Yüksek binalarda merdiven kovalarının basınçlandırılması ile duman kontrolü

Başlık çevirisi mevcut değil.

Tez No: 75252
Yazar: SERKAN SOYEL
Danışmanlar: PROF. DR. ABDURRAHMAN KILIÇ
Tez Türü: Yüksek Lisans
Konular: Makine Mühendisliği, Mechanical Engineering
Anahtar Kelimeler: Belirtilmemiş.
Yıl: 1998
Dil: Türkçe
Üniversite: İstanbul Teknik Üniversitesi
Enstitü: Fen Bilimleri Enstitüsü
Ana Bilim Dalı: Belirtilmemiş.
Bilim Dalı: Belirtilmemiş.
Sayfa Sayısı: 158

Özet

ÖZET Yangınlarda ölüm ve yaralanmaların büyük çoğunluğu, katlar arasına, merdiven ve asansör şaftları içerisine dolan duman nedeniyle olmaktadır. Bu konu üzerinde yapılan istatistiki çalışmalar göstermiştir ki; ölümlerin %90'ından fazlasına zehirli duman sebep olmaktadır. Duman kontrolü için yangın merdiven kovasının basınçlandırılması günümüzde en yaygın olarak kullanılan yöntemdir. Bunun yapılmasının nedeni ise yukanda belirtildiği gibi, bina kullanıcılarının bir yangın esnasında binayı rahatça tahliye edebilmelerini güvenli bir ortam içerisinde ve itfaiyenin yangına kolayca müdahale edebilmesini sağlamaktadır. Belirtilen tüm bu imkanlann sağlanabilmesi için, yangın merdiven kovasına uygulanan basınçlandırma sisteminin düzgün bir şekilde çalışması gerekmektedir. Yangın merdiven kovasının basınçlandırılması tekli ve çoklu enjeksiyonlu sistem ile yapılmaktadır. Tekli enjeksiyonlu sistemde merdiven kovası içerisine üflenen basınçlandırma havası tek bir noktadan, çoklu enjeksiyonlu sistemlerde ise merdiven kovası içerisine üflenen basınçlandırma havası birden fazla noktadan verilmektedir. Burada üfleme nokta sayısı, üfleme havasının merdiven kovası içerisine nasıl verildiğine bağlıdır. Bu her katta olabileceği gibi, iki veya üç katta bir de yapılabilmektedir. Çoklu enjeksiyonlu sistemler yüksek binalar için tercih edilmektedir. Bu çalışmada, yangın merdivenleri kovalarının basınçlandırılması ve dumanın tahliye edilmesi için uygulanacak sistemlerin tasanmına etki eden faktörler ve tasanm kriterleri incelenmiştir. Geliştirilen bir model için bilgi-işlem programı hazırlanmış ve değişik parametrelere göre elde edilen sonuçlar karşılaştırılmıştır. Yapılan modellemelerde ülkemiz coğrafi bölgelerinin her birine ait bir ilimiz ele alınarak incelemelerimiz yapılmıştır. Elde edilen sayısal neticeler grafikler şeklinde verilip, sonuçlar irdelenmiştir. Yaz ve kış iklim şartlarına göre kritik mevsim olarak kış mevsimi belirlenmiştir. Kış şartlarına göre, açık iç kapıların konumunun basınçlandırma sistemine etkisi ele alınmış, üst iç kapıların en kritik neticeyi verdiği saptanmıştır. Tek noktadan enjeksiyonlu sistemlerde, enjeksiyon yapılan noktanın konumunun sistem performansı üzerindeki etkisi incelenmiş ve üstten üflemenin en iyi sonucu verdiği görülmüştür. Tekli enjeksiyonlu sistemler için kat sınırlamasının 8 kat olduğu hesaplarla gösterilmiştir. Çoklu enjeksiyonlu sistemler de üfleme aralığının kaç katta bir yapılırsa optimum sonucu verdiği, sistem verimi, maliyeti ve otomasyon kolaylığı açısından irdelenmiş ve optimum kat sayısının 3 olduğu bulunmuştur. Ayrıca tekli ve çoklu enjeksiyonlu sistemlerin mukayesesi 7 katlı bir bina ele alınarak yapılmıştır. Yapılan karşılaştırmalarda çoklu enjeksiyonun çok daha uygun olduğu görülmüştür. XIV

Özet (Çeviri)

SUMMARY PRESSURIZED STAIRWELLS IN HIGH-RISE BUILDINGS FOR SMOKE CONTROL In building fire, smoke often flows to locations remote from the fire, threatening life and damaging property. Stairwells and elevators frequently become smoke filled, thereby blocking or inhibiting evacuation. Smoke causes the most deaths in fires. Smoke is defined as the airborne solid and liquid particulates and gases evolved when a material undergoes pyrolysis or combustion, together with the quantity of air that is entrained or otherwise mixed into the mass. In the early 1980s, the idea of pressurization to prevent smoke infiltration of stairwells began to attract attention. This concept was followed by the idea of the“pressure sandwich,”i.e., venting or exhausting the fire floor and pressurizing the surrounding floors. Frequently, a building's ventilation system is used for this purpose. Smoke control systems use pressurization produced by mechanical fans to limit smoke movement in fire situations. This paper discusses smoke control systems in high-rise buildings as they relate to the design critical parameters. The objective of fire safety is to provide some degree of protection for building's occupants, the building and the property inside it, and neighboring buildings. Various forms of system analysis have been used to help quantify protection. Specific life safety objectives differ with occupancy; for example, nursing home requirements are different from those for office buildings. Two basic approaches to fire protection are to prevent fire ignition and to manage fire impact.. The building occupants and managers have the primary role in preventing fire ignition. The building design team may incorporate features into the building to assist to occupants and managers in effort. Because it is impossible to prevent fire ignition completely, managing fire impact has become significant in fire protection design. Examples of fire impact management