20111225绿色建筑leed认证热回收问题和建议

1、绿色建筑leed认证热回收问题和建议（2011-12-24 20:3发送到微博分类：未分类 标签：成通宝商业建筑机电系统问题和对策绿色建筑leed认证热回收I说明：为了看博客收益达到最大化建议您一定要看前期博客我的所有博文都是涉及空调、采暖、给排水、消防、强电、弱电、电梯及绿色建筑认证的设计、招标、施工、调试、验收的相关内容我致力于地产总裁顾问和房地产企业培训建议您抽时间看一下置顶博文及博主公告凡是在博文中写的继前文那一定是前边某一篇博客中谈及相关问题凡是在博文中写的继上篇博文您只需要往回看一篇即可如果以下博文对您有启发建议您常来搜房网专业媒体我这专业博客看看每天都会有更新继前文我们谈到了绿色

2、建筑能耗报告和能耗计算问题也谈到了三星认证过程中的相关问题更谈leed认证和三星认证的一些误区和分析今天给各位谈的是绿色建筑认证过程中的热回收问题和建议我们知道由于节能计算的需要必须要建立基本建筑和设计建筑的模型从而对各自能耗进行模拟再作比较而当建筑模型建好后需要对模型的物理过程进行描述这样计算机才能知道如何计算建筑的模型的物理描述表面上看似乎是很简单实际上这其中有很多的技巧例如对于实际建筑是否要用热回收热回收应如何设计和运行才能让实际建筑的能耗降低对于基本建筑我们既不要人为的把能耗算高也不要刻意算低那需要针对不同气候类型不同机电系统进行物理模型的描述这在绿色建筑leed参考标准中都给了详细规

3、定例如其中就有规定在气候区域编号为3c,4c,5b,5c,6b，7和8中如果是供冷则不用热回收而对于实际建筑中的热回收有多种形式如何选择一个适合项目的热回收形式这是目前很多设计院、顾问公司和房产开发商忽略的例如在很多设计图纸中都是写的用转轮热回收而不去管转轮热回收是用在东北地区更合理还是用在华南地区更合理希望引起同行思考下边的图片是绿色建筑美国leed认证和三星认证关于热回收的相关要求和各种热回收的介绍供各位实际工作中参考G0 Eh;uit Air Energy Recovery. Individual tan systems that have both a design su

4、pply air capacity of2400 L s or greater and have a minimum outdoor air supply of 70 or greater of the design supply air quantity shall have an energy recovery system with at least 50% recovery effectiveness. Fifty percent energy recovery effectiveness shall mean a change in the enthalpy of the outdo

5、or air supply equal to 50% of the difference between the outdoor air and return air at design conditions. Provision shall be made to bypass or control the heat-recovery system to pennit air economizer operation. where applicable.5314建筑物内设有集中排风系统且符合下列条件之一时，宜 设置排风热回收装置。排风热回收装置（全热和显热）的额定热 回收效率不应低于60%。1

6、送风量大于或等于3000n?/h的直流式空气调节系统, 且新风与排风的温度是大于或等于8们2设计新风量大于或等于4000m3/h的空气调节系统，且 新风与排风的温度差大于或等于8七3设有独立新风和排风的系统。Exhaust Air Heat Recovery SystemsExhaust air licat recmery systems have been used extensively for many years to reduce energy costs in commercial facilities. This Technob ogy Update describes the

7、available systems, discusses their adntages and disadvantages, explains zvtien such systems arc eccrtctnically viable, and lists potential applications.System TypesExhaust air licat recmery systems have been used extensively for many years to reduce energy costs in commercial facilities. This Techno

8、b ogy Update describes the available systems, discusses their adntages and disadvantages, explains zvtien such systems arc eccrtctnically viable, and lists potential applications.There are various types of exhaust air heat recovery (EAHR) systems: run-around closed loop, heat wheel passive refrigera

9、nt, air-toair, and exhaust recirculation. Each has its advantages and disadvantages. All of the systems described here (except exhaust recirculation) are based on the principle that heat naturally flows frxm wann matter to cwl matter. The systems described below can both preheat ventilation air in t

10、he winter and precool ventilation air in the summer. Each of the systems will add to the static pressure loss of air distribution systems and may require larger exhaust and ventilation fans.Run-Around Closed Lo叩This system consists of a recovery coil in the exhaust air stream connected to a preheat

11、coil in the outside (venhlation) air stream (Figure 1). A pump circulates a water/glycol soluGon between the two coils. Warm return air passes over the recovery coil, the glycol solution picks up the heat the solution is pumped to the preheat coil, and the heat isHgure 2. Heat wheelHgure 2. Heat whe

12、eltransferred to the cool ventilation air stream. Then the pump circulates the cool solution back to the exhaust side to repeat the cycle.Advantages:Can recover heat from a remote exhaust location.Exhaust and ventilation air streams arc isolated (i.e., no chance of cross contamination).Disadvantages

13、:. Installation of piping be- tween remotely located coils is costly.Greater separation between exhaust and ventilation decreases efficiency of heat recovery.Heat WheelA heat wheel is mounted with half o the whed In the exhaust dud and half in the supply air duct (Rgure 2). The wheels axle splits th

