ASHRAE 125-1992 Method of Testing Thermal Energy Meters for Liquid Streams in HVAC Systems《暖通空调系统中液流热能测试方法》.pdf

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1、ASHRAE STANDARDANSI/ASHRAE Standard 125-1992 (RA 2011)Reaffirmation of ANSI/ASHRAE Standard 125-1992Method of Testing Thermal Energy Meters for Liquid Streams in HVAC SystemsApproved by the ASHRAE Standards Committee on June 27, 1992, and reaffirmed January 29, 2011.Approved by the ASHRAE Board of D

2、irectors on July 2, 1992, and reaffirmed February 2, 2011. Approved bythe American National Standards Institute on August 24, 1992, and reaffirmed February 3, 2011.ASHRAE Standards are scheduled to be updated on a five-year cycle; the date following the standard numberis the year of ASHRAE Board of

3、Directors approval. The latest edition of an ASHRAE Standard may be pur-chased on the ASHRAE Web site (www.ashrae.org) or from ASHRAE Customer Service, 1791 Tullie Circle,NE, Atlanta, GA 30329-2305. E-mail: ordersashrae.org. Fax: 404-321-5478. Telephone: 404-636-8400(worldwide) or toll free 1-800-52

4、7-4723 (for orders in US and Canada). For reprint permission, go towww.ashrae.org/permissions. 2011 American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.ISSN 1041-2336American Society of Heating, Refrigeratingand Air-Conditioning Engineers, Inc.1791 Tullie Circle NE, Atlant

5、a, GA 30329www.ashrae.orgSPECIAL NOTEThis American National Standard (ANS) is a national voluntary consensus standard developed under the auspices of the AmericanSociety of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Consensus is defined by the American National StandardsInstitut

6、e (ANSI), of which ASHRAE is a member and which has approved this standard as an ANS, as “substantial agreement reachedby directly and materially affected interest categories. This signifies the concurrence of more than a simple majority, but not necessarilyunanimity. Consensus requires that all vie

7、ws and objections be considered, and that an effort be made toward their resolution.”Compliance with this standard is voluntary until and unless a legal jurisdiction makes compliance mandatory through legislation.ASHRAE obtains consensus through participation of its national and international member

8、s, associated societies, and publicreview.ASHRAE Standards are prepared by a Project Committee appointed specifically for the purpose of writing the Standard. TheProject Committee Chair and Vice-Chair must be members of ASHRAE; while other committee members may or may not be ASHRAEmembers, all must

9、be technically qualified in the subject area of the Standard. Every effort is made to balance the concerned interestson all Project Committees. The Manager of Standards of ASHRAE should be contacted for:a. interpretation of the contents of this Standard,b. participation in the next review of the Sta

10、ndard,c. offering constructive criticism for improving the Standard, ord. permission to reprint portions of the Standard.ASHRAE INDUSTRIAL ADVERTISING POLICY ON STANDARDSASHRAE Standards and Guidelines are established to assist industry and the public by offering a uniform method of testingfor ratin

11、g purposes, by suggesting safe practices in designing and installing equipment, by providing proper definitions of thisequipment, and by providing other information that may serve to guide the industry. The creation of ASHRAE Standards andGuidelines is determined by the need for them, and conformanc

12、e to them is completely voluntary.In referring to this Standard or Guideline and in marking of equipment and in advertising, no claim shall be made, eitherstated or implied, that the product has been approved by ASHRAE.DISCLAIMERASHRAE uses its best efforts to promulgate Standards and Guidelines for

13、 the benefit of the public in light of available informationand accepted industry practices. However, ASHRAE does not guarantee, certify, or assure the safety or performance of anyproducts, components, or systems tested, installed, or operated in accordance with ASHRAEs Standards or Guidelines or th

14、atany tests conducted under its Standards or Guidelines will be nonhazardous or free from risk.ASHRAE STANDARDS COMMITTEE 20102011Stephanie Reiniche, Manager of StandardsH. Michael Newman, Chair Krishnan Gowri Janice C. PetersonCarol E. Marriott, Vice-Chair Maureen Grasso Douglas T. ReindlDouglass S

15、. Abramson Cecily M. Grzywacz Boggarm S. SettyKarim Amrane Richard L. Hall James R. TaubyRobert G. Baker Nadar R. Jayaraman James K. VallortHoy R. Bohanon, Jr. Byron W. Jones William F. WalterSteven F. Bruning Jay A. Kohler Michael W. WoodfordKenneth W. Cooper Frank Myers Craig P. WrayMartin Dieryck

16、x Hugh F. Crowther, BOD ExOAllan B. Fraser William P. Bahnfleth, COASHRAE Standing Standard Project Committee 125 Cognizant TCs: TC 6.1, Hydronic and Steam Equipment and Systems, and TC 6.7, Solar Energy UtilizationSPLS Liaison: Ronald H. HowellGerald R. Guinn, Chair Peter P. PhilipsCharles J. Crome