include compartmentation, suppression, control of construction materials, exit systems, and smoke management. Smoke Movement and Control in High-Rise Buildings (Tamura 1994) contain detailed fire safety information. Historically, fire safety professionals have considered the HVAC system as a potentially dangerous penetration of natural building membranes (wall, floors, and so forth) that can readily transport smoke and fire. For this reason, the systems have traditionally been shut down when fire is discovered. Although shutting down the system prevents fans from forcing smoke flow, it does not prevent smoke movement through ducts due to smoke buoyancy, stack effect, or wind. To solve the problem of smoke movement, methods of smoke control have been developed; it should be viewed as only one part of the overall building fire protection system. Smoke Movement; a smoke control system must be designed so that it is not overpowered by the driving forces that cause smoke movement, which include stack effect, buoyancy, expansion, the wind, and the heating, ventilating, and air- conditioning system. In fire, smoke is generally moved by a combination of these forces. XVStack effect; when it is cold outside, air often moves upward within building shafts, such as stairwells, elevator shafts, dumbwaiter shafts, mechanical shafts, or mail chutes. This normal stack effect occurs because the air in the building is warmer and less dense that the outside air. Normal stack effect is great when outside temperatures are low, especially in tall buildings. However, normal stack effect can exist even in a one-story building. When the outside air is warmer than the building air, downward airflow, or reverse stack effect, frequently exists in shafts. At standard atmospheric pressure, the pressure difference due to either normal or reverse stack effect is expressed as (l O AP = 3460 - -- h U T,) where AP : pressure difference, (Pa) To : absolute temperature of outside air, (K) T, : absolute temperature of inside air, (K) h : distance above neutral plane, (m) (D For a building 60 m tall with a neutral plane at the midheight, an outside temperature of -18°C, and an inside temperature of 21 °C, the maximum pressure difference due to stack effect would be 55 Pa. This means that at the top of the building, a shaft would have a pressure 55 Pa greater than the outside pressure. At the bottom of the shaft, the shaft would have a pressure 55 Pa less than the outside pressure. Figure 1 diagrams the pressure difference between a building shaft and the outside. A positive pressure difference indicates that jhe shaft pressure is higher than the outside pressure, and a negative pressure difference indicates the opposite. Stack effect usually exists between a building and the outside. The air movement in buildings caused by both normal and reverse stack effect. In this case, the pressure difference expressed in equation (1) refers to the pressure difference between the shaft and the outside of the building. TOP OF BUILDING Negaüve(-) PosiUve (+) Figure 1. Pressure Difference Between a Building Shaft and the Outside Due to Normal Stack Effect. XVISmoke movement from a building fire can be dominated by stack effect. In a building with normal stack effect, the existing air currents can move smoke considerable distances from the fire origin. If the fire below the neutral plane, smoke moves with the building air into and up the shafts. This upward smoke flow is enhanced by buoyancy forces due to the temperature of the smoke. Once above the neutral plane, the smoke flows from the shafts into the upper floors of the building. If the leakage between floors is negligible, the floors below the neutral plane, except the fire floor, are relatively smoke-free until the quantity of smoke produced is greater than can be handled by stack effect flows. Smoke from a fire located above the neutral plane is carried by the building airflow to the outside through exterior openings in the building. If leakage between floors is negligible, all floors other than the fire floor remain relatively smoke-free until the quantity of smoke produced is greater than can be handled by stack effect flows. When the leakage between floors is considerable, the smoke flows to the floor above the fire floor. The air currents caused by reverse stack effect tend to move relatively cool smoke down. In the case of hot smoke, buoyancy forces can cause smoke to flow upward, even during reverse stack effect conditions. Buoyancy; High-temperature smoke from a fire has a buoyancy force due to its reduced density. The pressure difference between a fire compartment and its surroundings can be expressed as follows; AP = 3460 \.To TfJ h (2) where AP : pressure difference, (Pa) To : absolute temperature of surroundings, (K) Tf : absolute temperature of fire compartment, (K) h : distance above neutral plane, (m) The neutral plane is the plane of equal hydrostatic pressure between the fire compartment and its surroundings. For a fire with a fire compartment temperature at 800°C, the pressure difference 1.5 m above the neutral plane is 13 Pa. Much larger pressure difference are possible for tall fire compartments where