Thermal performance characteristics of a triple spiral tube heat exchanger

Abstract

In the current paper, the thermo fluid characteristics of a new design of curved tube called a triple spiral tube heat exchanger (TSTHE) was achieved with a brave comparative with a double spiral tube heat exchanger (DSTHE) as particular reference. A three-dimensional computational fluid dynamic model was developed using Ansys 14.5 software package. The Realize k–ε model had been applied with enhanced wall treatment to simulate the thermo-fluid characteristics. The governing equations were solved by a finite volume discretization method. The new design was created by adding a third tube to a double concentric spiral tube heat exchanger. The study carried out under consideration of turbulent fluid to fluid heat transfer condition. The influence of different key design parameter such as; inlet hot fluid temperatures, flow arrangements, concentration of Alumina (Al2O3) nanoparticles, and Dean number were the main point of interest. The effect of Alumina-water nanofluid was considered in three different concentrations of 0.5%, 1% and 2% by volume. The results carried out at Dean number ranged from 1100 to 10,500 in the turbulent region corresponding to Reynolds number from 6400 to 57,400. The results presented that the Nusselt number obtained from a TSTHE was higher than that value of DSTHE at the same flow conditions. The results also presented that a significant effect of hot water inlet temperature on the Nusselt number while the increase in pressure drop can be approximately considered neglect. Also, the counter flow arrangement gives better effect on hot fluid Nusselt number compared with the three other flow arrangements. A notice augmentation of heat transfer enhancement occurs due to use Alumina–water nanofluid in TSTHE by 20.8 %. New correlations for inner annulus hot fluid Nusselt number, effectiveness, and friction factor of heat exchanger were presented.