17、r, Vice-Chair Alexander H. SleimanLawrence R. Brand Sherwood G. TalbertDieter R. Goettling William H. ThrasherJoern Huusom Jerrold F. ZimmerDavid J. Keegan Dong Tian-LuTom MichelCONTENTSANSI/ASHRAE Standard 125-1992 (RA 2011)Method of Testing Thermal Energy Meters for Liquid Streams in HVAC SystemsS

18、ECTION PAGEForeword. 21 Purpose 22 Scope . 23 Definitions. 24 Nomenclature . 35 Classifications. 36 Requirements . 37 Facility Instrumentation. 48 Apparatus and Method of Testing. 59 Test Procedures and Computations . 710 Data to be Recorded and Test Report 911 References . 9Informative Appendix A:

19、Bibliography of Related Standards 9NOTEApproved addenda, errata, or interpretations for this standard can be downloaded free of charge from the ASHRAE Web site at www.ashrae.org/technology. 2011 American Society of Heating,Refrigerating and Air-Conditioning Engineers, Inc.1791 Tullie Circle NEAtlant

20、a, GA 30329www.ashrae.orgAll rights reserved. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written

21、 permission.2 ANSI/ASHRAE Standard 125-1992 (RA2011)(This foreword is not a part of this standard. It is merelyinformative and does not contain requirements necessaryfor conformance to the standard. It has not beenprocessed according to the ANSI requirements for astandard and may contain material th

22、at has not beensubject to public review or a consensus process.)FOREWORDThis standard describes tests for determining the mea-surement accuracy of thermal energy meters for indicatingthe amount of thermal energy added to or extracted from aliquid stream. Procedures are provided for testing metersdes

23、igned for domestic hot water, heating only, cooling only,or combined heating and cooling service. Two test facilityconcepts are described that have proved useful for calibrat-ing such meters.This is a reaffirmation of Standard 125-1992 (RA 2006).This standard was prepared under the auspices of the A

24、meri-can Society of Heating, Refrigerating and Air-ConditioningEngineers, Inc. (ASHRAE). It may be used in whole or inpart by an association or government agency with due creditto ASHRAE. Adherence is strictly on a voluntary basis andmerely in the interest of obtaining uniform standardsthroughout th

25、e industry. The changes made for the 2011 reaffirmation are asfollows: References were updated.Appendix A was clarified as “Informative.”Disclaimers were updated.Variable “ ” was added to Section 4, “Nomenclature.”Expression “(h2 h1)” was replaced with “(T2 T1)” inEquation 8 of Section 9.5, “Computa

26、tion of ThermalEnergy.” 1. PURPOSEThe purpose of this standard is to provide a method oftesting factory-assembled thermal energy meters used tomeasure the thermal energy added to or extracted from a liquidstream supplying an HVAC system.2. SCOPE2.1 The test methods, procedures, and facility descript

27、ions inthis standard are intended for use in determining measurementaccuracy, pressure losses, service flow rate limits, temperaturedifference limits, and reliability effects of mounting attitude.2.2 This standard is limited to applications in which thefluid remains in a completely liquid state whil

28、e traversing thethermal energy meter.2.3 The applications of this standard include, but are notlimited to, thermal energy meters used for billing or revenuemetering for hydronic applications.2.4 This standard does not apply to meters using principlesof change-of-state of the fluid, simple elapsed ti

29、me, or mea-sured indoor or outdoor temperature difference to allocateconsumption among various end-use customers.3. DEFINITIONS3.1 Figure 1 illustrates the elements of a thermal energymeter.3.2 The following definitions apply:accuracy: the ability of an instrument to indicate the true valueof the me

30、asured physical quantity.Btu meter: see thermal energy meter.flowmeter: see flow sensor.flow sensor: a sensor capable of providing a signal (output)that is related to the volumetric flow of liquid through thesensor.heat meter: see thermal energy meter.integrator: a device using signals from temperat

31、ure and flowsensors through time for computing thermal energy trans-ferred.negative sense: a test condition in which the temperature ofthe remote sensor is less than the temperature of the proximatesensor.positive sense: a test condition in which the temperature of theremote sensor is greater than t

32、he temperature of the proximatesensor.precision: the closeness of agreement among repeatedmeasurements of a constant physical quantity.proximate sensor: the temperature sensor located in the sametemperature stream as the flow sensor.remote sensor: the temperature sensor located in a streamwhose temp

33、erature is different from the temperature of theproximate sensor.temperature differential sensor: a sensor system, composedof two temperature sensors, which is capable of providing asignal that is related to the temperature differential of the twosensors.mFigure 1 Elements of a thermal energy meter

