1、 2014 Standard for Performance Rating of Walk-in Coolers and Freezers AHRI Standard 1251 (SI) Price $10.00 (Members) $20.00 (Non-Members) Copyright 2014, by Air-Conditioning, Heating, and Refrigeration Institute Printed in U. S.A. Registered United States Patent and Trademark Office IMPORTANT SAFETY
2、 DISCLAIMER AHRI does not set safety standards and does not certify or guarantee the safety of any products, components or systems designed, tested, rated, installed or operated in accordance with this standard/guideline. It is strongly recommended that products be designed, constructed, assembled,
3、installed and operated in accordance with nationally recognized safety standards and code requirements appropriate for products covered by this standard/guideline. AHRI uses its best efforts to develop standards/guidelines employing state-of-the-art and accepted industry practices. AHRI does not cer
4、tify or guarantee that any tests conducted under its standards/guidelines will be non-hazardous or free from risk. Note: This standard supersedes AHRI Standard 1251 (SI)-2009 For I-P ratings, see ANSI/AHRI Standard 1250 (I-P)-2014. i TABLE OF CONTENTS PAGE Section 1 Purpose 1 Section 2 Scope . 1 Sec
5、tion 3 Definitions . 1 Section 4 Test Requirements . 3 Section 5 Rating Requirements . 5 Section 6 Calculation for Walk-in Box Load 19 Section 7 Calculation for Annual Walk-in Energy Factor . 20 Section 8 Symbols and Subscripts 42 Section 9 Minimum Data Requirements for Published Ratings 45 Section
6、10 Marking and Nameplate Data . 45 Section 11. Conformance Conditions. 45 TABLES Table 1 Instrumentation Accuracy . 3 Table 2 Test Operating and Test Condition Tolerances for Steady-state Test . 4 Table 3 Fixed Capacity Matched Refrigerator System, Condensing Unit Located Indoor 5 Table 4 Fixed Capa
7、city Matched Refrigerator System, Condensing Unit Located Outdoor . 5 Table 5 Two Capacity Matched Refrigerator System, Condensing Unit Located Outdoor . 6 Table 6 Variable Capacity Matched Refrigerator System, Condensing Unit Located Outdoor . 8 Table 7 Fixed Capacity Matched Freezer System, Conden
8、sing Unit Located Indoor 10 Table 8 Fixed Capacity Matched Freezer System, Condensing Unit Located Outdoor . 10 Table 9 Two Capacity Matched Freezer System, Condensing Unit Located Outdoor . 11 Table 10 Variable Capacity Matched Freezer System, Condensing Unit Located Outdoor . 14 Table 11 Fixed Cap
9、acity Refrigerator Condensing Unit, Condensing Unit Located Indoor 16 Table 12 Fixed Capacity Refrigerator Condensing Unit, Condensing Unit Located Outdoor 16 Table 13 Fixed Capacity Freezer Condensing Unit, Condensing Unit Located Indoor 17 Table 14 Fixed Capacity Freezer Condensing Unit, Condensin
10、g Unit Located Outdoor 17 ii TABLES (continued) PAGE Table 15 Refrigerator Unit Cooler . 18 Table 16 Freezer Unit Cooler . 18 Table 17 EER for Remote Commercial Refrigerated Display Merchandisers and Storage Cabinets 31 Table 18 Unit Cooler Nominal Values for Condensing Unit Energy Calculations 34 F
11、IGURES Figure 1 Schematic of the Operation for Units with Single Capacity Compressor . 21 Figure 2 Schematic of the Various Modes of Operation for Units with Two Capacity or Two-Stage Compressors 23 Figure 3 Schematic of the Various Modes of Operation for units with Variable Speed Compressors 26 APP
12、ENDICES Appendix A. References Normative 46 Appendix B. References Informative 48 Appendix C. Methods of Testing Walk-in Cooler and Freezer Systems Normative . 49 Appendix D. Weather Data in Region IV Normative 62 TABLES FOR APPENDICES Table C1 Test Readings 51 Table C2 Data to be Recorded 53 Table
13、C3 Unit Cooler Nominal Values for Condensing Unit Energy Calculations 61 Table D1 Bin Temperatures and Corresponding Bin Hours for AWEF Calculation 62 FIGURES FOR APPENDICES Figure C1 Method 1: DX-Dual Instrumentation 54 Figure C2 Method 2: DX- Calibrated Box 55 AHRI STANDARD 1251 (SI)-2014 1 PERFOR
14、MANCE RATING OF WALK IN COOLERS AND FREEZERS Section 1. Purpose 1.1 Purpose. The purpose of this standard is to establish, for walk-in coolers and freezers: definitions; test requirements; rating requirements; minimum data requirements for Published Ratings; operating requirements; marking and namep
15、late data and conformance conditions. 1.1.1 Intent. This standard is intended for the guidance of the industry, including manufacturers, designers, installers, contractors and users. 1.1.2 Review and Amendment. This standard is subject to review and amendment as technology advances. Section 2. Scope
16、 2.1 Scope. This standard applies to mechanical refrigeration equipment consisting of an integrated single package refrigeration unit, or separate Unit Cooler and condensing unit sections, where the condensing section can be located either outdoor or indoor. Controls may be integral, or can be provi
17、ded by a separate party as long as performance is tested and certified with the listed mechanical equipment accordingly. 2.2 Exclusions. This standard does not apply to: 2.2.1 Enclosures used for telecommunications switch gear or other equipment requiring cooling 2.2.2 Enclosures designed for medica
