Smoke Movement for High Rise Building - Coursework Example

Smoke Movement for High Rise Building Name Date Course Smoke Movement for High Rise Building Introduction Smoke is a dangerous product of combustion and it has negative effects on safety in a high rise building during a fire. It is a mixture of hot vapour and gases produced during the combustion process. Smoke forms two areas when it is moving within a high rise building and it involves the hot smoke zone and cool smoke zone (Ji, et al., 2013). The movement of smoke within the high rise building is of concern as it may affect the evacuation process. It causes suffocation and it also blocks vision. The smoke movement in ventilations has to be considered during the design to minimize its fast spread. The movement of smoke in the cool and hot smoke zones differs due to the temperatures. The paper discusses the concepts of smoke movement in high rise building under different ventilations. Background of the subject area The characteristics of a high storey building increase the risk of fast spread of smoke in the event of a fire. Evacuation is made difficult when the smoke is spreading at a high rate within the high rise building. Different factors influence the movement of smoke in different ventilations within a high rise building (Ji, et al. 2013). Pressure, temperature and the stack effects are the factors that determine the movement of smoke within a high rise building. The high rise building requires the smoke control mechanism in order to control the movement of smoke in case of fire. Mechanical means can be used for the purposes of preventing the spread of smoke within a high rise building. Control of smoke requires detailed knowledge of the smoke movement within a high rise building. Different fire models can be used for the purposes of analyzing the movement of smoke within a high rise building. Some of the openings within the building usually encourage the movement of smoke from one floor to the other in a high rise building (Cai & Chow, 2012). The equation for the conservation of mass and energy may be useful in terms of explaining the movement of smoke within different ventilations. The concepts of heat transfer play a significant role in determining the movement of smoke during the event of a fire in a high rise building. Specific details of research presented in the paper The theoretical analysis of the smoke movement within different ventilations within a high rise building is being presented in the paper. Relationship between the smoke movements and different patterns of release. Effects of complex geometries on smoke movement in a high rise building. The concepts of heat transfer and effects of smoke in a high rise building. Evaluation of the modeling Physical bases for modeling During a fire, hot gases from the fire rise and entrain the fresh air from the room as it rises through the ceiling. The hot air becomes thicker and it forms smoke which starts to spread to spread to the other parts of the building through the door, stairs and other openings in the building. The formation of the two smoke zones takes place when the fire is huge and has started spreading. Plume, turbulence and buoyancy play an influential role in affecting the smoke movement within the high rise building (Cai & Chow, 2012). The mathematical aspects are involved in the model for the purposes of determining the flow rate of air. Numerical calculations are required for calculating the equations for conservation of mass and energy. The equation for the conservation of mass and energy can explain the some movement from one room to the other in a storey building. Hot smoke zone The hot smoke zone is the place where the temperature is high enough and in most cases it is close to the fire. At the hot smoke zone, natural buoyancy of the body tends to lift the smoke towards the ceiling and the fresh air is drawn art the lower part (Shi, et al, 2014). The hot smoke zone in most cases is common at the room where the fires started. Energy produced by the fire influences the movement of the smoke and hot smoke zones can be created at the corridors. Cool smoke zone At this zone, the mixing of air takes place for and the driving force of the fire has not been felt completely. The buoyant lift of smoke in this zone is a minor facto due to the low levels of heat based on the concept of heat transfer (Shi, et al, 2014). The movement of smoke at this point is controlled by factors such as the wind or stack effect. Other factors that controls the smoke movement in the cool smoke zone includes ventilation, mechanical heat, air conditioning or air movement system. The movement of smoke at the cool smoke zone is the same as that of any other pollutant in the building. The smoke in the cool some zone has minimal effects on the evacuation process. The cool zone is however dependant on the distance from the fire or the heat. The occupants at the cool zone can safely evacuate the high rise building in case of a fire incident. Flow through openings A higher pressure to a lower pressure will result in case of a gap or opening within the high rise building. The presence of gaps in the building contributes to the movement of the smoke to the other floors of the high rise building. The flow rate of smoke through an opening can be calculated using the following formula: V=. Where: V=volumetric flow rate in meters per second. C= flow coefficient, A=flow area in cubic metres.  Pressure difference and = density. When the smoke is flowing through the door or construction cracks, the coefficient is 0.6 to 0.7 and the standard air density is 1.2Kg/(Yuan, et al., 2014). The amount of openings plays an essential role in terms of determining the rate at which the smoke flows through the building. Stack effects The stack effect accounts for the natural air movement in a building under ordinary conditions. Stack effect is responsible for the distribution of smoke within a high rise building in the event of a fire. The stack effect is responsible for the movement of smoke from the ground floor to the roof of the high rise building. Magnitude of the stack effect depends on the height of the building and hence impacting negatively on the high rise building (Yuan, et al, 2014). The natural vertical air movement within the high rise building is due to the stack effects and it leads to the movement of smoke from the floor to the roof. Inside and outside temperature of the high rise building influences the stack effect in the event of a fire. The pressure difference between the interior and exterior part of the building also affects the stack effect. Fire release heat also affects the movement of smoke in a high rise building through the stack effect (Yuan, et al, 2014). The temperature difference within the building also affects the smoke movement through the stack effect. Pressure difference with the building during the event of a fire affects the smoke movement through the stack effect concept. Floors and partitions The presence of cracks within the different floors encourages the smoke movement within the high rise building during a fire. Elevators and stairwells usually causes the vertical flow of smoke in the high rise building leading to its spread to other parts of the building. The pressure difference between the floors is responsible for the smoke movement in the high rise buildings (Sun, et al, 2012). Pressure differences between the floes are responsible for the movement of smoke to either the lower floors or upper floors. Depending on the pressure, the rate of smoke movement can be quite high leading to the spread of smoke within a short time. Wind effects The wind effects have impacts on the smoke movement in the high rise building. A high wind velocity is increases the smoke movement within the high rise building and hence causing difficulties during the evacuation process (Sun, et al, 2012). The natural air movement within the building is usually affected by a high wind velocity leading to an increased air movement. Neutral planes in the exterior wall are affected by the horizontal pressures from the wind and hence affecting the smoke movement. The neutral effects on the neutral plane by the wind increases the smoke movement in the high rise buildings. On a windy day, the evacuation process may therefore be difficult in case of a fire in a high rise building. Significance of the results The findings about the smoke movement in a high rise building can be used during the design of the building. The information can also be used for the purposes of reducing the flow rate of the smoke during a fire and making recommendations with regards to how the smoke movement problems can be minimized. The findings can also be applied for the purposes of promoting fire safety measures in high rise buildings. List of References Ji, J. et al. 2013, Experimental investigation on the rising characteristics of the fire-induced buoyant plume in stairwells, International Journal of Heat and Mass Transfer, 64, 193-201. Cai, N., & Chow, W. K 2012, Numerical studies on heat release rate in room fire on liquid fuel under different ventilation factors, International Journal of Chemical Engineering, 2012. Shi, W. et al. 2014, Influence of fire power and window position on smoke movement mechanisms and temperature distribution in an emergency staircase, Energy and Buildings, 79, 132-142. Yuan, X. Y. et al. 2014, Experimental study on influence of stack effect on fire in the compartment adjacent to stairwell of high rise building, Journal of Civil Engineering and Management, 20(1), 121-131. Sun, J. H. et al. 2012, Experimental investigation on influence of different transverse fire locations on maximum smoke temperature under the tunnel ceiling, International Journal of Heat and Mass Transfer, 55(17), 4817-4826. Read More