ASHRAE GUIDELINE 2-2010 Engineering Analysis of Experimental Data.pdf

1、ASHRAE GUIDELINEASHRAE Guideline 2-2010(Supersedes ASHRAE Guideline 2-2005)Approved by the ASHRAE Standards Committee on June 26, 2010, and by the ASHRAE Board of Directorson June 30, 2010. ASHRAE Guidelines are updated on a five-year cycle; the date following the Guideline is the year of ASHRAEBoar

2、d of Directors approval. The latest edition of an ASHRAE Guideline may be purchased on the ASHRAEWeb 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-

3、800-527-4723 (for orders in US and Canada). For reprint permission, go to www.ashrae.org/permissions. Copyright 2010 American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.ISSN 1049-894XAmerican Society of Heating, Refrigeratingand Air-Conditioning Engineers, Inc.1791 Tullie

4、Circle NE, Atlanta, GA 30329www.ashrae.orgEngineering Analysisof Experimental DataSPECIAL NOTEThis Guideline was developed under the auspices of the American Society of Heating, Refrigerating and Air-Conditioning Engineers(ASHRAE). ASHRAE Guidelines are developed under a review process, identifying

5、a guideline for the design, testing, application, or evaluationof a specific product, concept, or practice. As a guideline it is not definitive but encompasses areas where there may be a variety of approaches,none of which must be precisely correct. ASHRAE Guidelines are written to assist profession

6、als in the area of concern and expertise ofASHRAEs Technical Committees and Task Groups.ASHRAE Guidelines are prepared by project committees appointed specifically for the purpose of writing Guidelines. The projectcommittee chair and vice-chair must be members of ASHRAE; while other committee member

7、s may or may not be ASHRAE members, allmust be technically qualified in the subject area of the Guideline.Development of ASHRAE Guidelines follows procedures similar to those for ASHRAE Standards except that (a) committee balance isdesired but not required, (b) an effort is made to achieve consensus

8、 but consensus is not required, (c) Guidelines are not appealable, and(d) Guidelines are not submitted to ANSI for approval.The Manager of Standards of ASHRAE should be contacted for:a. interpretation of the contents of this Guideline,b. participation in the next review of the Guideline,c. offering

9、constructive criticism for improving the Guideline, ord. permission to reprint portions of the Guideline.DISCLAIMERASHRAE uses its best efforts to promulgate Standards and Guidelines for the benefit of the public in light of available information andaccepted industry practices. However, ASHRAE does

10、not guarantee, certify, or assure the safety or performance of any products, components,or systems tested, installed, or operated in accordance with ASHRAEs Standards or Guidelines or that any tests conducted under itsStandards or Guidelines will be nonhazardous or free from risk.ASHRAE INDUSTRIAL A

11、DVERTISING POLICY 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 pr

12、ovidingother information 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

13、be made, either stated or implied,that the product has been approved by ASHRAE.ASHRAE Guideline Project Committee 2Cognizant TC: TC 1.2, Instruments and MeasurementsSPLS Liaison: Douglas T. Reindl*Denotes members of voting status when the document was approved for publicationRick M. Heiden, Chair* B

14、. Ronald Moncrief*David P. Yuill, Vice-Chair* John W. MroszczykPeter R. Armstrong T.W. PetrieAnthony G. Buschur* Agami ReddyChad B. Dorgan Douglas T. ReindlWilliam M. Healy* Lauren M. Ronsse*Sally A. Hooks Michael A. WegenkaClaudia WoodASHRAE STANDARDS COMMITTEE 20092010Steven T. Bushby, ChairH. Mic

15、hael Newman, Vice-ChairDouglass S. AbramsonRobert G. BakerMichael F. BedaHoy R. Bohanon, Jr.Kenneth W. CooperK. William DeanMartin DieryckxAllan B. FraserNadar R. JayaramanByron W. JonesJay A. KohlerCarol E. MarriottMerle F. McBrideFrank MyersJanice C. PetersonDouglas T. ReindlLawrence J. SchoenBogg

16、arm S. SettyBodh R. SubherwalJames R. TaubyJames K. VallortWilliam F. WalterMichael W. WoodfordCraig P. WrayWayne R. Reedy, BOD ExOThomas E. Watson, COStephanie Reiniche, Manager of Standards American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). For person

