ASHRAE 20-1997 Method of Testing for Rating Remote Mechanical-Draft Air-Cooled Refrigerant Condensers《远程机械草图空气冷却系统额定值的试验方法》.pdf

1、ASHRAE STANDARDAmerican Society of Heating, Refrigeratingand Air-Conditioning Engineers, Inc.1791 Tullie Circle NE, Atlanta, GA 30329www.ashrae.orgMethod of Testing forRating RemoteMechanical-DraftAir-Cooled RefrigerantCondensersANSI/ASHRAE Standard 20-1997 (RA 2006)Reaffirmation of ANSI/ASHRAE Stan

2、dard 20-1997Approved by the ASHRAE Standards Committee on January 29, 1997, and reaffirmed on June 24, 2006; by theASHRAE Board of Directors on January 30, 1997, and reaffirmed on June 29, 2006; and by the American NationalStandards Institute on April 7, 1997, and reaffirmed on June 30, 2006.ASHRAE

3、Standards are scheduled to be updated on a five-year cycle; the date following the standard number isthe year of ASHRAE Board of Directors approval. The latest copies may be purchased from ASHRAE CustomerService, 1791 Tullie Circle, NE, Atlanta, GA 30329-2305. E-mail: ordersashrae.org. Fax: 404-321-

4、5478. Tele-phone: 404-636-8400 (worldwide) or toll free 1-800-527-4723 (for orders in US and Canada). Copyright 2006 ASHRAE, Inc.ISSN 1041-2336When addenda, interpretations, or errata to this standard have been approved, they can be downloaded free ofcharge from the ASHRAE Web site at http:/www.ashr

5、ae.org.www.ansi.orgASHRAE Standard Project Committee 20-1997Cognizant TC: TC 8.4, Air-to-Refrigerant Heat Transfer EquipmentStandards Project Committee Liaison: Gordon F. ClydeRoland A. Ares, Chair* Todd Amsey Michael* Paul F. Lammert*Daniel E. Kramer* Richard S. Oas* Denotes members of voting statu

6、s when the document was approved for publication.ASHRAE STANDARDS COMMITTEE 20052006Richard D. Hermans, ChairDavid E. Knebel, Vice-ChairDonald L. BrandtSteven T. BushbyPaul W. CabotHugh F. CrowtherSamuel D. Cummings, Jr.Robert G. DoerrHakim ElmahdyRoger L. HedrickJohn F. HoganFrank E. JakobStephen D

7、. KennedyJay A. KohlerJames D. LutzMerle F. McBrideMark P. ModeraCyrus H. NasseriStephen V. SantoroStephen V. SkalkoDavid R. TreeJerry W. White, Jr.James E. WoodsWilliam E. Murphy, BOD ExORonald E. Jarnagin, COClaire B. Ramspeck, Assistant Director of Technology for Standards and Special ProjectsSPE

8、CIAL 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 StandardsInstitute (ANSI), of which ASHRAE is

9、 a member and which has approved this standard as an ANS, as “substantial agreement reached bydirectly and materially affected interest categories. This signifies the concurrence of more than a simple majority, but not necessarily unanimity.Consensus requires that all views and objections be conside

10、red, and that an effort be made toward their resolution.” Compliance with thisstandard is voluntary until and unless a legal jurisdiction makes compliance mandatory through legislation.ASHRAE obtains consensus through participation of its national and international members, associated societies, and

11、 public review.ASHRAE Standards are prepared by a Project Committee appointed specifically for the purpose of writing the Standard. The ProjectCommittee Chair and Vice-Chair must be members of ASHRAE; while other committee members may or may not be ASHRAE members, allmust be technically qualified in

12、 the subject area of the Standard. Every effort is made to balance the concerned interests on all ProjectCommittees. 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 Standard,c. offering construct

13、ive criticism for improving the Standard,d. permission to reprint portions of the Standard.DISCLAIMERASHRAE uses its best efforts to promulgate Standards and Guidelines for the benefit of the public in light of available information and acceptedindustry practices. However, ASHRAE does not guarantee,

14、 certify, or assure the safety or performance of any products, components, orsystems tested, installed, or operated in accordance with ASHRAEs Standards or Guidelines or that any tests conducted under its Standardsor Guidelines will be nonhazardous or free from risk.ASHRAE INDUSTRIAL ADVERTISING POL

15、ICY ON STANDARDSASHRAE Standards and Guidelines are established to assist industry and the public by offering a uniform method of testing for ratingpurposes, by suggesting safe practices in designing and installing equipment, by providing proper definitions of this equipment, and by providingother i

16、nformation that may serve to guide the industry. The creation of ASHRAE Standards and Guidelines is determined by the need for them,and conformance 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, eithe

