Experimental analysis of jet fire impingement on industrial pipe

International audienceIn industrial plants, jet fires and pool fires can increase hazards when they impinge and engulf on pipes or vessels. Then, these structures may also become themselves the centre of major accidents (domino effects). Therefore, as part of hazard surveys and more particularly survey of domino effects, some questions are asked about, for example: the relevance to consider the explosion of such or such tank as a result of the contribution of heat since a close fire considered besides, or again the quantitative contribution expected by the implementation of materials of heat insulation or the implementation of means of cooling. Thus a research program supported by the French Ministry for Ecology and Sustainable Development focuses on the thermal impact of fires on industrial pipes and tanks. Its main objective is to develop, to validate and to produce one or several tools of calculation satisfying needs mentioned above. This paper presents an experimental campaign aiming to the analysis of the heat transfers exerting on a pipe impinged by a jet fire. Thus, an experimental apparatus was set up making it possible to determine on the one hand, precisely the characteristics of jet fire and on the other hand, the thermal response of the steel pipe crossed by water flow. First of all, to characterise jet fire, measurements of gas temperatures, gas velocities and heat fluxes are performed for three gases that are the methane, propane and ethylene and for various gas release rates. Additionally, test monitoring has also been done with video camera. These measurements make it possible to define dimensions of jet fires, its surface emissive power as well as the hot gas velocities for finally deducing the heat transfers received by the pipe. The experimental data are compared with the SHELL model which is a semi-empirical model (Chamberlain, 1987) modified by Cook (1987). In the second time, the pipe crossed by cold water is subjected to these various jet fires and the thermal response of pipe is quantified by monitoring the pipe with thermocouples. This second test campaign aims to quantify the influence of the hot soot conduction in the heat transfers

Experimental analysis of storage fires for a better understanding of warehouse fires

International audienceLand-use Planning rules applicable in France around listed hazardous industrial premises rely on a deterministic evaluation of the consequences of major accidents such fires, explosions, toxic cloud releases. Major fire scenarios relevant to storage areas shall in this context be carefully analyzed by safety engineers in concerned industrial facilities like large warehouses storing combustible materials. In this background, the French Ministry for Ecology and Sustainable Development currently supports INERIS for the performance of a research program concerning the warehouse fire problem. The program mainly focuses on the development of a methodology addressing the evaluation of the toxic and thermal threats pertaining to warehouse fires. This paper presents a series of large experiments aiming at analyzing the influence of storage configuration on the development and overall behavior of warehouse fires. The document is divided in two sections : the first one presenting the experimental apparatus, the second introducing results derived from the global measurement analysis

Domino effects : thermal impact of jet fires on industrial pipes

International audienceDue to accidental thermal attacks, industrial plants can be damaged or more seriously become themselves the centre of major accidents (domino effects). At the origin of these attacks, it is advisable to mention the "classical" fires such as pool fires, jet fires, but also more exceptional phenomena which generate fire balls with an intense radiation as BLEVE or Boil-Over. Therefore, as part of hazard surveys and more particularly survey of domino effects, some questions are asked about, for example: - the relevance to consider the explosion of such or such tank as a result of the contribution of heat since a close fire considered besides, - or again the quantitative earnings expected by the implementation of materials of heat insulation or the implementation of means of cooling. Now it concerns typical structures as pipes or tanks, there are not or few tools which are enough fine to answer the previous asked questions and at the same time there is not enough quick implementation to be compatible with the deadline constraints of usual studies. Thus a research programme focuses on the thermal impact of different fires on industrial pipes and tanks. Its objective is to develop, to validate and to produce one or several tools of calculation satisfying needs mentioned above in order to approach in a most realistic possible way the thermal impact of fires on equipment such as the industrial pipes and tanks. This paper presents an experimental campaign aiming to the analysis of the heat transfers being exerted on a pipe submitted at a fire jet. Thus, an experimental apparatus was set up making it possible to determine on the one hand, precisely the characteristics of jet fire and on the other hand, the thermal response of the pipe crossed by water. To characterise jet fire, measurements of gas temperatures, gas velocities and heat fluxes are realised for three gases that are the methane, propane and ethylene and for various gas release rates. Additionally, test monitoring has also been done, making use of both infrared camera and conventional video camera. These measurements make it possible to define dimensions of jet fires, its surface emissive power as well as the hot gas velocities for then deducing from them the heat transfers received by the pipe. In the second time, the pipe crossed by water is subjected to these various jet fires and the thermal response of pipe is quantified by monitoring the pipe with thermocouples. The experimental apparatus makes it possible to vary various parameters such as: - the presence or not of an heat insulator like rockwool, - the thermal attack (various gases and heat release rates), - the flow velocity in the pipe going from 0,1 to 1 m/s. This test campaign aims to validate the physical models concerning the thermal response of a structure to a thermal attack and to quantify the influence of the hot soots conduction in the heat transfers by testing jet fires of gas producing soots more or less

