Theoretical and Experimental Methods for the Sensible Effectiveness of Air-to-Air Energy Recovery Wheels

Abstract

This paper compares a new theoretical method with three other methods to determine the sensible effectiveness of energy wheels. The methods in this study include a new theoretical transient response prediction method, the standard steady state test method, a simulation or correlation method, and a transient response test method. The fully developed flow theoretical model includes sensible effectiveness corrections for effects due to entrance, axial heat conduction, carryover due to wheel rotation, phase change of water vapor, and flow channel variations due to manufacturing tolerances. All of these effectiveness correction factors are presented as dimensionless ratios that will be convenient to use for designers of energy wheels and HVAC systems. Comparison of the four methods shows agreement for typical summer and winter operating conditions. It is concluded that the new transient theoretical correction method gives a sensible effectiveness that is as least as accurate as the test methods. Only the transient theoretical model and simulations correctly predict the effects of controlled wheel speeds.