工业与民用建筑的通风课件.ppt

2023/3/21,1,第八章 工业与民用建筑的通风,2023/3/21,东华大学/环境学院/暖通空调,2,合格空气品质定义,ASHRAE62-1989:合格的空气品质应当是空气中没有浓度达到有权威机构确定的有害程度指标的已知污染物,并且在这种环境中人群绝大多数(80%或更多)没有表达不满意.,2023/3/21,东华大学/环境学院/暖通空调,3,工业与民用建筑的污染物,1）化学污染物：主要包括从装修材料、化妆用品、涂料、厨房等地方释放或排放出来的包括氨、氮氧化物、硫氧化物、碳氧化物等无机污染物及甲醛、苯、二甲苯等在内的有机污染物；2）放射性污染：主要是来自从混凝土中释放出来的氡气及其衰变子体，还有由石材制成品如大理石台面、洁具、地板等释放的射线；3）物理污染：包括室外交通工具产生的噪音、室内灯光照明不足或过亮、温湿度过高或过低所引起的相关问题及石棉污染等；,2023/3/21,东华大学/环境学院/暖通空调,4,工业与民用建筑的污染物,4）生物污染：生物污染可分为四类:一是霉菌,它是造成过敏性疾病的最主要原因；二是来自植物的花粉；三是由人体、动物、土壤和植物碎屑携带的细菌和病毒；四是尘螨以及猫、狗和鸟类身上脱落的毛发、皮屑。5）大气颗粒物污染：由室外进入或厨房烹饪过程中产生的颗粒物，它们往往由于吸附一些能导致人体癌变的化学物质而被人类所普遍关注，同时人们在梳妆或搔痒过程中产生的一些皮屑也可归于此类。,2023/3/21,东华大学/环境学院/暖通空调,5,室内污染物危害,1.甲醛对人体健康的影响主要表现在嗅觉异常、刺激、过敏、肺功能异常、免疫功能异常等方面。当室内空气中甲醛含量为0.1mg/m3时就有异味和不适感；0.5mg/m3时可刺激眼睛引起流泪；0.6mg/m3时引起咽喉不适或疼痛；浓度再高可引起恶心、呕吐、咳嗽、胸闷、气喘甚至肺气肿。长期低浓度接触甲醛气体，可出现头痛、头晕、乏力、两侧不对称感觉障碍和排汗过剩以及视力障碍，且能抑制汗腺分泌，导致皮肤干燥皲裂；浓度较高时，对粘膜、上呼吸道、眼睛和皮肤具有强烈刺激性，对神经系统、免疫系统、肝脏等产生毒害。,2023/3/21,东华大学/环境学院/暖通空调,6,室内污染物危害,2、苯 吸入4000ppm以上的苯短时间除有黏膜及肺刺激外中枢神经亦有抑制作用，同时会伴有头痛、欲呕、步不稳、昏迷抽痉及心律不整。吸入14000ppm以上的苯会立即死亡。3、甲苯甲苯进入体内以后约有48%在体内被代谢，经肝脏、脑、肺和肾后排出体外，在这个过程中会对神经系统产生危害，自愿者实验明当血液中甲苯浓度达到1250mg/m3时，接触者的短期记忆能力注意力持久性以及感觉运动速度均显著降低。,2023/3/21,东华大学/环境学院/暖通空调,7,室内污染物危害,4、氨 氨进入肺泡后易和血红蛋白结合破坏运氧功能美国制造化学师协会规定，不允许工作人员在于100ppm的氨浓度下工作8小时。5,臭氧臭氧的强氧化性对人体健康却有危害作用。一般认为臭氧吸入体内后，能迅速转化为活性很强的自由基-超氧基(O2-)，主要使不饱和脂肪酸氧化，从而造成细胞损伤。,2023/3/21,东华大学/环境学院/暖通空调,8,室内污染物危害,6、一氧化碳 一氧化碳的中毒机理是：它进入肺泡后很快会和血红蛋白(Hb)产生很强的亲合力，使血红蛋白形成碳氧血红蛋白(COHb)，阻止氧和血红蛋白的结合。血红蛋白与一氧化碳的亲合力要比与氧的亲合力大200300倍，同时碳氧血红蛋白的解离速度却比氧合血红蛋白的解离慢3600倍。,2023/3/21,东华大学/环境学院/暖通空调,9,室内污染物危害,7、二氧化碳 室内空气二氧化碳在0.07%以下时属于清洁空气，人体感觉良好；当浓度在0.07%0.1%时属于普通空气，个别敏感者会感觉有不良气味；在0.1%0.15%时属于临界空气，室内空气的其它症状开始恶化，人体开始感觉不适；达到0.15%0.2%时属于清度污染，超过0.2%属于严重污染；在0.3%0.4%的人呼吸加深，出现头疼、耳鸣、血压增加等症状当达到0.8%以上时就会引起死亡。,2023/3/21,东华大学/环境学院/暖通空调,10,室内污染物危害,8、挥发性有机污染物(VOCs)室内有机污染物对人体的污染基本可分为三种主要类型：气体和其它感觉效应(如刺激作用)、粘膜刺激和其它系统毒性导致的病变、基因毒性和致癌性。,2023/3/21,东华大学/环境学院/暖通空调,11,室内污染物危害,9、氡 氡通过呼吸进入人体，衰变时产生的短寿命放射性核素会沉积在支气管、肺和肾组织中。当这些短寿命放射性核衰变时，释放出的粒子对内照射损伤最大，可使呼吸系统上皮换换细胞受到辐射。长期的体内照射可能引起局部组织损伤，甚至诱发肺癌和支气管癌等。据估算，人的一生中，如果在氡浓度370Bq/m3的室内环境中生活，每千人中将有30120死于肺癌。若长期生活在含氡量高的环境里，就可能对人的血液循环系统造成危害，如白细胞和血小板减少，严重的还会导致白血病。,2023/3/21,东华大学/环境学院/暖通空调,12,室内污染物危害,10、可吸入颗粒物对人体健康的危害据了解，在可吸入颗粒物中，直径小于10微米的污染颗粒物可通过呼吸作用侵入人的上呼吸道；当其直径小于2.5微米时，污染物可进入人的下呼吸道，有时甚至穿过肺泡进入血液。目前，首要污染物就是颗粒物，而其中直径小于2.5微米的细微颗粒物则是空气污染要解决的难点。可吸入颗粒物还是细菌等微生物依附之物。在可吸入颗粒物中10左右依附着各种细菌等微生物,2023/3/21,东华大学/环境学院/暖通空调,13,室内污染物危害,金黄色葡萄球菌短时间内可能会导致急性食物中毒，上吐下泻。,克雷白氏菌杆菌常造成呼吸道及肠道的伺机性感染。,冠状病毒这类病毒具有胃肠道、呼吸道和神经系统的嗜性，对人体诱发非典型肺炎。,2023/3/21,东华大学/环境学院/暖通空调,14,中国室内空气气体浓度标准,居室内使用的建筑材料中放射性比活度符合国家规定的建筑材料放射性要求；居室内空气中甲醛最高容许浓度不超过0.08 mg/m3；居室内空气中二氧化碳卫生标准值0.10（2000mg/m3）居室内可吸入颗粒物日平均最高容许浓度为0.15mg/m3；居室内易挥发有机物的总释放量(TVOC)应低于0.2mg/m2/h；居室内空气中细菌含量4000CFU/；居室内无石棉建筑制品；居室内无超标电磁辐射污染；居室不应有令人不快的气味。