ASHRAE D-MECP15-2-2014 Modeling and Energy Consumption with Parallel and Series VAV Terminal Units with ECM and PSC Motors (Third Edition Product Code D-MECP15-2).pdf

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1、An ASHRAE Topical CompilationExpanded to Include New ResearchModeling andEnergy Consumptionwith Parallel and Series VAV Terminal Unitswith ECM and PSC MotorsThird EditionISBN 978-1-939200-07-5 2014, 2015 ASHRAE1791 Tullie Circle, NEAtlanta, GA 30329www.ashrae.orgAll rights reserved._ASHRAE is a regi

2、stered trademark in the U.S. Patent and Trademark Office, owned by the American Society of Heating, Refrigeratingand Air-Conditioning Engineers, Inc.ASHRAEhascompiledthispublicationwithcare,butASHRAEhasnotinvestigated,andASHRAEexpresslydisclaimsanydutytoinves-tigate, any product, service, process, p

3、rocedure, design, or the like that may be described herein. The appearance of any technical data oreditorial material in this publication does not constitute endorsement, warranty, or guaranty byASHRAE of any product, service, process,procedure, design, or the like.ASHRAE does not warrant that the i

4、nformation in the publication is free of errors, andASHRAE does notnecessarily agree with any statement or opinion in this publication. The entire risk of the use of any information in this publication isassumed by the user.No part of this publication may be reproduced without permission in writing

5、from ASHRAE, except by a reviewer who may quote briefpassages or reproduce illustrations in a review with appropriate credit, nor may any part of this publication be reproduced, stored in aretrievalsystem,ortransmittedinanywayorbyanymeanselectronic,photocopying,recording,orotherwithoutpermissioninwr

6、itingfrom ASHRAE. Requests for permission should be submitted at www.ashrae.org/permissions._ASHRAE STAFF SPECIAL PUBLICATIONS Mark S. Owen, Editor/Group Manager of Handbook and Special PublicationsCindy Sheffield Michaels, Managing EditorJames Madison Walker, Managing Editor of StandardsSarah Boyle

7、, Assistant EditorLauren Ramsdell, Assistant EditorMichshell Phillips, Editorial CoordinatorPUBLISHER W. Stephen ComstockThis collection of papers reflects ASHRAE Research co-sponsored byASHRAE Technical Committee 5.3, Room Air Distribution,and ASHRAE Technical Committee 7.7, Testing and Balancing.T

8、he collection was compiled by Eugene W. (Gus) Faris.Project Monitoring Committee MembersThe following members of the Project Monitoring Committees are gratefully acknowledged.Floyd Blackwell Dan Int-Hout Jerry SipesDouglas Fetters David John Jack StegallGaylon RichardsonInvestigatorsJohn Bryant Mich

9、ael A. Davis Dennis ONealIntroductionSince fan-powered variable-air-volume (VAV) terminal units were introduced to the marketplace, proponents ofboth parallel and series types have argued about which provides a system with the highest energy efficiency.*ASHRAE/AHRI research was undertaken to define

10、the operation of each type and investigate the issue.Descriptions of the findings are described in the first six papers included in this collection. Additional researchwas undertaken by a consortium of terminal unit manufacturers, motor manufacturers, and Texas A Qfan, the airflow through thefan, an

11、d Powerfan, the power consumption of the terminal unitfan. The independent variables were:1. The static pressure upstream of the terminal unit, Pup,2. The static pressure downstream of the terminal unit, Pdwn,3. The speed of the terminal unit fan controlled by the SCR,as represented by the RMS avera

12、ge voltage to the unit,4. The position of the terminal units damper, and 5. The control pressure from the flow sensor, Piav,. Thisvariable was directly affected by the position of thedamper and the upstream static pressure. Before testing a unit, each of the independent variableswas assigned a set o

13、f specific values. The number of levels foreach of the variables and their values are shown in Table 5. Thevalues for the levels differed across VAV terminal unitsbecause the maximum and minimum values for certain vari-ables differed across units. The maximum and minimumvalues for the SCR voltage we

14、re determined by adjusting theSCR setscrew completely in both directions. The maximumvalue for the damper setting was defined as when the damperwas horizontal, or fully open and minimum was defined aswhen the damper was closed. The levels for downstream staticpressure varied from 0.1 to 0.5 in w.g.

