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ASHRAE Standard 25-2018 - Methods of Testing Forced-Circulation Free-Delivery Unit Coolers for Refrigeration (ANSI Approved), 2018
- ANSI/ASHRAE Standard 25-2018 [Go to Page]
- CONTENTS
- 1. PURPOSE
- 2. SCOPE
- 3. DEFINITIONS AND SYMBOLS [Go to Page]
- 3.1 Definitions
- 3.2 Symbols
- 3.3 Subscripts
- 4. TEST REQUIREMENTS [Go to Page]
- 4.1 Appurtenances. Unit coolers shall be factory made and furnished with all appurtenances that affect thermal performance and energy consumption.
- Table 1 Instrumentation Accuracy
- 4.2 Refrigerant. The refrigerant used during the test shall be recorded on the test report.
- 4.3 Instrumentation. Instruments shall comply with the accuracy requirements in Table 1.
- Table 2 Test Condition Tolerances
- 4.4 Calibration. Measurements from the instruments shall be traceable to primary or secondary standards calibrated by National Institute of Standards and Technology (NIST) or to the Bureau International des Poids et Mesures (BIPM) if a National Metro...
- 4.5 Test Chamber Dimensions. The unit cooler shall be installed in a room of sufficient size to avoid airflow restrictions or recirculation such that the following apply:
- 4.6 Test Condition Tolerances. Test acceptance criteria listed in Tables 2, 3, and 4 apply to all methods of test.
- 5. TEST INFORMATION [Go to Page]
- 5.1 Measurement Intervals. Measurement intervals shall be in accordance with Table 4.
- 5.2 Test Data. The following data shall be recorded, where applicable, for each unit tested, including the units of measurement used.
- Table 3 Refrigerant Temperature Tolerances
- Table 4 Required Test Measurement Intervals
- 6. METHODS OF TESTING [Go to Page]
- 6.1 DX Dual Instrumentation (Method 1)
- 6.2 DX Calibrated Box Test Procedure (Method 2)
- Figure 1 Illustrative Method 1 setup.
- Figure 2 Illustrative Method 2 setup.
- Figure 3 Illustrative Method 3 setup.
- 6.3 Liquid Overfeed Test Procedure (Method 3)
- 7. CALCULATIONS [Go to Page]
- 7.1 To calculate average measured power (all methods), use Equation 7-1:
- 7.2 Average Measured Temperatures
- 7.3 Average Measured Pressures
- 7.4 Average Air Density. Determine the test air density rtest (lbm/ft3[kg/m3]) using dry-bulb temperature Tdb (°F [°C]), barometric pressure Pb (in. Hg [kPa]), and wet-bulb temperature Twb (°F [°C]) by referencing the ASHRAE Psychrometric Analysi...
- 7.5 Calculated Saturation Temperatures. Thermophysical properties are to be determined from the current version of NIST Reference Fluid Thermodynamic and Transport Properties Database (REFPROP) 1 or from a reference that provides compliant properties...
- 7.6 Liquid subcooling entering expansion valve (all methods), use Equation 7-12.
- 7.7 Vapor superheat leaving unit cooler (Methods 1, 2), use Equation 7-13.
- 7.8 Enthalpies
- 7.9 Temperature Difference Calculation
- 7.10 To calculate Enthalpy Difference of air (Methods 1, 3), use Equation 7-16.
- 8. NORMATIVE REFERENCES
- 9. INFORMATIVE REFERENCES
- NORMATIVE APPENDIX A: CALCULATION OF MEAN EVAPORATION TEMPERATURE [Go to Page]
- A1. Methods 1 and 2—Direct Expansion
- A2. Method 3—Liquid Overfeed Operation [Go to Page]
- Table A-1 Symbols
- Table A-2 Saturation Pressure for Tables 2 and 3 (I-P)
- Table A-3 Saturation Pressure for Tables 2 and 3 (SI)
- Table A-4 Offsets (t01 – ), Methods 1 and 2 (Direct Expansion) (I-P)
- Table A-5 Offsets (t01 – ), Methods 1 and 2 (Direct Expansion) (SI)
- Table A-6 Offsets (t0,m – ), Method 3 (Liquid Overfeed, Recirculation Ratio = 1) (I–P)
- Table A-7 Offsets (t0,m – ), Method 3 (Liquid Overfeed, Recirculation Ratio = 2) (I–P)
- Table A-8 Offsets (t0,m – ), Method 3 (Liquid Overfeed, Recirculation Ratio = 5) (I–P)
- Table A-9 Offsets (t0,m – ), Method 3 (Liquid Overfeed, Recirculation Ratio = 10) (I–P)
- Table A-10 Offsets (t0,m – ), Method 3 (Liquid Overfeed, Recirculation Ratio = 1) (SI)
- Table A-11 Offsets (t0,m – ), Method 3 (Liquid Overfeed, Recirculation Ratio = 2) (SI)
- Table A-12 Offsets (t0,m – ), Method 3 (Liquid Overfeed, Recirculation Ratio = 5) (SI)
- Table A-13 Offsets (t0,m – ), Method 3 (Liquid Overfeed, Recirculation Ratio = 10) (SI)
- Figure A-1 Direct-expansion cycle.
- Figure A-2 Liquid overfeed process.
- INFORMATIVE APPENDIX B: CAPACITY EQUATIONS [Go to Page]
- B1. Capacity Calculations for each method [Go to Page]
- B1.1 Temperature Correction Factor
- B1.2 Air Enthalpy Correction Factor
- B1.3 Gross Total Cooling Effect (Method 1)
- B1.4 Gross Total Cooling Effect—Dry Condition only (Method 2)
- B1.5 Gross Total Cooling Effect Calculation (Method 3)
- Table B-1 Symbols
- ONLINE SUPPORTING FILES [Go to Page]
