建筑环境与能源应用工程专业英语15.ppt
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1、,Unit Fifteen Commissioning of Variable Air Volume Systems,What is Commissioning (Cx) ?,Definition: “A quality-focused process for enhancing the delivery of a project. The process focuses on verifying and documenting that the facility and all of its systems and assemblies are planned, designed, inst
2、alled, tested, operated, and maintained to meet the Owners Project Requirements.” ASHRAE Guideline 0-2005, The Commissioning Process,Commissioning is often performed by an independent third-party engineering company. Operates as an owners representative to insure the installed systems meet the owner
3、s requirements and the plans and specifications Usually hired by the owner, sometimes by the architect, or general contractor.,Commissioning Person,All participants in the construction project have a commissioning responsibility. Participants include the commissioning authority, owner, design profes
4、sionals, construction manager, general contractor, subcontractors, operation and maintenance manager, suppliers, and equipment manufacturers.,Benefits of Commissioning,Reduced change orders Less warranty and callbacks for contractor Smoother turnover to maintenance Improved equipment reliability Red
5、uced IEQ problems Reduced occupant complaints Improved productivity Correct system operation and installation Facility meets Owners expectation and operational needs Reduced utility consumption and operational costs,Commissioning Objectives Ensure the facility meets the owners performance requiremen
6、ts Provide a safe and healthy environment Provide optimum energy performance Provide a facility that can be efficiently operated and maintained Provide complete orientation and training to facility staff and occupants Provide improved documentation of system characteristics,Commissioning - What did
7、we use to do and why do we need it? CX of mechanical and electrical systems was done by the installing contractors No standardization, or clear approach Most of the real CX occurred during the warranty period as warranty calls Buildings operated less efficiently First year of occupancy was frustrati
8、ng for the owner Contractors spent more money during the warranty periods Contractors can be rushed without enough time to double-check their work Design Engineers do not have enough budget to oversee the construction in detail Owners have had bad experiences with prolonged project closeout, and see
9、 CX as a solution Hold contractors accountable for the specifications,Commissioning Scope,Mechanical Systems All HVAC equipment Building automation system and hardwired controls Electrical Systems Switchgear, major disconnects, backup generators and UPS (Uninterrupted Power Supply) Fire Safety Syste
10、ms Security Systems Kitchen equipment Irrigation system Laboratory Fume hoods, gas control,Commissioning and Construction Phases,Other Types of Commissioning,Retro-commissioning Performed to existing buildings that have not previously been commissioned, after they have been occupied Usually instigat
11、ed as a result of high energy bills or poor occupant comfort Recommissioning Performed 5 to 10 years after a building was previously commissioned Sometime used as a form of deferred maintenance,Variable Air Volume (VAV) use of varying airflow to control the condition of air, in contrast to the use o
12、f constant flow (often) with varying temperature. VAV system controls temperature in a space by varying the quantity of supply air rather than varying the supply air temperature. A VAV terminal unit at the zone varies the quantity of supply air to the space. The supply air temperature is held relati
13、vely constant: while supply air temperature can be moderately reset depending on the season, it must always be low enough to meet the cooling load in the most demanding zone, and to maintain appropriate humidity.,Why use VAV?,Provides multiple zones of comfort Life cycle cost will be less than other
14、 HVAC Systems trying to accomplish similar comfort levels Load diversity Smaller equipment ( lower AC unit first cost compared to Constant Volume) Less supply air ( less energy consumption) Able to adapt to changes in building use,Why Not ?,Higher first cost than comparable single zone Controls, equ
15、ipment, commissioning Increased maintenance cost More pieces to look after,Constant volume - variable temperature system have been dominating the HVAC applications in the past for obvious reasons. The implementation of variable volume control has been done with dampers or other mechanical control me
16、thods. The advantages of variable air volume system implemented with variable speed control are: Fast control to keep the comfort zone limits Low consumption of electrical energy Lower consumption of heating and cooling energy than in constant air volume systems Simpler to keep noise level down,1. I
17、ntroduction 2. Commissioning method statement 3. System components 4. Preliminary checks 5. Commissioning sequence 6. Setting to work 7. Terminal units 8. Secondary air distribution 9. Return air spigots 10. System diversity 11. Fan design performance check 12. System performance checks,Frequently u
18、sed words and phrases: Variable air volume (VAV) system 变风量系统 commissioning 试运行 调试 air volume flow rate 空气体积流量 terminal unit 终端设备 flexible duct 柔性风管 Pitot tube 毕托管 thermal anemometer 热线风速仪 supply fan 送风风机 extract fan 排风机 over-pressurization 压力过高 spigot 套管、栓、龙头,1. Variable air volume (VAV) systems ar
19、e dynamic air distribution systems and, as their name implies, the air volume flow rate is varied according to various parameters to achieve the required design conditions. 2. The fact that VAV systems are designed to vary system performance imposes a number of specific tasks on the commissioning sp
20、ecialist, which must be carried out in order to achieve satisfactory overall performance. 3. Proprietary units may employ a variety of means of regulating air volume flow rate including motorized dampers, inflating bellows, restricting flexible duct sections or a combination of such devices.,Variabl
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