AHRI Standards 550/590 (I-P)-2015 & 551/591 (SI) Updates from 2011 Version with Addendum 3

Transcription

1 AHRI Standards 550/590 (I-P)-2015 & 551/591 (SI)-2015 Updates from 2011 Version with Addendum 3

2 Agenda Background Purpose Learning Objectives Referenced Documents Section 1, Purpose Section 2, Scope Section 3, Definitions Section 4, Test Requirements Section 5, Rating Requirements Section 6, Minimum Data Requirements for Published Ratings Section 7, Conversions and Calculations Section 8, Symbols and Subscripts Appendix C, Method of Test Appendix D, Derivation of IPLV Appendix E, Chiller Condenser Entering Air Temperature Measurement Appendix F, Atmospheric Pressure Adjustment Appendix G, Water Pressure Drop Measurement Procedure Appendix H, Heating Capacity Test Procedure Accompanying Tools Kadj Atmospheric Correction 2

3 Background Purpose Background In 2015 work was completed on updating the AHRI 550/590 (IP) and AHRI 551/591 (SI) Standards which have been released as AHRI 550/590 (IP)-2015 and AHRI 551/591 (S)-2015 All sections except Section 4 are effective April 1, 2016 Section 4 is effective January 1, 2017 In addition the Operational Manuals for the ACCL and WCCL certification programs have been updated and released as of 4/1/2016 Purpose This presentation will focus on the changes to the Standards and a separate presentation will cover the Operational Manual changes Review changes in the 2015 version of both standards that differ from the 2011 version 3

4 4 Learning Objectives

5 Learning Objectives Learning Objective Goals To provide and overview of the changes to the AHRI 550/590 (IP) and AHRI 551/591 (SI) standards relative to the 2011 version with addendum 3 The intent is to provide a uniform training document that can be used by users of the standard and laboratories around the world As there have been significant changes to testing requirements and procedures the presentation will also provide further insight into the reasons for the changes and how they are applied The intent of this presentation is to supplement the Standards but is not intended to replace the standard and all requirements interpretations will be based on the standard documents 5

6 Reference Documents Document Location The following documents are available free of charge at the AHRI website Reference Documents AHRI Standard 550/590 (I-P) 2015 with Errata, Performance Rating of Water-chilling and Heat Pump Water-heating Packages Using the Vapor Compression Cycle ANSI/AHRI Standard 550/590 (I-P)-2011 with Addendum 3 AHRI Standard 551/591 (SI)-2015 with Errata, Performance Rating of Water-chilling and Heat Pump Water-heating Packages Using the Vapor Compression Cycle ANSI/AHRI Standard 551/591 (SI)-2011 with Addendum 3 Appendix G Pressure Drop Adjustments Calibration Worksheet Other References Kadj Calculation Spreadsheet Tool ASHRAE

7 7 Section 1, Purpose

8 Section 1, Purpose The purpose of this standard is to establish for Water-chilling and Heat Pump Water-heating Packages using the vapor compression cycle with the following areas of focus: Definitions Test requirements Rating requirements Minimum data requirements for Published Ratings Marking and nameplate data Conversions and calculations Nomenclature Conformance conditions The standard is intended for guidance of the industry, including manufacturers, engineers, installers, efficiency regulators, contractors and users. This standard is subject to review and amendment as technology advances. It is typically updated every 5 years but there may also be addendums 8

9 9 Section 2, Scope

10 Section 2, Scope This standard applies to air-cooled and water-cooled chillers in both heating and cooling mode These Water-chilling and Water-heating Packages include: Water-cooled, Air-cooled, or Evaporatively-cooled Condensers Water-cooled heat recovery condensers Air-to-water heat pumps Water-to-water heat pumps with a capacity greater or equal to 135,000 Btu/h. Water-to-water heat pumps with a capacity less than 135,000 Btu/h are covered by the latest edition of ASHRAE/ANSI/AHRI/ISO Standard This standard does not cover Absorption chillers which are covered by AHRI Standard 560 Chillers with secondary fluids other than water. 10

11 Section 2, Scope The scope of the standards includes products and capacity ranges that may not be current covered under the AHRI ACCL and WCCL certification programs Shown is the current 2016 WCCL scope for the certification program Refer to the WCCL Presentation for more details 11

12 Section 2, Scope Shown is the current 2016 ACCL scope for the certification program Refer to the ACCL Presentation for more details 12

13 13 Section 3, Definitions

14 Overview of Changes Section 3: Definitions 3.3 Capacity Clarification Gross Heating Capacity - clarification of heat balance to energy balance Gross Refrigerating Capacity - clarification of heat balance to energy balance 3.4 Compressor Saturated Discharge Temperature added more detail about what should be included in measurements Water-cooled Heat Recovery Condenser enhanced to add additional information Cooling Energy Efficiency Cooling Coefficient of Performance (COP R ) enhanced for clarity Energy Efficiency Ratio (EER) - enhanced for clarity Power Input per Capacity. (kw/ton R ) - enhanced for clarity 14

15 Overview of Changes Section 3: Definitions Heating Energy Efficiency Heating Coefficient of Performance (COP H ) - enhanced for clarity Simultaneous Cooling and Heating Energy Efficiency (new section) Heat Recovery Coefficient of Performance (COP HR ) - enhanced for clarity Simultaneous Heating and Cooling Coefficient of Performance (COP SHC ) New definition added for units that are operating in a manner that uses both the net heating and refrigerating capacities generated during operation Fouling Factor Allowance Changed the symbol to R foul,sp and enhanced for clarity Non-Standard Part-Load Value (NPLV) - enhanced for clarity on application specifics Percent Load (%Load) - enhanced for clarity to specifically define the use of this term 15

16 Overview of Changes Section 3: Definitions 3.14 Significant Figure new definition for this term 3.16 Total Input Power revised to clarify intent 3.17 Turn Down Ratio - enhanced for clarity 3.18 Unit Type (new section) Configurable Unit - new definition for this term Packaged Unit - new definition for this term Water-chilling or Water-heating Package Heat Recovery Water-chilling Package - new definition for this term Heat Pump Water-heating Package - new definition for this term Modular Chiller Package - new definition for this term Condenserless Chiller - new definition for this term 3.20 Water Pressure Drop - enhanced for clarity and simplification 16

17 17 Section 4, Test Requirements

18 Impact of Significant Figures & Rounding on Pass-Fail Acceptance 18

19 Significant Figures & Rounding Digits Prior editions of Standard 550/590 & 551/591 were silent on rounding digits for published ratings The following items are subject to significant figure rules: Published ratings (capacity, efficiency, pressure drop; rating conditions) Pass/fail limits (Tol1, Tol2, Tol3 calculated from published ratings) Test results (final reported values of measurements and calculated results) Table 14 has the required number of significant figures for each value Generally 3 or 4 sig figs, though temperature is technically 5 19

