EXPERIMENTAL-DETERMINATION OF PERMEABILITY AND INERTIA COEFFICIENTS OF MECHANICALLY COMPRESSED ALUMINUM POROUS MATRICES

A heat exchanger; using mechanically compressed microporous matrices, is being developed for cooling high power electronics. The thermal eff iciency of this new device depends on the hydraulic characteristics (p orosity phi, permeability K, and Forchheimer coefficient c(F)) of the matrix inserted in it. These quantities have to be obtained experiment ally as predictive models do not exist. Twenty-eight compressed matric es are initially chosen for experimental testing. Based on structural requirements, nine matrices are selected for full hydraulic characteri zation. The determination of permeability and inertia coefficient of e ach matrix is performed following a proposed direct methodology based on the curve fitting of the experimental results. This methodology is found to yield more consistent and accurate results than existing meth ods. The uncertainty of the experimental results is evaluated with a n ew and general procedure that can be applied to any curve fitting tech nique. Results indicate that the tested matrices have a unique charact eristic, that of a relatively wide porosity range, from 0.3 to 0.7, wi thin a relatively narrow permeability range, from 1.0 x 10(-10) m(2) t o 12 x 10(-10) m(2). The inertia coefficient varies from 0.3 to 0.9. T hese hydraulic characteristics lead to a microporous heat exchanger pe rforming within requirements.