Effects of Pore Size Variations on Regenerative Wheel Performance

Abstract

Manufacturing tolerances usually cause the air flow channel pore sizes to have a random variation in the matrices of regenerative wheels. The effects of random pore size distribution on pressure drop across a regenerative energy wheel transferring heat and moisture and effectiveness are investigated using analytical methods. Compared to an identical wheel with no pore size variation, simple algebraic expressions for pressure drop ratio, Δp/Δp0, and effectiveness ratio, ε/ε0, are developed for a Gaussian distribution of flow channel hydraulic diameters. Graphical results are presented showing that large random variations in flow channel pore size decrease the pressure drop across a wheel and the effectiveness (sensible, latent, and total) significantly for a regenerative wheel. Optical and micrometer measurements of four typical regenerative wheels showed a random variation in flow channel hydraulic diameters. These data imply significant decreases in Δp/Δp0 and ε/ε0 for each wheel.