Method for the quantification of in-plane drying non-uniformity

摘要

A method has been developed in order to determine the in-plane non-uniformity of drying of wet paper samples dried by an air flow. The surface temperature of the samples, recorded by an infrared camera, is used to determine a mean drying time and the local drying time of each pixel. Based on the initial dryness and the mean drying time, a mean drying rate can be obtained, and furthermore, the drying time of each pixel can be presented as a 2-dimensional map. Apart from conventional statistical information on the variation in drying time, the map also gives information regarding the size and shape of the drying non-uniformity. The pressure drop over the sample and the air flow rate through the sample were used to calculate a flow resistance as a function of grammage.