the distance h from the neutral plane can be larger. If the fire compartment temperature is 700°C, the pressure difference 10.7 m above the neutral plane is 90 Pa. This is large fire, and the pressure it produces are beyond present smoke control methods. However, the example illustrates extent to which Equation (2) can be applied. Expansion ; in addition to buoyancy, the energy released by a fire can move smoke by expansion. In a fire compartment with only one opening to the building, building air will flow in, and hot smoke will flow out. Neglecting the added mass of the fuel, which is small compared to the airflow, the ration of volumetric flows can be expressed as a ration of absolute temperatures: yiout _ '.out where Qout : volumetric flow rate of smoke out of fire compartment, (m3/h) Qin : volumetric flow rate of air into fire compartment, (m3/h) Tout : absolute temperature of smoke leaving fire compartment, (K) xviif y. y.\ bpsbt -APstb.3/ 0 = 0.559^ T* *?“”(11) where Q : volumetric flow rate, (m7s) N : number of floors Apsbt : pressure difference from stairwell to building at stairwell top, (Pa) Stairwell Pressurization and Open Doors; the simple pressurization system discussed previously has two limitations regarding open doors. First, when a stairwell door to the outside and doors to the building are open, the simple system cannot provide sufficient airflow through doorways to the building to prevent smoke backflow. Second, when stairwell doors are open, the pressure difference across the closed doors can drop to low levels. Two systems used to overcome these problems are overpressure relief (Tamura 1990) and supply fan bypass. CONCLUSION: This study is designated to smoke control systems in high-rise buildings as they are related to the designed critical parameters. These parameters determined by using computer programs which are introducing at appendix A. The models which were shown before, in this part of study, have few critical parameters. One of these parameters is, the specific provinces chosen from different geographic areas were investigated about their climate conditions of our country, as a comparison of these seasons, it was seen that, winter season is the most critical and important season of a year. Then the pressurization system which were designed for winter conditions it was seen that, the greatest amount of pressurization air is needed when the limited number of opened doors are located in a section at the top of stairwell. After that, the subject of discussion was the single injection system; the effect of the injection point on the performance of pressurized system was researched and as a result, top injection system is the most efficient system between the other ones. In the second step about single injection system, it was indicated by calculations that the limited number of stories for our country's climate conditions are eight. After the studies about single injection systems, the multiple injection systems were designated. In multiple injection system, if the injection points are repeated every 3 stories, the best result according to the system efficiency, cost and easiness of automation can be taken. To sum it up, the comparison of these two systems were made on a 7 stories building which was supposed to be a model. As a result of this comparison, it can be said that the multiple injection systems, always more useful and appropriate than the single injection systems. XXIVRoof Level Duct Shaft Figure 3. Stairwell pressurization by multiple injection with fan located at ground level. Stairwell Analysis; this section presents an analysis for a pressurized stairwell in a building without vertical leakage. The performance of pressurized stairwells in buildings without elevators may be closely approximated by this method. It is also useful for buildings with vertical leakage in that it yields conservative results. Only one stairwell is considered in the building; however, the analysis can be extended to any number of stairwells by the concept of symmetry. For evaluation of vertical leakage through the building or with open stairwell doors, computer analysis is recommended. The analysis is for buildings where the leakage areas are the same for each floor of building and where the only significant driving forces are stairwell pressurization system and the temperature difference between the indoors and outdoors. The pressure difference Apsb between the stairwell and building can be expressed as *p*=*pM+Byl where Apsbb : pressure difference from stairwell to building at stairwell bottom, (Pa) y : distance above stairwell bottom, (m) A3b : flow area between stairwell and building (per floor), (m2) Abo : B = 3460 (10) to t8 flow area between building and outside (per floor), (m ) J1 (273 + 0 (273-0. : temperature of outside air, (°C) : temperature of stairwell air, (°C) For a stairwell with no leakage directly to outside, the flow rate of pressurization air is XXlllf y. y.\ bpsbt -APstb.3/ 0 = 0.559^ T* *?