Experimental investigation on flow characteristics of regenerators considering variable fluid properties

A method was proposed to improve the accuracy of permeability and inertial resistance coefficient measurements for the flow characteristics of a regenerator, considering density and dynamic viscosity. Given the thickness of the porous medium at only 2 mm, and to simplify gradient data processing, the harmonic mean of the fluid density and dynamic viscosity was utilized. Various mesh counts of wire mesh and sintered powder filler were tested. The results showed that permeability decreased for both types of fillers as mesh count increased. Due to the high randomness inherent in the sintered powder, repeated tests were conducted, with errors being within 17 %. The inertial resistance coefficient fluctuated between 300 and 600 mesh counts, with a significant increase at 700 mesh. In contrast, the inertial resistance coefficient of the wire mesh increased consistently with the mesh count. The significant inertial resistance within the sintered powder was due to its irregularity, and a high positive correlation was observed between the regularity of the filler microstructure and the pressure drop across the regenerator. The flow characteristic correlations for two types of fillers were derived, applicable within the Reynolds number ranges of 6.54 to 99.17 for the wire mesh filler and 0.86 to 15.91 for the powder filler, with both exhibiting a goodness of fit exceeding 95 % being achieved.