Browsing by Author "Calderón Espinoza, Ignacio Alonso"

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    A theoretical framework for the design of high-fidelity test lungs for mechanical ventilators based on a thermodynamic approach
    (2022) Calderón Espinoza, Ignacio Alonso; Chiang Sánchez, Luciano Eduardo; Pontificia Universidad Católica de Chile. Escuela de Ingeniería
    La pandemia de COVID-19 que aún persiste en la actualidad provocó una sobredemanda de ventiladores mecánicos alrededor del mundo. Muchos equipos de investigación han intentado desarrollar ventiladores. Sin embargo, asegurar su correcto funcionamiento y fiabilidad es un reto. Un enfoque eficiente para probar y validar ventiladores es usar pulmones de prueba. En esta tesis se presenta un nuevo modelo matemático teórico. Se presenta un sistema de ventilador mecánico-paciente basado en un enfoque termodinámico. El pulmón se modela en base a la dinámica de una masa-amortiguadorresorte (no lineal), sistema con caracterización de los pulmones del paciente a través de funciones de segmentos lineales de presión-volumen por partes en lugar de considerar conformidades lineales o constantes. El flujo de aire y la presión se modelan según ecuaciones de flujo de aire compresible en lugar de aproximaciones lineales. Se realizaron simulaciones computacionales de curvas de presión y volumen versus tiempo y se compararon con datos de ocho pacientes reales bajo ventilación mecánica invasiva (IMV). Este modelo propuesto permite reproducir con un alto grado de fidelidad las curvas de presión, caudal y volumen de la vida real. Lo más notable es que la forma de las curvas de presión, flujo y volumen simuladas se parecen mucho a la pacientes de la vida real. Los gráficos de dispersión dan pendientes cercanas a 1,0 y un valor de R2 superior al 93%. Los parámetros del modelo matemático se obtienen de las curvas reales del paciente cuyo comportamiento quiere ser reproducido. Por lo tanto, el modelo matemático presentado aquí se puede utilizar como una herramienta de diseño para una configuración de pulmón de prueba tal como se describe en esta tesis
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    Strategies for fire-fighting in underventilated compartments: Reducing the likelihood and severity of a potential backdraught
    (2025) Majdalani H. , Agustín; Carvel, R.; Calderón Espinoza, Ignacio Alonso; Jahn, Wolfram
    Fires in underventilated compartments remain an unresolved problem for fire brigades. While some brigades have specific guidance in place regarding procedures for approaching and fighting such fires, this guidance is, for the most part, based on anecdotal evidence, having been instigated following historical incidents involving fire-fighter injuries or fatalities. As fire-fighters open a door or window to an under-ventilated compartment fire, there is a risk of a sudden fire development that may come in the form of a rapid flare up or backdraught. A programme of reduced scale fire experiments was designed to obtain deeper insight into this phenomenon. The results of these experiments are presented showing the conditions under which changes in the ventilation conditions of an underventilated compartment were beneficial for firefighting activities and under which conditions this was detrimental. This paper provides further scientific understanding of the fire dynamics in underventilated compartments when changes in ventilation conditions occur. The use of ventilation tactics, preceded by strict safety precautions and comprehensive tactical considerations, appears to be a practical solution that reduces the likelihood and severity of a potential backdraught. The results presented could be used to develop simple guidance, which may be used in fire brigade practice, to decide when and how to intervene in this kind of fires.
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    Understanding Compartmentation Failure for High-Rise Timber Buildings
    (2024) Majdalani, Agustín H.; Calderón Espinoza, Ignacio Alonso; Jahn Von Arnswaldt Wolfram, Michael Andreas Oliver; Torero, José L.
    The traditional concept of compartmentation guaranteed by fire resistance is mainly concerned with the problem of destructive internal spread potential. External convective spread potential pertains to the loss of compartmentation associated with windows and facade systems. As such, it is assumed that internal fire spread occurs following mechanisms of excessive heat conduction and/or successive failure of the compartment boundaries, which can be, in most cases, conservatively characterised using traditional methods of performance assessment such as fire resistance. Nevertheless, external fire spread represents a potentially more effective route by which fire can spread through the convective advancement of flames and hot gases. This is particularly important in cases such as timber construction, where the presence of exposed timber can result in increased convective spread potential and where loss of compartmentation can result in disproportionate consequences. A simplified compartment fire model is proposed with the objective of quantifying the fuel contribution of exposed timber elements to the compartment fire and determining the impact of variable percentages of exposed timber on the convective spread potential. The overall results show that the convective fire spread potential increases with the increasing percentage of available timber