20 Significant Figures & Rounding Digits Definition of significant figures: (Section 3.14) Significant Figure. Each of the digits of a number that are used to express it to the required degree of accuracy, starting from the first nonzero digit (Refer to Sections 4.3 and 6.2). Detailed rules are in Section 4.3, a brief summary: All non-zero digits are considered significant Leading zeroes are not significant Trailing zeroes to the right of a decimal point are significant Trailing zeroes in a number to the left of a decimal point can be ambiguous, so several methods are defined to present such numbers without ambiguity; the easiest is many cases is to change the prefix on the units of measure (i.e. for large numbers use either W, kw, or MW to avoid trailing zeroes) 20

21 Significant Figures π = Significant Figures Rounded Value AHRI Standards 550/590 (I-P)-2015 and 551/591 (SI)-2015 define rules for significant figures and rounding in Section 4. 21

22 Rounding Error Rounding error can be up to ±½ digit beyond the least significant digit (last digit moving to the right) Example: Take the number 2.5 with two significant digits The least significant digit is 5 ±½ of the next digit is ±0.05 Result 2.5 may have come from a value ranging from to The rounding error could be up to ±0.05, or (±0.05)/2.5 = ±2.0% 22

23 Rounding Error 2 Significant Figures Evaluating rounding error over several orders of magnitude there is a clear pattern: With only 2 significant figures, the rounding error ranges from 0.50% to 5.0% 0.50% < ε 5.0% 23

24 Rounding Error 3 Significant Figures Evaluating rounding error over several orders of magnitude there is a clear pattern: With 3 significant figures, the rounding error ranges from 0.050% to 0.50% 0.050% < ε 0.50% 24

25 Rounding Error 4 Significant Figures Evaluating rounding error over several orders of magnitude there is a clear pattern: With 4 significant figures, the rounding error ranges from % to 0.050% % < ε 0.050% 25

26 Acceptance Criteria Issues If an acceptance criteria includes a tolerance on the order of magnitude of 5% (such as for a chiller with ΔT=10 F where Tol 1 =5.0% at full load), then a rounding error of 0.5% becomes a significant issue to consider ± = ±10% 26

27 Examples The next few slides walk through some examples that demonstrate the impact of rounding issues First showing how a rating software program might calculate an efficiency value, which is then rounded to the published rating value Next showing how the tolerance limit is calculated from the published rating, and then rounded to established the pass/fail criterion for a test Next showing how a test result calculated from test measurements is rounded and used to determine pass/fail The example starts from very coarse resolution, then moving towards finer resolution that demonstrates why AHRI Standards 550/590 and 551/591 selected the required significant figures shown in Table 14 27

28 Example Using Efficiency (EER) As a gross example, if rounding to the nearest integer, these are the only possible values for rated efficiency, or Tol1 tolerance limit, or for tested efficiency

29 Example Using Efficiency (EER) Rating program calculates EER = If rounding to the nearest integer (not using significant figures): full load ΔT 10 F capacity load point 100% Tol1 tolerance 5.00% published rating rounds to 11 Tol1 calculated from 11 Min Allowed EER tested =EER rated -Tol1 Min Allowed EER tested = Min Allowed EER tested result rounds to 10 RATED VALUE MIN ALLOWED Min Allowed EER tested =Round EER rated 1 + Tol1, 0 digits 29

30 Example Using Efficiency (EER) Rating program calculates EER = If rounding to the nearest integer (not using significant figures): Due to rounding the limit (minimum allowable EER), and rounding of the test result, there is a grey zone where pass-fail is not 100% clear RATED VALUE MIN ALLOWED

31 Example Using Efficiency (EER) If using 2 significant figures, these are the only possible values for rated efficiency, or for tested efficiency

32 Example Using Efficiency (EER) Rating program calculates EER = If using 2 significant figures: full load ΔT 10 F capacity load point 100% Tol1 tolerance 5.00% published rating rounds to 11 Tol1 calculated from 11 Min Allowed EER tested =EER rated -Tol1 Min Allowed EER tested = Min Allowed EER tested result rounds to 10 RATED VALUE MIN ALLOWED Min Allowed EER tested =Round EER rated 1 + Tol1, 2 sig figs 32

33 Example Using Efficiency (EER) Rating program calculates EER = If using 2 significant figures: Due to rounding the limit (minimum allowable EER), and rounding of the test result, there is a grey zone where pass-fail is not 100% clear RATED VALUE MIN ALLOWED

34 Example Using Efficiency (EER) Rating program calculates EER = If using 2 significant figures: 12 pass pass full load ΔT 10 F capacity load point 100% Tol1 tolerance 5.00% error bars show the uncertainty due to rounding (lack of resolution) 11 RATED VALUE 10 MIN ALLOWED fail fail pass (but 9% possibility it is a wrong conclusion) POSSIBLE TEST POINTS 34

35 Example Using Efficiency (EER) Rating program calculates EER = If using 3 significant figures: 11.1 pass full load ΔT 10 F capacity load point 100% Tol1 tolerance 5.00% error bars show the uncertainty due to rounding (lack of resolution) pass RATED VALUE MIN ALLOWED POSSIBLE TEST POINTS fail pass (but 50% possibility it is a wrong conclusion) 35 fail

36 Example Using Efficiency (EER) Rating program calculates EER = If using 3 significant figures: As in the 2 significant figure example, due to rounding the limit (minimum allowable EER), and rounding of the test result, there is a grey zone where pass-fail is not 100% clear. With 3 significant figures the grey zone is smaller, though still sizeable. fail 36

37 Example Using Efficiency (EER) Rating program calculates EER = If using 4 significant figures: full load ΔT 10 F capacity load point 100% Tol1 tolerance 5.00% error bars show the uncertainty due to rounding (lack of resolution) RATED VALUE MIN ALLOWED POSSIBLE TEST POINTS fail fail pass pass pass (but 50% possibility it is a wrong conclusion)

38 Example Using Efficiency (EER) In previous figures, note that the effective width of the tolerance band was impacted due to rounding (not always exactly equal to Tol 1 ) parameter units significant figures rating program internal calculation published rating (rounded) difference due to rounding calculated min or max allowable for pass-fail rounded min or max allowable for pass-fail difference due to rounding allowable limit compounded rounding error for tolerance zone size efficiency EER % % % efficiency EER % % -2.69% efficiency EER % % -0.81% 38

