1、 2011 Standard for Performance Rating of Remote Mechanical- Draft Evaporatively- Cooled Refrigerant Condensers AHRI Standard 491 (SI) Price $10.00 (M) $20.00 (NM) Copyright 2011, by Air-Conditioning, Heating, and Refrigeration Institute Printed in U.S.A. Registered United States Patent and Trademark
2、 Office IMPORTANT SAFETY 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,
3、constructed, assembled, 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 prac
4、tices. AHRI does not certify or guarantee that any tests conducted under its standards/guidelines will be non-hazardous or free from risk. Note: This standard supersedes ARI Standard 490-2003. For the I-P version, see AHRI Standard 490 (I-P) 2011 TABLE OF CONTENTS SECTION PAGE Section 1. Purpose .1
5、Section 2. Scope 1 Section 3. Definitions 1 Section 4. Test Requirements 2 Section 5. Rating Requirements 3 Section 6. Calculations 3 Section 7. Minimum Data Requirements for Published Ratings .5 Section 8. Marking and Nameplate Data .5 Section 9. Conformance Conditions 5 TABLE Table 1. Standard Rat
6、ing Conditions 3 APPENDICES Appendix A. References - Normative 6 Appendix B. References - Informative 6 AHRI STANDARD 491 (SI)-2011 1 PERFORMANCE RATING OF REMOTE MECHANICAL-DRAFT EVAPORATIVELY- COOLED REFRIGERANT CONDENSERS Section 1. Purpose 1.1 Purpose. The purpose of this standard is to establis
7、h for Remote Mechanical-Draft Evaporatively-Cooled Refrigerant Condensers (Evaporative Condensers): definitions; test requirements; rating requirements; calculations; minimum data requirements for Published Ratings; marking and nameplate data; and conformance conditions. 1.1.1 Intent. This standard
8、is intended for the guidance of the industry, including manufacturers, engineers, installers, contractors and users. 1.1.2 Review and Amendment. This standard is subject to review and amendment as technology advances. Section 2. Scope 2.1 Scope. This standard applies to Evaporative Condensers as def
9、ined in Section 3 of this standard and is limited to Halocarbon Refrigerants and ammonia (R-717), for use with or without external air resistance. 2.2 Exclusions. 2.2.1 This standard does not apply to Evaporative Condensers designed primarily for installation within the machinery compartment of a se
10、lf-contained product or on a factory-assembled condensing unit. 2.2.2 This standard does not apply to Remote Mechanical-Draft Air-Cooled Refrigerant Condensers as covered by AHRI Standard 460. Section 3. Definitions Definitions. All terms in this document will follow the standard industry definition
11、s in the current edition of ASHRAE Terminology of Heating, Ventilation, Air Conditioning and Refrigeration unless otherwise defined in this section. 3.1 Entering Air Wet-Bulb Temperature. The average wet-bulb temperature of the air entering the condenser assembly, C. 3.2 Halocarbon. A hydrocarbon de
12、rivative containing one or more of the halogens bromine, chlorine, or fluorine; hydrogen also may be present. 3.3 Net Refrigeration Effect. The rate of total heat absorption by the Refrigerant, at stated evaporator conditions, of the complete refrigeration system. This effect is equal to the product
13、 of the refrigerant mass flow rate through the system and the enthalpy difference between the refrigerant vapor leaving the evaporator and the refrigerant liquid entering the liquid control device of the evaporator, W. 3.4 Published Rating. A statement of assigned values of those performance charact
14、eristics, 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 characteristics shown on
15、the unit or published in specifications, advertising or other literature, including computer software and computer-generated reports, controlled by the manufacturer, at stated Rating Conditions. 3.4.1 Application Rating. A rating based on tests performed at application rating conditions (other than
16、Standard Rating Conditions). 3.4.2 Standard Rating. A rating based on tests performed at Standard Rating Conditions. AHRI STANDARD 491 (SI)-2011 2 3.5 Rating Conditions. Any set of operating conditions under which a single level of performance results, and which causes only that level of performance
17、 to occur. 3.5.1 Standard Rating Conditions. Rating Conditions used as the basis of comparison for performance characteristics. 3.6 Refrigerant. Fluid used for heat transfer in a refrigerating system which absorbs heat at a low temperature and low pressure of the fluid and transfers heat at a higher
18、 temperature and a higher pressure of the fluid, usually involving changes of state of the the fluid. 3.7 Remote Mechanical-Draft Evaporatively-Cooled Refrigerant Condenser (Evaporative Condenser). A factory-made encased unit for connection to a refrigerant piping system. The unit shall include mean
