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Tube Bundles (tube + bundle)

Distribution by Scientific Domains

Engineering	71%
Chemistry	21%

Selected Abstracts

Heat transfer on tube bundles embedded horizontally in a liquid-fluidized bed: 2nd report: On tube bundles of fundamental layouts including in-line layouts

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 3 2009
Kenichi Hashizume
Abstract Heat transfer coefficients were measured on tube bundles of fundamental layouts including in-line layouts embedded horizontally in a liquid-fluidized bed. Tested tube layouts were single tubes, transverse single tube rows, longitudinal single tube rows, and in-line arranged tube bundles. A total of 7 kinds of particles were used. Comparisons of the experimental data showed a good agreement with the heat transfer correlation developed for staggered layouts, when the average liquid velocity through each tube bundle was used as the reference velocity for the particle Reynolds number. Distribution of the local heat transfer coefficient was also investigated around tubes. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20245 [source]

Effect of fins on forced convection heat transfer around a tube in an aligned-arranged tube bundle

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 8 2005
Kenichi Hashizume
Abstract The effect of fins on heat transfer around a tube in an aligned-arranged tube bundle was investigated experimentally, and the obtained results were compared for three arrangements, i.e., single tube, single tube row, and staggered-arrangement. It was found from the experiment that the effect of fins begins to appear in an aligned-arrangement with larger fin spacing than in a staggered-arrangement. The degradation in the local heat transfer coefficient due to fins can be recognized not only on the rear region of the tube, as observed in other arrangements, but also on the frontal region. As a result of this phenomenon, the degradation in the average heat transfer coefficient in an aligned-arrangement becomes larger than in other arrangements with the same fin spacing. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(8): 555,563, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20091 [source]

Practical techniques for a three-dimensional FEM analysis of incompressible fluid flow contained with slip walls and a downstream tube bundle

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 3 2001
Yuzuru Eguchi
Abstract Two practical techniques are proposed in this paper to simulate a flow contained in a plenum with a downstream tube bundle under a PC environment. First, a technique to impose slip wall conditions on smooth-faced planes and sharp edges is proposed to compensate for the mesh coarseness relative to boundary layer thickness. In particular, a new type of Poisson equation is formulated to simultaneously satisfy both such velocity boundary conditions on walls and the incompressibility constraint. Second, a numerical model for a downstream tube bundle is proposed, where hydraulic resistance in a tube is imposed as a traction boundary condition on a fluid surface contacting the tube bundle end. The effectiveness of the techniques is numerically demonstrated in the application to a flow in a condenser water box. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Field study on superheater tubes in the loop seal of a wood fired CFB plant

MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 12 2004
A. Nafari
Abstract Two full scale superheaters were exposed in the loop seal of a 30 MW wood-fired CFB plant in Nässjö, Sweden, for one firing season each. Some austenitic steel tubes from the first tube bundle were reinstalled in the second superheater. The superheater tubes were made from one ferritic steel, X10 (Fe8.8Cr) and three austenitic steels; Esshete 1250 (Fe15Cr9Ni6Mn), 347H (Fe17Cr11Ni) and AC66 (Fe27Cr32Ni). Commercial coatings mainly on iron, nickel and carbide base were deposited on some of the X10 and 347H tubes. The material wastage kinetics was non-linear showing that pure corrosion and not erosion-corrosion is the major degradation mechanism in the loop seal. It is however clear that the environment is not very aggressive and the corrosion attack on the uncoated tubes is very small. The largest oxide thickness was only about 150 ,m recorded on the X10 alloy. The austenitic steels mainly suffered from internal corrosion and grain boundary corrosion, the extent and distribution of which strongly depended on the alloy composition. Generally, it was more pronounced in the regions with the thinnest deposit layers. Eight out of 17 coating qualities tested were unaffected by the exposure. Corrosion was only recorded on the lowest alloyed iron based coatings. The only coatings which could not resist the conditions in the loop seal were the carbide containing Metco 3006 and Metco 3007, where severe oxidation and delamination took place. Also the thermally sprayed Inconel 625 coating delaminated, but this was rather due to a mechanical failure resulting from thermal expansion. [source]

Heat transfer on tube bundles embedded horizontally in a liquid-fluidized bed: 2nd report: On tube bundles of fundamental layouts including in-line layouts

