Thermo-hydraulic and entropy generation analysis for magnetohydrodynamic pressure driven flow of nanofluid through an asymmetric wavy channel

Abstract

Purpose The purpose of this paper is to analyze the thermal, hydraulic and entropy generation characteristics for the magneto-hydrodynamic (MHD) pressure-driven flow of Al2O3-water nanofluid through an asymmetric wavy channel. Design/methodology/approach Galerkin finite element method is used to solve the governing transport equations numerically within the computational domain using the appropriate boundary conditions. The temperature and flow fields are computed by varying Reynolds number (Re), Hartmann number (Ha) and nano-particle volume fraction (ϕ) in the following range: 10 ≤ Re ≤ 500, 0 ≤ Ha ≤ 75 and 0 ≤ ϕ ≤ 5%. Findings The formation of the recirculation zones in the wavy passages, the size of it and the strength of the vortices formed can be modulated by the application of the magnetic field. The overall heat transfer rate increases with Ha for all ϕ both for a lower and higher regime of Re although the enhancement is more for lower values of Re and nanofluids as compared to base fluid and for intermediate values of Re, the effect of a magnetic field is almost insignificant. The magnetic performance factor (PFmagnetic) decreases with Ha although the rate of decrement varies with Re. The increase ϕ also enhances PFmagnetic especially at lower and higher values of Re. The addition of nano-particle enhances the entropy generation at lower values of the Re, while the opposite effect is seen for higher values of Re. Practical implications The present study has enormous practical relevance for the design of heat exchanger applied for solar collectors, process plants, textile and aerospace applications. Originality/value The combined effects on the heat transfer rate and the associated pressure drop penalty due to the applied magnetic field for the flow of nanofluid through an asymmetric wavy channel have not been reported to date. The effect of the magnetic field on the formation of recirculation zones and hot spot intensity in the asymmetric wavy channel has been examined in detail. The PFmagnetic is investigated first time for the MHD nanofluid flow through a wavy channel.

Analysis of thermo-hydraulic and entropy generation characteristics for flow through ribbed-wavy channel

“…Thus, the study of flow and temperature fields for flow through the ribbed-wavy channel is important before analyzing the heat transfer characteristics. The undulated converging and diverging surfaces of the top wall cause negative and positive pressure gradient, respectively, as a result of which flow becomes accelerated and decelerated, respectably (Mehta et al , 2021; Mehta and Pati, 2021a, 2020b; Mondal et al , 2019). With the increase in the inlet velocity, the adverse pressure gradient in the diverging part reaches its threshold limit and flow gets separated for a given geometrical configuration.…”

“…In this context, researchers have commonly used two methods for heat transfer enhancement; namely, active and passive ones. The passive method includes surface modifications such as corrugation at the channel wall, using baffles, blocks, twisted or helical tape (Jaferian et al , 2019; Li and Ake Sunden, 2018; Mereu et al , 2013; Tiwari and Moharana, 2019c; Zhang and Liu, 2020; Nandi and Chattopadhyay, 2013, 2014; Mehta et al , 2021), nanofluid and highly conductive porous media (Mehta and Pati, 2021a; Mehdi et al , 2014; Kameswaran et al , 2014; Bhowmick et al , 2021). While the active method needs external perturbation for flow with external sources such as electric or magnetic fields other than the pumping power.…”

“…Therefore, such heat exchanging devices should be designed in such a way that they operate with higher thermo-hydraulic performance factor (PF) and minimum entropy generation. From the reported work in the literature, it is found that the individual effects of the wavy wall (Rush et al , 1999; Wang and Chen, 2002; Rashidi et al , 2017; Pati et al , 2017; Pehlivan et al , 2013; Mayeli et al , 2018; Bahiraei et al , 2020; Akbarzadeh et al , 2017; Esfahani et al , 2017; Mehta and Pati, 2019, 2021a), as well as ribs (Chang et al , 2018; Heydari et al , 2018; Feijó et al , 2018) in the flow field, have been studied for forced convective flow. However, no such work has been reported yet to study the effect of shape and a number of ribs inserted on the wavy-ribbed wall on the transport characteristics for flow in the laminar regime.…”

Numerical investigation of the impact of inclined baffles and an elastic vibrating beam on the thermo-fluid behavior in a rectangular channel

“…Reynolds number, Prandtl number, and geometrical configuration of the channel strongly influenced the local thermal entropy generation distribution. Mehta and Pati [22] studied the thermal, hydraulic, and entropy generation characteristics of magneto-hydrodynamic pressure-driven flow of Al2O3water nanofluid in a wavy channel. They used Galerkin finite element method to solve the governing transport equations.…”

Implication of geometrical configuration on heat transfer enhancement in converging minichannel using nanofluid by two phase mixture model: A numerical analysis

“…9 Both two phase and single phase approaches have been used by the researchers to study the effect on fluid flow and heat transfer. Mehta and Pati 10 and Moraveji et al. 11 used the single phase model that ensures by using nanofluids, heat transfer coefficient increases.…”