction of the data. Fully developed flow results satisfactorily compare with predictions by a theoretical method previously developed by the authors [Heat Technol. 2,72 (1984)]. Results are also reported for the case where the velocity profile is partially developed at the inlet of the heat transfer section. The combined effects on heat transfer of flow development and of wall axial heat conduction are discussed
Effetti della stabulazione in acquario sui neuroni sopramidollari di Coris julis (L.)
No full textQuesta esperienze è stata condotta per verificare gli effetti di una stabulazione di 6 e di 1 anno sui neuroni sopramidolari di C. julis. E' stato possibili e ossevare un netto calo numerico e numerose alterazioni morfologiche e ultrastrutturali
Effects of prolonged aquarium life on supramedullary neurons of Coris julis (Labridae)
No full textHistological, ultrastructural and immunohistochemical studies were performed on specimens of Coris julis kept in acquarium for periods of one year and two years to assess effects on the supramedullary neurons. The results indicate that considerable damage is caused
Ulteriori considerazioni sulla produzione di entropia in scambiatori di calore a correnti laminari contrapposte
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Indagine sperimentale sullo scambio termico laminare in condotti cilindrici: misure preliminari
No full textIndagine sperimentale sulla regione di ingresso termico in condotti cilindrici: modellazione dell'apparato mediante tecnica numerica
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