Authors
Abstract
The present study is to investigate experimentally the enhancement of forced convection heat transfer by means of passive techniques for a turbulent air flow through an Aluminum test tube. Reynolds number range is from 6000 to 13500 with boundary conditions of constant heat flux. The augmentation process is done by using divergent Nozzle-Turbulator arrangement with and without perforation models (triangle holes, square holes, and circle holes). The experimental results at the same Reynolds number show that the divergent nozzle-turbulators without perforation provides the highest heat transfer rate 317% and highest friction factor 17 times over that of plain tube with a performance factor of (1.58). On the other hand the perforated Nozzle-Turbulators with triangle holes gave a thermal performance factor of (1.7) which is the highest thermal performance factor among all other perforated and non perforated nozzle turbulators used in the present study
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