“”(11) where Q : volumetric flow rate, (m7s) N : number of floors Apsbt : pressure difference from stairwell to building at stairwell top, (Pa) Stairwell Pressurization and Open Doors; the simple pressurization system discussed previously has two limitations regarding open doors. First, when a stairwell door to the outside and doors to the building are open, the simple system cannot provide sufficient airflow through doorways to the building to prevent smoke backflow. Second, when stairwell doors are open, the pressure difference across the closed doors can drop to low levels. Two systems used to overcome these problems are overpressure relief (Tamura 1990) and supply fan bypass. CONCLUSION: This study is designated to smoke control systems in high-rise buildings as they are related to the designed critical parameters. These parameters determined by using computer programs which are introducing at appendix A. The models which were shown before, in this part of study, have few critical parameters. One of these parameters is, the specific provinces chosen from different geographic areas were investigated about their climate conditions of our country, as a comparison of these seasons, it was seen that, winter season is the most critical and important season of a year. Then the pressurization system which were designed for winter conditions it was seen that, the greatest amount of pressurization air is needed when the limited number of opened doors are located in a section at the top of stairwell. After that, the subject of discussion was the single injection system; the effect of the injection point on the performance of pressurized system was researched and as a result, top injection system is the most efficient system between the other ones. In the second step about single injection system, it was indicated by calculations that the limited number of stories for our country's climate conditions are eight. After the studies about single injection systems, the multiple injection systems were designated. In multiple injection system, if the injection points are repeated every 3 stories, the best result according to the system efficiency, cost and easiness of automation can be taken. To sum it up, the comparison of these two systems were made on a 7 stories building which was supposed to be a model. As a result of this comparison, it can be said that the multiple injection systems, always more useful and appropriate than the single injection systems. XXIVRoof Level Duct Shaft Figure 3. Stairwell pressurization by multiple injection with fan located at ground level. Stairwell Analysis; this section presents an analysis for a pressurized stairwell in a building without vertical leakage. The performance of pressurized stairwells in buildings without elevators may be closely approximated by this method. It is also useful for buildings with vertical leakage in that it yields conservative results. Only one stairwell is considered in the building; however, the analysis can be extended to any number of stairwells by the concept of symmetry. For evaluation of vertical leakage through the building or with open stairwell doors, computer analysis is recommended. The analysis is for buildings where the leakage areas are the same for each floor of building and where the only significant driving forces are stairwell pressurization system and the temperature difference between the indoors and outdoors. The pressure difference Apsb between the stairwell and building can be expressed as *p*=*pM+Byl where Apsbb : pressure difference from stairwell to building at stairwell bottom, (Pa) y : distance above stairwell bottom, (m) A3b : flow area between stairwell and building (per floor), (m2) Abo : B = 3460 (10) to t8 flow area between building and outside (per floor), (m ) J1 (273 + 0 (273-0. : temperature of outside air, (°C) : temperature of stairwell air, (°C) For a stairwell with no leakage directly to outside, the flow rate of pressurization air is XXlllf y. y.\ bpsbt -APstb.3/ 0 = 0.559^ T* *?“”(11) where Q : volumetric flow rate, (m7s) N : number of floors Apsbt : pressure difference from stairwell to building at stairwell top, (Pa) Stairwell Pressurization and Open Doors; the simple pressurization system discussed previously has two limitations regarding open doors. First, when a stairwell door to the outside and doors to the building are open, the simple system cannot provide sufficient airflow through doorways to the building to prevent smoke backflow. Second, when stairwell doors are open, the pressure difference across the closed doors can drop to low levels. Two systems used to overcome these problems are overpressure relief (Tamura 1990) and supply fan bypass. CONCLUSION: This study is designated to smoke control systems in high-rise buildings as they are related to the designed critical parameters. These parameters determined by using computer programs which are introducing at appendix A. The models which were shown before, in this part of study, have few critical parameters. One of these parameters is, the specific provinces chosen from different geographic areas were investigated about their climate conditions of our country, as a comparison of these seasons, it was seen that, winter season is the most critical and important season of a year. Then the pressurization system which were designed for winter conditions it was seen