Experimental determination and fractal modeling of the effective thermal conductivity of autoclaved aerated concrete: Effects of moisture content

Jin, Hyunjong; Yao, Xiao-Li; Fan, Li‐Wu; Xu, Xu; Yu, Zi‐Tao

doi:10.1016/j.ijheatmasstransfer.2015.08.103

Cited by 137 publications

(47 citation statements)

References 54 publications

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“…Errors in overwetting protection design can reduce enclosing structure durability and result in premature failure of the building [1][2][3][4][5]. Moisture in enclosing structure thickness influences both on power saving properties of building thermal protective shell [6][7][8][9][10][11], and on human health [12].…”

Section: Moisture Regime and Its Role In Constructionmentioning

confidence: 99%

Assessment of enclosing structure moisture regime using moisture potential theory

2018

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Abstract. The paper describes principal development directions of mathematical models of enclosing structure moisture regime. Benefits of mathematical models based on moisture potential theory are demonstrated. Moisture regime calculation by means of moisture potential, taking liquid and vapor moisture transfer into consideration, and using discretecontinual approach is proposed. New formulas for single-layer and multilayer enclosing structures allowing for numerical analytic determination of moisture potential value in any enclosing structure section, at any moment of time, under continuous control of temperature distribution, have been derived. Moisture distribution has been studied for a number of enclosing structures using different methods of moisture potential theory: unsteadystate method, quasi-stationary method, the proposed discrete-continual method. Moisture regime has been determined for single-layer enclosing structure with ceramic brick basement and lime brick cladding in Moscow. It is shown that the greatest moisture value is achieved in enclosing structure calculation by means of steady-state method. Unsteady-state method gives more accurate moisture distribution. The proposed discretecontinual method gives quantitative and qualitative result of moisture distribution similar to results obtained by unsteady-state method. The benefit of discrete-continual method is a distribution obtained analytically, which allows to use solution results without numerical method application.

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Section: Moisture Regime and Its Role In Constructionmentioning

confidence: 99%

Assessment of enclosing structure moisture regime using moisture potential theory

2018

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“…The internal structure of sand is described by Sierpinski carpet model and the thermal resistance network is built according to the Sierpinski geometry based on the 1-D steady state heat transfer analysis (Ma, et al 2003;Feng, et al 2004;Li, et al 2012;Jin, et al 2016). The basic Sierpinski geometry (Mandelbrot 1983) is shown in Figure 1.…”

Section: Approximation Of the Structure Of Sand By Sierpinski Carpetmentioning

confidence: 99%

“…By building the thermal resistance network, the dimensionless thermal conductivity can be expressed in different steps, as shown in Equations (7) to (8). Figure 3 Thermal resistance network for Sierpinski carpet when step = 0 (two phases) (Jin, et al 2016) Figure 4 Thermal resistance network for Sierpinski carpet when step = 0 (three phases) (Jin, et al 2016) Three-phase fractal model for unsaturated, moist sand…”

Section: Two-phase Fractal Model For Dry Sandmentioning

confidence: 99%

“…The liquid water cannot exist independently in the cavities under unsaturated condition, but covers the exterior surface of solid particles (water films) and accumulate around the intersection points (water bridges) (Ma, et al 2003;Jin, et al 2016), as shown by the blue regions in Figure 4. The degree of moisture level can be expressed by the degree of saturation S w and S w = V w /V, where V w (m 3 ) and V (m 3 ) represent the total volume of the liquid phase and total volume of the sample respectively.…”

Section: Two-phase Fractal Model For Dry Sandmentioning

confidence: 99%

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Fractal Approach to Calculate the Thermal Conductivity of Moist Soil

Cai¹,

Cui²,

Zheng³

et al. 2017

Proceedings of the IGSHPA Technical/Research Conference and Expo 2017

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The ground heat exchanger (GHE) is a key component in the design of a GSHP system and the effective thermal conductivity is one of the most important parameters that determine the heat transfer underground. In this paper, the effect of particle sizes and distributions on the sand thermal conductivity were studied both experimentally and analytically. Fractal method was considered for simulating the thermal conductivity of both dry and moist, unsaturated sand. Seven types of dry sand samples and six types of moist, unsaturated sand were selected in the experiments and results showed that both porosity, fractal dimension and particle size ratio affect the sand thermal conductivity. Based on the fractal theory, the fractal models were applied to predict the sand thermal conductivity under both dry and wet conditions. By comparing to the experimental findings, the proposed model was able to predict the variation on the sand thermal conductivity. However, the contact thermal resistance and water distribution pattern are two key impacts on the soil behaviors and need to be further studied.

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“…Error in construction material moisture condition assessment can result in premature deterioration of the enclosing structure [1,2], high heat loss of the building [3,4], and negative humidity effect on human life [5].…”

Section: Introductionmentioning

confidence: 99%

Unsteady-state moisture behavior calculation for multilayer enclosing structure made of capillary-porous materials

Gagarin

Akhmetov

Zubarev

2018

IOP Conf. Ser.: Earth Environ. Sci.

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View the article online for updates and enhancements. Abstract. The paper studies unsteady-state moisture behavior of multilayer enclosing structure using discrete-continuous method. Modification of Gagarin's differential moisture transfer equation is proposed. The proposed moisture transfer equation within one layer of a multilayer enclosing structure is a second-order differential parabolic equation with constant coefficients. Third-kind boundary conditions of moisture exchange are set for enclosing structure boundaries. Fourth-kind boundary conditions represented by moisture potential flows equality are set at the joint of two different materials. An analytical expression for moisture potential calculation in any enclosing structure section, at any time, under continuous control for temperature distribution, has been derived using discrete-continuous method. Calculations for multilayer enclosing structure consisting of clay brick base and lime brick lining have been made. The obtained results have been compared to calculation results obtained by well-known Gagarin's unsteady-state method and Kozlov's engineering method. It has been shown that the discrete-continuous method allows calculating unsteady-state moisture behavior of multilayer enclosing structures by analytical expression, and obtaining moisture distribution similar to Gagarin's unsteady-state method, thus it can be used by design engineers in practice.

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Experimental determination and fractal modeling of the effective thermal conductivity of autoclaved aerated concrete: Effects of moisture content

Cited by 137 publications

References 54 publications

Assessment of enclosing structure moisture regime using moisture potential theory

Assessment of enclosing structure moisture regime using moisture potential theory

Fractal Approach to Calculate the Thermal Conductivity of Moist Soil

Unsteady-state moisture behavior calculation for multilayer enclosing structure made of capillary-porous materials

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