19、s for mechanical air circulation, water distribution and heat transfer surface by which heat is transferred from Refrigerant to water and air. The purpose of this unit is to condense refrigerant vapor by rejecting heat to water and air which are circulated over its heat transfer surface, thereby cau
20、sing evaporation of the water and an increase in the enthalpy of the air. 3.8 Saturated Condensing Temperature (Condensing Temperature). For single component and Azeotrope Refrigerants, the saturation temperature corresponding to the refrigerant pressure at the condenser entrance. For Zeotropic Refr
21、igerants, the arithmetic average of the Dew Point and Bubble Point corresponding to the Refrigerant pressure at the condenser entrance, C. 3.8.1 Azeotropic Refrigerant. Blend of two or more component Refrigerants whose equilibrium vapor-phase and liquid-phase compositions are the same at a given pre
22、ssure. 3.8.2 Bubble Point. The Refrigerant temperature at which bubbles begin to appear in a saturated liquid. 3.8.3 Dew Point. The Refrigerant temperature at which moisture begins to form. 3.8.4 Zeotropic Refrigerant. Blend of two or more component Refrigerants whose equilibrium vapor-phase and liq
23、uid-phase compositions are different at a given temperature. 3.9 Shall or Should. Shall or Should shall be interpreted as follows: 3.9.1 Shall. Where shall or shall not is used for a provision specified, that provision is mandatory if compliance with the standard is claimed. 3.9.2 Should. Should is
24、used to indicate provisions which are not mandatory but which are desirable as good practice. 3.10 Total Heat Rejection Effect (Capacity). The rate of total heat removal from the Refrigerant. This effect is equal to the product of the mass flow rate and enthalpy difference between the refrigerant va
25、por entering the condenser and the refrigerant liquid leaving the condenser, W. (The Total Heat Rejection Effect, for all practical purposes, is equal to the Net Refrigeration Effect in the evaporator of the system plus the heat added to the Refrigerant by the refrigerant compressor.) 3.10.1 Adjuste
26、d Total Heat Rejection Effect. The Total Heat Rejection Effect at application rating conditions corrected to Standard Rating Conditions, W. Section 4. Test Requirements 4.1 Test Requirements. Evaporative Condensers shall be tested in accordance with ANSI/ASHRAE Standard 64 except that barometric pre
27、ssure shall be measured. The test-measured capacity shall be adjusted per Section 6 of this standard to determine the Adjusted Total Heat Rejection Effect at Standard Rating Conditions. 4.2 Test Conditions. Actual test conditions shall not deviate from Standard Rating Conditions by more than: Barome
28、tric pressure 10 kPa AHRI STANDARD 491 (SI)-2011 3 Entering air wet-bulb temperature 0.5C Condensing Temperature 0.5C Actual temperature of Refrigerant vapor entering condenser 3C Makeup water entering the condenser (when operational) shall be within 3C of the measured spray water temperature. The f
29、an and pump motor shaft output power, kW shall be within 10% of the Published Ratings. Section 5. Rating Requirements 5.1 Standard Ratings. Standard Ratings for Evaporative Condensers shall be determined at the Standard Rating Conditions specified in Table 1. Table 1. Standard Rating Conditions Halo
30、carbon Refrigerants Ammonia (R-717) Barometric Pressure, kPa 101.0 101.0 Entering Air Wet-Bulb Temperature, C 24 24 Condensing Temperature, C 40 36 Actual Temperature of Refrigerant Vapor Entering Condenser, C 60 60 External Static Pressure, kPa 0 0 5.1.2 Standard Unit Configuration. Standard Rating
31、s shall be based on the standard unit configuration as supplied by the manufacturer with all guards, safety screens and other appurtenances in place. 5.2 Application Ratings. Application Ratings are used to select an Evaporative Condenser for a specific operating condition within the operating range
32、 for which it is intended and shall include the Total Heat Rejection Effect in the same terms as the Standard Rating in Section 5.1. 5.3 Tolerances. To comply with this standard, any representative production unit selected at random shall have an Adjusted Total Heat Rejection Effect at Standard Rati
33、ng Conditions, qsrc, not less than 95% of the published Standard Rating. 5.4 Optional Accessories. The effect on performance of optional accessories available from the manufacturer should clearly be stated in the manufacturers Published Ratings. Section 6. Calculations 6.1 Adjustments. The Total Hea
34、t Rejection Effect at test conditions, qc, shall be adjusted to determine the Adjusted Total Heat Rejection Effect at Standard Rating Conditions, qsrc. 6.1.1 Adjusted Total Heat Rejection Effect at Standard Rating Conditions. For each test, a Total Heat Rejection Effect at Standard Rating Conditions