17、al use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.CONTENTSASHRAE Guideline 2-2010Engineering Analysis of Experimental DataSECTION PAGEForeword. 21 Purpose 22 Scope . 23 Definitions. 24 Types o

18、f Measurements. 35 The Experimental Process . 36 Uncertainty Analysis Methods and Techniques 67 Data Validation . 68 Regression Analysis. 99 References . 14Informative Annex A: Uncertainty Analysis/Propagation of Error 14Informative Annex B: HVAC recorded values of the variables;readings.deviation:

19、the difference between a single result and the meanof many results.error: the difference between the true value of the quantitymeasured and an observed value. Since the true value is oftennot known, it is estimated by the mean. The differencebetween the mean and an observed value is often called its

20、deviation. experiment: a systematic approach for collecting informationon a physical apparatus or system to determine the nature of itsoperation.mean: the sum of measurement values divided by the numberof measurements. It is considered the best approximation ofthe true value.parent population: synon

21、ymous with population but empha-sizing the relation to a sample.population: any finite or infinite aggregation of items or indi-viduals (inanimate or animate).precision: the closeness of agreement among repeatedmeasurements of the same characteristic by the same methodunder the same conditions.propa

22、gation of uncertainty: the degree to which the uncer-tainties in the values of the parameters affect the uncertainty inthe result.random error (or precision error): a statistical error that iscaused by chance and is not recurring. There are two types ofrandom errors: additive errors that are indepen

23、dent of the magnitude ofthe observationsmultiplicative errors that are dependent on the magni-tude of the observationsrepeatability: the closeness of agreement among repeatedmeasurements of the same characteristic under the sameconditions by the same instrument.replication: repetitions of measuremen

24、ts at the same condi-tions that are taken to estimate the uncertainty in the results.reproducibility: the closeness of agreement among repeatedmeasurements of the same characteristic under the sameconditions by different instruments.sample: a portion, subset, or limited number of items of apopulatio

25、n; a set of values, experimentally obtained, that isrepresentative of the parent population. standard deviation: the square root of the mean of the squaresof the deviations.uncertainty: a measure of the potential error in a measure-ment or experimental result that reflects the lack of confidencein t

26、he result to a specified level.uncertainty range (or confidence interval): the band for theerror in an estimate at a certain confidence level. The greaterthe acceptable confidence level (e.g., 95% rather than 50%),the wider the uncertainty range.variance: the square of the standard deviation. Americ

27、an 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 permission.ASHRAE Guideline 2-2010 34. TYPES OF MEA

28、SUREMENTS4.1 Types of Measurements. Measurements are categorizedas either primary measurements or derived measurements.4.1.1 Primary. A primary measurement is one that isobtained directly from the measurement sensor. This can betemperature, pressure, speed, etc. The key is that a primarymeasurement

29、is of a single item from a specific measurementdevice.4.1.2 Derived. A derived measurement is one that is cal-culated using one or more measurements. This calculation canoccur at the sensor level (an energy meter uses flow and tem-perature difference to report an energy rate). It can be done bya dat

30、a logger, or it can occur during data processing. Derivedmeasurements can use both primary and other derived mea-surements.4.2 Categories of Data. There are two primary categoriesof data: type and sample.4.2.1 Type. The type of data is determined based on thedependence of the data on time and can be

31、 either stationary ortime dependent.4.2.1.1 Stationary. Stationary data do not change withtime. Examples of stationary data include the volume of atank, the area of a room, the length of ductwork, or the size ofa building. Therefore, whenever the measurement is repli-cated, the result should be the

32、same, independent of time,within the bounds of measurement uncertainty.4.2.1.2 Time Dependent. Time-dependent data varieswith time. Examples of time-dependent data include the tem-perature of a space, the chilled water flow to a building, andthe electrical power use of a facility. A time-dependent r

33、ead-ing taken now would probably be different than a readingtaken in 5 min, a day, or a year. Time-dependent data can berecorded either as time-series or cross-sectional data.4.2.1.2.1 Time-Series Data. Time-series data con-sists of a multiplicity of data taken at a single point or locationover fixe

