The Effect of Heat Flux to the Fire-Technical and Chemical Properties of Spruce Wood (Picea abies L.)

The paper assesses the influence of the heat flux on spruce wood (Picea abies L.) behavior. The heat flux was performed at 15, 20, 25, and 30 kW∙m−2. The fire-technical properties, such as the mass burning rate, charring thickness, charring rate, as well as the chemical composition (contents of the extractives, lignin, cellulose, holocellulose), of wood were determined. The highest burning rate of spruce wood of 0.32 %·s−1 was reached at the heat flux of 30 kW∙m−2. The charring rate ranged from 1.004 mm·min−1 (15 kW∙m−2) to 2.016 mm.min−1 (30 kW∙m−2). The proposed model of the charring process of spruce wood in time and appropriate thickness as a selected parameter is applicable in validation of the results of computer fire models in the design of fire protection of wooden buildings. The decrease in the holocellulose content mostly caused by the degradation of hemicelluloses was observed during thermal loading. The biggest decrease in hemicelluloses (24.94%) was recorded in samples loaded at 30 kW∙m−2. The contents of cellulose increased due to the structural changes (carbonization and crosslinking), the content of lignin increased as well due to its higher thermal stability compared to saccharides, as well as the resulting lignin condensation.

Experimental Investigation of the Effect of Heat Flux on the Fire Behavior of Engineered Wood Samples

This paper presents the experimental study results on the effect of heat flux emitted by a standard source on the charring and ignition characteristics of wood construction materials (plywood, chipboard, and oriented strand board) using infrared thermography (IRT) in the narrow spectral ranges of infrared wavelength. The time to ignition (TTI), charring rate and depth were obtained for the samples. In addition, the effect of several fire retardants on the charring rate and depth of the samples and TTI was analyzed. All fire retardants contribute to an increase in TTI, which confirms their main function—fire protection. However, the effect of fire retardants differs noticeably depending on the material. A new experimental technique is suggested, with the infrared imaging of the temperature distribution along the end of a sample under the heat flux effect on its frontal surface. The uniqueness of this approach consists in the registration of the entire process of ignition and combustion of the presented materials, which occurs in real time without contact with high spatial and temporal resolution. Using the infrared camera of the research class, it becomes possible to record the entire process from the occurrence of the temperature exposure region to the deep carbonized crater in the body of the material. The results can serve as additional recommendations in the development of fire hazard testing methods for construction materials and fire retardants.

Incidencia del gasto público en I+D+i energético sobre la corrección medioambiental en España

During the last years the Spanish energy policy has been heavily biased towards replacing traditional energy sources, highly polluting, other renewable, without charring rate. The large amount of public resources being allocated to finance the production of these energy contrasts with the growing general shortage of resources and reduced public input to R&D in the spanish energy sector. Using, for empirical analysis, the model of Environmental Kuznets Curve, we obtained evidence for existence of an inverse relationship between public spending policies R&D energy and greenhouse gas emissions.

Numerical model to predict the effect of wood density in wood–steel–wood connections with and without passive protection under fire

The main objective of this work is to present a numerical model to predict the effect of wood density in unprotected wood connections with an internal steel plate (wood–steel–wood), when comparing with the same connections using passive protection with gypsum plasterboard, submitted to fire conditions. Wood–steel–wood connections are made of four wood members, two on each side, with an internal steel plate that connects the pieces using steel dowel fasteners. First, analytical methodologies according to Eurocode 5 part 1-1 were used to design the connections at room temperature. After that, to predict the fire exposure and the connection ability, a numerical model was performed which permits to compare the fire resistance in wood–steel–wood connections without and with passive protection following the Eurocode 5 part 1-2. Results of the temperature and the wood char layer depth were compared using three different wood densities. The evolution of the charring rate was calculated in different locations of the connections and compared with the analytical value proposed by the Eurocode 5 part 1-2.

Development of Models for Charring Rate of Selected Construction Timber Species in Southwestern Nigeria

The performance of Nigeria timber species under fire exposure to prevent collapse of structure has not been adequately investigated. This study was to determine the charring rate models of some selected timber species mostly used for constructional purposes in Southwestern Nigeria. Six species out of ten identified timbers were selected for studies. They are: Afara, Iroko, Opepe, Mahogany, Mansonia, and Teak. The densities of the timber species were determined at Moisture Contents (MC) of 9.0, 12.0, and 15.0%. Samples from each of the selected species, were exposed to fire at temperature ranges of 20° to 230° C for 30 minutes; 20° to 300° C for 60 minutes; 230° to 600° C for 30 minutes. Empirical statistical model was developed for charring rate of the timber species. The models were analysed using ANOVA at . At 30 minutes fire exposure (20 to 230° C), Afara of 9.0, 12.0 and 15.0% MC had the highest mean charring rates of 0.84±0.02mm/min, 0.82±0.02mm/min and 0.82±0.02mm/min respectively, while Opepe had the lowest charring rates of 0.48±0.02 mm/min, 0.48±0.02 mm/min and 0.47±0.02 mm/min at the three MC levels. This study indicated that density was a major predictor of the charring rate of constructional timber. Opepe which had the highest density also exhibited the lowest charring rate of all the species tested and is useful and recommended to ensure the safety and comfort of occupants in case of fire outbreaks.