,2023/3/21,东华大学/环境学院/暖通空调,15,多种污染物,根据各种污染物对人体某一器官危害的相关性:各种污染物单独作用(CO2与CO)各种污染物有叠加作用(O3与NO2),2023/3/21,东华大学/环境学院/暖通空调,16,全面通风系统,自然通风机械通风(机械进风系统和机械排风系统),2023/3/21,东华大学/环境学院/暖通空调,17,机械进风系统,2023/3/21,东华大学/环境学院/暖通空调,18,机械排风系统,2023/3/21,东华大学/环境学院/暖通空调,19,病态建筑的防治,Sick or Tight-building syndromea series of acute complaints for which there is no obvious cause and where medical tests reveal no particular abnormalitiessymptoms generally subside after leaving building,2023/3/21,东华大学/环境学院/暖通空调,20,病态建筑的防治,NIOSH Study found:52%-poor ventilation17%-indoor pollutantsUnknown 12%Outside Pollutants 11%Microbiological 5%Furnishings 3%,2023/3/21,东华大学/环境学院/暖通空调,21,LOCAL VENTILATION,Short definition:Local Ventilation systems are used to transport contaminants or heatfrom the occupancy zone.Long definition:Local Ventilation uses an air flow rate that is as low as possible,butsufficient to minimize the amount of airborne contaminants entering aspecified volume or passing specified point(s).These are usuallyintended to be at the breathing zone of occupants.This minimization ofair flow can be achieved either by capturing(or containing)the airbornecontaminant into an exhaust hood before it enters the workspace,byblowing non-contaminated air from a supply inlet through the volume toprevent the contaminant from entering the workspace,or a combinationof those.,2023/3/21,东华大学/环境学院/暖通空调,22,Local supply ventilation,2023/3/21,东华大学/环境学院/暖通空调,23,Local Ventilation Modes,All Local Ventilation systems can be manufactured for use in one or more of three different modes.Fixed systems are those where movement of the hood or other changes to the system,except perhaps opening and closing of lids and doors,are not possible.One example is the laboratory fume hood.Flexible systems are those where the suction opening or supply device may be placed at different locations inside a limited area or volume.This is performed by connecting the exhaust(or supply)opening and duct(or tube)to the fan by flexible connections(ducts with moveable elbows or flexible tube).One example is a wall mounted hood for welding exhaust.Mobile systems are those where the exhaust(supply)opening may be placed almost anywhere inside a workroom.This is performed by placing the whole system(exhaust/supply opening,duct,fan)on wheels or a portable frame.It can also be accomplished by having a separate exhaust part(opening and short tube)which could be connected to a central duct system at many places(in walls,on the floor or from the ceiling).One example of the former is a welding exhaust(with filter)on a small carriage and an example of the latter is a centralized exhaust system for connection to car exhaust pipes.Mobile exhaust or supply systems also include portable systems,2023/3/21,东华大学/环境学院/暖通空调,24,2023/3/21,东华大学/环境学院/暖通空调,25,Classification of hood types,EnclosuresComplete:“Glove Box”Booth:One side open for access Tunnel:Two open sides,2023/3/21,东华大学/环境学院/暖通空调,26,Classification of hood types,The Class III Biological Safety Cabinet is a combined exhaust-supply system.A:Glove ports with O ring for attaching arm length gloves to cabinet.B:Sash.C:Exhaust HEPA filter.D:Supply HEPA filter.E:Double ended autoclave or pass through box.Note:Connection of the exhaust to building exhaust system is required.,2023/3/21,东华大学/环境学院/暖通空调,27,Basic rules to give best overall enclosure