14、e two ducts. The wheel n be Hold 奴 t in diameter and 6 to 30 inches thickThe material that makes up the wheel is the heat exchange surface The whed can be fillwi with shredded xneUl dike a pot scnib- berh shredded plaKkr. or corm- 料ted paper fiber (hke cardboard). SUny modem wheels have a ccnu伊Ud ph

15、otic sheet wrapped around the axle to form jxwagrt through the dpth of the wheelThe wheel rotates slowly through the two air streag As warm exhaust tir jmxms through the wheels material heat is tram- ferred from the air to the material A$ the whed rotatw around to the vcfUHMion side, this heat is tn

16、uuferred from the matcrud to the cool ventilation air. Sotn heat wheete contain a dct- CAnt miUoriM that transfer* moh- tvre betwwn the air m well as hedL In areas with humid summers, this wn reduce the Mlenl loAd on air conditioning systems In areas with coW, dry winter this effectively inerves the

17、 humidity inside tbc building without expanding additiooil cn- gyAdvantages：Cost is reasoniibiy low. New exchanger cores are relatively easy to deanRccovot heat eflkienUy.DisadvAntagrs:Exhausit and vcntiUtion ductj be phykidly ad-Some cross contaminationoccur, whxh may 函 t applications In hospitals,

18、 bwilth care facilities, hath- rooms, and research facilitiesThe wheel aomeu-hat more susceodble to than that In the run-around system. Although modem core mtehAls are fairly durable and much easier to clean than tluiLf older counterparts/ they can be maintenance inteiuive or require additional fill

19、enn. Thene- fore, this system thoukl not be used for kitchen range hood exhaust. Moiv spaee height may required (or installation thin for ether EAHR system typ.Passh/e RefrigerantThis system consuls of two attached chambers, one located in the exluul air duct and one in the x*cntUa!k)n air duct. One

20、 ot the chambers contains a Hquxl re- frigmnt that pcwsivrly tranitfrn; heat (energy) from exhaust air to venlihticn air. Tlip procE starts ac exhaust air fkisscs over the dumber containing the liquid xctrigcranL The rdrigcnint 心 sortn hear and vaporizes., rising into the chamber tn the ventila-HMt

21、exchanger conExhaust RecirculationAdvantages:HMt exchanger conExhaust RecirculationAdvantages:tion air stream. The cooler ventilation air removes the heat from the refrigerant. Then the refrigerant condenses and returns to the exhaust air chamber to repeat the cycle.Advantages:Requires no pumps, mot

22、ors, or compressors.Easy to maintain and keep dean.Disadvantages:Exhaust and ventilation ducts must be physically adjacent.Cost is somewhat higher than other EAHR system types-Will not work at low differ- entigl temperatures.Air-to-AirThis system transfers energy through a crossover grid or through

23、olate heat exchaneersAir-to-AirThis system transfers energy through a crossover grid or through plate heat exchangers made of metal or plastic (Figure 3). Warm air passing between the plates transfers its energy by conduction through the material to another grid or plate where the air is warmed. The

24、 plates form alternating exhaust and ventilation air pathways.Advantages:Cross contamination between ducts is minimal (if any). Requires no liquid or pumps.Most systems are relatively easy to clean and maintain.Disadvantages:. Exhaust and ventilation ducts must be physically ad jacent.Exhaust Recirc

25、ulationThis system recirculates most of the exhausted air back into the space after Hltering it, eliminating the need to exhaust air. Although it does not eliminate minimum ventilation air requirements, it may reduce them. This system is best used in areas where large amounts of particulates must be

26、 removed from the exhaust air stream, such as wood or metal shops, high smoking areas, and welding shops. These areas would otherwise require substantial rates of exhaust and ventilation air.Methods of filtering the air include bag houses, cyclone extractors, and electrostatic precipitators.Advantag

27、es:Eliminates energy waste by recirculating rather than exhausting warm air.Provides higher efficiency than exhaust systems.Disadvantages:May not be able to remove gaseous contaminants from the air stream.Requires regular maintenance.EfficiencyEfficiencies (also referred to as effectiveness) of thes

28、e systems vary from around 50 to 75 percent and sometimes higher. That is, they recover about 50 to 70 percent ofthe energy that would otherwise be wasted. The efficiency of each system varies widely, depending on size, duct work layout, equipment type, and inside and outside air tempraturcs.Economi

29、csThe conditions generally necessary for an EAHR system to be economically viable are the following:High Volume. To make EAHR pay off you need to operate a volume of about 3,000 CFM of exhaust air (at one point) for 8 hours per day or more.Cold Climate. Given the same operating conditions； EAHR will

30、 save more money in colder climates than in milder climates. Without EAHR, more fuel is used in colder climates than in milder climates, because the ventilation air must be heated. Since EAHR decreases the need for this energy, you will see a greater difference in your heating bills when the weather

31、 is cold.Expensive Heating Fuel. EAHR is most economical when it displaces the need for expensive heating fuels, such as fuel oil and electricity, rather than less expensive fuels, such as natural gas.ApplicationsCommon applications for EAHR include the following：Facilities that require 100 percent outoide ventilation, such as hospitals, health care facilities, and research facilitiesFacilities that require large exhaust air volume flow rates, such as light industrial facilities, kitchens, and natatoriums (swimming poofe)Facilities in which l