18、l, scientific or research purposes 2.2.3 Performance testing and efficiency characterization of large parallel rack refrigeration systems (condensing unit) Section 3. Definitions All terms in this document will follow the standard industry definitions in the ASHRAE Wikipedia website (https:/www.ashr
19、ae.org/resources-publications/free-resources/ashrae-terminology) unless otherwise defined in this section. 3.1 Annual Walk-in Energy Factor (AWEF). A ratio of the total heat, not including the heat generated by the operation of refrigeration systems, removed, in watt-hours, from a walk-in box during
20、 one year period of usage for refrigeration to the total energy input of refrigeration systems, in watt-hours, during the same period. 3.2 Coefficient of Performance (COP). A ratio of the Net Refrigeration Capacity in W to the power input values in W at any given set of Rating Conditions expressed i
21、n W/W. 3.3 Forced-circulation Free-Delivery Unit Coolers (Unit Coolers). A factory-made assembly, including means for forced air circulation and elements by which heat is transferred from air to refrigerant without any element external to the cooler imposing air resistance. These may also be referre
22、d to as Air Coolers, Cooling Units, Air Units or Evaporators. 3.4 Gross Refrigeration Capacity. The heat absorbed by the refrigerant, W. This is the sum of the Net Refrigeration Capacity and the heat equivalent of the energy required to operate the Unit Cooler. This includes both sensible and latent
23、 cooling. 3.5 Load Factor. A ratio of the Total Walk-in System Heat Load to the steady-state net refrigeration capacity. 3.6 Load Period. A twenty-four hour day. 3.6.1 High Load Period. The period of the day corresponding to frequent door openings, product loading events, and other design Load Facto
24、rs. For the purposes of this standard, this period shall be 8 continuous hours. AHRI STANDARD 1251 (SI)-2014 2 3.6.2 Low Load Period. The period of the day other than the High Load Period. For the purposes of this standard, this period shall be the remaining 16 continuous hours of the total Load Per
25、iod. 3.7 Net Refrigeration Capacity. The refrigeration capacity available for space and product cooling, W. It is equal to the Gross Refrigeration Capacity less the heat equivalent of energy required to operate the Unit Cooler (e.g.: evaporator fans, defrost) 3.8 Positive Displacement Condensing Uni
26、t. A specific combination of refrigeration system components for a given refrigerant, consisting of one or more electric motor driven positive displacement compressors, condensers, and accessories as provided by the manufacturer. 3.9 Published Rating. A statement of the assigned values of those perf
27、ormance characteristics, under stated rating conditions, by which a unit may be chosen to fit its application. These values apply to all units of like nominal size and type (identification) produced by the same manufacturer. The term Published Rating includes the rating of all performance characteri
28、stics shown on the unit or published in specifications, advertising or other literature controlled by the manufacturer, at stated Rating Conditions. 3.9.1 Application Rating. A rating based on tests performed at application Rating Conditions, (other than Standard Rating Conditions). 3.9.2 Standard R
29、ating. A rating based on tests performed at Standard Rating Conditions. 3.10 Rated Fan Power. 3.10.1 For single phase motors, total fan motor input power, W. 3.10.2 For polyphase motors, individual fan motor output power, W. 3.11 Rating Conditions. Any set of operating conditions under which a singl
30、e level of performance results and which 1causes only that level of performance to occur. 3.11.1 Standard Ratings Conditions. Rating conditions used as the basis of comparison for performance character-istics. 3.12 Refrigeration Capacity. The capacity associated with the increase in total enthalpy b
31、etween the liquid refrigerant entering the expansion valve and superheated return gas multiplied by the mass flow rate of the refrigerant. 3.13 “Shall“ or “Should“. “Shall” or “should” shall be interpreted as follows: 3.13.1 Shall. Where “shall“ or “shall not“ is used for a provision specified, that
32、 provision is mandatory if compliance with the standard is claimed. 3.13.2 Should. “Should,“ is used to indicate provisions which are not mandatory, but which are desirable as good practice. 3.14 Refrigerant Saturation Temperature. Refrigerant temperature at the Unit Cooler inlet or outlet determine
33、d either by measuring the temperature at the outlet of the two-phase refrigerant flow, for a Liquid Overfeed Unit Cooler, or by measuring refrigerant pressure and determining the corresponding temperature from reference thermodynamic tables or equations for the refrigerant, C. For zeotropic refriger