design,Make enclosure as complete as possible(i.e.reduce opening area)Design so that air inflow is evenly distributedMake booth deeperBaffles or filters at exit to even airflow,2023/3/21,东华大学/环境学院/暖通空调,28,Classification of hood types,ExteriorDraws air away from contaminant source but does not surround the source at point of releaseContaminant must be captured by the hoodExample:Movable welding hood,2023/3/21,东华大学/环境学院/暖通空调,29,Exterior Hoods,Practical considerations make exterior hoods necessary in some casesExterior hoods are susceptible to local air movement(cross-drafts,etc.)caused by other forcesLocation of hood with respect to source and worker,2023/3/21,东华大学/环境学院/暖通空调,30,Potential Sources for Air Motion Around Hood,Thermal air currents from nearby hot processes or heat generating machinesMotion of nearby machinery(belt conveyors,etc.)Material in motion(dumping or container filling)Movements of the operatorRoom air currents(generally 50 feet/min or higher)Spot cooling or heating equipment,2023/3/21,东华大学/环境学院/暖通空调,31,Range of Capture Velocities,2023/3/21,东华大学/环境学院/暖通空调,32,Theoretical point source suction,Point source suction,Capture velocity,x,Surface area of sphere:,Require air flow(cfm),2023/3/21,东华大学/环境学院/暖通空调,33,Approximate Impact on Inlet Face Velocity,2023/3/21,东华大学/环境学院/暖通空调,34,Air Shower,2023/3/21,东华大学/环境学院/暖通空调,35,Open unidirectional airflow benches,2023/3/21,东华大学/环境学院/暖通空调,36,A push-pull system,2023/3/21,东华大学/环境学院/暖通空调,37,Combined exhaust-supply system,2023/3/21,东华大学/环境学院/暖通空调,38,Combined exhaust-supply system,the volume of exhaust air flow is 150 m3h-1,the volume of supply air is 82 m3h-1,the volume of exhaust air flow is 290 m3h-1,the volume of supply air is 50 m3h-1,2023/3/21,东华大学/环境学院/暖通空调,39,Auxiliary air supply fume hood,2023/3/21,东华大学/环境学院/暖通空调,40,Characteristic geometrical parameters of air curtains,2023/3/21,东华大学/环境学院/暖通空调,41,EVALUATION OF LOCAL VENTILATION,The evaluation methods could be direct,e.g.,measuring a containment index,or indirect,e.g.,measuring pressure loss or velocity distribution.For some hood types,measurements usually seen asindirect methods,are used to measure the hoodsperformance to determine regulatory compliance.Forexample,there are regulations specifying minimumand maximum face velocities for laboratory fumehoods and static pressure(negative)inside enclosedhoods.Continuously monitoring instruments can beconnected to alarms which sound when themeasurement is outside the specified limits,2023/3/21,东华大学/环境学院/暖通空调,42,EVALUATION OF LOCAL VENTILATION,Capture efficiency is the fraction of generated contaminant that is directly captured by the hood.Measurement of capture efficiency involves measuring concentration of process-generated contaminant or a tracer material.Using process-generated contaminant requires use of instruments suited to each specific contaminant and its conditions(temperature,pressure,concentration,form,etc).In order to facilitate these measurements,a tracer is often substituted for the process-generated