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Thermal analysis in fire-resistance Furnace

Publication . Piloto, P.A.G.; Mesquita, L.M.R.; Pereira, Alexandre Augusto

Fire resistance rating of building construction elements is defined under fire-resistance test furnace. The geometry and shape of fire-resistance furnaces is not defined by any prescriptive document, being necessary to comply thermally with specified nominal fire curves, such as ISO 834 or hydrocarbon [1,2]. This research work intends to measure temperatures inside furnace volume, using sixteen plate thermocouples to compare average temperature in four planes. Those planes are compared with reference thermocouple which is responsible for controlling furnace operation, see figure 1. Three tests were performed, the first two running with ISO 834, during 45 minutes and the last one running with hydrocarbon curve, during 30 minutes. Experimental results demonstrate that relative temperature differences are smaller than 30 % in the initial test stage, being smaller than 5 %, after 500 [s] until the end of the tests. The numerical simulations were performed using Fluent CFD, using the structured finite volume mesh method. The Eddy Dissipation Model (EDM) was used for chemical species transport and reacting flow. The governing equations for mass, momentum and energy were solved for the three dimensional unsteady incompressible flow, with radiative heat transfer and turbulence model. The numerical results agree well with experimental results, being the relative temperature difference smaller than 5% for each nominal test. Numerical simulation also reveals the localized effect of each burner.

2009Conference object

Open access

Caracterização da decomposição térmica e formação carbonosa de tintas intumescentes

Publication . Mesquita, L.M.R.; Piloto, P.A.G.; Magalhães, F.; Pimenta, Joana; Vaz, M.A.P.

Este trabalho apresenta um estudo dos mecanismos de decomposição e de intumescência de duas tintas comerciais de base aquosa. São apresentados resultados experimentais, obtidos através de termogravimetria e num calorímetro de cone. Os resultados do primeiro teste permitem aferir a variação da perda de massa com a temperatura, para distintas taxas de aquecimento e, considerando que as reacções químicas são descritas pela equação de Arrhenius, é apresentado o método de cálculo dos parâmetros cinéticos, energia de activação e factor pré-exponencial, comparando diferentes métodos cinéticos. Os testes realizados no calorímetro de cone, especificando um fluxo de calor radiante, permite quantificar a variação da camada intumescente e a evolução da temperatura no substrato.

2011Journal article

Open access

Fire resistance of steel members protected with intumescent coatings

Publication . Mesquita, L.M.R.; Piloto, P.A.G.; Roque, Sérgio; Vaz, M.A.P.

The required intumescent coating thicknesses needed for fire resistance are proposed by the paints manufactures based on the results of a limited number of standard fire resistance tests, considering different steel section factors and DFTs. This work presents a set of 50 experimental fire resistance tests made in a pilot gas furnace and considering: (i) different member cross-sections (IPE, SHS, CHS, LNP), (ii) analysis at ambient temperature and fire conditions, (iii) application of a mechanical loading in a tree-point bending setup, (iv) different utilization degree level (30%, 50%, 70%) and (v) different intumescent thicknesses. Results show that increasing intumescent fire protection thickness an increase in fire resistance time is achieved. For the same nominal protection thickness the critical temperature and fire resistance time decreases with increasing degree of utilisation. The results from the unprotected fire tests are compared with the ones obtained by the Eurocode 3 part 1.2 simplified calculation method.. Taking into account the nominal properties only the CHS section experimental results shows unsafe fire resistance times in comparison to the Eurocode values.

2012Conference object

Open access

Decomposition of intumescent coatings: comparison between numerical method and experimental results

Publication . Mesquita, L.M.R.; Piloto, P.A.G.; Vaz, M.A.P.; Pinto, T.

An investigation of two different intumescent coatings used in steel fire protection has been performed to evaluate their efficiency. A set of experimental tests is presented. They were conducted in a cone calorimeter, considering different thicknesses and heat fluxes. Among other quantities, the steel temperature and the intumescence thickness variation were measured. A numerical model for the paint decomposition is also presented. Based on the intumescence experimental value, the model is able to provide a reasonably good prediction of the steel temperature evolution.

2009Journal article

Open access

Intumescent coating modelling based on small scale experimental tests

Publication . Mesquita, L.M.R.; Piloto, P.A.G.; Vaz, M.A.P.

An investigation of two different intumescent coatings used in steel fire protection has been performed to evaluate their efficiency. Among other quantities, the steel temperature and the intumescence thickness variation were measured. A mathematical model for the intumescent coating is developed. It considers the coating decomposition and models the protection by two layers, the reacted and the unreacted layer. A comparison between the experimental results and the ones obtained from the numerical model is presented.

2009Conference object

Open access