Numerical study on heat transfer and nanofluid flow in pipes fitted with different dimpled spiral center plate

This research presents a numerical study on heat transfer and flow characteristics for two pipe fitted by two different dimpled spiral center plate by utilizing Al 2 O 3 , CuO and TiO 2 nanofluids as cooling fluids. Considering the effect of dimples arrangement, nanoparticle diameter d p , nanofluids volume fraction φ and also the heat transfer coefficient, thermal property. Average amount of entropy generation S a and maximum local temperature of wall T max were discussed. Results demonstrate that the in-line arrangement geometry behaves better in compare to the geometry with the staggered arrangement. 47.3% is the maximum enhancement of convection heat transfer for the in-line arrangement in compare with the smooth spiral central plate with base flow. Using nanofluids improved the wall temperature distribution, and using nanofluid caused great improvement in thermal conductivity with a little raise in dynamic viscosity. Using nanofluids caused a considerable decrease in S a , which also as the result of rising φ, and S a maximum reduction is about 24.7%. T max considerably declines by using nanofluids and enhanced by a rising φ. Also, CuO–water nanofluid has a better effect on heat transfer and flow characteristics than the other nanofluids.