contaminant.,2023/3/21,东华大学/环境学院/暖通空调,43,EVALUATION OF LOCAL VENTILATION,A simple evaluation can be done by checking the air flow rate into the opening,presuming the source characteristics,the placement of the exhaust,and other parameters(crossdraft,work routines,supply air flow rate,etc)have not changed since the detailed evaluation was done.Since the static pressure loss for a hood is dependent on form and flow rate it can be used alone to monitor the flow rate into the hood.If the flow rate and the pressure loss were measured at the same time as the efficiency,the pressure loss can be used for monitoring hood performance.,2023/3/21,东华大学/环境学院/暖通空调,44,EVALUATION OF LOCAL VENTILATION,Another simple way to evaluate the exhaust is to use smoke to visualize the air streamlines.It is sometimes possible to see how far an exhaust reaches by observing smoke movement when it is generated at different distances from the hood opening.,2023/3/21,东华大学/环境学院/暖通空调,45,Natural Ventilation,Chimney effect(烟囱效应)-Difference in air density due to temperature difference between indoor and outdoor air,2023/3/21,东华大学/环境学院/暖通空调,46,2023/3/21,东华大学/环境学院/暖通空调,47,Thermal effect,neutral pressure level(NPL):where the interior and exteriorpressures are equal.At all other levels,the pressure differencebetween the interior and exterior depends on the distance from theneutral pressure level and the difference between the densities ofinside and outside air.Airflow rate:Location,shape and temperature difference.Multistory building:Layout and Construction,2023/3/21,东华大学/环境学院/暖通空调,48,Natural Ventilation,Wind pressure on building Venturi effect,2023/3/21,东华大学/环境学院/暖通空调,49,Wind Pressure&Flow Around Buildings,2023/3/21,东华大学/环境学院/暖通空调,50,Wind Pressure&Flow Around Buildings,2023/3/21,东华大学/环境学院/暖通空调,51,Wind Pressure&Flow Around Buildings,2023/3/21,东华大学/环境学院/暖通空调,52,Wind Pressure&Flow Around Buildings,The building is renowned for having had numerous engineering flaws;the most notorious design flaw was the attachment of its glass windows,causing windows to keep falling off the building until the flaw was finally solved and all the windows were replaced.The windows are reflective.If they were not,the building would be too hot to occupy most of the year.As it is,the air-conditioning system runs year round.The falling-window problem was caused by a combination of the mounting method used and pressure differentials between the inside air and the outside.During the repairs,the windows were replaced with plywood,earning it the sobriquet Plywood Palace.,2023/3/21,东华大学/环境学院/暖通空调,53,Combined effect of wind and temperature difference,In most cases,natural ventilation depends on a combined force of wind andstack effects.The pressure patterns for actual buildings continually changewith the relative magnitude of thermal and wind forces.The pressures dueto each effect are added together to determine the total pressure differenceacross the building envelope.,2023/3/21,东华大学/环境学院/暖通空调,54,Maximize Natural Ventilation,2023/3/21,东华大学/环境学院/暖通空调,55,课后要求,了解PM2.5的污染源及防治措施？,