Heat Transfer Enhancement in a Helically Corrugated Tube by Employing W/Eg Based Non-Newtonian Hybrid Nanofluid Under Turbulent Conditions

Abstract

In this study a numerical investigation is carried out for heat transfer and fluid flow analysis using ethylene glycol-based TiO 2 -SiO 2 non-Newtonian hybrid nanofluid over a range of volume fractions from 0 to 5% inside a helically corrugated tube under turbulent flow conditions. The analysis is performed with different mixing ratios of TiO 2 and SiO 2 at different corrugation-height ratios (e/D h = 0.05, 0.07, 0.09) and pitch ratios (p/D h = 0.25, 0.30, 0.35). Numerical simulations have been conducted using ANSYS FLUENT 19.0 with a constant heat flux of 25 kW/m 2 maintained at the wall surface for a range of Reynolds numbers from 5000 to 30,000. The thermal-hydraulic performance factor exceeds unity in almost every tested combination. It increases by increasing the values of e/D h and p/D h and decreasing the concentration of TiO 2 in the hybrid-nanoparticle mixing ratio. Thus employing hybrid nanofluids inside corrugated tubes is a worthwhile arrangement at a proper mixing ratio of TiO 2 and SiO 2 .

Numerical investigation on thermal-hydraulic performance of air preheater equipped with helical inserts

“…The k-em odel has been used in many previous studies related to heat exchange devices as the k-e`model gives an efficient solution for steady-state and turbulent flow problems. 7,[23][24][25][26] The k-e`model is defined by two equations, one for the turbulent kinetic energy and another for the rate of dissipation. The values of k and e calculated at s k = 1 and s e = 1.3 using the following equations.…”

“…The heat transfer can be improved by using different tubes and fluids in the heat exchanger. [3][4][5][6][7] The various types of interior fabrications can also be used in heat exchanger which is depending on the desired rate of transfer of heat and the performance of drop of pressure and the approach implemented to prevent leakage, to certain operating pressure, to decrease thermal stresses, easily cleaning, to accommodate highly. Jin et al 8 analysed a novel type of tube which is spirally corrugated which is of six starts and found both the coefficient of resistance and pressure drop decreases gradually.…”