Effect of cooling on pressure losses in U-type wavy pipe flow

Results of pressure drop measurements under adiabatic and nonadiabatic (at TW, const.) flow conditions in U-type wavy pipes having fixed dimensionless radius of centerline curvature 2Rd=6.62 and two dimensionless spacer lengths ld=0 and ld=39.7 are presented. The working fluid was water. The effects of cooling and spacer length were investigated. It is shown that cooling of water increases the friction factor. This increase is plausible attributed to the deformation of the velocity distribution resulting from the temperature dependence of the viscosity and density of water. The experimental data were correlated with the simply equation f=(a+bIn(Re)+cRe)∗(μμw)m where: a=0.121433−0.00182313∗ld, b=−0.010311+0.00019359∗ld, c=16.68855−0.16757∗ld, m=(−0.62+0.013 Pr 0.84Gr0.17)∗(380