39 Tips for Implementing Significant Figures Excel formula to round a value to a specified number of sigfigs: =ROUND(value,sigfigs-(1+INT(LOG10(ABS(value))))) Excel formula to display a value as text properly formatted to appear with the correct number of sigfigs : =TEXT(TEXT(value,"."&REPT("0",sigfigs)&"E+000"), "0"&REPT(".",(sigfigs-(1+INT(LOG10(ABS(value)))))>0)& REPT("0",(sigfigs-(1+INT(LOG10(ABS(value)))))*((sigfigs- (1+INT(LOG10(ABS(value)))))>0))) Note 1: replace value and sigfigs with either a number or a cell reference Note 2: when value is zero, these formulas return an error message (#NUM ) Note 3: similar methods may be used in other programming languages 39

40 40 Section 5, Rating Requirements

41 Section Heating Energy Efficiency New Efficiency Value - Simultaneous Heating and Cooling Coefficient of Performance (COP SCH ) Equation 6: COP SCH = Qcd + Qev/K3 Winput 41

42 AHRI 2011 Rating Conditions Standard rating conditions cooling mode IP AHRI 550/ SI AHRI 551/ fixed (specified) fixed (reference only) variable 42

43 New AHRI 2015 Rating Conditions Standard rating conditions cooling mode IP AHRI 550/ SI AHRI 551/ fixed (specified) fixed (reference only) variable 43

44 Section Standard Ratings and Conditions - Why the change? An error was discovered in the implementation of the ASHRAE 90.1 Kadj formula. The calculated value for Kadj does not equal 1.00 at Standard Rating Conditions (SRC) for all cases. IP: At one particular efficiency level Kadj is indeed equal to 1.00, but chiller models at lower or higher efficiency levels result in values that deviate from SI: There is a small but constant error regardless of chiller efficiency due to slightly different standard rating conditions defined for SI and IP 44

45 Section Application Rating Conditions Full and Part-load Application Rating Conditions Table 2 No changes to ranges from 2011 Standard Additional notes have been added to clarify the intent of the application rating conditions 45

46 Section 5.4 Part-Load Ratings Table 3, Part-load Conditions for Rating, Changes New Clarification for Note 6: Air-cooled and evaporatively-cooled unit ratings are at standard atmospheric condition (sea level). Measured data shall be corrected to standard atmospheric pressure of psia per Appendix F. 46

47 Section 5.4 Part-Load Ratings IPLV & NPLV Nomenclature It is important to identify which standard was used to determine ratings because the IP & SI Standard Rating Conditions are not exact conversions IPLV or NPLV should be appended with.si or.ip IPLV.SI IPLV.IP NPLV applies only to Water-Cooled chillers 47

48 Section Stepped Capacity Part Load Ratings IPLV If a chiller can not operate at a defined part load point, the point may be interpolated, but not extrapolated In cases where the equipment cannot unload to obtain a point, and the subsections provide numerous examples of various types to calculate IPLV 48

49 Section 5.6, Table 12 - Definition of Operating Condition Tolerances and Stability Criteria For testing, each stability criteria has been statistically defined 49

50 Section 5.6.3, Table 13 - Definition of Validity Tolerance Energy Balance (Tol 4 ) tolerance reduced by 30% New requirement for Voltage Balance (V bal ) of 2.0% between phases 50

51 Section 6, Minimum Data Requirements for Published Ratings 51

52 Section Minimum Data Requirements for Published Ratings Clarifies that Standard Ratings are per Section 5.1 (Standard Rating Metrics) and Section 5.2 (Standard Ratings and Conditions) Adds direction for centrifugal chillers to use Section 5.3 (Application Rating Conditions) with the Fouling Factor Allowance per Table 1 Notes unless the specified application states a different value. 52

53 Section Published Ratings Requires all Published Ratings to be rounded to the number of significant figures shown in Table 14 (effective 1/1/17) Rated Total Input Power to Chiller ( ) Explicitly includes all auxiliary power (previously only stated in testing requirements). Include losses from starters, transformers, drives, or gearboxes (line side power measurement) when those components are provided by the chiller manufacturer (whether unit-mounted, selfcontained, free-standing, or remote-mounted). Include losses from non-electric drive (prime mover and all driveline components) when those components are provided by the chiller manufacturer. Excludes losses (not included in the ratings) from starters, transformers, drives, gearboxes, or prime mover when such equipment is provided by the customer or other third party. If variable speed, assume same speed control method as if provided by the chiller manufacturer. 53

54 Section Published Ratings (cont d) Fouling Factor Allowances per Table 1 or Table 2 (either Standard or Application Rating Conditions, as applicable) Water Cooled Condensers (6.2.2) Requires ECWT and LCWT, or LCWT and ΔT Air-cooled (6.2.3) and evaporatively-cooled (6.2.4) condensers. Rated altitude for application rating conditions (defines the atmospheric pressure associated with the rating). Standard ratings are still at sea level. Fan power and spray pump power are now optional itemizations (as subsets of the total input power) 54

55 Section Summary Table of Data to be Published Added column for significant figures requirement Required reporting of altitude Optional itemization notes (fan, spray pump) Temperature decimal place rounding requirements 55

56 Section 7, Conversions and Calculations 56

57 57 Conversion Factors 550/590

58 58 Conversion Factors 551/591

59 Water Side Properties Calculation Methods Either of the following 2 methods can be used. In both cases, the value of the water temperature or pressure to be used as input is dependent on the context of the calculation using the density and specific heat terms. 59

60 Method 1 Use NIST (National Institute of Standards and Technology) Refprop software (version 9.1 or later) to calculate physical properties density and specific heat, as a function of both pressure and temperature. 60

61 Method 2 Use the following polynomial equations to calculate density and specific heat of water as a function of temperature only. 61

62 Converting Altitude to Atmospheric Pressure The relationship is based on the International Standard Atmosphere (ISA) and represents a mean value of typical weather variations. The ISA is defined by International Civil Aviation Organization (ICAO). The slight difference between geometric altitude (ZH) and geopotential altitude (H) is ignored for the purposes of this standard (ZH H). 62

63 63 Section 8, Symbols and Subscripts

64 Symbols and Subscripts All symbols and subscripts from the standard and all appendices were compiled into a single section All symbols and subscripts have unique usage A few new symbols and subscripts were added 64

65 Appendix C, Method of Testing Water-Chilling and Water-Heating Packages Using the Vapor Compression Cycle 65

66 66 Test Setup

67 Test Setup Installation No changes Data to be collected Previously listed in text of Appendix C. Now organized in Tables C3, C4, and C5. 67

