ASHRAE Standard 84 2013

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ANSI/ASHRAE Standard 84-2013 Method of Testing Air-to-Air Heat/Energy Exchangers

Published By	Publication Date	Number of Pages
ASHRAE	2013	28

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Description

This standard provides rules for the testing of air-to-air heat/energy exchangers in both the laboratory and in the field. The purpose of this standard is to establish a uniform method of test for obtaining performance data for air-to-air heat/energy exchangers; to specify the test conditions, data required, uncertainty analysis to be performed, calculations to be used, and reporting procedures for testing the performance of an air-to-air heat/energy exchanger; and to specify the types of test equipment for performing such tests. The types of air-to-air heat/energy exchangers covered by this standard are regenerative energy exchangers (including heat wheels and total energy wheels), heat pipe exchangers, thermosiphon exchangers, recovery loop exchangers (also called run-around exchangers), and fixed-plate exchangers. The scope of this standard also includes both laboratory and field tests, provided that appropriate levels of uncertainty can be achieved when testing.

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PDF Pages	PDF Title
4	FOREWORD 1. PURPOSE 2. scope 2.1 This standard prescribes the methods for testing the performance of air-to-air heat/energy exchangers. 2.2 In this standard, an air-to-air heat/energy exchanger is a device to transfer heat and/or water vapor from one airstream to another. The types of air-to-air heat/energy exchangers covered by this standard are 2.3 The scope of this standard also includes both laboratory and field tests, provided that appropriate levels of uncertainty can be achieved when testing. 2.4 A test is deemed to be within the scope of this standard if both a pretest uncertainty analysis and a posttest uncertainty analysis yield satisfactory uncertainty limits. 3. definitions
5	4. Guidelines for performance testing 4.1 General.The performance of air-to-air heat/energy exchangers depends upon many factors but especially upon operating conditions. It must be understood that changes in operating conditions will affect the apparent heat/energy exchanger performance. 4.2 Performance Determinations. The performance of an air-to-air heat/energy exchanger is primarily determined by (a) its effectiveness and recovery efficiency ratio, (b) its pressure drop and mass flow characteristics, (c) the outside air correction…
7	4.3 Pretest Uncertainty Analysis. A pretest uncertainty analysis, defined in ANSI/ASME Standard PTC 30,2 shall be performed prior to any testing on all the parameters outlined in Section 4.2. Test points, procedures, and equipment should be analyzed … 4.4 Apparatus. The test apparatus shall consist of four measurement stations. Three measurements shall be taken at each measurement station as follows: 4.5 Instrument Calibration. All measurement instruments shall be calibrated using sensors, transfer standards, and primary instruments that are traceable to NIST standards. Uncertainty levels shall be acceptable by the pretest uncertainty analysis. C… 5. Test parameters 5.1 Laboratory Test Configurations. Laboratory test facilities can be of two types: closed-loop systems or open- loop systems. 5.2 Thermal Performance. Performance tests are subject to the following provisions.
9	5.3 Leakage (plus Purge Flow when Applicable) 5.4 Pressure Drop 6. OPERATING CONDITIONS, inequality Checks, and conditions for Rejection of Test Data 6.1 Laboratory Testing. During thermal performance testing, when a set of property data is measured and stored, the inlet air property variations shall satisfy the following inequalities.
10	6.2 Field Testing. For field testing, which is presented in Informative Appendix D, the upper limits on inequalities of Equations 7 to 18 shall be increased by a factor of 2.0. 7. Posttest Uncertainty Analysis 7.1 Laboratory Testing. For testing of effectiveness, pretest and posttest uncertainties shall satisfy the following equations:
11	7.2 Field Testing. For field testing, which is presented in Informative Appendix D, the uncertainty limits in inequalities in Equations 19 through 21 and 24 through 28 shall be increased by a factor of 1.5. 8. iNSTRUMENTS AND METHODS OF MEASUREMENT 8.1 Bias and Precision Uncertainty. The bias and precision limits for each measurement shall be such that the total uncertainty for the heat/energy exchanger effectiveness satisfy the limits in Section 7. 8.2 Instrumentation. Temperature and humidity measurement instruments, unless otherwise specified below, shall be in accordance with ANSI/ASHRAE Standard 41.13 and ANSI/ASHRAE Standard 41.6,4 respectively. 8.3 Airflow Measurement 8.4 Tracer Gas Measurement
12	9. Calculations 9.1 Airflow Rate 9.2 Effectiveness 9.3 Total Enthalpy. The total enthalpy shall be calculated from the following equations: 9.4 The Air Friction Pressure Drop
13	9.5 Exhaust Air Transfer 9.6 Outside Air Correction Factor. OACF characterizes mechanical air transfer from the entering supply airstream to the leaving exhaust airstream. OACF is used to determine the entering supply airflow required to provide the gross leaving supply airf… 10. reporting results 10.1 Laboratory Testing 10.2 Field Testing 11. Nomenclature 11.1 Symbols
14	11.2 Subscripts 12. references INFORMATIVE APPENDIX A— ALTERNATE EFFECTIVENESS EXPRESSION INFORMATIVE APPENDIX B— AN EXPLANATION FOR THE USE OF EFFECTIVENESSES TO CHARACTERIZE AIR-TO-AIR HEAT/ENERGY EXCHANGERS
15	B1. Development of Effectiveness Definitions
17	B2. Research Findings
18	B3. EATR and OACF B4. RER
19	INFORMATIVE APPENDIX C— SELECTION OF Test CONDITIONS C1. Testing Conditions C2. Selection of Operating Conditions C2.1 The Graphical Selection Method. The psychrometric chart in Figure C1 allows a pretest estimation of the uncertainty levels associated with any combination of supply condition with an exhaust condition of 24°C and 50% relative humidity. Figure C… C2.2 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 D— Field Testing D1. Mass Flow Measurement
22	D2. Temperature and Humidity Determinations
23	D3. Quasi-Steady Field Test Criteria D4. Rejection of Test Data
24	INFORMATIVE APPENDIX E— Extrapolation of test performance data INFORMATIVE APPENDIX F— BIBLIOGRAPHY