Using Computational Fluid Dynamics in the forensic analysis of a prison fire

On the 8th of December of 2010 a fire killed 81 inmates in a Chilean prison. While the collected evidence (including eye witness’ accounts) indicated an intentional fire, started by a group of inmates who were fighting against another group and who ignited a mattress and threw it over a bunk bed inside the cell, it could not be established how fast the fire grew and whether the prison guards acted promptly enough to prevent the tragedy. In this context, the public defender office in charge of the case requested an independent investigation in order to determine the approximated time the fire started, and the temperature evolution of the padlocks at the cell doors during the initial stage, based on the construction characteristics of the prison, the existing materials and the evidence collected during the investigation. Computational Fluid Dynamics (CFD) were used to analyse the movement of the smoke and to match the first appearance of smoke on CCTV recordings at locations away from the fire, allowing for the estimation of the time-line of events. The padlock temperatures as a result of hot gases from the fire was also simulated. It was shown that the fire grew quickly and became uncontrollable before the guards could intervene. By the time the guards arrived at the cells’ door, the padlocks were shown to be too hot to be handled without protection

Rigorous monitoring is necessary to guide food system transformation in the countdown to the 2030 global goals

Food systems that support healthy diets in sustainable, resilient, just, and equitable ways can engender progress in eradicating poverty and malnutrition; protecting human rights; and restoring natural resources. Food system activities have contributed to great gains for humanity but have also led to significant challenges, including hunger, poor diet quality, inequity, and threats to nature. While it is recognized that food systems are central to multiple global commitments and goals, including the Sustainable Development Goals, current trajectories are not aligned to meet these objectives. As mounting crises further stress food systems, the consequences of inaction are clear. The goal of food system transformation is to generate a future where all people have access to healthy diets, which are produced in sustainable and resilient ways that restore nature and deliver just, equitable livelihoods. A rigorous, science-based monitoring framework can support evidence-based policymaking and the work of those who hold key actors accountable in this transformation process. Monitoring can illustrate current performance, facilitate comparisons across geographies and over time, and track progress. We propose a framework centered around five thematic areas related to (1) diets, nutrition, and health; (2) environment and climate; and (3) livelihoods, poverty, and equity; (4) governance; and (5) resilience and sustainability. We hope to call attention to the need to monitor food systems globally to inform decisions and support accountability for better governance of food systems as part of the transformation process. Transformation is possible in the next decade, but rigorous evidence is needed in the countdown to the 2030 SDG global goals

The state of food systems worldwide in the countdown to 2030

This Analysis presents a recently developed food system indicator framework and holistic monitoring architecture to track food system transformation towards global development, health and sustainability goals. Five themes are considered: (1) diets, nutrition and health; (2) environment, natural resources and production; (3) livelihoods, poverty and equity; (4) governance; and (5) resilience. Each theme is divided into three to five indicator domains, and indicators were selected to reflect each domain through a consultative process. In total, 50 indicators were selected, with at least one indicator available for every domain. Harmonized data of these 50 indicators provide a baseline assessment of the world’s food systems. We show that every country can claim positive outcomes in some parts of food systems, but none are among the highest ranked across all domains. Furthermore, some indicators are independent of national income, and each highlights a specific aspiration for healthy, sustainable and just food systems. The Food Systems Countdown Initiative will track food systems annually to U. Rashid Sumaila, Maximo Torero Cullen, Francesco N. Tubiello, Jose-Luis Vivero-Pol, Patrick Webb & Keith Wieb

Flame extinction and burning behaviour of timber under varied oxygen concentrations

Self-extinction plays a crucial role in enabling the safe use of timber structures in mid- and high-rise construction, where structural integrity during and after a fire is critical. To date, the influence that oxygen concentration may have in the conditions that lead to self-extinction has not been studied in depth. Also, the thermal conditions of timber after self-extinction has occurred have not been carefully studied. During fires, oxygen concentrations will defer from those during ambient conditions. Within this study, the testing conditions were carefully controlled to investigate the circumstances before and after the occurrence of self-extinction; considering a range of heat exposures and oxygen concentrations in the air surrounding the test sample. For samples tested in air containing 21% oxygen, self-extinction always occurs for an incident heat flux of 30 kW/m but never occurs for 40 kW/m; with the critical mass loss rate that leads to self-extinction being 3.6 ± 0.4 g/ms. The study concluded that lower oxygen concentrations result in an increase of the critical mass loss rate leading to self-extinction and an increase of the minimum incident heat flux leading self-extinction

The potential of integrating fire safety in modern building design

Whether explicitly acknowledged or not, modern building design is strongly influenced by fire safety considerations. The building design community, broadly construed, appears to remain surprisingly unaware of the extent to which prescriptive fire safety considerations impact building designs. However, several decades of advances in fire safety science have gradually revealed the potential value of integrating fire safety as one of the many variables that should be optimized during the building design process. This paper presents outcomes from a series of mediated roundtable discussions that occurred during an international seminar aimed at reflecting on the current status of fire safety and fire protection concepts within overall building design processes. An attempt is made to emphasize discrepancies between the perceptions of fire safety considerations, requirements, and drivers exemplified by the various stakeholder participants. A distinction is made between the status of those individuals presently charged with the fire safety design of a building, and the future potential for further integration of fire safety considerations within the building design process. Fundamental changes in support of holistic provision of fire safety in the modern built environment are proposed