17、r stated or implied,that the product has been approved by ASHRAE.CONTENTSANSI/ASHRAE Standard 20-1997 (RA 2006)Method of Testing for Rating Remote Mechanical-Draft Air-Cooled Refrigerant CondensersSECTION PAGEForeword. 21 Purpose 22 Scope . 23 Definitions. 24 Test Methods 25 Test Instruments . 36 Te

18、st Apparatus 67 Test Procedure . 88 Data to be Recorded 99 Source of Physical Properties. 1010 Symbols 1011 Computations 1112 References . 12Appendix A . 13Appendix B . 15NOTEWhen addenda, interpretations, or errata to this standard have been approved, they can be downloaded free of charge from the

19、ASHRAE Web site at http:/www.ashrae.org. Copyright 2006 American Society of Heating,Refrigerating and Air-Conditioning Engineers, Inc.1791 Tullie Circle NEAtlanta, GA 30329www.ashrae.orgAll rights reserved.2 ANSI/ASHRAE Standard 20-1997 (RA 2006)(This foreword is not a part of this standard. It is m

20、erelyinformative 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 that has not beensubject to public review or a consensus process.)FORWARDThis is a reaffirmation of ANSI/ASH

21、RAE Standard 20-1997. This standard was prepared under the auspices of theAmerican Society of Heating, Refrigerating and Air-Condi-tioning Engineers (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 bas

22、is andmerely in the interests of obtaining uniform standardsthroughout the industry. The changes made for the 2006 reaffirmation were thatthe references were updated.1. PURPOSEThis standard prescribes methods of laboratory testing tomeasure the heat rejection capabilities of remote mechanicaldraft,

23、air-cooled refrigerant condensers for refrigerating andair conditioning. The objective is to ensure uniform perfor-mance information for establishing ratings.2. SCOPE2.1 This standard provides a. uniform methods of testing for obtaining performance data,b. definition of terms,c. specification of dat

24、a to be recorded and calculationformulas, andd. test limits and tolerances.2.2 This standard does not covera. methods of test for production or field use,b. liquid-cooled condensers, norc. heat reclaim condensers using less than full refrigerantliquid condensing.3. DEFINITIONS3.1 Generalcalorimeter:

25、 a device for accurately determining refrigerantflow rate by the principle of known heat input or output,known physical characteristics of the transfer media, andobserved thermal differences.condenser subcooling: number of degrees that a pressur-ized liquid is cooled lower than its saturated tempera

26、ture atthat pressure.condensing temperature: the saturation temperature, indegrees, corresponding to the measured refrigerant pressure atthe condenser inlet.remote mechanical-draft air-cooled refrigerant condenser:a self-contained, waterless refrigerating system componentthat fully condenses refrige

27、rant vapor by rejecting heat to air,mechanically circulated by integral fans and fan drives over itsfinned-tube heat transfer surface, causing a temperature rise inthe air. Refrigerant gas desuperheating and liquid subcoolingare expected to occur.shall (“it is required”): term used in standards and

28、regula-tions (as “shall” or “shall not”) to indicate a provision that ismandatory.should (“it is recommended”): term used in standards andregulations to indicate a provision that is not mandatory butthat is recommended as good practice.temperature difference (TD): the difference in degreesbetween th

29、e condensing temperature and the entering air dry-bulb temperature.3.2 Coil Dimensionscoil depth: the dimension of the finned surface as measuredfrom the entering air face to the leaving air face in the directionof airflow.coil face area: the product of the coil length and coil width.coil length: th

30、e dimension of the face of the coil in the direc-tion of the finned tubes exposed to the flow of air.coil width: the dimension of the face of the coil perpendicularto the direction of the tubes and includes only the width overthe tube and fins exposed to the airflow. Note: Height may besubstituted f

31、or width if the condenser has a vertical coil orien-tation.3.3 Testing Termsequilibrium: the steady-state condition during which the fluc-tuations of variables being measured remain within statedlimits.test: the recorded group of readings of test variables takenwhile equilibrium is maintained and us

32、ed in the computationof results.test run: the complete group of readings of test variables,which includesa. those observed or recorded during a sufficient periodto indicate that equilibrium was obtained prior to thetest andb. those recorded during the period of the test.4. TEST METHODS4.1 General4.1

33、.1 To fulfill the requirements of this standard, twosimultaneous methods of determining condenser capacityshall be usedone primary method and one confirmingmethod. The primary method utilizes the refrigerant massflow rate and enthalpy differences of the refrigerant enteringand leaving the condenser.

