建筑环境与设备工程专业英语课件.ppt

1、Technical EnglishFor Building Environment and Equipment EngineeringDr.Jinbo Wang(王劲柏王劲柏)2012 FTel:87792107Cell:1321 275 6863General Information An advanced level English.The principal aim:to improve the ability to read professional literature.The topics will cover authentic material specific to our

2、field(Major).Requirements:Grammar and syntax relevant to technical and scientific writing is covered.In addition,the course stresses oral skill and written skill will be touched.Main teaching material:ASHRAE HANDBOOK2005 Fundamentals,2006 Refrigeration2007 HVAC Application,2008 System&Equipment Cour

3、se grade formula(5 level score)Total Score=1(class attendance)+1(class performance)+3(final course report)Final course report is translation of couple of paragraphs from technical article in English (ASHARE HANDBOOK).Main Teaching Material ASHRAE HANDBOOKAmerican Society of Heating,Ventilation and A

4、ir-conditioning EngineersASHRAEASHRAE is the worlds foremost technical society in the fields of heating,ventilation,air conditioning,and refrigeration.Its members worldwide are individuals who share ideas,identify needs,support research,and write the industrys standards for testing and practice.The

5、result is that engineers are better able to keep indoor environments safe and productive while protecting and preserving the outdoors for generations to come.One of the ways that ASHRAE supports its members and industrys need for information is through ASHRAE Research.Thousands of individuals and co

6、mpanies support ASHRAE Research annually,enabling ASHRAE to report new data about material properties and building physics and to promote the application of innovative technologies.Chapters in the ASHRAE Handbook are updated through the experience of members of ASHRAE Technical Committees and throug

7、h results of ASHRAE Research reported at ASHRAE meetings and published in ASHRAE special publications and in ASHRAE Transactions.SECTION 1.0FUNDAMENTALS AND GENERAL1.1 Thermodynamics and Psychrometrics1.2 Instruments and Measurement1.3 Heat Transfer and Fluid Flow1.4 Control Theory and Application1.

8、5 Computer Applications1.6 Terminology1.7 Business,Management,and General Legal Education1.8 Mechanical Systems Insulation1.9 Electrical Systems1.10 Cogeneration Systems1.11 Electric Motors and Motor Control1.12 Moisture Management in BuildingsSECTION 2.0ENVIRONMENTAL QUALITY2.1 Physiology and Human

9、 Environment2.2 Plant and Animal Environment2.3 Gaseous Air Contaminants and Gas Contaminant Removal Equipment2.4 Particulate Air Contaminants and Particulate Contaminant Removal Equipment2.5 Global Climate Change2.6 Sound and Vibration Control2.7 Seismic and Wind Restraint Design2.8 Building Enviro

10、nmental Impacts and SustainabilityTRG Blast,Chemical and Biological RemediationSECTION 3.0MATERIALS AND PROCESSES3.1 Refrigerants and Secondary Coolants3.2 Refrigerant System Chemistry3.3 Refrigerant Contaminant Control3.4 Lubrication3.6 Water Treatment3.8 Refrigerant ContainmentSECTION 4.0LOAD CALC

11、ULATIONS AND ENERGYREQUIREMENTS4.1 Load Calculation Data and Procedures4.2 Weather Information4.4 Building Materials and Building Envelope Performance4.5 Fenestration4.7 Energy Calculations4.10 Indoor Environmental ModelingThe net change of entropy of any refrigerant in any cycle is always zero.In E

12、xample 1,the change in entropy of the refrigerated space is SR=125/250=0.5 kJ/K and that of the atmosphere is So=125/250=0.5 kJ/K.The net change in entropy of the isolated system is Stotal=SR+So=0.The Carnot cycle in the figure below shows a process in which heat is added and rejected at constant pr

13、essure in the two-phase region of a refrigerant.Saturated liquid at state 3 expands isentropically to the low temperature and pressure of the cycle at state d.Heat is added isothermally and isobarically by evaporating the liquid-phase refrigerant from state d to state 1.The cold saturated vapor at s

14、tate 1 is compressed isentropically to the high temperature in the cycle at state b.However,the pressure at state b is below the saturation pressure corresponding to the high temperature in the cycle The compression process is completed by an isothermal compression process from state b to state c.Th

15、e cycle is completed by an isothermal and isobaric heat rejection or condensing process from state c to state 3.MULTISTAGE VAPOR COMPRESSION REFRIGERATION CYCLES Multistage or multipressure vapor compression refrigeration is used when several evaporators are needed at various temperatures,such as in

16、 a supermarket,or when evaporator temperature becomes very low.Low evaporator temperature indicates low evaporator pressure and low refrigerant density into the compressor.Two small compressors in series have a smaller displacement and usually operate more efficiently than one large compressor that

17、covers the entire pressure range from the evaporator to the condenser.This is especially true in ammonia refrigeration systems because of the large amount of superheating that occurs during the compression process.Thermodynamic analysis of multistage cycles is similar to analysis of single-stage cyc

18、les,except that mass flow differs through various components of the system.A careful mass balance and energy balance on individual components or groups of components ensures correct application of the first law of thermodynamics.Care must also be used when performing second-law calculations.Often,th

19、e refrigerating load is comprised of more than one evaporator,so the total system capacity is the sum of the loads from all evaporators.Likewise,the total energy input is the sum of the work into all compressors.For multistage cycles,the expression for the coefficient of performance given in Equatio

20、n(15)should be written asACTUAL REFRIGERATION SYSTEMS Actual systems operating steadily differ from the ideal cycles considered in the previous sections in many respects.Pressure drops occur everywhere in the system except in the compression process.Heat transfers between the refrigerant and its env

21、ironment in all components.The actual compression process differs substantially from isentropic compression.The working fluid is not a pure substance but a mixture of refrigerant and oil.All of these deviations from a theoretical cycle cause irreversibilities within the system.Each irreversibility r

22、equires additional power into the compressor.It is useful to understand how these irreversibilities are distributed throughout a real system;this insight can be useful when design changes are contemplated or operating conditions are modified.ABSORPTION REFRIGERATION CYCLES An absorption cycle is a h

23、eat-activated thermal cycle.It exchanges only thermal energy with its surroundings;no appreciable mechanical energy is exchanged.Furthermore,no appreciable conversion of heat to work or work to heat occurs in the cycle.Absorption cycles are used in applications where one or more of the exchanges of

24、heat with the surroundings is the useful product(e.g.,refrigeration,air conditioning,and heat pumping).The two great advantages of this type of cycle in comparison to other cycles with similar product are No large,rotating mechanical equipment is required Any source of heat can be used,including low

25、-temperature sources(e.g.,waste heat)Some idea on How to prepare the teaching material for this class Divide the content into two levels for the two semester.The level one for the 1st semester should focuses on those material that can give students an overview of the field or major The level two is supposed to discuss some details on specific topics which allow the students access to advanced technical aspects.Therefore,a teaching note or textbook may be prepared according to the consideration of two levels and appropriate materials should be selected carefully and prudently.