68 Data to be Recorded (refer to Table C3) Data to be Recorded During the Test Type Data Item Units of Measure All Condenser Types General Time of day for each data point sample hh:mm:ss.s Atmospheric pressure psia Evaporator T in F T out F m w or V w lb/h or gpm Δp test psid Water-cooled Condenser Condenser T in F Water-cooled Heat Recovery Condenser T out F m w or V w lb/h or gpm Δp test psid Air-cooled Condenser Condenser Spatial average dry-bulb temperature of entering air F Evaporatively-cooled Condenser Condenser Spatial average dry-bulb temperature of entering air F Spatial average wet-bulb temperature of entering air F Without Condenser Compressor Discharge temperature F Discharge pressure psia Liquid Line Liquid refrigerant temperature entering the expansion F device Liquid pressure entering the expansion device psia Electric Drive Chiller W input (and W refrig if needed) kw Voltage for each phase V If 3-phase: average voltage V Frequency for one phase Hz Non-Electric Drive Chiller Refer to Standard for detailed requirements 68

69 Data to be Recorded (refer to Tables C4 and C5) Table C4. Auxiliary Data to be Recorded Type Data Item Units of Measure All Date, place, and time of test dd-mmm-yyyy hh:mm:ss Names of test supervisor and witnessing personnel - Ambient temperature at test site F Nameplate data including make, model, size, serial number and refrigerant designation number, sufficient to completely identify the water chiller. Unit voltage and frequency shall be recorded. - Prime mover nameplate data (motor, engine or turbine). - Non-electric Drive Fuel specification (if applicable) and calorific value - Table C5. Optional Auxiliary Data to be Recorded Type Data Item Units of Measure Open-type compressor Compressor driver rotational speed rpm Electric Drive Current for each phase of electrical input to chiller package amp 69

70 Data to be Recorded Special Notes Pressure Refer to Section C4.1.4 for requirements for Water Pressure Drop measurements. Appendix G is the procedure for Water Pressure Drop Measurement. Sections G3 and G4 detail the measurement locations and static pressure tap requirements. Many labs construct special Appendix G Pipes in various sizes that meet these requirements and reuse them on multiple tests. Section G5 details the procedure for correcting for additional static pressure drop due to external piping. This procedure may not be required on every test. Some labs find it advantageous to include the correction calculations in their computerized data acquisition system so it is calculated in real time during the test. Other labs do the correction calculations on the final test results. Power Refer to Section C4.1.5 Clarified that auxiliary, condenser fan, and condenser spray pump power must be included in W input, but are not required to be recorded separately. 70

71 Data to be Recorded Special Notes Flow Refer to Section C4.1.3 for details on the requirements for mass flow rate and how to calculate it if volumetric flow rate meters are used. Flow meter installation location If using volumetric type flow meter(s), consider installing the flow meter(s) on the flow entering the heat exchanger. Not a requirement but strongly preferred. This avoids the need to make small adjustments in test conditions versus rating conditions (per Section C ). Also refer to Sections and for chiller ratings requirements being based on volumetric flow entering the evaporator or condenser (so that rated flow and test measured flow correspond to the same temperature and density). At low ΔT the adjustment is insignificant, but at higher ΔT, particularly in the condenser at higher temperatures, the adjustment is significant and can be more than 10% of the ±5% tolerance on flow rate. 71

72 72 Collecting/Recording Data

73 Testing Process Section C6.2.1, General Unit being tested shall maintain steady state operating conditions and performance for a minimum of 15 minutes. A minimum of 30 data point measurements shall be collected and recorded Data to be recorded is identified in Tables C3 and C4 Table C5 data may be recorded but is not mandatory Each data point measurement shall be time stamped Time interval between data point measurements shall be uniform in duration, e.g. 30 seconds between each of the minimum 30 measurement data points on a 15 minute duration test Intervals between time stamps shall not vary by more than +/- 5% from the average time interval for all data points. This means that the time intervals for the minimum 30 measurement data points at an average time interval of 30 seconds can t vary by more than +/- 1.5 seconds. For example, Data point n time stamp 10:25:25.2 (hh:mm:ss.s) Data point n+1 time stamp shall be between 10:25:53.7 and 10:25:

74 Recording Data Rules What is not allowed: No longer recording 4 points over a 15 minute period. No longer using tolerances only for pass/fail criteria. What shall be done: Using software or other recording method to capture time stamped data. Test must run a minimum of 15 minutes, no maximum. A minimum of 30 data point measurements to be collected at uniform time intervals. Intervals between time stamps shall not vary more than +/- 5% Each data point measurement can represent either individual reading or time averaged value. If time averaged value is used; whether in hardware or software, the time interval for averaging of the data samples shall not exceed 1/60 of the total test time period. Pass/Fail decisions will use a combination of tolerance and stability criteria. 74

75 Table of Parameters using 1/60 th Total Time Period number of data points data sample interval time (seconds) total test time (minutes) Time Interval 1/ % maximum time scale for averaging (sec) 75

76 15 Minute Trend Using Time Averaged Values 11 Example of 15 Minute Trend- 30 Points To generate point: Can only time average 15 seconds of data Time in Minutes 15 Minute Trend 7.5 Sec Sampling Rate 76

77 Testing Process Section C6.2.1, General Each measured value, such as temperature or power, may be single reading or a time averaged value from a larger number of data points. For example, 7 measurement samples on a power meter averaged and used as the measured data point for power. Note the time interval for averaging of data samples shall not exceed 1/60 th of the total test period. For a 15 minute round, this would be 15 seconds Steady State or Stability Criteria. Determination of stability shall be based upon the criteria established in Table 12. Calculation of the Standard Deviation for each of the measurements identified in Table 12 shall be performed. 77

78 Testing Process Section C6.2.1, General Determination of Steady State Operating Conditions is based upon the mean value of the 30 or more data points relative to the target value. Steady State Operating Conditions (i.e. Stability Criteria) Determination of stability shall be based upon the criteria established in Table 12. Calculation of the Standard Deviation for each of the measurements identified in Table 12 shall be performed. The calculated standard deviation shall be used to determine if the stability criteria is meet as based upon Table 12. Performance Determination of performance shall be based upon Table 11, Definition of Tolerances and Table 12, Definition of Operating Condition Tolerances and Stability Criteria 78

79 Testing Process Section C6.2.1, General Performance A Test Validity assessment shall be made per Section Measurement values and calculation results shall not deviate more than the validity tolerance limits of Table 13 Table 13. Definition of Validity Tolerances Parameter Limits Related Tolerance Equations 3 Energy Balance 1 E bal Tol 4 100% Tol 4 = %Load + Voltage Balance 2 V bal 2.0% Notes: 1. Energy balance where applicable shall be calculated in accordance with Section C Not applicable to single phase units. Voltage unbalance calculated per Section C %Load and Tol 4 are in decimal form T FL %Load 26 79