15、(25 to 125 Pa). Thelevels for upstream static pressure varied depending on the testbeing run. Figure 11 Schematic of experimental test setup.Figure 12 Volumetric airflow balance of a terminal unit.ASHRAE Transactions 81The characterization of a terminal unit consisted ofseveral tests. These tests we

16、re conducted for each combinationof damper and SCR settings. In every test, data for each combi-nation of upstream and downstream static pressure levels wereobtained. This process was a full-factorial design because datapoints for all combinations of independent variables wereobtained. The sequence

17、of these tests usually consisted ofrunning the tests for all of the SCR speeds at a single damperposition, adjusting the damper to the next position, andcontinuing the sequence.Before starting a test, the damper and SCR were manuallyadjusted to the desired positions according to the test beingrun. T

18、hroughout a test, the damper and SCR would remain inthe same position. During a test, the data acquisition systemallowed the user to adjust the VSDs on the upstream anddownstream blowers to meet desired conditions for a testpoint. The upstream static pressure was first adjusted to thesmaller of the

19、following: the point where the primary airflowwas approximately 5% greater than the terminal units speci-fied maximum or 2 in. w.g. (498 Pa). This pressure was desig-nated as the maximum level for the upstream static pressurevariable. The minimum upstream static pressure setting wasdetermined by the

20、 downstream pressure. It could not be lowerthan the downstream static pressure because primary airwould flow backwards into the terminal unit. Each test hadthree minimum level upstream static pressures. These mini-mums were selected to be approximately 0.25 in. w.g (60 Pa)greater than the correspond

21、ing downstream static pressure,except in cases where damper position caused insufficientprimary airflow. For each downstream static pressure, a thirdpoint was obtained for the upstream static pressure approxi-mately halfway between the corresponding minimum andmaximum. This procedure resulted in thr

22、ee data points foreach downstream static pressure level, and nine points per test.The upstream and downstream blowers were manuallyadjusted to the desired conditions for a specific data point.After static pressures reached steady state, data were acquired DATA ACQUISITION SYSTEMA computer data acqui

23、sition system was used to obtain,process, and store data. This system consisted of a personalcomputer, two separate data acquisition cards, and the termi-nation blocks for all signal wires.An eight channel, sixteen-bit sample-and-hold data cardwas used to measure instantaneous current and voltage. T

24、hesimultaneous sample and hold prevented any introduction oferror due to phase shift between the voltage and currentsignals. The elimination of phase shift allowed for accuratedetermination of the power factor for the VAV unit fans. Theanalog inputs had a resolution of 16 bits. The other data acquis

25、ition card was an eight channel card,with two analog outputs to control the variable speed drives onthe test setup assist blowers. The resolution of the analoginputs on this card was 12 bits.SUMMARYThis paper is the first of three papers. Tests wereconducted on six parallel and six series variable a

26、ir volume fanpowered terminal units. Both 8 in. (203 mm) and 12 in. (304mm) primary air inlet terminal units from three manufacturerswere evaluated. This paper provides a description of theTable 4. Pressure Transducer SizingPoint Name Transducer SizeDifferential Pressure Across Nozzles, Fig 12 0-6 i

27、n. w.g.(0 1.5 kPa)Differential Pressure Across Nozzles, Fig 15 0-6 in. w.g. (0-1.5 kPa)Chamber Static Pressure, Fig 12 0-10 in. w.g. (0-2.5 kPa)Chamber Static Pressure, Fig 15 0-10 in. w.g. (0-2.5 kPa)Upstream Static Pressure 0-2 in. w.g. (0-0.5 kPa)Downstream Static Pressure 0-2 in. w.g. (0-0.5 kPa

28、)Inlet air velocity Sensor Pressure 0-2 in. w.g. (0-0.5 kPa)Table 5. Test Variable LevelsIndependent Variable Number of Levels ValuesUpstream Static Pressure 3varied from 0.3 to 2 in. w.g.(75 to 498 Pa)Downstream Static Pressure 30.1, 0.25, 0.5 in. w.g(25, 62, 125 Pa)SCR Voltage (Fan Speed) 4 Equall

29、y spacedDamper Position 4 Equally spaced82 ASHRAE Transactionstwelve fan powered terminal units, the experimental appara-tus, the test procedure, and the data acquisition system. ACKNOWLEDGMENTS This work was a part of a project funded by ASHRAEunder RP-1292 and we would like to thank the project mo

30、ni-toring subcommittee of TC 5.3 and the manufacturers theyrepresent for their support during the project. Several manu-facturers donated terminal units for use in this study. Throughcooperative ventures such as these, ASHRAE research fund-ing can be utilized to the fullest. We appreciate the contri

31、bu-tions from these industry leaders.NOMENCLATUREPdwn = downstream static pressure, in. w.gPiav= pressure across inlet air velocity flow sensor, in. w.g.Punit= static pressure inside terminal unit, in. w.g.Pup= upstream static pressure, in. w.g.Powerfan= power consumption of terminal unit fan, WQfan

32、= amount of airflow through terminal unit fan, cfmQinduced= amount of airflow induced from plenum, cfmQleakage= amount of airflow leaking from a terminal unit, cfmQout= amount of parallel terminal unit airflow output, cfmQprimary= amount of primary airflow, cfmV = RMS average of SCR voltage output,

33、VREFERENCESAlexander, J. and D. Int-Hout. 1998. Assuring zone IAQ.White paper. Titus. Retrieved Sept. 15, 2005 http:/www.titus- AMCA. 1999. ANSI/AMCA standard 210-99, Laboratorymethods of testing fans for aerodynamic performancerating. Arlington Heights, IL: Air Movement and Con-trol Association.ASH

