Introducing Some Correlations to Calculate Entropy Generation in Extended Surfaces with Uniform Cross Sectional Area

The optimum length of extended surfaces with uniform cross sectional area has been analyzed numerically, based on the concept of entropy generation minimization. The extended surface studied is a pin fin. The rate of entropy generation is investigated for different boundary conditions. First, some correlations are introduced to calculate this rate, and then a model is offered to find optimum length of the fin for adiabatic and convection heat transfer boundary conditions. The accuracy of the model presented is compared with experimental data. Although Bejan introduced a correlation to calculate optimal Reynolds number and consequently the optimum length of a pin fin, but the results showed the new method has high accuracy compared with the Bejan method. Also, it is found that there is a strong relation between optimum length (based on the entropy generation minimization concept) in one side, and temperature distribution in the other side.