80 Testing Process Section C6.2.1, General Performance Section requires that tolerance limit for test results for Net Capacity, full and part load Efficiency and Water Pressure Drop shall be determined from Table 11 All of these values shall be rounded to the number of significant figures in Table 14. Table 11 tolerance limits are to be used when testing a unit to verify and confirm performance 80

81 Example: Operating Condition Tolerance & Stability Temperature ( F) data data set point adjusted target sample mean sample standard deviation tolerance limit for sample mean (upper) tolerance limit for sample mean (lower) Table 12 Limits mean to target tolerance limit check T T tar et 0.50 F stability limit check 0.18 F PASS PASS [IP] 81

82 Example: Operating Condition Tolerance & Stability Temperature ( F) data data set point adjusted target sample mean sample standard deviation tolerance limit for sample mean (upper) tolerance limit for sample mean (lower) Table 12 Limits mean to target tolerance limit check T T tar et 0.50 F stability limit check 0.18 F PASS PASS [IP] 82

83 Example: Operating Condition Tolerance & Stability Temperature ( F) data data set point adjusted target sample mean sample standard deviation tolerance limit for sample mean (upper) tolerance limit for sample mean (lower) Table 12 Limits mean to target tolerance limit check T T tar et 0.50 F stability limit check 0.18 F PASS PASS [IP] 83

84 Example: Operating Condition Tolerance & Stability Temperature ( F) data data set point adjusted target sample mean sample standard deviation tolerance limit for sample mean (upper) tolerance limit for sample mean (lower) Table 12 Limits mean to target tolerance limit check T T tar et 0.50 F stability limit check 0.18 F PASS PASS [IP] 84

85 Example: Operating Condition Tolerance & Stability Temperature ( F) data data set point adjusted target sample mean sample standard deviation tolerance limit for sample mean (upper) tolerance limit for sample mean (lower) Table 12 Limits mean to target tolerance limit check T T tar et 0.50 F stability limit check 0.18 F FAIL FAIL [IP] 85

86 Example: Operating Condition Tolerance & Stability Temperature ( F) data data set point adjusted target sample mean sample standard deviation tolerance limit for sample mean (upper) tolerance limit for sample mean (lower) Table 12 Limits mean to target tolerance limit check T T tar et 0.50 F stability limit check 0.18 F FAIL FAIL [IP] 86

87 Example: Operating Condition Tolerance & Stability Temperature ( F) data data set point adjusted target sample mean sample standard deviation tolerance limit for sample mean (upper) tolerance limit for sample mean (lower) Table 12 Limits mean to target tolerance limit check T T tar et 0.50 F stability limit check 0.18 F FAIL FAIL [IP] 87

88 88 Analyzing Results

89 Section C4.5, Validation As a part of test validation, the concept previously referred to as heat balance is now referred to as energy balance to better reflect the true purpose. Section C4.5.3 includes new requirement to calculate voltage balance per Section C3.4.2 for units that use a multi-phase power supply. Energy Balance (Tol 4 ) tolerance reduced by 25% New requirement for Voltage Balance (V bal ) of 2.0% between phases 89

90 Analyzing Results Refer to Section C4.3, Tolerances. Section C4.3.1 defines tolerance requirements on Operating Conditions and refers to Table 12. Changes related to continuous data collection Operating Condition Tolerance Limits for measured data are now based on average value for each measurement Stability Criteria added, based on standard deviation. Section C4.3.2 defines requirements on performance and refers to Table 11 Section defines requirements for Test Validity and refers to Table 13 90

91 Analyzing Results (Air-Cooled Chillers) Test Passed Does test meet validity tolerances in Table 13? YES Do air temperature tolerances meet Table E2? YES Do operating tolerances and stability meet Table 12? YES VALID TEST Do performance tolerances meet Table 11 NO NO NO NO RE-RUN TEST Test Failed 90

92 Analyzing Results (Water-Cooled Chillers) Test Passed Does test meet validity tolerances in Table 13? YES Do operating tolerances and stability meet Table 12? YES VALID TEST Do performance tolerances meet Table 11 NO NO NO RE-RUN TEST Test Failed 90

93 Table 12, Definition of Operating Condition Tolerances and Stability Criteria Measurement or Calculation Result Net Capacity, Q (Cooling or Heating) Cooling Mode Evaporator Entering Water Temperature Leaving Water Temperature Table 12. Definition of Operating Condition Tolerances and Stability Criteria Applicable Operating Mode(s) Values Calculated from Data Samples Mean Std Dev Cooling, Heating, Heat Recovery - - Cooling, Heating, Heat Recovery ഥT s T Operating Condition Tolerance Limits Unit with Continuous Unloading: 1 Part Load test capacity shall be within 2% of the target part-load capacity 2 Q Q target 2.000% Q 100% Units with Discrete Capacity Steps: Part Load test points shall be taken as close as practical to the specified part-load rating points as stated in Table 3 No Requirement ഥT T target 0.50 F Exception for heating mode only: no requirement during defrost portion. Stability Criteria No Requirement s T 0.18 F Entering Water Temperature Heating Only during defrost portion of cycle: ഥT T target 2.00 F s T 0.50 F 1. The target set point condenser entering temperatures (Figure 1) for continuous unloading units will be determined at the target part-load test point. 2. The ± 2.0% tolerance shall be calculated as 2.0% of the full load rated capacity (ton R ). For example, a nominal 50.0% part load point shall be tested between 48.0% and 52.0% of the full load capacity to be used directly for IPLV.IP and NPLV.IP calculations. Outside this tolerance, interpolation shall be used.. 93

94 Table 12, Definition of Operating Condition Tolerances and Stability Criteria Table 12. Definition of Operating Condition Tolerances and Stability Criteria Values Calculated Measurement or Calculation Result Applicable Operating Mode(s) from Operating Condition Tolerance Data Samples Limits Stability Criteria Mean Std Dev Cooling Mode Heat Rejection Heat Exchanger (Condenser) Entering Water Temperature Cooling ഥT s T ഥT T target 0.50 F s T 0.18 F Leaving Water or Fluid Temperature Heating, Heat Recovery Cooling Mode Heat Rejection Heat Exchanger (Condenser) Cooling, Heating (non-frosting) ഥT T target 1.00 F s T 0.75 F Entering Air Mean Dry Bulb Temperature 3 Heating (frosting) 4 ഥT s T Heating portion: ഥT T target 2.00 F Defrost portion: no requirement for ഥT Heating portion: s T 1.00 F Defrost portion: s T 2.50 F Cooling, Heating (non-frosting) ഥT T target 1.00 F s T 0.50 F Entering Air Mean Wet Bulb Temperature 3 Heating (frosting) 4 Heating portion: ഥT T target 1.50 F Defrost portion: no requirement for ഥT Heating portion: s T 0.75 F No requirement 3. The heat portion shall apply when the unit is in the heating mode except for the first ten minutes after terminating a defrost cycle. The defrost portion shall include the defrost cycle plus the first ten minutes after terminating the defrost cycle. 4. When computing average air temperatures for heating mode tests, omit data samples collected during the defrost portion of the cycle. 94

