Effect of γ-Al2O3/water nanofluid on the thermal performance of shell and coil heat exchanger with different coil torsions

This work investigated experimentally the thermal performance of shell and coil heat exchanger with different coil torsions (lambda) for gamma-Al2O3/water nanofluid flow. Five helically coiled tube (HCT) with 0.0442 <= lambda <= 0.1348 were tested within turbulent flow regime. The average size of gamma-Al2O3 particles is 40 nm and volume concentration (phi) is varied from 0 to 2%. Results showed that reducing coil torsion enhances the heat transfer rate and increases HCT-friction factor (f(c)). Also, it is noticed that HCT average Nusselt number (Nu(t)) and f(c) of nanofluids increase with increasing gamma-Al2O3 volume concentration. The thermal performance index, TPI = (h(t,nf)/h(t,bf))/(Delta P-c,P-nf/Delta P-c,P-bf). increases with increasing nanoparticles concentration, coil torsion, HCT-side inlet temperature and nanofluid flow rate. Over the studied range of HCT-Reynolds number, the average value of TPI is of 1.34 and 2.24 at phi = 0.5% and phi = 2%, respectively. The average value of TPI is of 1.64 at lambda = 0.0442 while its average value at lambda = 0.1348 is of 2.01. One of the main contributions is to provide heat equipments designers with Nu(t) and f(c) correlations for practical configurations shell and coil heat exchangers with a wide range of nanofluid concentration.