35、, qsrc, shall be calculated as follows: AHRI STANDARD 491 (SI)-2011 4 qSRC= qcCFbpCFtcCFtfp1 Where: CFbp = Barometric pressure correction factor CFtc = Temperature condition correction factor CFtfp = Total fan power correction factor qc = Total Heat Rejection Effect at test conditions, W qsrc = Adju
36、sted Total Heat Rejection Effect at Standard Rating Conditions, W 6.1.2 Barometric Pressure Correction Factor. The barometric pressure correction factor shall be calculated as follows: )(111 cstdbpBPBPKCF+= 2 Where: BPc = Barometric pressure at test conditions, kPa stdBP = 101.0, kPa 1K = 0.0023, 1/
37、kPa 6.1.3 Temperature Condition Correction Factor. The temperature correction factor shall be based on the manufacturers published Application 6.1.4 Ratings shall be calculated as follows: papppsrctcqqCF = 3 Where: qpsrc = Published Total Heat Rejection Effect at Standard Rating Conditions, W qpapp
38、= Published Total Heat Rejection Effect at Application Rating Conditions, W 6.1.5 Fan Power Correction Factor. The fan power correction factor shall be based on the manufacturers published fan power exponent for capacity adjustment and shall be calculated as follows: xcsrctfpTFPTFPCF= 4 Where: TFPsr
39、c = Total fan motor shaft output power at Standard Rating Conditions, W TFPc= Total fan motor shaft output power at test conditions, W x = Manufacturers fan power exponent for Adjusted Total Heat Rejection Effect AHRI STANDARD 491 (SI)-2011 5 Section 7. Minimum Data Requirements for Published Rating
40、s 7.1 Minimum Data Requirements for Published Ratings. As a minimum, Published Ratings shall include all Standard Ratings. All claims to ratings within the scope of this standard shall include the statement “Rated in accordance with AHRI Standard 491 (SI).” All claims to ratings outside the scope of
41、 this standard shall include the statement “Outside the scope of AHRI Standard 491 (SI).” Wherever Application Ratings are published or printed, they shall include a statement of the conditions at which the ratings apply. 7.2 Each Published Rating of Evaporative Condensers shall include the followin
42、g information: 7.2.1 Refrigerant designation(s) in accordance with ANSI/ASHRAE Standard 34 with Addenda 7.2.2 Total Heat Rejection Effect, W 7.2.3 Fan motor shaft output power, W at 0 kPa external pressure 7.2.4 Condenser air flow rate, m3/s 7.2.5 Pump motor shaft output power, kW 7.2.6 Condenser re
43、circulating water flow rate, L/s 7.2.7 Equipment dimensions, mm/m 7.2.8 Connection quantity and size, mm Section 8. Marking and Nameplate Data As a minimum, the nameplate shall display the manufacturers name, model designation and serial number. Nameplate voltages for 60 Hertz systems shall include
44、one or more of the equipment nameplate voltage ratings shown in Table 1 of AHRI Standard 110. Nameplate voltages for 50 Hertz systems shall include one or more of the utilization voltages shown in Table 1 of IEC Standard 60038. Section 9. Conformance Conditions While conformance with this standard i
45、s voluntary, conformance shall not be claimed or implied for products or equipment within the standards Purpose (Section 1) and Scope (Section 2) unless such product claims meet all of the requirements of the standard and all of the testing and rating requirements are measured and reported in comple
46、te compliance with the standard. Any product that has not met all the requirements of the standard shall not reference, state, or acknowledge the standard in any written, oral, or electronic communication. AHRI STANDARD 491 (SI)-2011 6 APPENDIX A. REFERENCES NORMATIVE A1 Listed here are all standard
47、s, handbooks and other publications essential to the formation and implementation of the standard. All references in this appendix are considered as part of the standard. A1.1 AHRI Standard 110-2002 , Air-Conditioning and Refrigeration Equipment Nameplate Voltages, 2002, Air Conditioning, Heating, a
48、nd Refrigeration Institute, 2111 Wilson Boulevard, Suite 500, Arlington, VA 22201, USA. A1.2 ANSI/AHRI 460-2005, Performance Rating of Remote Mechanical-Draft Air-Cooled Refrigerant Condensers, 2005, Air Conditioning, Heating, and Refrigeration Institute, 2111 Wilson Boulevard, Suite 500, Arlington,
49、 VA 22201, USA. A1.3 ANSI/ASHRAE Standard 34-2010 with Addenda, Designation and Safety Classification of Refrigerants, 2010, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 1791 Tullie Circle, N.E., Atlanta, GA 30329-5478, USA. A1.4 ANSI/ASHRAE Standard 64-2011, Methods of Testing Remote Mechanical-Draft Evaporative Refrigerant Condensers, 2011, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 1