NUMERICAL STUDY OF FORWARD SMOLDERING COMBUSTION (in Spanish)

(in English) AbstractThis paper presents the results from the numerical study of the forward smoldering combustion process. The study is based on the transient model developed at University of Texas at Austin but extended with some modifications. In the model, the equations of conservation of energy and mass are solved. The chemistry is represented by a simplified scheme which consists of three reactions. Equations are discretized in space and solved in time. Neither thermal nor chemical equilibrium between solid and gas phases is assumed. The more important extensions made to the original model are: radiation heat transfer is included, a new ignition process is implemented and the porous structure of the solid is reconsidered. The extensions to the original model were implemented in order to predict the experimental data. The model with its extensions has been calibrated at a higher inlet air velocity and validated. The results show that the model predicts reasonably well the velocity of propagation of the smoldering front.(in Spanish) Estudio numerico de combustion latente en flujo directoResumenEste articulo presenta los resultados del estudio numerico del proceso de combustion latente en flujo directo. La combustion latente es una reaccion exotermica sin llama que se propaga en combustibles porosos. El estudio se basa en el modelo transitorio desarrollado en la Universidad de Texas en Austin, pero ampliado con varias modificaciones. En el modelo se resuelven las ecuaciones de conservacion de la energia y la masa. La cinetica quimica se modela con un esquema simplificado de tres reacciones. Las ecuaciones diferenciales se discretizan en el espacio y se resuelven en funcion del tiempo. El modelo no fuerza el equilibrio ni termico ni quimico entre las fases solida y gaseosa. Las modificaciones mas importantes realizadas son la inclusion de la transmision del calor por radiacion, la incorporacion de un nuevo proceso de ignicion y la reconsideración de la microestructura de los poros del solido. El objetivo de las ampliaciones es completar y adaptar el modelo a los experimentos publicados para comparar resultados. El modelo se calibra de nuevo a una velocidad mayor del aire de entrada. Los resultados muestran que se estima adecuadamente la velocidad de propagacion del frente de combustion

Self-sustaining smouldering combustion of faeces as treatment and disinfection method

Smouldering combustion is a novel solution for sustainable treatment of waste. This is a low cost, off-grid and self-sustaining technology, that has been recently applied for soil remediation. Due to the high energy efficiency and the application scale, this technology is suitable for the treatment of organic waste with high moisture content (e.g. agricultural, manure, faeces). In addition, the temperatures achieved during smouldering combustion ensure pathogen destruction; therefore this technology is ideal to disinfect human waste. In this work, we present the study of the smouldering of faeces mixed with sand, at different reactor scales. Sand is used because smouldering needs a porous medium for the propagation of the reaction, enhancing oxygen diffusion. We investigated the limit of experimental parameters (moisture content, air velocity and sand-to-faeces mass ratio) that lead to the minimum faeces destruction rate in a self-sustaining process, using four different reactor sizes. It was found that there is a strong dependence on the moisture content limit with the reactor scale. On the other hand sand-to-faeces mass ratio and air velocity showed almost constant limit values. Experiments with mixed waste (faeces and agricultural) were also carried out to demonstrate the versatility and the robustness of this process towards the waste nature. Sand is clean and hot after the smouldering treatment. Part of the energy of the process can be recovered by mixing the hot sand to pre-dry a new batch of faeces. This can be repeated for at least five consecutive experiments

Investigation of self-sustaining smouldering of faeces: key parameters and scaling effects

The lack of adequate sanitation infrastructure within developing countries enables the transport of faecal matter containing harmful pathogenic compounds into the drinking water sources. The principal consequence of the pathogenic pollutant is 2.5 million preventable annual deaths. The utilisation of self-sustaining smouldering for the treatment of faecal matter mixed with sand is proposed as a solution as the high temperatures achieved ensure the destruction of the pathogens. Sand is used because it is low cost and it has been identified as an effective agent for increasing the porosity of fuels for application of smouldering treatments. Previous studies have shown the sustainability of smouldering combustion to be dependent upon experimental parameters such as moisture content, relative amount of sand and the airflow rate. In this work, we present the results of smouldering combustion experiments that were carried out to determine the sensitivity of the smouldering velocity to those experimental parameters. Experiments were conducted using four cylindrical reactors with varying size. To avoid variability, surrogate faeces which exhibits similar energetic, thermal, and mechanical properties to real faeces, are used in this study. Results showed moisture content is a critical parameter to control the sustainability of the process; however it has no effect on the smouldering velocity under robust conditions. The smouldering velocity showed a linear relationship with the air velocity and the faeces-to-sand mass ratio. Furthermore, it was demonstrated that these relationships are independent of scale. These results can be used to determine the reactor size and experimental conditions under realistic conditions

Desarrollo De Proyectos Internacionales-AN84-201801

Desarrollo de Proyectos Internacionales es un curso integrador que recoge las competencias y capacidades adquiridas por el estudiante en la línea operativa y comercial y le proporciona las herramientas y la estructura lógica e idónea para analizar identificar formular desarrollar y evaluar un proyecto innovador de negocios internacionales en cualquiera de sus modalidades.El curso le permite al estudiante contrastar la teoría con la práctica al tener que aplicar los diferentes conceptos y herramientas teóricas en el contexto real de los mercados internacionales