A Single-Blow Test Procedure for Compact Heat and Mass Exchangers

Abstract

This paper discusses a single-blow test procedure for estimating the overall heat and mass transfer coefficients of compact dehumidifier matrices. The procedure consists of three sequential experimental procedures for obtaining, respectively, the core geometry of the test matrix, the active mass of sorbent within the matrix, and the distributions of the temperature and humidity ratio responses with time and distance in the flow direction. The analysis technique paired to the experimental procedure is based upon the transformation of the model partial differential equations into a set of ordinary differential equations. The temperature and mass-fraction distributions are then modeled by a system of nonstiff ordinary differential equations, which can be easily integrated numerically. The Lewis number, defined as the ratio of the overall heat to mass transfer coefficients, determines the shape of the distributions with a dimensionless flow coordinate x+. With a curve fit method, the experimental Lewis number can be determined with acceptable accuracy. The procedure is illustrated with selected experimental results for humid air and a silica gel matrix.