Model evaluation of heat and mass transfer in wood exposed to fire

Pečenko, Robert; Svensson, Staffan; Hozjan, Tomaž

doi:10.1007/s00226-016-0813-5

Cited by 8 publications

(3 citation statements)

References 21 publications

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“…In Pečenko et al (2015Pečenko et al ( , 2016, a model for multiphase transfers of different mediums coupled by the heat transfer was introduced. There, the heat-mass transfer in wood is described by an energy conservation equation and multiple mass conservation equations for air, water vapour and bound water taking into account the sorption process between bound water and water vapour as well.…”

Section: Coupling Heat-mass Transfer Model With the Pyrolysis Modelmentioning

confidence: 99%

“…There, the heat-mass transfer in wood is described by an energy conservation equation and multiple mass conservation equations for air, water vapour and bound water taking into account the sorption process between bound water and water vapour as well. The model (Pečenko et al 2015(Pečenko et al , 2016 is upgraded in this paper, where, in addition, the phenomena occurring during wood pyrolysis are coupled with heat and moisture transfer processes. Air transfer equation is replaced by the equation describing the transfer of residual gas mixture, i.e.…”

Section: Coupling Heat-mass Transfer Model With the Pyrolysis Modelmentioning

confidence: 99%

“…Yuen et al (2013) introduced a 3D model for wet wood pyrolysis neglecting the influence of the bound water diffusion and the diffusion of gas mixture components. However, as shown in Pečenko et al (2016), where multiphase mass transfer is considered, the process of bound water diffusion in the cell wall significantly affects the charring depth and should not be disregarded. In addition, the multi-phase models are in comparison to single-phase models, such as (Younsi et al 2006(Younsi et al , 2007 more accurate since the actual physical state in wood during the moisture and temperature variation is taken into account (Frandsen et al 2007a, b;Hozjan and Svensson 2011).…”

Section: Introductionmentioning

confidence: 99%

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A novel approach to determine charring of wood in natural fire implemented in a coupled heat-mass-pyrolysis model

Pečenko

Hozjan

2020

Holzforschung

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The paper presents a novel approach to determine charring of wood exposed to standard and natural fire that is based on a new numerical model named PyCiF. The new model couples an advanced 2D heat-mass model with a pyrolysis model. A new charring criterion based on a physical phenomenon is implemented in the PyCiF model to determine charring of wood. This presents the main advantage of the new PyCiF model in comparison to common modelling approaches, which require an empirical value of the charring temperature that is often called the char front temperature. The fact that the char front temperature is not an explicit value as assumed by the isotherm 300 °C is advantageously considered in the presented approach where an assumed empirical value of the char front temperature is not directly required to determine the thickness of char layer. The validation of the PyCiF model against experimental results showed great model accuracy, meaning that the model is appropriate for the evaluation of charring depths of timber elements exposed to the standard fire as well as the natural fires. Additionally, as shown in the case study, the presented approach also enables to determine the char front temperature for various natural fire exposures. This will be especially important for the upgrade of the new design methods for fire safety of timber elements exposed to natural fire given in the various design codes such as Eurocode 5.

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Section: Coupling Heat-mass Transfer Model With the Pyrolysis Modelmentioning

confidence: 99%

Section: Coupling Heat-mass Transfer Model With the Pyrolysis Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A novel approach to determine charring of wood in natural fire implemented in a coupled heat-mass-pyrolysis model

Pečenko

Hozjan

2020

Holzforschung

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Photoresponsive wood-based composite fabricated by a simple drop-coating procedure

Gao

2018

Wood Sci Technol

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Thickness of zero-strength layer in timber beam exposed to fuel-controlled parametric fires

2023

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Fire resistance is one of the essential requirements to be fulfilled in the design of timber structures. For this purpose, a reduced cross-section method is given in the European standards, Eurocodes. The method is based on the assumption that an initial, rectangular timber cross-section exposed to fire conditions reduces to an effective cross-section, which has material properties as at a room temperature. The reduced part of the cross-section with no resistance is determined by a sum of two parameters, namely a charring depth and a thickness of zero-strength layer. Eurocodes give a value of the latter only for the standard fire exposure, which is only one of the fire curves proposed in the same standards. Therefore, the present paper examines the thickness of zero-strength layer in case of 46 different fuel-controlled parametric fire exposures applied to a timber beam from three sides. A four-phase numerical analysis is applied for this purpose that includes the use of a hygro-thermal model and a mechanical model to determine temperatures of timber over the cross-section and the mechanical resistance of timber beam in fire conditions, respectively. The results show that the thickness of zero-strength layer takes the values between 7.9 and 18.4 mm for the fuel-controlled parametric fire exposures. Since it is clearly dependent on the parameters describing the parametric fire curve, five equations are proposed that can be used for determination of the thickness of zero-strength layer in case of parametric fire exposures.

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Model evaluation of heat and mass transfer in wood exposed to fire

Cited by 8 publications

References 21 publications

A novel approach to determine charring of wood in natural fire implemented in a coupled heat-mass-pyrolysis model

A novel approach to determine charring of wood in natural fire implemented in a coupled heat-mass-pyrolysis model

Photoresponsive wood-based composite fabricated by a simple drop-coating procedure

Thickness of zero-strength layer in timber beam exposed to fuel-controlled parametric fires

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