Browsing by Author "CONTRERAS LOYOLA, FELIPE EDUARDO"
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Thesis DISEÑO DE UN EXPERIMENTO MODELO PARA ESTUDIAR LA IGNICIÓN ESPONTANEA EN VEGETACIÓN TIPICA DE CHILE(Universidad Técnica Federico Santa María, 2015) CONTRERAS LOYOLA, FELIPE EDUARDO; CONTRERAS LOYOLA, FELIPE EDUARDO; FUENTES CASTILLO, ANDRES; Universidad Tecnica Federico Santa Maria UTFSM DEPARTAMENTO DE INDUSTRIAS; DEMARCO BULL, RODRIGO ANDRÉSThis paper develops the design of a experimental model to study the spontaneous ignition of typical chilean vegetation. This in the context of the spread of forest fires, where the spontaneous ignition plays an important role in the “Spotting” process of the spread, creating new fire source at great distances from the initial fire source. The above is based on the three main Mechanisms of Heat Transfer; Conduction, Convection and Radiation, with main focus on the radiation, and a thermal model which explains the heat transfer within the vegetation, which takes into consideration the depth (δ) to which penetrates the heat into the sample of vegetation. The design is based on both input factors of the experiment (Incident Radiation, Bulk Density, Radio of the Heater, Radio of the Cylinder free of vegetation, Moisture fraction of the Sample, Heater’s Temperature) and the Response Variables to be studied (Time of Ignition, Mass loss rate, Temperature inside the layer). The experimental setup consists of a Power supply device, a system of data acquisition, digital Multimeter, Thermocouples type K, an Analytical Balance, a Ceramic Heater (which is responsible for irradiating the vegetation sample) and a structure built with Thorlabs (brand) pieces, allowing the disposition of the devices in order to be able to do the registration of the measurements. Measurements are made on a representative wildland litter contained in a glass container of 125 mm diameter and 50 mm height, leaving a cylinder shaped space free of vegetation in the center with 40 mm diameter, where the heater is located. The characterization of the vegetation under study is done by calculating the Density, Bulk Density, Porosity and Surface Volume Ratio. It is defined the methodology to understand the Heater behavior, to standardize the measurements of the response variables and to This paper develops the design of a experimental model to study the spontaneous ignition of typical chilean vegetation. This in the context of the spread of forest fires, where the spontaneous ignition plays an important role in the “Spotting” process of the spread, creating new fire source at great distances from the initial fire source. The above is based on the three main Mechanisms of Heat Transfer; Conduction, Convection and Radiation, with main focus on the radiation, and a thermal model which explains the heat transfer within the vegetation, which takes into consideration the depth (δ) to which penetrates the heat into the sample of vegetation. The design is based on both input factors of the experiment (Incident Radiation, Bulk Density, Radio of the Heater, Radio of the Cylinder free of vegetation, Moisture fraction of the Sample, Heater’s Temperature) and the Response Variables to be studied (Time of Ignition, Mass loss rate, Temperature inside the layer). The experimental setup consists of a Power supply device, a system of data acquisition, digital Multimeter, Thermocouples type K, an Analytical Balance, a Ceramic Heater (which is responsible for irradiating the vegetation sample) and a structure built with Thorlabs (brand) pieces, allowing the disposition of the devices in order to be able to do the registration of the measurements. Measurements are made on a representative wildland litter contained in a glass container of 125 mm diameter and 50 mm height, leaving a cylinder shaped space free of vegetation in the center with 40 mm diameter, where the heater is located. The characterization of the vegetation under study is done by calculating the Density, Bulk Density, Porosity and Surface Volume Ratio. It is defined the methodology to understand the Heater behavior, to standardize the measurements of the response variables and to VIII standardize the measurements of the studied factors. Finally the corresponding measurements are performed to validate the experimental model with samples of Radiata pine needles (density = 614,64 [kg/m3], bulk density = 37,23 [kg/m3], porosity = 0,939, surface-volume ratio = 3,68 [mm-1]), with maximum intensity of input voltage that can be delivered to the heater. It is obtained a value of emitted radiation of 29,69 [W], a value of incident radiation on vegetation of 23,89 [W] and spontaneous ignition times close to 290 seconds. Plots of the behavior of mass loss rate and temperature inside the layer during the process are shown.