95 Table 12, Definition of Operating Condition Tolerances and Stability Criteria Table 12. Definition of Operating Condition Tolerances and Stability Criteria Measurement or Calculation Result Applicable Operating Mode(s) Values Calculated from Data Samples Operating Condition Tolerance Limits Stability Criteria Water Flow (Volumetric, Entering) Voltage 5 (if multiphase, this is the average of all phases) Frequency 5 Cooling, Heating, Heat Recovery Cooling, Heating, Heat Recovery Cooling, Heating, Heat Recovery Mean Std Dev ഥV w s Vw V w V w,target V w,target 5.000% ഥV s V ഥV V target V target 10.00% s ω ഥω ω target ω target 1.000% s V V 0.750% s V V 0.500% s ω ഥω 0.500% 5. For electrically driven machines, voltage and frequency shall be maintained at the nameplate rating values within tolerance limits and stability criteria on voltage and frequency when measured at the locations specified at Appendix C. For dual nameplate voltage ratings, tests shall be performed at the lower of the two voltages. 95

96 Table 12, Definition of Operating Condition Tolerances and Stability Criteria Table 12. Definition of Operating Condition Tolerances and Stability Criteria Measurement or Calculation Result Applicable Operating Mode(s) Values Calculated from Data Samples Operating Condition Tolerance Limits Stability Criteria Mean Std Dev Condenserless Refrigerant Saturated Discharge Temperature Cooling ഥT s T ഥT T target 0.50 F s T 0.25 F Condenserless Liquid Temperature Cooling ഥT s T ഥT T target 1.00 F s T 0.50 F Steam Turbine Pressure/Vacuum 6 Gas Turbine Inlet Gas Pressure 6 Governor Control Compressor Speed 7 Cooling, Heating, Heat Recovery Cooling, Heating, Heat Recovery Cooling, Heating, Heat Recovery p s p p p rating psid s p psid p s p p p rating psid s p psid n s n n n target n target 0.500% s n n 0.250% 6. For steam turbine and gas turbine drive machines the pressure shall be maintained at the nameplate rating values within the tolerance limits. 7. For speed controlled compressors the speed shall be maintained at the nameplate rating value within the tolerance limits. 96

97 Efficiency Capacity Table 11, Definition of Tolerances Table 11. Definition of Tolerances Limits Related Tolerance Equations 2,3 Cooling or heating capacity for units with continuous unloading 1 Full Load minimum: 100%- Tol 1 Full Load maximum: 100%+ Tol 1 Tol1 Cooling or heating capacity for units with discrete capacity steps Full Load minimum: 100% - Tol 1 Full load maximum: no limit (Full Load shall be at the maximum stage of capacity) = %Load T FL %Load EER kw/ton R COP IPLV.IP NPLV.IP EER IPLV.IP NPLV.IP kw/ton R IPLV.IP NPLV.IP COP R Minimum of: (rated EER) / (100%+ Tol 1 ) Maximum of: (100%+ Tol 1 ) (rated kw/ton R ) Minimum of: (rated COP) / (100%+ Tol 1 ) Minimum of: (rated EER) / (100%+ Tol 2 ) Maximum of: (100%+ Tol 2 ) (rated kw/ton R ) Minimum of: (rated COP R ) / (100%+ Tol 2 ) T FL = Difference between entering and leaving water temperature at full-load, F See Figure 3 for graphical representation of the Tol 1 tolerance. Tol 2 = T FL 24 See Figure 4 for graphical representation of the Tol 2 tolerance p Water Pressure Drop p corrected Tol 3 Tol 3 = max ቊ rated p rated + 2 ft H 2 O Notes: 1. The target set point condenser entering temperatures (Figure 1) for continuous unloading units will be determined at the target part load test point. 2. For air-cooled units and evaporatively-cooled units, all tolerances are computed for values after the atmospheric correction is taken into account. 3. %Load, Tol 1 and Tol 2 are in decimal form

98 Table 13, Definition of Validity Tolerances Table 13. Definition of Validity Tolerances Parameter Limits Related Tolerance Equations 3 Energy Balance 1 E bal Tol 4 100% Tol 4 = %Load + Voltage Balance 2 V bal 2.0% Notes: 1. Energy balance where applicable shall be calculated in accordance with Section C Not applicable to single phase units. Voltage unbalance calculated per Section C %Load and Tol 4 are in decimal form T FL %Load 26 98

99 Tolerance and Stability Where to Find It Parameter Measured Calculated Table 11 Table 12 Table 12 Table 13 Table E2 Tol. Tol. Stab. Tol. Tol. Water Temps X X X Flow Rates X X X Power X Voltage Average of ALL Phases X X X Frequency X X X Volts A X Volts B X Volts C X Mean Air Temp X X X X Thermopiles X X Psychrometer X X Differential Pressure X X Wet Bulb X X X Atmospheric Pressure X Ambient Temp at Site X Voltage Unbalance X X Capacity X X X Efficiency X X Water Pressure Drop X X IPLV X X Energy Balance X X 99

100 Test Report Requirements A written or electronic test report shall be generated including items for each test point at a specific load and set of operating conditions. AHRI breaks this down into 3 main parts. Data Include mean and standard deviation for each measurement value (refer to Section C7.1) Calculations Refer to Section C7.2 Results Refer to Section C7.3 and Table C6 Examples of each will follow 100

101 Sample Water Cooled Test Report Page 1 Cooling Mode WATER COOLED AHRI TEST REPORT Date Place of Test Test Supervisor Model Number Unit Voltage Refrigerant Test Time Period Ambient Temperature Evaporator Water In Evaporator Water Out Evaporator Delta T Evaporator GPM Evaporator Delta P test (psid) Condenser In Condenser Out Condenser Delta T Condenser GPM Condenser Delta P test (psid) Power (W input ) Frequency Voltage A Voltage B Voltage C Voltage Average of all Phases DATA Time of Test Witness Personnel Serial Number Unit Frequency Motor Nameplate # Data Point Measurements Atmosheric Pressure(psia) Standard Standard Design Mean STDEV Tolerance STDEV 101

