A Methodology for Experimental Research of the Freezing Process of Logs

Deliiski, Nencho; Tumbarkova, Natalia

doi:10.1515/aslh-2016-0013

Cited by 8 publications

(16 citation statements)

References 8 publications

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“…(16) make the mentioned curves more lenient. During our simulations with the model, using the approach suggested above and the mathematical descriptions of Q v-fw and Q v-bw , we obtained good qualitative and quantitative conformity between the calculated and experimentally determined temperature distribution in the log's longitudinal section during the whole process of the freezing of both the free and the bound water not only in the studied beech log for the purposes of this paper, but also many other logs above the hygroscopic range (including the poplar logs presented in Deliiski -Tumbarkova (2016).…”

Section: Figure 5 Change In Q V-fw Q V-bw and Q V-total During Thsupporting

confidence: 67%

“…Based on the data in the references cited above, the value of 3.34•10 5 J•kg -1 as constant for the specific latent heat for both the free and the bound water in the wood materials has been accepted in the present paper. Our wide experiments with different wood species showed that the free water freezing occurs in the small range from 0 o C to -1 o C (Deliiski -Tumbarkova 2016). This means that the acceptance of the non-temperature dependent constant value of 3.34•10 5 J•kg -1 as a specific latent heat of the free water is correct.…”

Section: Mathematical Description Of the Internal Heat Sources In Logmentioning

confidence: 68%

“…A logical condition in the software for the model's solution that registers and records the moments when the temperature of each knot decreases below 273.15 K (i.e. below 0 o C) and then registers and records temperature conditions for the crystallization of the free water separately for each knot has been introduced earlier (Deliiski -Tumbarkova 2016). This means that the current number of the knots in which the free water already "crystallizes", N ice-fw , has been constantly determined synchronously with the obtaining of the temperature distribution.…”

Section: Figure 3 Calculated With the Model Change In T M-fr T S mentioning

confidence: 99%

“…The heat energies for the freezing of the free and bound water are not equal to the specific latent heat of the water. As pointed out in (Deliiski -Tumbarkova 2016), the latent heat is used for description of the thermal energy only, which is needed for the change of the aggregate state of a given substance without changing its temperature.…”

Section: Figure 5 Change In Q V-fw Q V-bw and Q V-total During Thmentioning

confidence: 99%

“…Reports about the temperature distribution in frozen logs subjected to defrosting are limited in the accessible specialized literature (Steinhagen 1986, 1991, Steinhagen -Lee 1988, Khattabi -Steinhagen 1992, 1993, 1995, Deliiski 2004, 2009, 2011, Deliiski -Dzurenda 2010, Deliiski et al 2015a, Hadjiski -Deliiski 2015. In addition, research into the temperature distribution in logs during the freezing process has been limited (Deliiski -Tumbarkova 2016. Thus, there is considerable scientific and practical interest in the modeling and the multi-parameter study of the freezing process of logs.…”

Section: Introductionmentioning

confidence: 99%

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An Approach for Computing the Heat Sources in Logs Subjected to Freezing

Deliiski¹,

Tumbarkova²

2018

Acta Silvatica Et Lignaria Hungarica

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This study suggests an approach for computing the specific energies of the internal heat sources in logs subjected to freezing. The approach maximally considers the physics of the freezing processes of both the free and the bound water in wood. It reflects the influence on the mentioned energies of the wood density above and below the hygroscopic range. It also considers the icing degrees formed separately by both the free and bound water in the logs, as well as the influence of the fiber saturation point of each wood species on its respective amount of non-frozen water depending on temperatures below 272.15 K. Mathematical descriptions of the specific heat energies Qv-fw and Qv-bw released in logs during free water freezing in the range from 0 °C to −1 °C and of the bound water below –1 °C, respectively, have been executed. These descriptions are introduced in own 2D non-linear mathematical model of the freezing process of logs. For the solution of the model and computation of the energies Qv-fw and Qv-bw, a software program based on the suggested approach and mathematical descriptions was prepared in FORTRAN, which was input into the calculation environment of Visual Fortran. With the aid of the program, computations were completed to determine the energies Qv-fw and Qv-bw and their sum, Qv-total of a beech log subjected to freezing. The beech log had a diameter of 0.24 m, a length of 0.48 m, an initial temperature of 20.5 °C, a basic density of 683 kg·m−3, and a moisture content of 0.48 kg·kg–1 during its 30 hours in a freezer at approximately −30 °C.

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Section: Figure 5 Change In Q V-fw Q V-bw and Q V-total During Thsupporting

confidence: 67%

Section: Mathematical Description Of the Internal Heat Sources In Logmentioning

confidence: 68%

Section: Figure 3 Calculated With the Model Change In T M-fr T S mentioning

confidence: 99%

Section: Figure 5 Change In Q V-fw Q V-bw and Q V-total During Thmentioning

confidence: 99%