Generalized Reynolds number and viscosity definitions for non-Newtonian fluid flow in ducts of non-uniform cross-section

• A generalization method in ducts with non-uniform cross-section has been proposed.
• Measurements of pressure drop in two enhanced heat exchangers have been used.
• A generalization expression for those heat exchangers has been obtained.

This work presents and experimental study of the generalization method of the Reynolds number and the viscosity of pseudoplastic fluid flow in ducts of non-uniform cross-section. This method will permit to reduce 1 degree of freedom of hydrodynamical and thermal problems in those ducts. A review of the state of the art has been undertaken and the generalization equation proposed for ducts of uniform cross section has been used as a starting point. The results obtained with this equation have not been found satisfactory and a new one has been proposed.Specifically, the procedure has been developed for two models of scraped surface heat exchanger with reciprocating scrapers. For both models, the scraper consists of a concentric rod inserted in each tube of the heat exchanger, mounting an array of plugs that fit the inner tube wall. The two models studied differ in the design of the plug.The procedure to perform the generalization method out of experimental data is accurately detailed in the present document.