102 Sample Water Cooled Test Report Page 2 Cooling Mode Evaporator Capacity Gross Density Gross Specific Heat Gross Mass Flow Gross Evaporator Capacity Net Density Net Specific Heat Net Mass Flow Net Condenser Capacity Gross Density Gross Specific Heat Gross Mass Flow Gross Evaporator Delta P adjustment (ft H2O) Condenser Delta P adjustment(ft H2O) Power (W input ) Evaporator Capacity Net Efficiency Evaporator Delta P Corrected(ft H2O) Condenser Delta P Corrected(ft H2O) Energy Balance Voltage Balance Caculations Standard Standard Design Mean STDEV Tolerance STDEV Results Standard Standard Design Mean Total STDEV Tolerance STDEV 102

103 Sample Air Cooled Test Report Page 1 Cooling Mode AIR COOLED AHRI TEST REPORT Date Place of Test Test Supervisor Model Number Unit Voltage Refrigerant Test Time Period Ambient Temperature Evaporator Water In 1 Evaporator Water In 2 AVG Evaporator Water In Evaporator Water Out 1 Evaporator Water Out 2 AVG Evaporator Water OUT Evaporator Delta T Evaporator GPM 1 Evaporator GPM 2 AVG Evaporator GPM Evaporator Delta P test (psid) Psychrometer 1 Temp Psychrometer 2 Temp Entering Air Mean Dry Bulb Thermopile 1A Thermopile 1B Thermopile 2A Thermopile 2B Air Discharge Thermocouple 1A Air Discharge Thermocouple 1B Air Discharge Thermocouple 2A Air Discharge Thermocouple 2B Power (W input ) 1 Power (W input ) 2 AVG Power (W input ) AVG Frequency AVG Voltage A AVG Voltage B AVG Voltage C Voltage Average of all Phases DATA Time of Test Witness Personnel Serial Number Unit Frequency Motor Nameplate # Data Point Measurements Atmosheric Pressure(psia) Standard Standard Design Mean STDEV Tolerance STDEV 103

104 Sample Air Cooled Test Report Page 2 Cooling Mode Un-Corrected Evaporator Capacity Net Density Net Specific Heat Net Mass Flow Net Un-Corrected Efficiency Caculations Standard Standard Design Mean STDEV Tolerance STDEV Correction Factor CF Q Correction Factor CF N Evaporator Delta P adjustment (ft H2O) AVG Power (W input ) Corrected Evaporator Capacity Net Corrected Efficiency Evaporator Delta P Corrected(ft H2O) Voltage Balance Entering Air Mean Dry Bulb Mean Dry Bulb - Psychrometer 1 Thermopile 1A - Psychrometer 1 Thermopile 1B - Psychrometer 1 Air Discharge TC 1A - Thermopile 1A Air Discharge TC 1B - Thermopile 1B Mean Dry Bulb - Psychrometer 2 Thermopile 2A - Psychrometer 2 Thermopile 2B - Psychrometer 2 Air Discharge TC 2A - Thermopile 2A Air Discharge TC 2B - Thermopile 2B Mean Dry Bulb Varation During Test Entering Water 1 - Entering Water 2 Leaving Water 1 - Leaving Water 2 Evap GPM 1 - Evap GPM 2 Power (W input ) 1 - Power (Winput) 2 Results Standard Standard Design Mean Total STDEV Tolerance STDEV 104

105 Calculations & Results to Report Calculations (Section C7.2) Delta P adj Delta T adj CF Q CF N Density, specific heat capacity, and mass flow values for capacity calculations Report all values of Q used in energy balance calculations Results (Section C7.3) Net Capacity Corrected Gross Capacity (water-cooled only) Power Input (W input and W refrig as applicable) Efficiency Delta P corrected Energy Balance (water-cooled only) Voltage Balance Note: All values calculated using the mean value of the recorded data as per Section C

106 APPENDIX D, Derivation of Integrated Part-Load Value (IPLV) 106

107 Appendix D Appendix D contains details on the derivation of the IPLV as defined by equation 8 and 9 including the weighting factors and ambient rebalance temperatures A single chiller s design rating condition as defined in table 1 represents the performance at the simultaneous occurrence of both full-load and design ambient conditions which typically are the ASHRAE 1% weather conditions. The design efficiency contains no information representative of the chiller s operating efficiency at any off-design condition (part-load, reduced ambient). The IPLV metric was developed to create a numerical rating of a single chiller as simulated by 4 distinct operating conditions, established by taking into account blended climate data to incorporate various load and ambient operating conditions. The intent was to create a metric of part-load/reduced ambient efficiency that, in addition to the design rating, can provide a useful means for regulatory bodies to specify minimum chiller efficiency levels and for Engineering firms to compare chillers of like technology. The IPLV value is not intended to be used to predict the annualized energy consumption of a chiller in any specific application or operating conditions. IPLV was intended to be a standard overall rating metric with a weighted full and part load component. NPLV was created to allow for centrifugal chillers to include a PLV metric for chillers that can not operate at full load standard rating conditions, but it has been expanded to cover all water cooled products. Currently it is not a valid metric for air cooled products 107

108 Appendix D There are many issues to consider when estimating the efficiency of chillers in actual use. Neither IPLV nor design rating metrics on their own can predict a building s energy use. Additionally, chiller efficiency is only a single component of many which contribute to the total energy consumption of a chiller plant. In addition chillers are typically used in multiple configurations and are part of an overall chilled water HVAC system. It is for these reasons that AHRI recommends the use of building energy analysis programs, compliant with ASHRAE Standard 140, that are capable of modeling not only the building construction and weather data but also reflect how the building and chiller plant operate. In this way the building designer and operator will better understand the contributions that the chiller and other chiller plant components make to the total chiller plant energy use. Modeling software can also be a useful tool for evaluating different operating sequences for the purpose of obtaining the lowest possible energy usage of the entire chiller plant. To use these tools, a complete operating model of the chiller, over the intended load and operating conditions, should be used. In summary, it is best to use a comprehensive analysis that reflects the actual weather data, building load characteristics, operational hours, economizer capabilities and energy drawn by auxiliaries such as pumps and cooling towers, when calculating the chiller and system efficiency. The intended use of the IPLV (NPLV) rating is to compare the performance of similar technologies, enabling a side-by-side relative comparison, and to provide a second certifiable rating point that can be referenced by energy codes. A single metric, such as design efficiency or IPLV shall not be used to quantify energy savings. 108

