Sharif Digital Repository

Safety against fire and its potential destructions is provided by detection, protection and ventilation methods. Knowledge on fire behavior such as ignition and propagation along with heat and smoke release is essential for implementing these methods. Having such deep information, the fire can be detected at the correct time and be controlled or suppressed, with its heat and smoke removed efficiently, so that rescue services will be enhanced and fatalities and damages will be reduced.Numerical simulation of fire requires deep understanding of multiple phenomena including turbulent flows, conductive, convective and radiative heat transfer, large buoyancy forces, chemical reactions and... 

Heat transfer associated with phase change occurs in many physical phenomena. One of the ways of thermal energy storage is the use of latent heat phase change. Therefore, it is important to know the thermal performance of phase change material. In this research, the aim is to investigate the process of phase change of a system consists of two immiscible phase change materials and the comparison of this system with a system consists of one phase change material. The experiments with the two materials system is conducted in two ways. In the first state, that is the normal state, denser material is placed in the bottom and in the second state, denser material is placed in the top. Constant heat... 

Fire in enclosures is one of the most important disasters due to the presence of human and physical risks, so, investigation of the firefighting scenarios in this case has much importance. In the present study, novel enclosures fire suppression scenarios are simulated using computational fluid dynamics (CFD). The simulations have two major categories. In the first part, performance of different natural ventilation, positive pressure ventilation (PPV) and negative pressure ventilation (NPV) scenarios, which are new methods in firefighting, are evaluated and compared. In this part, the influence of different parameters like geometry, position of inlet and outlets and fire heat release rate... 

Fires in buildings and closed environments are considered as the most important types of fires due to the possibility of the presence of people and the possibility of life-threatening. Understanding and predicting fire behavior is critical to preventing damage. Backdraft is a special phenomenon of fire that occurs in a chamber with limited ventilation. In a closed environment where there is fire, over time, due to the closed doors and windows, the oxygen required for combustion decreases and as a result, semi-combustible materials can be dangerously exposed to the environment with flammable vapors and gases. Fill and when sufficient air reaches this chamber, a sudden explosion or the same... 

Positioning refers to the process of estimating the receiver coordinates aiming for an accurate understanding of the surrounding environment. This branch of science has attracted considerable attention in recent years. Today, the influence sphere of positioning is so expanded that encompasses applications in daily life (e.g., navigation) as well as commercial and even military fields. Global Positioning System (GPS) is the most widely used tool in real-time positioning. Because GPS imposes great measurement errors in challenging conditions (e.g., turbulent water environments), alternative methods such as methods based on Wi-Fi, Bluetooth, and visible light have been proposed. Benefiting... 

in this study, turbulent natural convection inside an air filled square cavity with several hot and cold internal bodies in the range of Rayleigh numbers between 1010 and 1012 has been investigated numerically. Vertical walls of the enclosure have been considered isothermal and horizontal walls are insulated in all cases. An appropriate arrangement of internal bodies in which the minimum heat transfer occurs is desired. For this purpose, two dimensional Reynolds-averaged Navier-Stokes equations have been solved with the finite volume discretization method in a staggered grid. In addition, two equation high-Reynolds-number model with standard wall functions is used to simulate the...