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Thermal Protection (thermal + protection)
Selected AbstractsNumerical determination of 3D temperature fields in steel jointsFIRE AND MATERIALS, Issue 2-4 2004Jean-Marc Franssen Abstract A numerical study was undertaken to investigate the temperature field in steel joints and to compare the temperatures in the joints with the temperatures of the adjacent steel members on the hypothesis that the thermal protection is the same on the joint and in the members. Very brief information is given on the numerical model, supplemented with parametric studies made in order to determine the required level of discretization in the time and in the space domain. A simplified assumption for representing the thermal insulation is also discussed and validated. Different numerical analyses are performed, with a variation of the following parameters: (i) type of joints, from very simple to more complex configurations, with welds and/or bolts, all of them representing joints between elements located in the same plane; (ii) unprotected joints or protected by one sprayed material; (iii) ISO, hydrocarbon or one natural fire scenario. The fact that the thermal attack from the fire might be less severe because the joints are usually located in the corner of the compartment is not taken into account. Copyright © 2004 John Wiley & Sons, Ltd. [source] Experimental study on flow characteristics of a sleeved jet into a main crossflowHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 1 2004H.L. Wu Abstract Experiments were carried out on the hydraulic mechanism of the thermal shock caused by cold jet injection at a T-junction with thermal sleeve in the reactor cooling system using digital particle imaging velocimetry (DPIV) technique to measure the flow in the main duct and in the annular space of the sleeve tube. The flow and vorticity characteristics were investigated at jet-to-crossflow velocity ratios of 0.5 to 4. There was a stream of discharge from the annular space at the rear part of the sleeve near the jet exit, which resulted in decreasing the influence of the jet on the downstream wall. The intensive vorticity in the near wake mainly originated from the shear layer vorticity of the jet and the annular discharge stream. The intensive vorticity soon broke down and dissipated, and further developed into the counterrotating vortex pair in the far wake. The flow in the annulus was closely dependent on R, and thermal protection of the sleeve would become evident at higher R. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(1): 24,31, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10131 [source] Untersuchung des Wärmeschutzes von Außenecken über unbeheizten Kellern in Wohngebäuden , die Achillesferse von massiven Außenwänden mit äußerer Wärmedämmung?BAUPHYSIK, Issue 4 2004Christoph Geyer Dr. rer. nat. Außenwände von Wohngebäuden werden häufig als massive Mauerwerkswände mit einer außenliegenden Wärmedämmung erstellt. Bei dieser Wandkonstruktion trennt aber der Mauerwerkssockel der massiven Außenwand im Erdgeschoß die Wärmedämmebene der Außenwand von der Wärmedämmebene der Kellerdecke über einem unbeheizten Keller. Hierdurch entsteht eine linienförmige Wärmebrücke. Die für den Mindestwärmeschutz kritischste Stelle tritt an der Außenecke im Erdgeschoß auf, wo sich je zwei dieser linienförmigen Wärmebrücken überlagern. Daher wird die minimale raumseitige Oberflächentemperatur an dieser Ecke für die Beurteilung des Mindestwärmeschutzes der Konstruktion herangezogen. Durch eine Vielzahl von dreidimensionalen Wärmebrückenberechnungen werden die Konstruktionseigenschaften der angrenzenden ebenen Bauteile herausgearbeitet, welche die minimale, raumseitige Oberflächentemperatur in der Außenecke über einem unbeheizten Keller und damit den Mindestwärmeschutz der Konstruktion beeinflussen. Es zeigt sich, daß eine minimale raumseitige Oberflächentemperatur in der Außenecke von 12, 6 °C erst mit Wärmedurchlaßwiderständen der Tragschale bzw. der gesamten Wandkonstruktion nachgewiesen werden kann, die wesentlich höher als 1, 2 m2K/W sind. Damit ist für diese Art von Außenwänden ein Mindestwärmeschutz nach Tabelle 3, DIN 4108-2 [1] mit einer Anforderung an den Wärmedurchlasswiderstand von R , 1,2 m2K/W nicht ausreichend, um den Mindestwärmeschutz auch für die Außenecke im Erdgeschoß rechnerisch nachweisen zu können. Es wird daher vorgeschlagen, ergänzende Hinweise in die Norm aufzunehmen. Examination of the thermal insulation characteristics of external corners above unheated basements in dwellings , the Achilles' heel of heavy-weight external walls with thermal insulation on the outside? External walls in dwellings consist often of a heavy-weight wall and a thermal insulation fixed outside. With this construction the insulation of the external wall is separated by the plinth of the external wall from the thermal insulation incorporated in the slab above an unheated basement. This results in a thermal bridge along the edge of the basement slab. The most critical point of the construction with regard to thermal protection occurs at the exterior corner at ground floor level, where two linear thermal bridges overlay. For this reason the minimum inner surface temperature of the corner is used to estimate the heat protection of the construction. A number of calculations of the minimum temperature at the interior surface of this three dimensional thermal bridge is performed to evaluate the parameters of the adjacent construction details which affect the minimum temperature at the inner surface of the corner. To reach the minimum temperature at he inner surface of the corner of 12.6 °C demanded by the German standard DIN 4108-2 as the minimum requirement of heat protection for thermal bridges, thermal resistances of the whole wall construction much higher than 1.2 m2K/W are necessary. For this construction type of exterior walls a thermal resistance of 1.2 m2K/W as demanded in table 3 of the German standard DIN 4108-2 as a minimum heat insulation for exterior walls can be shown to be insufficient to assure a minimum temperature of 12.6 °C at the inner surface of the corner at ground floor level. Thus it is proposed to add additional notes concerning this construction type in this standard. [source] The impact of newborn bathing on the prevalence of neonatal hypothermia in Uganda: A randomized, controlled trialACTA PAEDIATRICA, Issue 10 2005Anna Bergström Abstract Aim: To elucidate the impact of bathing on the prevalence of hypothermia among newborn babies exposed to the skin-to-skin (STS) care technique before and after bathing. Methods: Non-asphyxiated newborns after vaginal delivery (n=249) in a Ugandan referral hospital were consecutively enrolled and randomized either to bathing at 60 min postpartum (n=126) or no bathing (n=123). All mothers practised skin-to-skin care of their newborns. Four rectal and tympanic registrations of newborn temperatures were carried out in both groups directly after drying at birth, and at 60, 70 and 90 min postpartum. Results: Bathing of newborns in the first hour after delivery resulted in a significantly increased prevalence of hypothermia, defined as temperature <36.5°C, at 70 and at 90 min postpartum despite the use of warmed water and the application of the STS method. There was no neonatal mortality. Aside from the bathing procedure, no background factor potentially predisposing the newborns to hypothermia was identified. Conclusion: Bathing newborn babies shortly after birth increased the risk of hypothermia despite the use of warm water and STS care for thermal protection of the newborn. [source] | ||||||||||