Predicting intumescent coating protected steel temperature in fire using constant thermal conductivity

2016 ◽  
Vol 98 ◽  
pp. 177-184 ◽  
Author(s):  
Guo-Qiang Li ◽  
Jun Han ◽  
Guo-Biao Lou ◽  
Yong C. Wang
Keyword(s):  
Thermal Conductivity ◽  
Intumescent Coating ◽  
Steel Temperature ◽  
Constant Thermal Conductivity ◽  
In Fire

Numerical modelling of heat transfer through protected composite structural members

2019 ◽  
Vol 5 (3) ◽  
pp. 96
Author(s):  
Burak Kaan Çırpıcı ◽  
Süleyman Nazif Orhan ◽  
Türkay Kotan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Numerical Model ◽  
Numerical Models ◽  
High Energy ◽  
Intumescent Coating ◽  
Steel Temperature ◽  
Intumescent Coatings ◽  
Number Of Layers ◽  
Dry Film Thickness

Among many various types of passive fire protection materials (i.e. plaster boards, sprayed materials and intumescent coatings) thin film intumescent coatings have become the preferable option owing to their good advantages such as flexibility, good appearance (aesthetics), light weight to the structure and fast application. Despite their popularity, there is also a lack of good understanding of fire behaviour. In general, experimental methods are used to push this knowledge with labour and high-energy consumption and extremely expensive processes. With the development of computer technology, numerical models to predict the heat transfer phenomena of intumescent coatings have been developed with time. In this work, the numerical model has been established to predict the heat transfer performance including material properties such as thermal conductivity and dry film thickness of intumescent coating. The developed numerical model has been divided into different layers to understand the sensitivity of steel temperature to the number of layers of intumescent coating and mesh sizes. The temperature-dependent thermal conductivity of intumescent coatings can be calculated based on inverse solution of the equation for calculating temperatures in protected steel according to the Eurocodes (EN 1993-1-2 and EN 1994-1-2). However, as the temperature distribution in the intumescent coatings is highly non-uniform, that Eurocode equation does not give accurate coating thermal conductivity-temperature relationship for use in numerical heat transfer modelling when the coating is divided into a number of layers, each having its characteristic thermal conductivity values. The comparison study of steel temperature under Standard (ISO 834) and Fast fire conditions against Eurocode analytical solution has also been made by assuming both constant thermal conductivity and variable thermal conductivity. The obtained results show close agreement with the Eurocode solution choosing a minimum certain mesh, number of layer and best-fitted thermal conductivity of the intumescent coating.

scholarly journals A NOTE ON THE CONSTANT THERMAL CONDUCTIVITY HYPOTHESIS AND ITS CONSEQUENCE FOR CONDUCTION HEAT TRANSFER PROBLEMS

2014 ◽  
Vol 13 (2) ◽  
pp. 48
Author(s):  
R. M. S. Gama
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
High Temperature ◽  
Heat Generation ◽  
Strong Dependence ◽  
Temperature Gradients ◽  
Conduction Heat Transfer ◽  
Kirchhoff Transformation ◽  
Constant Thermal Conductivity ◽  
Transfer Problems

This work discuss the usual constant conductivity assumption and its consequences when a given material presents a strong dependence between the temperature and the thermal conductivity. The discussion is carried out considering a sphere of silicon with a given heat generation concentrated in a vicinity of its centre, giving rise to high temperature gradients. This particular case is enough to show that the constant thermal conductivity hypothesis may give rise to very large errors and must be avoided. In order to surpass the mathematical complexity, the Kirchhoff transformation is used for constructing the solution of the problem. In addition, an equation correlating thermal conductivity and the temperature is proposed.

Experimental and Numerical Investigations of Steel Profiles with Intumescent Coating Adjacent to Space-Enclosing Elements in Fire

2015 ◽  
Vol 6 (4) ◽  
pp. 237-246 ◽  
Author(s):  
Peter Kraus ◽  
Martin Mensinger ◽  
Florian Tabeling ◽  
Peter Schaumann
Keyword(s):  
Temperature Field ◽  
Numerical Model ◽  
Fire Protection ◽  
Experimental Investigations ◽  
Expansion Process ◽  
Intumescent Coating ◽  
Numerical Investigations ◽  
Steel Members ◽  
New Development ◽  
In Fire

In this paper, the research program “Optimized use of intumescent coating systems on steel members” is presented. The aim of the project is to quantify the influence of space-enclosing elements on the thermal behavior of supporting steel members. Those elements partially result in a restrained expansion of the fire protection system. Experimental investigations on coated beams and columns directly connected to space-enclosing elements are presented. Additionally, numerical simulations are performed for temperature field calculations of steel elements with intumescent coating. As a new development, the numerical model takes into account the expansion process of the intumescent coating.

Analytical Model to Establish the Thermal Conductivity of Porous Structure

2014 ◽  
Vol 69 (1) ◽  
Author(s):  
C. H. Mao ◽  
M. A. Othuman Mydin ◽  
X. B. Que
Keyword(s):  
Thermal Conductivity ◽  
Porous Structure ◽  
Pore Size ◽  
Uniform Distribution ◽  
Analytical Model ◽  
Numerical Study ◽  
Fire Retardant ◽  
Mass Conservation ◽  
Intumescent Coating ◽  
Pore Size Distributions

The presented research paper deals with analytical method to determine the thermal conductivity of porous material (intumescent coating) where the main objective is to assess whether it is possible to treat the voids in intumescent coating as having a uniform diameter. Considering the nature of intumescent coating, the mechanisms of its fire retardant properties are expansion and heat absorption. A predictive model should therefore include prediction of expansion behaviour, energy and mass conservation based on both physical and chemical behaviour, and also thermal conductivity of the coating. A 3-D analytical model will be developed to determine the thermal conductivity of intumescent coating. Finite Element simulations using ABAQUS also will be performed to assess the influence of different pore size distributions. The results of this numerical study indicate that, given the same porosity, the overall thermal conductivity of the porous structure is very close to that with uniform distribution of pores of the dominant size. This strongly suggests that, given the difficulty of obtaining precise pore size distribution, it is reasonable to treat an intumescent coating as having a uniform distribution of pores of the same size.

Thermodynamic Extremum Principles for Nonequilibrium Stationary State in Heat Conduction

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Yangyu Guo ◽  
Ziyan Wang ◽  
Moran Wang
Keyword(s):  
Thermal Conductivity ◽  
Heat Conduction ◽  
Stationary State ◽  
Transient Heat Conduction ◽  
Clear Understanding ◽  
Minimum Entropy ◽  
Dissipation Potential ◽  
Nonequilibrium Stationary State ◽  
Minimum Entropy Production ◽  
Constant Thermal Conductivity

Minimum entropy production principle (MEPP) is an important variational principle for the evolution of systems to nonequilibrium stationary state. However, its restricted validity in the domain of Onsager's linear theory requires an inverse temperature square-dependent thermal conductivity for heat conduction problems. A previous derivative principle of MEPP still limits to constant thermal conductivity case. Therefore, the present work aims to generalize the MEPP to remove these nonphysical limitations. A new dissipation potential is proposed, the minimum of which thus corresponds to the stationary state with no restriction on thermal conductivity. We give both rigorous theoretical verification of the new extremum principle and systematic numerical demonstration through 1D transient heat conduction with different kinds of temperature dependence of the thermal conductivity. The results show that the new principle remains always valid while MEPP and its derivative principle fail beyond their scopes of validity. The present work promotes a clear understanding of the existing thermodynamic extremum principles and proposes a new one for stationary state in nonlinear heat transport.

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