Validation of Extrapolation of Test Performance for Air-to-Air Rotary Energy Exchangers (ASHRAE RP-1799)

Abstract

Air-to-air energy exchangers are used in buildings to transfer energy between the exhaust air and the incoming outdoor air. Typically, the performance of air-to-air energy exchangers is tested, rated and certified according to industry-accepted standards and procedures. Because of the expenses and facility constraints associated with laboratory testing, performance rating tests of air-to-air energy exchangers are usually performed at a limited number of test conditions for selected products. This paper uses laboratory tests to validate the extrapolation approaches available from the literature. Two sets of air-to-air energy wheels from different manufacturers were tested at the energy recovery testing facility of Intertek. Each set included three wheels of different sizes (i.e., small, medium, and large). The analysis of test results showed an overlap in performance ratings between different wheel sizes after accounting for allowable allowances, which in turn supported the extrapolation approach used by the Air-Conditioning, Heating, and Refrigeration Institute for performance rating. By comparing the test results with the results from the selected effective correlations, it was found that axial heat conduction should be considered when applying the numerical heat and mass transfer models for energy wheels.