E-NTU Method as a Mass Transfer Model in Design and Operation of Textile Finishing Equipment

In the first part of this contribution, a mass transfer model according to the so-called E-NTU method is developed in order to describe mass transfer phenomena in counter-current equipment in general and in a textile washing machine in particular. A relatively simple dimensionless relation between the effectiveness E, the separation factor S, and the total number of transfer units NTU is obtained. The second part of this work concentrates on problems of economically optimal design of textile finishing equipment, based on the application of the mass transfer model proposed. It appears that the optimal design point may easily be found by a simple combination of process curves and iso-cost lines. The third part deals with estimates of optimal operation of existing equipment in which the profit of increased production is counterbalanced by the costs of increased wash water flow. Application of the mass transfer model presented contributes substantially to a better understanding of design and operation of textile finishing equipment.