Eur. Phys. J. Plus (2021) 136: 841
https://doi.org/10.1140/epjp/s13360-021-01807-z

Regular Article

Hybrid nanofluid flow and heat transfer in a parabolic trough solar collector with inner helical axial fins as turbulator

¹ Faculty of Mechanical Engineering, Semnan University, Semnan, Iran
² Faculty of Mechanical Engineering, Babol Noshirvani University of Technology, Babol, Iran
³ Department of Mechanical Engineering, K.N.Toosi University of Technology, Tehran, Iran

^a zaboli@semnan.ac.ir

Received: 21 June 2021
Accepted: 27 July 2021
Published online: 13 August 2021

Abstract

In the present work, a parabolic trough solar collector with inner helical axial fins as a swirl generator is considered and analyzed. All the numerical outcomes are obtained by utilizing the finite volume method's commercial code, ANSYS Fluent 18.2. The discretization of turbulence kinetic energy, turbulence dissipation rate, and energy equations as well as the spatial momentum equation have been done by a second-order upwind scheme. Hybrid nanofluid is utilized as a working fluid. This work consists of two sectors. In the first one, the influence of hybrid nanofluid types and, in the next sector, the impact of the volume concentration of selected hybrid nanofluid on the turbulence thermal efficiency are appraised numerically. The two considered hybrid nanofluids here contain multi-wall carbon nanotubes–iron oxide/water and silver and graphene nanoparticles/water. Obtained results showed that utilizing hybrid nanofluids causes more heat exchange rate than pure water. Also, among the evaluated hybrid nanofluids, multi-wall carbon nanotubes/iron oxide indicated the highest thermal performance. At the lowest studied Re number (Re = 5000), multi-wall carbon nanotubes/iron oxide presented higher thermal performance than silver–graphene/pure water by about 9.66 and 13.68%, respectively. Moreover, the peak thermal performance belongs to the case with volume concentration equal to 4% (φ_nf,1 = φ_nf,2) by an 18.5% growth in thermal performance.