that, the greatest amount of pressurization air is needed when the limited number of opened doors are located in a section at the top of stairwell. After that, the subject of discussion was the single injection system; the effect of the injection point on the performance of pressurized system was researched and as a result, top injection system is the most efficient system between the other ones. In the second step about single injection system, it was indicated by calculations that the limited number of stories for our country's climate conditions are eight. After the studies about single injection systems, the multiple injection systems were designated. In multiple injection system, if the injection points are repeated every 3 stories, the best result according to the system efficiency, cost and easiness of automation can be taken. To sum it up, the comparison of these two systems were made on a 7 stories building which was supposed to be a model. As a result of this comparison, it can be said that the multiple injection systems, always more useful and appropriate than the single injection systems. XXIVRoof Level Duct Shaft Figure 3. Stairwell pressurization by multiple injection with fan located at ground level. Stairwell Analysis; this section presents an analysis for a pressurized stairwell in a building without vertical leakage. The performance of pressurized stairwells in buildings without elevators may be closely approximated by this method. It is also useful for buildings with vertical leakage in that it yields conservative results. Only one stairwell is considered in the building; however, the analysis can be extended to any number of stairwells by the concept of symmetry. For evaluation of vertical leakage through the building or with open stairwell doors, computer analysis is recommended. The analysis is for buildings where the leakage areas are the same for each floor of building and where the only significant driving forces are stairwell pressurization system and the temperature difference between the indoors and outdoors. The pressure difference Apsb between the stairwell and building can be expressed as *p*=*pM+Byl where Apsbb : pressure difference from stairwell to building at stairwell bottom, (Pa) y : distance above stairwell bottom, (m) A3b : flow area between stairwell and building (per floor), (m2) Abo : B = 3460 (10) to t8 flow area between building and outside (per floor), (m ) J1 (273 + 0 (273-0. : temperature of outside air, (°C) : temperature of stairwell air, (°C) For a stairwell with no leakage directly to outside, the flow rate of pressurization air is XXlllf y. y.\ bpsbt -APstb.3/ 0 = 0.559^ T* *?“”(11) where Q : volumetric flow rate, (m7s) N : number of floors Apsbt : pressure difference from stairwell to building at stairwell top, (Pa) Stairwell Pressurization and Open Doors; the simple pressurization system discussed previously has two limitations regarding open doors. First, when a stairwell door to the outside and doors to the building are open, the simple system cannot provide sufficient airflow through doorways to the building to prevent smoke backflow. Second, when stairwell doors are open, the pressure difference across the closed doors can drop to low levels. Two systems used to overcome these problems are overpressure relief (Tamura 1990) and supply fan bypass. CONCLUSION: This study is designated to smoke control systems in high-rise buildings as they are related to the designed critical parameters. These parameters determined by using computer programs which are introducing at appendix A. The models which were shown before, in this part of study, have few critical parameters. One of these parameters is, the specific provinces chosen from different geographic areas were investigated about their climate conditions of our country, as a comparison of these seasons, it was seen that, winter season is the most critical and important season of a year. Then the pressurization system which were designed for winter conditions it was seen that, the greatest amount of pressurization air is needed when the limited number of opened doors are located in a section at the top of stairwell. After that, the subject of discussion was the single injection system; the effect of the injection point on the performance of pressurized system was researched and as a result, top injection system is the most efficient system between the other ones. In the second step about single injection system, it was indicated by calculations that the limited number of stories for our country's climate conditions are eight. After the studies about single injection systems, the multiple injection systems were designated. In multiple injection system, if the injection points are repeated every 3 stories, the best result according to the system efficiency, cost and easiness of automation can be taken. To sum it up, the comparison of these two systems were made on a 7 stories building which was supposed to be a model. As a result of this comparison, it can be said that the multiple injection systems, always more useful and appropriate than the single injection systems. XXIV

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