Structure d'écoulement au sein d'une nappe liquide soumise à un flux de chaleur

POITIERS-BU Sciences (861942102) / SudocSudocFranceF

Development of an innovative method for elementary heat release rate computation

International audienceFire safety engineering is nowadays an important way to improve safety in a large variety of buildings. Whatever the typology of building, one of the key points in order to evaluate the consequences of a fire consists in the ability in predicting the fire growth and total heat release rate inside the building. The beginning of such a modeling consists in evaluating the heat release rate of elementary component of the fire. In the specific case of warehouse storage, the pallets heat release rate is then crucial not only to predict fire growth inside the building and occupants' safety but to evaluate the total heat release rate for a generalized fire and consequences on the building environment too. A new model is then proposed to predict the heat release rate of a pallet in case of fire. This model consider the entire component located on this pallet, this means combustible that produce energy but also non combustible material that acts as a well. It also takes into account the arrangement of the combustible regarding that more ventilated is the fire, more important will be the power reached. Then, solving the global equilibrium between source and well enables to give a prediction of the heat release rate. This model was validated using a large number of fire tests achieved in the INERIS fire tunnel used as a large calorimeter. These tests include pallets that contain for example appliances, food products, toys, water bottle, clothes and some other. The comparison between the measured and computed heat release rate for those different products demonstrate the capability of the model

Dynamic Observing and Tiling Strategies for the DESI Legacy Surveys

International audienceThe Dark Energy Spectroscopic Instrument Legacy Surveys, a combination of three ground-based imaging surveys, have mapped 16,000 deg2 in three optical bands (g, r, and z) to a depth 1–2 mag deeper than the Sloan Digital Sky Survey. Our work addresses one of the major challenges of wide-field imaging surveys conducted at ground-based observatories: the varying depth that results from varying observing conditions at Earth-bound sites. To mitigate these effects, the Legacy Surveys (the Dark Energy Camera Legacy Survey, or DECaLS; the Mayall z-band Legacy Survey, or MzLS; and the Beiijing-Arizona Sky Survey, or BASS) employed a unique strategy to dynamically adjust the exposure times as rapidly as possible in response to the changing observing conditions. We present the tiling and observing strategies used by the first two of these surveys. We demonstrate that the tiling and dynamic observing strategies jointly result in a more uniform-depth survey that has higher efficiency for a given total observing time compared with the traditional approach of using fixed exposure times

The DESI experiment part I: science, targeting, and survey design

DESI (Dark Energy Spectroscopic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations (BAO) and the growth of structure through redshift-space distortions with a wide-area galaxy and quasar redshift survey. To trace the underlying dark matter distribution, spectroscopic targets will be selected in four classes from imaging data. We will measure luminous red galaxies up to $z=1.0$. To probe the Universe out to even higher redshift, DESI will target bright [O II] emission line galaxies up to $z=1.7$. Quasars will be targeted both as direct tracers of the underlying dark matter distribution and, at higher redshifts ($2.1 < z < 3.5$), for the Ly-$\alpha$ forest absorption features in their spectra, which will be used to trace the distribution of neutral hydrogen. When moonlight prevents efficient observations of the faint targets of the baseline survey, DESI will conduct a magnitude-limited Bright Galaxy Survey comprising approximately 10 million galaxies with a median $z\approx 0.2$. In total, more than 30 million galaxy and quasar redshifts will be obtained to measure the BAO feature and determine the matter power spectrum, including redshift space distortions

The DESI Experiment Part II: Instrument Design

DESI (Dark Energy Spectropic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations and the growth of structure through redshift-space distortions with a wide-area galaxy and quasar redshift survey. The DESI instrument is a robotically-actuated, fiber-fed spectrograph capable of taking up to 5,000 simultaneous spectra over a wavelength range from 360 nm to 980 nm. The fibers feed ten three-arm spectrographs with resolution $R= \lambda/\Delta\lambda$ between 2000 and 5500, depending on wavelength. The DESI instrument will be used to conduct a five-year survey designed to cover 14,000 deg$^2$. This powerful instrument will be installed at prime focus on the 4-m Mayall telescope in Kitt Peak, Arizona, along with a new optical corrector, which will provide a three-degree diameter field of view. The DESI collaboration will also deliver a spectroscopic pipeline and data management system to reduce and archive all data for eventual public use