Browsing by Author "Abdelmagied, Mahmoud"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Correlations for heat transfer coefficient and pressure drop in the annulus of concentric helical coils
    (SPRINGER, 2014) Gomaa, Abdalla; Aly, Wael I. A.; Omara, M.; Abdelmagied, Mahmoud
    Heat transfer and pressure drop characteristics in the annulus of concentric helical coils heat exchangers were experimentally investigated. The effects of coil curvature ratio, flow configuration, number of turns and addition of surfactant were investigated. Five test coils were designed and manufactured to study the effect of different parameters on heat transfer and pressure drop. The liquids used in the present study were water and oleyldihydroxy- etheyl-amine-oxide (ODEAO, C22H45NO3 = 371) non-ionic aqua surfactant solution flowing through the annulus side. The inner side Reynolds number range 11,000-27,000 and the annulus side range 5,000-19,000. The results showed that the annulus Nusselt number decreases as annulus curvature ratio increases and increases when number of turns decrease. Moreover, the friction factor increases with the curvature ratio and also increases as number of turns decreases. Both Nusselt number and friction factor decrease when ODEAO concentration increases.
  • Thumbnail Image
    Item
    Numerical Study of Thermofluid Characteristics of a Double Spirally Coiled Tube Heat Exchanger
    (ASME, 2019-08) Abdelmagied, Mahmoud
    In this study, the thermofluid characteristics of double spirally coiled tube heat exchanger (DSCTHE) were investigated numerically. A three-dimensional (3D) computational fluid dynamic (CFD) model was developed using ANSYS 14.5 software package. To investigate the heat transfer and pressure drop characteristics of DSCTHE, the Realize k-epsilon turbulence viscous model had been applied with enhanced wall treatment for simulating the turbulent thermofluid characteristics. The governing equations were solved by a finite volume discretization method. The effect of coil curvature ratio on DSCTHE was investigated with three various curvature ratios of 0.023-0.031 and 0.045 for inner tube side and 0.024-0.032-0.047 for annular side. The effects of addition of Al2O3 nanoparticle on water flows inside inner tube side or annular side with different volume concentrations of 0.5%, 1%, and 2% were also presented. The numerical results were carried out for Reynolds number with a range from 3500 to 21,500 for inner tube side and from 5000 to 24,000 for annular side, respectively. The obtained results showed that with increasing coil curvature ratio, a significant effect was discovered on enhancing heat transfer in DSCTHE at the expense of increasing pressure drop. The results also showed that the heat transfer enhancement was increased with increasing Al2O3 nanofluid concentration, and the penalty of pressure drop was approximately negligible.