1,721,026 research outputs found
Possible experimental X-ray diffractometry evidence of couple-stresses - ASME
No full textASME JOURNAL OF APPLIED MECHANIC
Conduttività termica di alimenti e sua variazione in conseguenza del processo di surgelamento
No full textNel presente lavoro è stata misura sperimentalmente con il metodo della sonda (probe method) la conduttività termica della carne di maiale, in funzione della temperatura, nelle seguenti condizioni: solo grasso (strutto), carne magra (lombo), nello stato tal quale, congelato, scongelato e ricongelato, con la direzione di propagazione del calore perpendicolare alle fibre e mista (variabile tra parallela e perpendicolare). Dalle misure si evince che la conduttività del grasso è poco dipendente dalla temperatura, che in direzione parallela alle fibre del tessuto magro è maggiore che in quella perpendicolare, e che nel risurgelamento la conduttività aumenta del 10% circa. Questo ultimo risultato porta ad definire un metodo di controllo qualità del prodotto congelato, che verifichi l’assenza di uno scongelamento accidentale durante la sua conservazione, operazione che rappresenta un rischio per la sicurezza alimentare
High temperature (till 1500°C) contemporary thermal conductivity and thermal diffusivity measurements with the step flat heat source
Full text linkThe method for contemporary measuring thermal conductivity, thermal diffusivity and thermal contact resistance up to 1500°C has been assessed. First the heat propagation model has been developed to be used in least square procedure to process temperature data and give the best estimate on the unknown parameters. Second special devices to be used in the experimental procedure have been designed and built or are going to be built. In the meanwhile ambient temperature tests on bricks have been carried out to establish the data processing procedure, and to recognize the experimental troubles likely to be found. These tests shows that the experimental data well follow the theoretical prediction, the thermophysical parameter can be evaluated with good accuracy, and that care must be taken to satisfying the theoretical assumptions on the base of the model, and to accurately process data for taking into account mutual dependence of the parameters © 2009 SPIE
Effetto della quantità di ghiaccio che si forma durante il congelamento sulla conduttività termica degli alimenti
No full textEffetto della quantità di ghiaccio che si forma durante il congelamento sulla conduttività termica degli aliment
Basic Problems in Thermal-Conductivity Measurements of Soils
No full textThe thermal conductivity of pozzolanic soil (a fine sandy, unconsolidated,
alluvial soil from Lazio, Italy, based on volcanic ash) and blue marlstone rocks (from
Alba, Piedmont, north Italy) was measured, using a thermal probe technique, over a
wide range of temperatures from−20 ◦Cto+20 ◦C. Unfrozen pozzolanic soil thermalconductivity
data display surprisingly lowvalues about 3 to 4 times smaller thanwater;
for frozen soils, the data are just slightly higher than for the unfrozen state but they are
still 2 to 3 times lower than for water and seven times lower than for ice. This outcome
is probably due to a high internal porosity of individual volcanic ash particles. The
influence of the bulk soil porosity on the measured thermal conductivitywas found to be
rather negligible; the observed slight variation of the thermal conductivity is possibly
due to the diverse grain size distribution of soil samples excavated from different
depths of the ground. The blue marlstone rock has a considerably higher thermal
conductivity than pozzolanic soil, likely due to its very small porosity, consolidated
structure, and different implicated minerals. The frozen rock has just about a 30 %
higher thermal conductivity than that for the unfrozen state. A temperature-dependent
thermal conductivity is observed in the freezing state only. Test results show how heat
transfer between the thermal probe and surrounding soil is influenced by storage of
heat in the tested material, conduction heat flow, water evaporation due to heating, and
finally by vapor diffusion and circulation
Misura della diffusività termica ad alta temperatura dei materiali delle SOFC con il flash method
No full textThermal Diffusivity of Sofc Materials by Means bf Flash Method at High Temperature
Fundamental problems in thermal conductivity measurements of soils
No full textMeasurements of thermal conductivity, open porosity, water content and water saturation degree have been made on two different kinds of samples, one incoherent (earth) extracted at different depths from the surface in a building excavation in the nearby of Rome, the second, a compact sedimentary rock (blue malmstone) just under the surface from the ills surrounding Alba (Piedmont, north of Italy).
For the thermal conductivity the probe method (line heat source) has been used, taking care of the practical problems arising during tests (minimizing thermal contact resistance, drilling hole for the probe housing). Results show the typical behaviour of thermal conductivity vs. temperature of a porous medium containing water. Thermal conductivity and saturation degree clearly increases with depth under the soil surface due to increased compactness and less water evaporation in air. Also open porosity reduces with depth due to increased compactness.
Results show also the presence of four typical phenomena happening during the soil heating: storage of heat due to thermal capacity of the material, heat conduction driven by thermal conductivity, water evaporation due to heating and vapour diffusion and circulation
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