34、(i.e., test article) in an open-loop configuration. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior w

35、ritten permission.ANSI/ASHRAE Standard 125-1992 (RA2011) 3temperature sensor: a sensor, located in the liquid circuit,which is capable of producing a signal (output) that is relatedto the temperature of the sensor.thermal energy meter: a metering system capable of measur-ing the thermal energy added

36、 to or extracted from a liquidstream.thermal energy meter error: for a set of test conditions, thedifference between the indicated quantity of energy and theexact quantity of energy passing through a thermal energymeter, divided by the exact quantity of energy, expressed as apercentage.thermal meter

37、: see thermal energy meter.4. NOMENCLATURECp= specific heat of liquid, Btu/(lbF) (kJ/(kgK)E = thermal energy meter error, %h1= enthalpy of cooler liquid, Btu/lb (kJ/kg)h2= enthalpy of hotter liquid, Btu/lb (kJ/kg)= mass flow rate of liquid, lb/min (kg/s)Qexact= exact amount of heat transferred, Btu

38、(kJ)Qdisplayed= heat quantity displayed by meter, Btu (kJ)T = average temperature of T1and T2, F (C)T1= temperature of colder liquid, F (C)T2= temperature of hotter liquid, F (C)Tf= temperature of flow sensor, F (C)Tremote= temperature of remote sensor,F (C)Tproximate= temperature of proximate senso

39、r, F (C)= volume flow rate of liquid, ft3/min (L/s)Vtotal= total volume of liquid to pass a locationduring a time interval, ft3(m3)T = temperature difference, F (C) = elapsed time or test interval, min (s) = density of liquid, lb/ft3(kg/m3)5. CLASSIFICATIONS5.1 Basis of Classification. Liquid therma

40、l energy metersshall be classified according to their service. Four classifica-tions of service are domestic hot water, hydronic space heat-ing, hydronic space cooling, and combined heating andcooling. These impose different environmental and opera-tional requirements that must be considered when te

41、sted.5.1.1 Meters for measuring the energy added for domestichot water purposes must be capable of sensing large temper-ature differences, on the order of 80F (44C), between thehot and cold temperature sensors. Flow may vary continu-ously over a wide range as domestic hot water demand varies.The flo

42、w sensor is usually installed in the cold water supplyand therefore is exposed to the cold temperature.5.1.2 Thermal energy meters may be used to measure ther-mal energy provided to a conditioned space from a hydronicheating system. The flow sensor may be located eitherupstream or downstream of the

43、heat exchanger. In either case,the flow sensor is exposed to a high-temperature environment.Temperature differentials may exceed 100F (56C) andcould drop to as low as 1F (0.5C). Flow rate can be constant,vary continuously, or experience ON to OFF transients.5.1.3 Thermal energy meters may be used to

44、 measure thecooling effect provided to a conditioned space from a chilled-water system. In this case, the flow sensor is exposed to tem-peratures lower than the environment. Such temperatures maylead to moisture condensation. Otherwise, the operating envi-ronment is similar to that described in Sect

45、ion 5.1.2.5.1.4 A combined heating and cooling application willexpose the flow sensor to the largest possible range of temper-ature and will be required to measure temperature differen-tials of both positive (+) and negative () sense by oneinstallation.6. REQUIREMENTS6.1 General. Thermal energy mete

46、rs shall be tested inaccordance with the provisions set forth in this section and inSection 9.6.1.1 Installation. The thermal energy meter shall beinstalled according to the manufacturers recommendations. Inthe case of incomplete, unclear, or arbitrary instructions, instal-lation shall be in accorda

47、nce with ISA RP31.11for temperaturesensors and ASHRAE Standard 41.12for flow sensors.6.2 Test Conditions. A meter shall be subject to test condi-tions according to the service indicated by its manufacturer. Ifthe manufacturer does not state the intended service, then theunit shall be tested for the

48、maximum envelope of conditionsdescribed below for each service.6.2.1 Domestic Hot Water Service. The flow sensor shallbe located in a fluid circuit in which the fluid temperature ismaintained at 78F (26C) 5F (3C). The proximate tem-perature sensor shall be located within the flow sensor or inthe sam

49、e fluid circuit, maintained at the same temperature asthe flow sensor. The remote sensor shall be located in a fluidcircuit in which the fluid temperature can be maintained at78F (26C) through 158F (70C) and within 1% of therequired differential temperature. The flow rate shall be capa-ble of being continuously controllable between 0% and 125%of the flow sensors rated capacity as specified by the manu-facturer or in ON to OFF steps between 0% and 125% of thisrated capacity.6.2.2 Hydronic Heating Service. The flow sensor shallbe located in