Analysis of errors in the evaluation of parallel transient hot wire measurements by means of line heat source fits

2019 ◽  
Vol 45 (2) ◽  
pp. 2131-2138 ◽  
Author(s):  
Da Wang ◽  
Qiang Li ◽  
Qian Wang ◽  
Jiansheng Zhang
Keyword(s):  
Heat Source ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
Line Heat Source

scholarly journals Hot-wire measurement in turbulent flow behind a parallel-line heat source

PAMM ◽  
2012 ◽  
Vol 12 (1) ◽  
pp. 493-494
Author(s):  
Pavel Antos ◽  
Vaclav Uruba
Keyword(s):  
Heat Source ◽  
Turbulent Flow ◽  
Parallel Line ◽  
Hot Wire ◽  
Line Heat Source

scholarly journals Apparatus for routine measurements of the thermal conductivity of ice cores

1999 ◽  
Vol 29 ◽  
pp. 151-154 ◽  
Author(s):  
Crescenzo Festa ◽  
Aristide Rossi
Keyword(s):  
Thermal Conductivity ◽  
Ice Cores ◽  
Maximum Temperature ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
Standard Samples ◽  
Experimental Conditions ◽  
Heating Source ◽  
Central Segment ◽  
Wire Method

AbstractAn apparatus is described for measuring the thermal conductivity of ice by the transient hot-wire method. Thermal conductivity A, is determined by tracking the thermal pulse induced in the sample by a heating source consisting of a platinum resistor. A central segment of the same platinum heating resistor acts also as a thermal sensor. A heat pulse transferred to the ice for a period of 40s gives a maximum temperature increment of about 7-14°C. In good experimental conditions, the expected reproducibility of the measurements is within ±3%. The accuracy of the method depends on whether the instrument has been calibrated by reliable standard samples, certified by absolute methods.

Fluid radiation effects in the transient hot-wire technique

2007 ◽  
Vol 90 (3) ◽  
pp. 693-698 ◽  
Author(s):  
Y. Shi ◽  
L. Sun ◽  
F. Tian ◽  
J. E. S. Venart ◽  
R. C. Prasad
Keyword(s):  
Radiation Effects ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
Transient Hot Wire Technique

Thermodynamic behaviour of microstretch viscoelastic solids with internal heat source

2014 ◽  
Vol 92 (5) ◽  
pp. 425-434 ◽  
Author(s):  
Sunita Deswal ◽  
Renu Yadav
Keyword(s):  
Heat Source ◽  
Normal Mode Analysis ◽  
Generalized Thermoelasticity ◽  
Internal Heat ◽  
Internal Heat Source ◽  
Mode Analysis ◽  
Moving Heat Source ◽  
Line Heat Source ◽  
Epoxy Material ◽  
Mech Phys Solid

The dynamical interactions caused by a line heat source moving inside a homogeneous isotropic thermo-microstretch viscoelastic half space, whose surface is subjected to a thermal load, are investigated. The formulation is in the context of generalized thermoelasticity theories proposed by Lord and Shulman (J. Mech. Phys. Solid, 15, 299 (1967)) and Green and Lindsay (Thermoelasticity, J. Elasticity, 2, 1 (1972)). The surface is assumed to be traction free. The solutions in terms of displacement components, mechanical stresses, temperature, couple stress, and microstress distribution are procured by employing the normal mode analysis. The numerical estimates of the considered variables are obtained for an aluminium–epoxy material. The results obtained are demonstrated graphically to show the effect of moving heat source and viscosity on the displacement, stresses, and temperature distribution.

scholarly journals Estimation of thermal conductivity of short pastry biscuit at different baking stages

2014 ◽  
Vol 45 (2) ◽  
pp. 64 ◽  
Author(s):  
Chiara Cevoli ◽  
Angelo Fabbri ◽  
Simone Virginio Marai ◽  
Enrico Ferrari ◽  
Adriano Guarnieri
Keyword(s):  
Thermal Conductivity ◽  
Thermal Processing ◽  
Physical Property ◽  
Physical Models ◽  
Hot Wire ◽  
Line Heat Source ◽  
Food Material ◽  
Wire Method ◽  
Thermal Conductivity Probe

Thermal conductivity of a food material is an essential physical property in mathematical modelling and computer simulation of thermal processing. Effective thermal conductivity of non-homogeneous materials, such as food matrices, can be determined experimentally or mathematically. The aim of the following research was to compare the thermal conductivity of short pastry biscuits, at different baking stages (60-160 min), measured by a line heat source thermal conductivity probe and estimated through the use of thermo-physical models. The measures were carried out on whole biscuits and on powdered biscuits compressed into cylindrical cases. Thermal conductivity of the compacted material, at different baking times (and, consequently at different moisture content), was then used to feed parallel, series, Krischer and Maxwell-Eucken models. The results showed that the application of the hot wire method for the determination of thermal conductivity is not fully feasible if applied directly to whole materials due to mechanical changes applied to the structure and the high presence of fats. The method works best if applied to the biscuit component phases separately. The best model is the Krischer one for its adaptability. In this case the value of biscuit thermal conductivity, for high baking time, varies from 0.15 to 0.19 Wm<sup>–1</sup> K<sup>–1</sup>, while the minimum, for low baking time, varies from 0.11 to 0.12 Wm<sup>–1</sup> K<sup>–1</sup>. These values are close to that reported in literature for similar products.

scholarly journals Application and testing of a new simple experimental set-up for thermal conductivity measurements of liquids

2017 ◽  
Vol 21 (3) ◽  
pp. 1195-1202 ◽  
Author(s):  
Andrej Stanimirovic ◽  
Emila Zivkovic ◽  
Nenad Milosevic ◽  
Mirjana Kijevcanin
Keyword(s):  
Thermal Conductivity ◽  
Measurement Uncertainty ◽  
Thermophysical Properties ◽  
Deionized Water ◽  
Conductivity Measurements ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
New Apparatus ◽  
Wire Method ◽  
Set Up

Transient hot wire method is considered a reliable and precise technique for measuring the thermal conductivity of liquids. The present paper describes a new transient hot wire experimental set-up and its initial testing. The new apparatus was tested by performing thermal conductivity measurements on substances whose reference thermophysical properties data existed in literature, namely on pure toluene and double distilled deionized water. The values of thermal conductivity measured in the temperature range 25 to 45 ?C deviated +2.2% to +3% from the literature data, while the expanded measurement uncertainty was estimated to be ?4%.

Analysis of the Transient Hot-Wire Method to Measure Thermal Conductivity of Silica Aerogel: Influence of Wire Length, and Radiation Properties

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Ellann Cohen ◽  
Leon Glicksman
Keyword(s):  
Thermal Conductivity ◽  
Silica Aerogel ◽  
Test Method ◽  
Wire Radius ◽  
Wire Length ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
End Effects ◽  
Transient Hot Wire Method ◽  
Wire Method

When the transient hot-wire method is used to measure the thermal conductivity of very low thermal conductivity silica aerogel (in the range of 10 mW/m·K at 1 atm) end effects due to the finite wire size and radiation corrections must be considered. An approximate method is presented to account for end effects with realistic boundary conditions. The method was applied to small experimental samples of the aerogel using different wire lengths. Initial conductivity results varied with wire length. This variation was eliminated by the use of the end effect correction. The test method was validated with the NIST (National Institute of Standards and Technology) Standard Reference Material 1459, fumed silica board to within 1 mW/m·K. The aerogel is semitransparent. Due to the small wire radius and short transient, radiation heat transfer may not be fully accounted for. In a full size aerogel panel radiation will augment the phonon conduction by a larger amount.

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