34、RAE. 1996. ANSI/ASHRAE standard 130, Methods oftesting for rating ducted air terminal units. Atlanta:American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.ASHRAE. 2001. ASHRAE fundamentals handbook.Atlanta: American Society of Heating, Refrigeratingand Air-Conditioning Engin

35、eers, Inc.ASHRAE. 2004. ANSI/ASHRAE standard 90.1-2004,Energy standard for buildings except low-rise residentialbuildings. Atlanta: American Society of Heating,Refrigerating and Air-Conditioning Engineers, Inc.Chen, S.Y.S., and S.J. Demster. 1996. Variable air volumesystems for environmental quality

36、. New York: McGraw-Hill.DOE 2.2: Building Energy Use and Cost Analysis Software.1998. Lawrence Berkeley National Laboratory at theUniversity of California and James J. Hirsch & Associ-ates.Elleson, J.S. 1993. Energy use of fan-powered mixing boxeswith cold air distribution. ASHRAE Transactions99(1):

37、1349-1358.Furr, J., ONeal, D.L., Davis, M. A., Bryant, J.A., and Cram-let, A. 2008a. Performance of VAV fan powered parallelterminal units: experimental results and models,ASHRAE Transactions, submitted for review.Furr, J., ONeal, D.L., Davis, M. A., Bryant, J.A., and Cram-let, A. 2008b. Performance

38、 of VAV fan powered seriesterminal units: experimental results and models,ASHRAE Transactions, submitted for review.Hydeman, M., S. Taylor, and J. Stein. 2003. Advanced vari-able air volume system design guide. Integrated energysystems: productivity and building science. San Fran-cisco: California E

39、nergy Commission.Khoo, I., G.J. Levermore, and K.M. Letherman. 1998. Vari-able-air-volume terminal units I: steady state models.Building Services Engineering Research & Technology19(3):155-162.Kolderup, E., T. Hong, M. Hydeman, S. Taylor, and J. Stein.2003. Integrated design of large commercial HVAC

40、 sys-tems. Integrated energy systems: productivity and build-ing science. San Francisco: California EnergyCommission.2008 ASHRAE 83ABSTRACTEmpirical models of airflow output, power consumption,and primary airflow were developed for parallel fan poweredvariable air volume terminal units at typical op

41、erating pres-sures. Both 8 in. (203 mm) and 12 in. (304 mm) primary air inletterminal units from three manufacturers were evaluated.Generalized models were developed from the experimentaldata with coefficients varying by size and manufacturer.Fan power and airflow data were collected at down-stream

42、static pressures over a range from 0.1 to 0.5 in. w.g.(25 to 125 Pa). Upstream static pressures ranged from 0.1 to2.0 in. w.g. (25 to 498 Pa). Data were collected at fourprimary air damper positions and at four terminal unit fanspeeds. Model variables included the RMS voltage enteringthe terminal un

43、it fan, the inlet air differential sensor pressure,and the downstream static pressure. A model was also devel-oped to quantify air leakage when the unit fan was off.In all but one of the VAV terminal units, the resultingmodels of airflow and power had R2values greater than 0.90.For the exception, ex

44、cessive air leakage from the unit appearedto limit the ability of the airflow and power models to capturethe variation in the experimental data. These performancemodels can be used in HVAC simulation programs to modelparallel fan powered VAV systems.INTRODUCTIONVariable Air Volume (VAV) systems main

45、tain comfortconditions by varying the volume of primary air that is deliv-ered to a space. A VAV system often consists of a central airhandling unit (AHU), where air is cooled by cooling coils(Wendes 1994). This air, referred to as primary air, is sentthrough a single-duct supply system to VAV termi

46、nal units bythe supply fan. Each terminal unit is ducted to air outlets,usually serving two or more offices or an open area. VAVterminal units that include a fan to improve circulation withina zone are called fan powered terminal units. These terminalunits can draw in warm air from the plenum area a

47、nd mix itwith primary air from the central Air Handling Unit (AHU) tomaintain comfort conditions in the occupied space.When the fan in a VAV fan powered terminal unit isoutside the primary airflow, the configuration is called a paral-lel terminal unit. During operation, the fan for a parallel termi-

48、nal unit cycles on and off. During periods of maximumcooling, the fan is off. A backdraft damper prevents cold airfrom blowing backwards through the fan. The terminal unitprimary air damper modulates the airflow to maintain thespace temperature setpoint. An inlet air differential sensorwithin the pr

49、imary air stream allows the unit controller tomaintain a consistent volume of airflow to the zone dependingon the temperature setpoint. When the primary airflow dropsbelow a specified amount, the controller activates the fan. Atthis point, the terminal unit mixes primary air with air beingdrawn in from the plenum. Electric or hot water supplementalheat can be used for additional heating. Depending on thecontrol scheme, the controller can continue to reduce primar