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Heat Transportation (heat + transportation)

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Engineering100%

Selected Abstracts

Heat transportation by oscillatory flow with steady flow component

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 7 2006
Akira Inukai
Abstract This paper deals with heat transportation by an oscillatory flow composed of a sinusoidal oscillatory flow superimposed with a steady flow. Velocity and temperature fields, heat transportation rate, work rate, and heat transportation efficiency were investigated through numerical analysis. Results obtained elucidated that (1) the phase difference between velocity and temperature variation remained the same as that of the sinusoidal reciprocal flow without the use of a steady flow component. (2) In the upstream direction heat was mainly transported by the steady flow component and in the downstream direction transportation was mainly performed by the oscillatory flow component. (3) The heat transportation rate of the present oscillatory flow composed of both steady and oscillatory flow components was less than the arithmetic sum of the rates produced by the steady flow and the sinusoidal oscillatory flow. (4) The heat transportation rate was increased immensely by superimposing the steady flow on the sinusoidal oscillatory flow. (5) Conversely, work done by the present oscillatory flow increased only slightly. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(7): 482,500, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20130 [source]

Feasibility of long-distance transport of thermal energy using solid sorption processes

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 8 2010
Nathalie Mazet
Abstract This paper deals with the challenging transportation of thermal energy over long distances (over 10,km). The innovative concept presented in this paper is based on the transportation of a reactive fluid coupled with two sorption systems involving this fluid in two endothermal and exothermal processes respectively on source site and user site. The transport of this fluid at ambient temperature minimizes the thermal losses and it is therefore relevant for long distances. Moreover, an original concept involving a cascade of two sorption cycles can allow a heat upgrading on the user site using a distant source. This paper focuses on the feasibility of such systems. The potentialities have been detailed according to the reactive pairs, such as the well-known hydrates and ammonia solid/gas reactants, and taking into account thermodynamic and technological constraints. The cold production and transport can be carried out by numerous ammonia-based pairs. Nevertheless, such reactive pairs can perform a heat upgrading, but only if an additional heat source is available on the user site. The transportation of the reactive fluid between source and user sites has been investigated and it is not a limiting point. As it is transported at ambient temperature, the thermal losses are very weak. On the other hand, the pressure losses can be overcome with either an acceptable energetic cost or by slightly changing the operating conditions. Compared to current district heating networks based on sensible heat transportation, such thermochemical systems involving the transportation of a reactive fluid seem more efficient when the user is located more than 10,km away from the source site. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Untersuchung der thermisch-hygrischen Eigenschaften von Ziegeln mit Hohlraumfüllung aus Recyclingmaterial

BAUPHYSIK, Issue 1 2004
Azra Korjenic Dipl.-Ing.
In dem Forschungsprojekt wurde untersucht, ob Ziegel mit einfacher Hohlraumstruktur durch Verwendung einer wärmedämmenden Hohlraumfüllung einen höheren Wärmedurchlaßwiderstand haben. Als Dämmstoff wurde ein Recyclingdämmaterial aus Reststoffen aus der Produktion von Polystyrolplatten sowie Holzbauteilen, die mittels Zementleim zu einem Gemisch verarbeitet wurden, verwendet. Es wurde der Einfluß von Anordnung und Stärke der Dämmschicht sowie von Lage und Geometrie der Hohlräume des Ziegelbausteines auf die thermisch-hygrischen Zustände untersucht. Für die Untersuchung der thermischen Eigenschaften und der Ermittlung der Wärmedurchgangskoeffizienten wurde das Programm THERM verwendet, das den Wärmetransport durch Wärmeleitung im Ziegelscherben und die Transportmechanismen Wärmeleitung, Konvektion und Strahlung in den luftgefüllten Hohlräumen berücksichtigt. Zur Untersuchung des Feuchtigkeitstransports in den Ziegelsteinen wurde das Programmpaket WUFI 2D verwendet. Die Untersuchungen haben gezeigt, daß die so strukturierten Ziegel-Verbundsteine einen etwa doppelt so hohen Dämmwert haben, wie der ursprüngliche Ziegelstein. Die hygrischen Zustände können im Ziegel teilweise über 80 % Luftfeuchtigkeit betragen. Diese Belastung wird als unkritisch eingeschätzt, weil die Holzpartikel mit Zementschlämme umhüllt sind. Investigation on the thermal-hygral behaniour of bricks with canity filling by recycling meterials. In the investigation project was examined whether bricks with simple cavity structure have a higher heat resistance by use of a heat insulation material filling in the cavities. The insulation material is a recycled product made of polystyrene and wood covered and bonded with cement. The influence of the configuration and thickness of the perforated bricks with vertical perforations and the geometry of the cavities of the brick on the thermal moisture states was evaluated. For investigation of the thermal resistance and the heat transmission coefficients were used the simulation program THERM, that considered the heat transportation through conduction in the brick fragments and the transport mechanisms conduction, convection and radiation in the airfilled cavities. The software package WUFI 2D was employed for the investigation of moisture transfer in the bricks. The investigations showed that the composite brick insulation stone has a thermal resistance twice as high as the initial brick. The moisture states can be partially in the brick more than 80 % humidity. This load is estimated as uncritical because the wooden particles are covered with cement slime. [source]