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ASHRAE Standard 84-2024 -- Method of Testing Air-to-Air Heat/Energy Exchangers (ANSI Approved), 2024
- ASHRAE Online Bookstore
- Addenda
- Errata
- ANSI/ASHRAE Standard 84-2024 [Go to Page]
- Contents
- Foreword
- 1. Purpose
- 2. Scope [Go to Page]
- 2.1 This standard prescribes the laboratory methods for testing the performance of air-to-air heat and energy exchangers. In this standard, an air-to-air heat/energy exchanger is a device to transfer heat, or heat and water vapor, from one airstream ...
- 3. Definitions
- 4. Requirements for Performance Testing [Go to Page]
- 4.1 Performance Determinations. The performance of an air-to-air heat/energy exchanger is primarily characterized by the following set of metrics: (a) effectiveness and net effectiveness, (b) recovery efficiency ratio and net recovery efficiency rati...
- 4.2 Pretest Uncertainty Analysis. A pretest uncertainty analysis, defined in ASME PTC 19.1 1, shall be performed prior to any testing on all the parameters outlined in Section 4.2. Test points, procedures, and equipment shall be analyzed to confirm t...
- 4.3 Apparatus. The test apparatus shall consist of four measurement stations. Three measurements shall be taken at each measurement station as follows:
- 4.4 Instrument Calibration. All measurement instruments shall be calibrated using sensors, transfer standards, and primary instruments that are traceable to NIST standards. Instrument uncertainty levels shall be shown by the pretest uncertainty analy...
- 5. Test Parameters [Go to Page]
- 5.1 Thermal Performance. Performance tests are subject to the following provisions.
- 5.2 Leakage
- 5.3 Pressure Drop. Air friction pressure drop across the heat/energy exchanger from Stations 1 to 2 and Stations 3 to 4 shall be determined at the tested airflows.
- 6. Operating Conditions, Inequality Checks, and Conditions for Rejection of Test Data [Go to Page]
- 6.1 The inlet air property variations during thermal performance testing shall satisfy the following inequalities:
- 6.2 During thermal performance testing, the dry airflow mass measured flow rates shall satisfy the following inequality equation:
- 6.3 For all thermal performance tests where no condensate or frosting occurs, the dry airflow mass measured flow rates and the water vapor mass measured flow rates shall satisfy the following inequality equations:
- 6.4 For the case of thermal performance tests of sensible-only devices where no phase change, condensate, or frosting occurs, the measured sensible energy flow rates shall satisfy the inequality of Equation 23 rather than that of Equation 22:
- 6.5 During testing to determine OACF and EATR, the readings shall satisfy the airflow mass inequality:
- 7. Pre- and Post-Test Uncertainty Analysis
- 8. Instruments and Methods of Measurement [Go to Page]
- 8.1 Systematic and Random Uncertainty. The systematic uncertainty and random uncertainty for each measurement shall be such that the total uncertainty for the heat/energy exchanger effectiveness satisfy the limits in Section 7. When testing fixed-bed...
- 8.2 Instrumentation. Instrument specification and application shall be in accordance with ANSI/ASHRAE Standards 41.1 3, 41.2 4, 41.3 5, and 41.6 6, respectively, unless otherwise specified in this document.
- 8.3 Temperature
- 8.4 Humidity
- 8.5 Pressure
- 8.6 Static Pressure
- 8.7 Barometric Pressure
- 8.8 Airflow Measurement. Any flow measurement method (pressure differential device) used shall not exceed the uncertainty introduced by an appropriate flow nozzle or velocity sensor traverse method, as described by ASHRAE Standard 41.2 4.
- 8.9 Tracer Gas Measurement. To measure air transfer from the exhaust to the supply side of an exchanger, an inert tracer gas is injected into a turbulent region of the exhaust inlet. Air samples are then drawn from each of Stations 1 to 4. The sampli...
- 8.10 Fixed-Bed Regenerator Performance Testing
- 8.11 Adjustable Purge Setting. When a rotary regenerator with adjustable purge section is tested, purge angle or area setting shall be recorded for all tests.
- 9. Calculations [Go to Page]
- 9.1 Airflow Rate. The airflow rate calculations shall be based on the measurements obtained in Section 8.8.
- 9.2 Total Enthalpy. The total enthalpy shall be calculated from the following equations:
- 9.3 The Standardized Air Friction Pressure Drop
- 9.4 Outdoor Air Correction Factor
- 9.5 Exhaust Air Transfer
- 10. Reporting Results [Go to Page]
- 10.1 Reporting Requirements. Test results shall not be reported as meeting the requirements of this standard unless
- 10.2 Results of Test. Test results shall be reported at no less than two selected mass flow rates and no less than two ratios of mass flow rates for the following:
- 10.3 Test Conditions. Reports of performance test results of air-to-air exchangers in a laboratory shall include the following data:
- 10.4 Uncertainties of Results. The uncertainties of each result in Section 10.2 shall be reported. Uncertainties shall be reported for all performance factors at the 95% data coverage level as described in ASME PTC 19.1 1.
- 11. Nomenclature [Go to Page]
- 11.1 Symbols (SI [I-P])
- 11.2 Subscripts
- 12. Normative References
- Informative Appendix A: Laboratory Test Configurations
- Informative Appendix B: Transient Testing of Energy Exchangers Using a Bag Sampling Method [Go to Page]
- B1. Bag Sampling Method
- B2. Transient Testing of Energy Exchangers
- Informative Appendix C: An Explanation for the Use of Effectivenesses to Characterize Air-to-Air Heat/Energy Exchangers [Go to Page]
- C1. Development of Effectiveness Definitions
- C2. Research Findings
- C3. Exhaust Air Transfer Ratio and Outdoor Air Correction Factor
- C4. Recovery Efficiency Ratio
- Informative Appendix D: Selection of Test Conditions [Go to Page]
- D1. Testing Conditions
- D2. Selection of Operating Conditions [Go to Page]
- D2.1 The Graphical Selection Method. The psychrometric chart in Figure D-1 allows a pretest estimation of the uncertainty levels associated with any combination of supply condition with an exhaust condition of 24°C and 50% rh. Figure D-2 presents si...
- D2.2 The Calculation Method. It is convenient to define an operating condition uncertainty (U*[ei(OC)]) using only the denominator from the definition of the effectiveness:
- Informative Appendix E: Field Testing [Go to Page]
- E1. Mass Flow Measurement
- E2. Temperature and Humidity Determinations
- E3. Quasi-Steady Field Test Criteria
- E4. Rejection of Test Data
- Informative Appendix F: Extrapolation of Test Performance Data
- Informative Appendix G: Informative References and Bibliography [Go to Page]
- G1. Informative References
- G2. Bibliography [Go to Page]
