تحليل بهبود انتقال حرارت در لوله هاي مبدل حرارتي با استفاده از ديناميك سيالات محاسباتي

Analyzing of Tube side Heat Transfer Enhancement Using Computational Fluid Dynamics

The effect of tube inserts w enhance heat transfer coefficient and to mitigate fouling rate in shell-and-tube heat exchangers has been investigated by many researchers. In spite of availability of several experimental models for different types of tube inserts, however because of complexity in their geometries, it has not per armed mathematical rnodeling for them vet. In this study, using CFO (Computational Fluid Dynamics), the influence of existence of tube inserts in tubes of a heat exchanger is mathematically analyzed. The Distributions of balk temperature, profile of surface temperature of tube inlet, wall shear stress on surface of tube inlet, velocity and pressure drop are studied. The results of two cases of tubes with and without insert are compared. The experimental conditions for a tube with 3/4 inch of diameter and 0.5 meter of length are considered: 220°C of surface temperature. 0.65 m/s velocity and 80 C of inlet temperature. For an enhanced tube the surface heat transfer coefficient is 590,33 W/m^2.K while in the absence of tube insert it yields to 468.06 W/m^2 .K. In addition, the small shear stress is 3.705 Pa in existence of tube insert and 2.180 Pa in the absence of tube insert.