34、d intervals of time.4.2.1.2.2 Cross-Sectional Data. Cross-sectional dataare data taken at multiple points at a single instant in time.4.2.2 Sample. The sample of data is determined based onthe number of measurements taken and can be single-sampleor multisample.4.2.2.1 Single-Sample. A single sample

35、is one or morereadings taken under identical conditions at the same or differ-ent times. Many experiments that appear to be multisample areactually, in part, single-sample experiments. If the same instru-ment is used for a set of observations, the fixed (bias) errorinherent in the reading and caused

36、 by the instrument orobserver will persist, no matter how many times each reading isrepeated.4.2.2.2 Multisample. A multisample is a repeated mea-surement of a fixed quantity using different observers, differ-ent instrumentation, or both. In multisample measurements,the uncertainty and reliability c

37、an be evaluated through theuse of statistics. Merely taking repeated readings with thesame procedure and equipment does not provide multisampledata.5. THE EXPERIMENTAL PROCESS5.1 The intent of this section is to provide a general over-view of the relationship between equipment selection, dataanalysi

38、s, and reporting of results obtained from engineeringexperiments. A well-planned experiment requires that theexperimental equipment and procedures be selected to obtainthe required results as a function of the measured variables. Adetailed experimental plan and measurement methodologymust be develop

39、ed. The basic experimental process involvesthe following steps: 1. Identify experimental goals and acceptable accuracy.2. Identify the important variables and appropriate relation-ships.3. Establish the quantities that must be measured and theirexpected range of variation.4. Tentatively select senso

40、rs/instrumentation appropriate forthe task. 5. Document uncertainty of each measured variable.6. Perform a preliminary uncertainty analysis.7. Study uncertainty results and reassess the ability of themeasurement methods and instrumentation to meet accept-able accuracy.8. Install selected instrumenta

41、tion in accord with relevantstandards or best practices.9. Perform initial verification of data quality.10. Collect experimental data subject to ongoing qualitycontrol criteria.11. Accomplish data reduction and analysis.12. Perform final uncertainty analysis.13. Report experimental results.5.2 Ident

42、ify Experimental Goals and Acceptable Accuracy5.2.1 A well-planned experiment begins with identifica-tion of experimental goals that can be achieved within thetime and budget available for the experiment. Dependingupon the goals, the quantity of data collected and the type ofinstrumentation required

43、 are the primary variables that willaffect the cost for the experiment. An essential part of estab-lishing realistic goals is to decide upon the required accuracyof the results. A higher accuracy results in a lower uncertainty.See Section 5.6 for detailed guidance on setting up the exper-iment and d

44、ocumenting the goals.5.3 Identify Variables and Relationships5.3.1 To further refine the goals of the experiment, theentire list of relevant measurable variables should be exam-ined. Not all of the measurable variables are independent.Therefore, as part of this step, identify the relationships thatw

45、ill limit the measurements or otherwise affect their validity.For example, in a steam-to-water heat exchanger, the capacitycan be determined based on the measurement of hot waterflow rate and inlet-to-outlet temperature difference, with theassumption of a constant heat capacity at the mean tempera-t

46、ure between the inlet and outlet. 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 permission.

47、4 ASHRAE Guideline 2-20105.3.2 Alternatively, capacity can be determined by mea-suring steam flow rate, inlet enthalpy, and outlet enthalpy.Since each enthalpy requires measurement of pressure andtemperature, more instrumentation and measurements arerequired, with the potential of increased uncertai

48、nty in theresults. The effect on uncertainty of more instrumentation andmeasurements for enthalpy could be larger than the effect ofassuming a constant heat capacity.5.4 Establish Measured Variables and Limits5.4.1 For each measured variable, determine its theoreti-cal limits and expected bounds to

49、match the selected instru-ment limits.5.4.1.1 Theoretical Limits. These are the limits of themeasured quantities based on definitions or laws of nature.For example, the relative humidity must always range from0% to 100%.5.4.1.2 Expected Bounds. These are the upper andlower bounds of the measured quantities and must be docu-mented to aid in identifying potentially false or physicallyimpossible measurements as part of ongoing quality control.For example, if the temperature of a conditioned room isbelow 10C (50F) or above 32C (90F), it is likely that theobservation is in error.5.4