109 APPENDIX E. Chiller Condenser Entering Air Temperature Measurement 109

110 Changes To Appendix E for 2015 Version Table E2 verbiage changed to clarify the use of average values for tolerance specification (location vs. time). Figure E1 revised to show more detail for construction of air sampling tree. Thermopiles or individual thermocouples averaged may be used with the air sampling trees. For part load test points, Aspirating Psychrometers positioned at non operating portions of the coil on the test chiller may be excluded from the calculations. 110

111 Example Air Sampling Tree Recirculation Thermocouple 1 per air sampling tree. Maximum 5 degree F Delta from average air inlet of Psychrometer. Thermopile Box Thermocouples wired in parallel to provide 1 reading per tree. Air Sampling Tree MAXIMUM 4 per Aspirating Psychrometer. Greater Than 50 Holes. Thermopiles Each black strip represents a thermocouple. MINIMUM 16 TREE PLACEMENT 6-12 inches from coil. Insulated hose of equal lengths connecting to Aspirating Psychrometer 111

112 Example Aspirating Psychrometer VFD Must maintain 2.5 ft./s or greater Velocity through Air Sampling Tree holes Temperature Measurement Redundant dry and wet bulb measurements. 112

113 Additional Information Mixing fans can be used to ensure adequate air distribution in test room Rule: Must not point at coil air inlet. Fan exhaust must be degrees to that of the air inlet of coil. Air Sampling Trees Aspect ratio no greater than 2 to 1 1 main flow trunk branch connections Greater than 50 holes Minimum of 16 temperature measurement locations per tree Tree location 6-12 inches from unit Test Setup See figures E3 and E4, Section E6 113

114 Additional Information Aspirating Psychrometers Fans for Psychrometer can be manual or automatic Maximum of 4 air sampling trees per psychrometer Redundant measurement wells for dry and/or wet bulb measurement 114

115 Appendix F, Atmospheric Pressure Adjustment 115

116 Appendix F, Atmospheric Pressure Adjustment Purpose To prescribe a method of adjusting measured test data according to local atmospheric conditions. Background To ensure performance can be uniformly compared from one unit and one manufacturer to another, performance testing for air-cooled and evaporatively-cooled chillers should be corrected for air-density variations. 116

117 Appendix F, Atmospheric Pressure Adjustment Correction factors based on pressure and not altitude to include effects of weather variations. Part load correction factors are scaled between 1 and the full load correction based on percentage of full load capacity Standard adds method to adjust test data to application conditions. Correction factor limit changed from psia (approx. 5,000 ft) in 2011 Standard to psia (approx. 6,500 ft) in 2015 Standard 117

118 Appendix F, Atmospheric Pressure Adjustment Equations The values for the correction factor polynomial equation coefficients (AQ, BQ, CQ, Aƞ, Bƞ, and Cƞ) are found in Table F1. The definitions of all variables are listed in Table 16. D Q = A Q p 2 + B Q p + C Q CF Q P=Pte t = 1 + Q ev,%loa d Q ev,100% D Q 1 e 0.35 D η η te t,100% 9.6 D η = A η p 2 + B η p + C η CF η P=Pte t = 1 + Q ev,%loa d Q ev,100% D η 1 e 0.35 D η η te t,100%

119 Appendix F, Atmospheric Pressure Adjustment Equations The capacity correction factor equation term (D Q ) is used only in the capacity correction factor equation. The efficiency correction factor equation term (D ƞ ) is used in both correction factor equations. D Q = A Q p 2 + B Q p + C Q CF Q P=Pte t = 1 + Q ev,%loa d Q ev,100% D Q 1 e 0.35 D η η te t,100% 9.6 D η = A η p 2 + B η p + C η CF η P=Pte t = 1 + Q ev,%loa d Q ev,100% D η 1 e 0.35 D η η te t,100%

120 Appendix F, Atmospheric Pressure Adjustment Equations The corrected capacity and efficiency are the tested values multiplied by the correction factors. If efficiency is expressed in kw/tonr, then the tested efficiency should be divided by the correction factor instead of multiplying, but efficiency used in correction factor equations must be in Btu/(W*h). Q corrected, tandard = Q te t CF Q P=P_te t η corrected, tandard = η te t CF η P=Pte t 120

121 Appendix F, Atmospheric Pressure Adjustment Application Rating Conditions To correct test data to application conditions, the data is first corrected to standard conditions then the reverse method is used to correct to the application rated atmospheric pressure (P rated ). The same equations are used for the correction factors, but with the application atmospheric pressure in place of the measured test pressure. The application capacity and efficiency are the standard condition corrected values divided by the correction factors. Q corrected,application = Q corrected, tandard CF Q P=Prated η corrected,application = η corrected,standard CF η P=Prated 121

122 122 Appendix F, Atmospheric Pressure Adjustment Example Full Load

123 123 Appendix F, Atmospheric Pressure Adjustment Example Part Load

124 124 Appendix F, Atmospheric Pressure Adjustment Example Application Conditions

125 Appendix G, Water Pressure Drop Measurement Procedure 125

126 APPENDIX G, WATER PRESSURE DROP MEASUREMENT PROCEDURE NORMATIVE Purpose To prescribe a measurement method for Water Pressure Drop and, when required, a correction method to compensate for friction losses associated with external piping measurement sections. The measurement method only applies to pipe of circular cross section. Background The aim is to determine measurement uncertainties pertaining to waterside pressure drop (WPD) dictated by the requirement of a certified test point. AHRI website ( provides an excel spreadsheet that can be used for water pressure drop adjustment calculations. 126

127 APPENDIX G, WATER PRESSURE DROP MEASUREMENT PROCEDURE NORMATIVE Static pressure (SP) taps in external upstream/downstream piping shall be used to measure chiller WPD Adjustment factors are used to compensate/correct pressure drop measurement. However, many studies recommend the restriction of the use of external correction factors because they can be source of potential errors. It is recommended to use straight pipe connections, with adequate length, for small connection sizes to minimize SP measurements errors 127

128 Appendix G, Water Pressure Drop Measurement Procedure Normative Larger chillers, with large connection sizes, may use elbows/reducers/ enlargers, upstream/downstream, to accommodate pipe diameter changes. It s a compromise between measurement uncertainties and costs of test facilities. 128

129 129 Appendix G, Water Pressure Drop Measurement Procedure Normative

130 130 Appendix G, Water Pressure Drop Measurement Procedure Normative

131 Measurement Locations SP taps may be located in the unit connections (nozzles) if long enough to meet L/D requirements of Table G1, or in external piping (test fixtures). External piping arrangement shall use rigid pipe. Flexible hose is not allowed between the unit connections and the pressure taps. 131

132 132 Geometrical Requirements for Location of SP Pressure Taps as per Table G1: