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found while thermal conductivity strongly increases. A hardening of concrete can be seen after setting process has finished. The RTM instrument is constructed to fulfill environmental and industrial exposition. Conclusions Paper presents applicability of the thermophysical tester RTB and the monitoring system RTM in various area of technology. Thermal conductivity, thermal diffusivity and specific heat of the porous structures can be easy determined providing that thermodynamic conditions are set up like temperature and the surrounding atmosphere and pressure. Freezing and thawing effects can be studied in detail. Instruments can be combined to reach more sophisticated experimentation in area of the propagation of freezing/thawing fronts and in area of moisture diffusion in porous system. Combination of instruments allow comfortable setting the required thermodynamic conditions like, surrounding atmosphere, surrounding pressure and the temperature. A monitoring of the concrete setting was shown. Clear endothermic effects together with the strong increase of the thermal conductivity was found. Both effects correspond to setting process. Acknowledgements: The paper was supported by the project APVV – 0497 – 07, the project MVTS ‐ MAFINCO and by the VEGA project 2/5100/25 References [1] R.P. TYE: Thermal Conductivity, (Academic Press, London, New York, 1968) [2] K.D. MAGLIĆ, A. CEZAIRLIYAN and V.E. PELETSKY: Compendium of Thermophysical Property Measurement Methods in Recommended Measurement Techniques and Practices, Vol.2, Plenum Press, New York and London (1992) [3] J. KREMPASKÝ: Meranie termofyzikálnych veličín (VEDA SAV, Bratislava 1969), in Slovak [4] Ľ. KUBIČÁR and V. BOHÁČ, in: Proc. of 24th Int. Conf on Thermal Conductivity / 12th Int. Thermal Expansion Symposium, October 26‐29, (1997), p. 135 [5] Ľ. KUBIČÁR, V. VRETENÁR and V. BOHÁČ, Solid State Phenomena Vol. 138 (2008) pp 3‐ 28 [6] Ľ. KUBIČÁR, V. VRETENÁR, V BOHÁČ, V ŠTOFANIK, P DIESKA, Engineering Geology 2009, submitted for print [7] Ľ. KUBIČÁR, V. BOHÁČ, V. VRETENÁR, V. ŠTOFANIK, P. DIESKA, C. C. ANÍBARRO, Ľ. BAGEĽ, I., NOVAK, I. CHODAK, Proc. of 30th Int. Conf on Thermal Conductivity / 18th Int. Thermal Expansion Symposium, August 29 – September 2, Pittsburgh, 2009 70
Computational modelling of temperature and moisture profiles in a multi‐layered system of building materials Jiří Maděra 1 , Jan Kočí 1 , Robert Černý 1 1 Czech Technical University in Prague, Faculty of Civil Engineering, Department of Materials Engineering and Chemistry, Prague, Czech Republic Abstract: Computational modelling of temperature and moisture profiles in a multi‐layered system of building materials is performed using TRANSMAT computer code developed at the Czech Technical University in Prague. A characteristic example of a building envelope with lightweight load‐ bearing material is chosen. The effect of both exterior render and thermal insulation material on the hygrothermal performance of the wall is clearly demonstrated. Keywords: computational modelling, building envelope, temperature and moisture Introduction In spite of the autoclaved aerated concrete (AAC) is a structural material commonly used around Europe, high frequency of AAC structures defects has become well known among the potential investors what leads in consequence to the weakening of the position of AAC on the European building materials market which is unfortunate because the material can be considered as environmentally friendly and has considerable potential for future applications. The design of AAC building envelopes has mostly been done by empirical rules for construction until now. As a result, approaches to design have differed case by case and failures have resulted as a result of incorrect specifications and errors in construction. Typical failure examples are cracking of both external and internal finishes, detachment of renders from the AAC block (sometimes with the AAC itself), cracks around windows and doors, frost failure of external render. The current standards cannot help to the designers in preventing failure. Moisture analysis in both Czech and European codes is restricted to water vapor transport in steady‐state conditions. This presents a risk for a designer as water suction, water vapor convection, and the cross effects between heat and moisture transport are not considered and this can often lead to the underestimation of the amount of liquid water in the envelope or the condensation zone can appear in another place than predicted by the standard calculation. In this paper, hygrothermal conditions in characteristic types of AAC‐based building envelopes are simulated using the methods of computational modeling which can provide more detailed and accurate information than the application of oversimplified methods in current standards, and thus can allow qualitatively better service life estimates. Materials and building envelopes In the computer simulations of temperature and relative humidity fields we have solved four different building envelopes, based on AAC load‐bearing structure and two types of external 71
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Thermophysics 2009 29 th and 30 th
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Content Ivan Baník, Jozefa Lukovi
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Measurement of the thermo‐physica
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As the right side of the previous r
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The initial vector k r in the k1, k
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2.4 The computer programs testing T
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Investigation of moisture influence
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⎛ t t ⎞ −1 ⋅ ln⎜ ⎝ tm t
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Density [kg.m -3 ] 620 600 580 560
Page 19 and 20: for a new building have to be great
Page 21 and 22: Fig.1. Photo of the hot ball sensor
Page 23 and 24: Fig.6.Left: formation of blocks. Ri
Page 25 and 26: 4. Conclusions With this experiment
Page 27 and 28: 1a. Three‐dimensional temperature
Page 29 and 30: n+ ∞ ( ) 4 ( ) ∑ π n= 1 ( 2 1)
Page 31 and 32: a 2 2 ( Fo) ⎛ l ⎞ r = ⎜ ⎟
Page 33 and 34: Substitution of ordinates of the in
Page 35 and 36: Moisture transport through porous m
Page 37 and 38: Data acquired through the hot ball
Page 39 and 40: In this way, the water spreading wa
Page 41 and 42: Thermal conductivity [W m -1 K -1 ]
Page 43 and 44: Relationship between relative permi
Page 45 and 46: ( ) i n Φ − Φ K i = ki i i, cri
Page 47 and 48: Figure 4: Comparison of measured an
Page 49 and 50: Computational modelling of coupled
Page 51 and 52: a ξ = d 2 ( lnκ − lnκ ) lnξ +
Page 53 and 54: on the results of experiments and c
Page 55 and 56: Figures 8a, b: Moisture content (a)
Page 57 and 58: Conclusions The computer simulation
Page 59 and 60: properties as are the bulk density,
Page 61 and 62: elation determined from the measure
Page 63 and 64: In the evaluation of the difference
Page 65 and 66: Heat source I RT-Lab II Specimen Ch
Page 67 and 68: Thermal conductivity [W m -1 K -1 ]
Page 69: silicon glue epoxy probe hole Figur
Page 73 and 74: 1 2 3 EXT. INT. 5-15 50-60 375 5 Nu
Page 75 and 76: Fig. 4 shows a comparison of the re
Page 77 and 78: Envelope D Figs. 14, 15 present the
Page 79 and 80: Application of computational modell
Page 81 and 82: Table 2: Basic material characteris
Page 83 and 84: Temperature [K] 320 300 280 260 240
Page 85 and 86: Mineral wool has the same effect as
Page 87 and 88: Nowadays, most of concrete building
Page 89 and 90: Figure 2: Ceramic dessicator plate
Page 91 and 92: dessicators are decreased by the pe
Page 93 and 94: The surface water vapour diffusion
Page 95 and 96: where h is the Planck constant and
Page 97 and 98: (a) (b) Figure 2: Schematic picture
Page 99 and 100: [7] BLUM, V.; HART, G. L. W.; WALOR
Page 101 and 102: Analysis of moisture hysteresis of
Page 103 and 104: The water content during scanning b
Page 105 and 106: All analysed cellulose based materi
Page 107 and 108: Thermodilatometry of ceramics using
Page 109 and 110: of the dilatometric cell with the s
Page 111 and 112: thermal expansion / % 2 1,5 1 0,5 0
Page 113 and 114: [8] KAMSEU, E. ; LEONELLI, C. ; BOC
Page 115 and 116: heating, the temperatures were meas
Page 117 and 118: temperature difference [°C] 140 12
Page 119 and 120: temperature difference [°C] 180 16
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[4] ČÍČEL, B. - NOVÁK, I. - HOR
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space and the crystallization press
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20 mm face to the penetrating KNO3
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Cb [kg/m 3 (sample)] 1800 1600 1400
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D [m 2 /s] 1.0E-03 1.0E-04 1.0E-05
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Thermomechanical modelling of matur
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ε ε (velocity rates) a x , t . By
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ε ε w v The process of redistribu
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Conclusion In this paper we have br
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most popular among direct technique
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• Closed pores (not available for
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espective volume of inclusions frac
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Summary Among the indirect methods
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Thermal, hygric and salt‐related
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The water vapor diffusion coefficie
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Thermal properties Thermal conducti
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On the other hand, apparent moistur
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Thermal conductivity.. [Wm -1 K -1
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Properties of innovative materials
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or hygrothermal analysis of buildin
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where Da is the diffusion coefficie
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The bending and compressive strengt
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moisture diffusivity which was caus
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Abstract: Thermal conductivity in d
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, (5) where λ is thermal conductiv
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4.Measured values and calculation I
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Acknowledgements This research has
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3 Results During heating, the struc
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Acknowledgment This work was suppor
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mixture by short mixing, the mixtur
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detected by MIP and thus the intrus
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diffusion. The general Arrhenius eq
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Thermal conductivity measurement of
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S s o 2 4 4 λ ∇ T = wεσ ( T
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steel (20 W m ‐1 K ‐1 ) is arou
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significant larger cross‐section.
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Water and heat transport properties
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The open porosity ψ0 [%], bulk den
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Table 3: Basic material parameters
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Acknowledgements This research has
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comparison of results we can determ
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specimen and heat source R at infin
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6.E-04 4.E-04 ΔU (V) 2.E-04 0.E+00
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[3] KUBIČÁR Ľ. Pulse method of m
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silicate binders as partial replace
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Table 2. Mechanical properties HPC
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HPC Table 5. Water transport proper
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The results obtained for using high
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aerospace engineering, cryogenic en
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4 ⎡ ′ ⎤ Δθ( t) = ⎢ l ∫
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Alloy Components Weight Percent, [%
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Figure 8: Final results of the ther
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Figure 11: Preliminary results of t
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In case of the FeNi35, FeNi39 and F
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Experimental Methods Compressive st
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Type of mixture Water transport pro
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Thermal properties The thermal para
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Identification of Some Thermophysic
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Physical model of the direct proble
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2 ( λ − Bi) sin( λ) − 2λ Bic
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To calculate the sensitivity coeffi
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symmetry of the specimen when the t
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Figure 5: View of experimental setu
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During the inverse calculations the
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temperature dependence for the blac
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4. Conclusions The results of the t
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cross‐planar direction applying s
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3. Thermal diffusivity identificati
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Table 2: Effect of the convective h
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[2] BODZENTA, J.; BURAKA, B.; NOWAK
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doc. Ing. Jiří Vala, CSc. Brno Un
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