In this paper, the effect of the presence of radiation on the convection heat transfer rate and the nanofluid entropy generation within a diagonal rectangular chamber is investigated numerically in the presence of a magnetic field. The governing equations have been solved via finite volume method using the simple algorithm. In this paper, the effects of Rayleigh number, Hartmann number, magnetic field angle changes, chamber angle changes, entropy parameter, radiation parameter and volume percent of nanoparticles on the entropy generation and heat transfer have been investigated. The results show that with increasing Rayleigh number and decreasing the Hartmann number, the Nusselt number and entropy generation increase and the Bejan number decreases. By increasing the angle of the magnetic field, the heat transfer rate and the entropy generation are reduced and the Bejan number increases. By increasing the angle of the chamber at high Rayleigh numbers, the heat transfer rate increases, or by adding 6% of the nanoparticles to the base fluid, the heat transfer rate increases by 9.3% and the entropy generation increases by 15.5% in the absence of radiation. This increase in the Rd = 3 radiation parameter is 5.4% and 6.2%, respectively. It was also observed that the Nusselt number and the entropy generation increased, and with increasing the radiation parameter, the Bejan number decreased. Increasing the heat transfer rate is more significant at higher Rayleigh numbers by increasing the radiation parameter.

Investigation of free convection heat transfer and entropy generation of nanofluid flow inside a cavity affected by magnetic field and thermal radiation

An innovative approach to escalate the heat generation in peristalsis flow of MHD nanofluids filled in an asymmetric channel is proposed. Three different shapes of nanoparticles, namely (1) spherical, (2) disc and (3) cylindrical are utilized. Results for temperature, velocity and concentrations have been obtained analytically. The physical features for heat generation, concentration, pressure gradient, pressure rise and magnetic parameter have been elaborated graphically, whereas effects of Nusselt number and skin friction have been numerically computed by using the MATLAB software. For bolus features, trapping phenomena are also inspected by dint of stream lines. It is found that cylindrical shapes of nanoparticles have very low thermal conductivity as compared to spherical and disc shapes. Moreover, it is seen that the heat generation parameter always increases the temperature of nanofluid, and consequently, the trapping phenomena produce more boluses for larger values of heat source parameter.

Effects of different shapes of nanoparticles on peristaltic flow of MHD nanofluids filled in an asymmetric channel

Comprehensive analyses of transport phenomena and thermodynamics of complex multiphysics systems are laborious and computationally intensive. Yet, such analyses are often required during the design of thermal and process equipment. As a remedy, this paper puts forward a novel approach to the prediction of transport behaviours of multiphysics systems, offering significant reductions in the computational time and cost. This is based on machine learning techniques that utilize the data generated by computational fluid dynamics for training purposes. The physical system under investigation includes a stagnation-point flow of a hybrid nanofluid (Cu−Al2O3/Water) over a blunt object embedded in porous media. The problem further involves mixed convection, entropy generation, local thermal non-equilibrium and non-linear thermal radiation within the porous medium. The SVR (Support Machine Vector) model is employed to approximate velocity, temperature, Nusselt number and shear-stress as well as entropy generation and Bejan number functions. Further, PSO meta-heuristic algorithm is applied to propose correlations for Nusselt number and shear stress. The effects of Nusselt number, temperature fields and shear stress on the surface of the blunt-body as well as thermal and frictional entropy generation are analysed over a wide range of parameters. Further, it is shown that the generated correlations allow a quantitative evaluation of the contribution of a large number of variables to Nusselt number and shear stress. This makes the combined computational and artificial intelligence (AI) approach most suitable for design purposes.

A machine learning approach to the prediction of transport and thermodynamic processes in multiphysics systems - heat transfer in a hybrid nanofluid flow in porous media

In this research, a numerical macroscopic approach has been employed to analyze nanofluid entropy generation and turbulent flow through a circular heat exchanger with an innovative swirl flow device. A homogenous model was considered for nanofluid. Minimizing entropy generation can be considered as a very important goal for designing a heat exchanger, so we focus on this factor in the present attempt. Simulations were presented to show the influences of the geometric parameter (revolution angle) and inlet velocity on hydrothermal and second-law treatment. Related correlations for thermal and frictional entropy parameters as well as Bejan number have been presented. Outputs reveal that augmenting revolution angle increases the frictional entropy generation. Increasing secondary flows leads to a reduction in thermal entropy generation due to a decrement in thermal boundary layer thickness. By improving convective flow, Bejan number reduces.

Nanofluid heat transfer and entropy generation through a heat exchanger considering a new turbulator and CuO nanoparticles

Investigation of nanofluid entropy generation in a heat exchanger with helical twisted tapes

Applications of magnetohydrodynamics in biological systems-a review on the numerical studies

A two-way couple of Eulerian-Lagrangian model for particle transport with different sizes in an obstructed channel

Natural convection heat transfer and entropy generation analysis inside a channel with a porous plate mounted at the bottom wall is investigated numerically. The effects of porous plate on the heat transfer improvement and entropy generation are studied in details. SIMPLE algorithm has been used to solve the set of algebraic discretized coupled equations. The ranges of Darcy number (Da), porosity (e), and porous plate widths (δ) are 10−2–10−6, 0–1, and 0–0.3, respectively. It is observed that for heat transfer augmentation goals, a porous medium with high permeability and high thermal conductivity is suggested. Moreover, the maximum temperature and velocity gradients are occurred at the upper half of the domain and this causes higher viscous and thermal entropy generations in this region.

Mahla Maskaniyan

Papers

Applications of magnetohydrodynamics in biological systems-a review on the numerical studies

A two-way couple of Eulerian-Lagrangian model for particle transport with different sizes in an obstructed channel

Natural convection and entropy generation analysis inside a channel with a porous plate mounted as a cooling system