1,721,034 research outputs found
Thermal analysis of a glass bending process
No full textThe paper presents the thermal simulation of naturally ventilated ovens used in glass sheets hot forming for windscreen production. The determination of thermal and flow conditions in the oven and, consequently, the windshield temperature distribution is necessary both for the productive process optimisation and to assure beforehand, without any iterative tuning process, the required characteristics of the product considered. To this purpose, the authors carried out a 3D numerical simulation of the thermal interaction between the glass and the oven internal surfaces during the whole heating process inside the oven. In particular, a finite volumes method was used to take into account both the convective, conductive and radiative heat transfer in the oven. The numerical temperature distribution in the glass was validated through the comparison with the data obtained from an experimental apparatus designed and built for the purpose. © 2005 Elsevier Ltd. All rights reserved
Effects of hydrophobic treatment on thermophysical properties of lightweight mortars
No full textThe effects of an innovative hydrophobic treatment and moisture content on thermal conductivity of lightweight mortars were investigated. The aim of this study was to provide data on the insulating properties of the above mentioned mortars, that can be used in engineering practice, once properly processed. Various mortars were prepared by mixing Portland cement and/or lime with different granulated aggregates such as Neapolitan tuff, expanded clay or siliceous standard sand. After a curing time of 28 days, a set of mortars was directly tested in terms of thermal conductivity at different moisture content, comparing the results obtained from the corresponding mortars previously submitted to hydrophobic treatment. Finally, the effects of hydrophobic treatment on other physical properties such as water vapour permeability and capillary rise were also investigated. © 2005 Elsevier Inc. All rights reserved
Influence of contact mechanics in the prediction of the effective thermal conductivity of spheroid packed beds
No full textThermal contact conductance is an important parameter in
a wide range of thermal phenomena, and consequently a large
number of experimental, numerical and statistical investigations
have been carried out in literature. In the present paper an
analysis of thermal contact resistance is carried out to predict
heat transfer between spherical rough surfaces in contact, by
means of a statistical approach. The micro-geometry of the
surface is described through a probabilistic model based on the
peak height variability and invariant asperity curvature radius.
The numerical model has been applied to evaluate the effective
thermal conductivity of packed beds of steel spheroids and
validated through the comparison with the experimental data
obtained by means of an apparatus designed and build up for
this purpose
Tracheobronchial and alveolar dose of submicrometer particles for different population age groups in Italy
No full textExposure to ultrafine particles (diameter less than 100 nm) is an important topic in epidemiological and toxicological studies. This study used the average particle number size distribution data obtained from our measurement survey in major microenvironments, together with the people activity pattern data obtained from the Italian Human Activity Pattern Survey to estimate the tracheobronchial and alveolar dose of submicrometer particles for different population age groups in Italy. We developed a numerical methodology based on Monte Carlo method, in order to estimate the best combination from a probabilistic point of view. More than 10<sup>6</sup> different cases were analyzed according to a purpose built sub-routine and our results showed that the daily alveolar particle number and surface area deposited for all of the age groups considered was equal to 1.5 × 10<sup>11</sup> particles and 2.5 × 10<sup>15</sup> μm<sup>2</sup>, respectively, varying slightly for males and females living in Northern or Southern Italy. In terms of tracheobronchial deposition, the corresponding values for daily particle number and surface area for all age groups was equal to 6.5 × 10<sup>10</sup> particles and 9.9 × 10<sup>14</sup> μm<sup>2</sup>, respectively. Overall, the highest contributions were found to come from indoor cooking (female), working time (male) and transportation (i.e. traffic derived particles) (children)
FEA calculation of pressure distortion coefficients of gas-operated pressure balances - EURAMET project 1039
No full textAnalisi sperimentale della conduttivita' termica di materiali edili al variare del contenuto di umidità
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Single vs multi parameter calibration for the numerical simulation of submerged flows in jet grouting applications
No full textExperimental investigation of thermal properties of insulating materials as the moisture content varies
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