34、ants, the corresponding temperature to a measured pressure is the refrigerant Dew Point. 3.15 Steady-state. An operating state of a system, including its surroundings, in which the extent of change with time is within the required limits within this standard. 3.16 Test Measurement. The reading of a
35、specific test instrument at a specific point in time. The Test Measurement may be averaged with other measurements of the same parameter at the same time to determine a Test Reading or averaged over the duration of the test to determine the value for the Test Run. Refer to Table C1 for Test Reading
36、minimum time rate, number of Test Readings and minimum test duration. AHRI STANDARD 1251 (SI)-2014 3 3.17 Test Reading. The recording of one full set of the Test Measurements required to assess the performance of the test unit. 3.18 Total Walk-in System Heat Load. Total heat load to the walk-in syst
37、em including Walk-in Box Load and the heat load to the box contributed by the operation of the refrigeration system. 3.18.1 Walk-in System High Load (). Total Walk-in System Heat Load during a High Load Period. 3.18.1 Walk-in System Low Load (). Total Walk-in System Heat Load during a Low Load Perio
38、d. 3.19 Volatile Refrigerant. A refrigerant which changes from liquid to vapor in the process of absorbing heat. 3.20 Walk-in Box Load. Heat load to the walk-in box resulting from conduction, infiltration and internal heat gains from equipment that is not related to the refrigeration system, such as
39、 lights and anti-sweat heaters, etc. 3.20.1 High Box Load (). Walk-in Box Load during a High Load Period. 3.20.2 Low Box Load (). Walk-in Box Load during a Low Load Period. Section 4. Test Requirements 4.1 Instruments. All measuring instruments shall be selected to meet or exceed the accuracy criter
40、ia listed in Table 1 for each type of measurement. All temperature measurement shall be made in accordance with Table 2, Test Tolerance. Precision instruments and automated electronic data acquisition equipment shall be used to measure and record temperature, pressure and refrigerant flow rate test
41、parameters. All measuring instruments and instrument systems (e.g. data acquisition coupled to temperature, pressure, or flow sensors) shall be calibrated by comparison to primary or secondary standards with calibrations traceable to National Institute of Standards and Technology (NIST) measurements
42、, other recognized national laboratories, or derived from accepted values of natural physical constants. All test instruments shall be calibrated annually, whenever damaged, or when the accuracy is called into question. Table 1. Instrumentation Accuracy Measurement Medium Minimum Accuracy Temperatur
43、e, C Air dry-bulb 0.3 Air wet-bulb Refrigerant liquid Refrigerant vapor 0.3 0.3 0.6 Air Dew Point Others, C Relative humidity1Air 3 % points rh Pressure Refrigerant Pressure corresponding to 0.1 C of saturation temperature Air 169 Pa Flow Refrigerant 1 % of reading Liquids 1 % of reading Electrical
44、Motor kilowatts/amperes/voltage 1 % of reading Auxiliary kilowatt input (e.g. heater) AHRI STANDARD 1251 (SI)-2014 4 Table 1. Instrumentation Accuracy (cont.) Measurement Medium Minimum Accuracy Speed Motor / fan shaft 1 % of reading Weight Oil / refrigerant solution 0.5 % of reading Specific Gravit
45、y Brine 1 % of reading Time Hours / minutes / seconds 0.5 % of time interval Note: 1. Relative humidity and air dew point measurements are intended to confirm the dry coil condition. Table 2. Test Operating and Test Condition Tolerances for Steady-state Test Test Operating Tolerance1Test Condition T
46、olerance2Indoor dry-bulb, C Entering temperature Indoor wet-bulb, C Entering temperature Outdoor dry-bulb, C Entering temperature Outdoor wet-bulb, C Entering temperature Electrical voltage, % of reading. . Electric voltage % of reading 2.0 2.0 2.0 2.0 2.0 0.6 0.3 0.3 0.6 0.6 Notes: 1. Test Operatin
47、g Tolerance is the maximum permissible range of any measurement. When expressed as a percentage, the maximum allowable variation is the specified percentage of the average value. 2. Test Condition Tolerance is the maximum permissible variation of the average value of the measurement from the specifi
48、ed test condition. 4.2 Method of Test. The test procedure for walk-in cooler and freezer systems that have matched Unit Coolers and condensing units, and the procedures of testing condensing units and Unit Coolers individually for are described in Appendix C of this standard. 4.3 Test Conditions. Wa
49、lk-in systems, condensing units and Unit Coolers shall be tested under the standard rating conditions defined in Section 5. AHRI STANDARD 1251 (SI)-2014 5 Section 5. Rating Requirements 5.1 Standard Ratings. Standard Ratings shall be established at the Standard Rating Conditions in the following listed tables and shall include its associated power input and Coefficient of Performance (COP). When tested with a specified motor, the associated compressor speed (external drive compressors only) shall also be inc