Heat transfer on tube bundles embedded horizontally in a liquid-fluidized bed

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 2 2005
Kenichi Hashizume
Abstract Heat transfer on tube bundles embedded horizontally in a liquid-fluidized bed was investigated experimentally. In the experiment, a total of 5 kinds of tube bundles in an equilateral triangular staggered arrangement, including a single tube, was used. Tested particles were of glass and ceramics, and their diameter range was from 2.1 to 6.0 mm. It was found that the distribution of local heat transfer coefficients around a tube depends not on the kind of particles, but on the tube pitch only, when a good fluidizing condition is maintained. Based on the experimental data, a new method was proposed to predict average heat transfer coefficient, which can be applicable for tube bundles having a tube pitch to diameter ratio of 1.2 to infinity (single tube). © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(2): 85,98, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20048 [source]

Enhancement of boiling heat transfer in restricted spaces in compact horizontal tube bundles

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 5 2001
Zhen-Hua Liu
Abstract ln desalinization devices and some heat exchangers making use of low-quality heat energy, both wall temperatures and heat fluxes of heated tubes are quite low and generally cannot cause boiling in flooded-type tube bundle evaporators with a large tube spacing. But when the tube spacing is very small, boiling in restricted spaces can occur and induce a higher heat transfer than that of a falling film or pool boiling at the same heat flux. This study investigated experimentally the effects of tube spacing, positions of tubes, and heating status of tubes as well as surface status (smooth and roll-worked) on boiling in restricted spaces in compact horizontal tube bundle evaporators under atmospheric pressure. The experimental results provide a restricted space boiling database for water in smooth and enhanced surface tube bundles. Of particular importance is information concerning the influence of tube spacing of flooded-type tube bundle evaporators, especially for the case of zero pitch, when the neighboring tubes are contacting each other. © 2001 Scripta Technica, Heat Trans Asian Res, 30(5): 394,401, 2001 [source]

Flow of Newtonian and power law liquids in tube bundles

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009
U. K. Singh
Abstract In this work, the annular (tangential) flow of Newtonian and non-Newtonian fluids in tube bundles has been studied experimentally. Extensive pressure drop data has been obtained embracing wide ranges of the Reynolds number (13,6600) and for two test modules of different geometrical arrangements, but of similar overall void fraction. Preliminary experiments suggest that the pressure drop is mainly determined by the overall void fraction of the bundle and is relatively insensitive to the detailed geometrical configuration of the bundle. A simple predictive correlation has been developed which reconciles the present results for Newtonian and power law fluids with acceptable levels of reliability. Dans le cadre de ces travaux, on a examiné de façon expérimentale l'écoulement annulaire (tangentiel) des fluides newtoniens et non newtoniens dans des faisceaux tubulaires. On a obtenu de nombreuses données de chute de pression englobant de vastes plages du nombre de Reynolds (13-6600), et pour deux modules d'essai de différentes dispositions géométriques, mais à taux de vide global similaire. Les expériences préliminaires suggèrent que la chute de pression est déterminée principalement par le taux de vide global du faisceau et est relativement insensible à la configuration géométrique détaillée du faisceau. La création d'une simple corrélation prédictive a permis de rapprocher les présents résultats pour les fluides newtoniens et des fluides en loi de puissance avec des niveaux acceptables de fiabilité. [source]

Enhancement Boiling Heat Transfer Study of a Newly Compact In-line Bundle Evaporator under Reduced Pressure Conditions

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 3 2006
Z.-H. Liu
Abstract For common flooded-type evaporators, nucleate boiling heat transfer cannot occur on the heated tubes since heat fluxes and wall superheats of heated tubes are generally quite low. However, when the tube spacing is very small, nucleate boiling in restricted spaces can occur easily under low heat flux or low wall superheat conditions. The generation of nucleate boiling can effectively enhance the heat transfer performance of bundle evaporators. This study investigated experimentally the boiling heat transfer enhancement effects of the restricted space in compact in-line tube bundles with smooth tubes under various reduced pressures. The experimental results show that the compact in-line tube bundles have a significantly enhanced heat transfer compared to those of the common tube bundles, and there is an optimum tube spacing that provides the greatest heat transfer enhancement effect. The test pressures have a marked influence on the boiling heat transfer enhancement in the compact bundles. The heat transfer enhancement effect decreases with decreasing test pressure. In addition, the heat transfer enhancement effects of the in-line tube bundles are also compared with those of the staggered bundles. Under reduced pressure, there is no significant difference between the heat transfer enhancement effects for the two types of bundles. [source]