1. High-Intensity Fast-Response Electric Radiant Panel (HIFREP) to impose fire equivalent heat fluxes on building elements with enhanced thermal boundary conditions accuracyFlorian Put, Balša Jovanović, Evelien Symoens, Andrea Lucherini, Bart Merci, Ruben Van Coile, 2025, izvirni znanstveni članek Povzetek: Bench-scale fire testing has gained popularity as a highly controllable and cost-effective solution, overcoming many of the shortcomings of traditional large-scale fire resistance tests. Whereas gas-fired radiant panels have demonstrated significant success in this area, the present study introduces a novel High-Intensity Fast-Response Electric radiant Panel (HIFREP). Utilizing electrically operated radiation emitters, it provides more precise and quasi-instantaneous control over the thermal boundary conditions. HIFREP delivers high and stable heat fluxes up to 105 kW/m2 , and, due to the low thermal inertia of the emitters, can rapidly adjust its output to changes in the input. In this regard, the time constant of the emitters has been found to be less than 1 s, both during heating and cooling. It eliminates gas combustion and hence avoids the need for extraction hoods when testing the fire performance of non-combustible materials, making it suitable for traditional structural testing laboratories. The presented High-Intensity Fast-Response Electric radiant Panel also provides a reliable tool for the validation of FEM simulation results by accurately replicating the thermal boundary conditions in structural fire engineering analyses.
Ključne besede: radiant panel, fire testing, heat transfer, radiation, heat flux, thermal boundary conditions
Objavljeno v DiRROS: 16.06.2025; Ogledov: 858; Prenosov: 441
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2. High-Intensity Fast-Response Electric radiant Panel (HIFREP) for increased accuracy on thermal boundary conditions during fire testingFlorian Put, Balša Jovanović, Evelien Symoens, Andrea Lucherini, Bart Merci, Ruben Van Coile, 2024, objavljeni znanstveni prispevek na konferenci Povzetek: Fire resistance tests rely on the use of standardized furnaces to apply specific thermal boundary conditions to assess the performance of construction materials and systems in fire conditions. However, these tests are very expensive and encounter challenges related to repeatability and uncertainties in establishing thermal boundary conditions. Moreover, their incapacitance to tailor experiments hinders advancements in understanding structural behaviour during fire exposure. In this work, a novel type of radiant panel, that operates on electricity, is introduced: the High-Intensity Fast-Response Electric radiant Panel (HIFREP). This innovation offers enhanced sustainability performance while ensuring more precise control over thermal boundary conditions. By eliminating the need for gas combustion, the panel can be used in a traditional structural testing lab to investigate non-combustible materials (e.g. concrete), without requiring extraction hoods and other provisions. The presented electric radiant panel system represents a significant step forward from fire resistance furnace testing.
Ključne besede: radiant panel, fire testing, heat transfer, radiation, heat flux, fire safety, thermal boundary conditions
Objavljeno v DiRROS: 19.12.2024; Ogledov: 1186; Prenosov: 597
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3. Experimental investigation on the effect of natural fire exposure on the post-fire behavior of reinforced concrete beams using electric radiant panelBalša Jovanović, Robby Caspeele, Edwin Reynders, Geert Lombaert, Florian Put, Andrea Lucherini, Ruben Van Coile, 2024, izvirni znanstveni članek Povzetek: In this study, the effects of natural fire exposure on the post-fire behavior of concrete beams are investigated. The study is based on laboratory tests where three reinforced concrete beams were subjected to fire exposure using an electric radiant panel. This panel enables a precise application of radiative heat exposure closely mimicking natural fire exposure in a safe manner. During the test, the deflections, deformations and temperature changes are measured for all three concrete beams. Additionally, finite element modeling (FEM) is applied to supplement these tests, demonstrating the performance of existing structural fire engineering calculation tools in evaluating the burnout performance of concrete beams. The results of the tests show that the electric radiant panel provide a novel approach for fire simulation which is effective in replicating natural fire conditions, by applying the heat flux as specified in the Eurocode Parametric Fire Curve in a highly controlled manner. The uniformity of the temperature field measured inside the beams and the consistent deformations observed during the heat exposure across all three tests underscores the accuracy of the fire simulation. Furthermore, post-fire assessments reveal that while the exposed beams suffered some reduction in load-bearing capacity, they retained a significant portion of their original strength that was consistent across all three beams. The numerical simulations conducted in this study demonstrate a high level of accuracy in predicting the behavior of the concrete beams during fire exposure. These simulations effectively mirrored the experimental results, validating that they are a valuable tool for assessing concrete structures' performance in fire scenarios.
Ključne besede: concrete beam, fire testing, numerical modeling, radiant panel
Objavljeno v DiRROS: 28.11.2024; Ogledov: 1125; Prenosov: 629
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4. Thermal characterisation of the cooling phase of post-flashover compartment firesAndrea Lucherini, Balša Jovanović, Jose L. Torero, Ruben Van Coile, Bart Merci, 2024, izvirni znanstveni članek Povzetek: The main characteristics of the cooling phase of post-flashover compartment fires are studied using a simplified first-principles heat transfer approach to establish key limitations of more traditional methodologies (e.g., Eurocode). To this purpose, the boundary conditions during cooling are analysed. To illustrate the importance of a first-principles approach, a detailed review of the literature is presented followed by the presentation of a simplified numerical model. The model is constructed to calculate first-order thermal conditions during the cooling phase. The model is not intended to provide a precise calculation method but rather baseline estimates that incorporate all key thermal inputs and outputs. First, the thermal boundary conditions in the heating phase are approximated with a single (gas) temperature and the Eurocode parametric fire curves, to provide a consistent initial condition for the cooling phase and to be able to compare the traditional approach to the first- principles approach. After fuel burnout, the compartment gases become optically thin and temperatures decay to ambient values, while the compartment solid elements slowly cool down. For simplicity, convective cooling of the compartment linings is estimated using a constant convective heat transfer coefficient and all linings surfaces are assumed to have the same temperature (no net radiative heat exchange). All structural elements are assumed to be thermally thick. While these simplifications introduce quantitative errors, they enable an analytical solution for transient heat conduction in a semi-infinite solid that captures all key heat transfer processes. Comparisons between the results obtained using both approaches highlight how, even when considering the same fire energy input, the thermal boundary conditions according to the Eurocode parametric fire curves lead to an increase energy accumulated in the solid after fuel burnout and a delay in the onset of cooling. This is not physically correct, and it may lead to misrepresentation of the impact of post-flashover fires on structural behaviour.
Ključne besede: cooling phase, fire decay, fire dynamics, compartment fires, structural fire engineering, fire safety
Objavljeno v DiRROS: 15.04.2024; Ogledov: 1891; Prenosov: 898
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