34、 This is determined from the accu-rate measurement of the pressure-temperature state of boththe refrigerant gas entering and liquid leaving the condenser.Condenser heat of rejection shall then be calculated as a prod-uct of refrigerant flow rate measured (see Section 4.1.2) andthe enthalpy differenc

35、e.ANSI/ASHRAE Standard 20-1997 (RA 2006) 34.1.2 Primary Methods4.1.2.1 Liquid-Line Flow Method. Refrigerant massflow rate is determined by direct meter reading. This is thepreferred primary method.4.1.2.2 Low-Side Electric Calorimeter Method.Refrigerant mass flow rate is determined from the measured

36、electrical heat input to a calorimeter divided by the enthalpychange of the refrigerant passing through it.4.1.2.3 Low-Side Water Chiller Method. Refrigerantflow rate is determined from the measured water-side heatinput to the chiller divided by the enthalpy change of therefrigerant passing through

37、it.4.1.3 Confirming Methods4.1.3.1 Low-Side Electric Calorimeter Method. Con-denser heat rejection rate is determined by arriving at the sumof the electrical heat input to the calorimeter and the electricalpower input utilized for the mechanical compression of therefrigerant circulated through the c

38、ondenser (as corrected forany non-insulated refrigerant line losses).4.1.3.2 Low-Side Water Chiller Method. Condenserheat rejection rate is determined by measuring the sum of thewater-side heat input to the chiller and the electrical powerinput utilized for the mechanical compression of the refriger

39、-ant circulated through the condenser.4.1.3.3 High-Side Air Calorimeter Method. Measure-ments of the airflow rate shall be made by the use of precisionairflow nozzle(s) (see Section 6.2.9). The condenser heattransfer rate shall then be calculated as the product of the airmass flow rate, specific hea

40、t, and temperature rise of the air.4.1.3.4 Calibrated Compressor Method. Condensercapacity shall be determined from lab test data utilizing a cal-ibrated compressor. The calibrated compressor shall beemployed within the range of test conditions of its calibration.The condenser heat rejection rate is

41、 taken from the compres-sor calibration curve at the test operating points of refrigerantpressure and temperature and power (kW) of the compressor.4.1.3.5 Suction Line Orifice Method. Refrigerantmass flow as determined by the orifice method set forth inANSI/ASHRAE Standard 41.7-1984 (RA 2006),Standa

42、rdMethod for Measurement of Flow of Gas.104.2 Energy Balance. For a test run to be valid, the heatrejection capacity of the condenser, as measured by the pri-mary and the confirming methods, shall agree within 5% (seeSection 7.7). Note: A confirming method may be another ofthe primary methods not th

43、erein used for that test run.5. TEST INSTRUMENTS5.1 General. Calibration of all instrumentation, includingpressure transducers and temperature diodes and their cir-cuits, utilized for test measurements for Sections 8.3, 8.4, and8.5, shall be performed before and after each run or series oftest runs

44、extending over not more than seven elapsed days.Calibration shall be traceable to primary or secondary stan-dards calibrated by the National Institute of Standards andTechnology (NIST). Standard test instruments that have beencalibrated in accordance with such standards, having the sameor greater ac

45、curacy than required by this standard, which areused solely for test laboratory standardizing purposes, complywith the intent of this paragraph.Each instrument calibration shall be recorded and a copythereof made part of the test record of the condenser. Beforeand after test calibration shall be wit

46、hin the accuracy limitsstated as follows for each instrument type. Where calibrationof an instrument after a test series exceeds the applicable limit,analysis may be conducted to determine whether the possibleerror induced by the uncertainty is significant, that is, wouldcause the primary and confir

47、ming heat rejections to differ bymore than 5%. If not, the result may be retained. This appliesexcept where the out-of-calibration instrument is employed inboth the primary and confirming method, the run or series ofruns shall be discarded.5.2 Temperature-Measuring Instruments5.2.1 Temperature measu

48、rements shall be made with aninstrument or instrument system meeting the accuracy andprecision requirements in Section 5.2.2. The following are incommon use for this purpose: a. mercury-in-glass thermometersb. thermocouples with potentiometerc. electric resistance thermometers, including thermistors

49、and other semiconductor-type devices5.2.2 The accuracy of the temperature-measuring instru-ments shall be within limits as follows:a. dry-bulb air and water temperatures: 1% of the smallestrequired test temperature difference (TD) computed inaccordance with Section l1.5, i.e., 0.1F (0.06 K) for a10F (6 K) minimum test TDb. refrigerant vapor temperatures: 1.0F (0.6C)c. all other temperatures: 0.5F (0.3C)5.2.3 In no case shall the smallest decimal scale divisionof the instrument exceed twice the specified accuracy; forexample, if the specified accuracy is to be 0.5F (0.3C), thes