Measurement of Pore Size Variation and Its Effect on Energy Wheel Performance

Two experimental techniques are used to investigate variations in airflow channel geometry for four energy wheels that transfer heat and water vapor between exhaust and supply airflows. Using optical and micrometer measurements and pressure drop probe measurements, the flow channel hydraulic diameters are shown to fit Gaussian distributions and the ratio of standard deviation of hydraulic diameter to mean hydraulic diameter, σ/D0, is calculated for a parallel surface, honeycomb, and two different corrugated airflow channel matrices for four energy wheels. The optical and micrometer results for these wheels showed a range of σ/D0 from 0.064 to 0.234, indicating a range of pressure drop divided by the pressure drop with no variation (i.e., a = 0), Δp/Δp0, from 0.982 to 0.859 and effectiveness ratio, ∊/∊۰, from 0.986 to 0.867 for the wheels tested.