Simulating entropy generation in solar magnetohydrodynamic heat ducts with Eringen’s micropolar model and Bejan thermodynamic optimization

Kadir, A; Jangili, S; Beg, TA; Beg, OA

Abstract

Magnetohydrodynamic (MHD) solar power has recently been developed in the USA and is an exciting novel area in renewable power. In this hybrid solar energy design, highpowered magnets are employed to increase the efficiency of conversion from sunlight to electricity by stripping electrons from high-energy plasma jets and thereby generating power with no moving parts. The significantly higher temperatures generated in solar MHD have been shown to achieve much higher efficiencies than other conventional types of solar thermal technologies that work at a much lower temperature. The working fluids in solar MHD designs may be non-Newtonian and are electrically-conducting and strong thermal convection effects may also be present. To optimize thermal performance, Bejan’s entropy generation minimization technique is a powerful approach. In the present poster we describe for the first time a novel analytical and computational model for entropy generation in magnetohydrodynamic non-Newtonian flows due to constant pressure gradient in a vertical-parallel plate channel as a simulation of an MHD solar power system. To more accurately simulate the rheological working fluid, the elegant Eringen thermo-micropolar material model is employed which features gyratory motions of micro-elements (suspended particles). This is a new approach to real fluids in solar MHD pumps. The normalized conservation equations are solved with the powerful Liao homotopy analysis method (HAM) with physically viable boundary conditions at the channel (duct) walls. Numerical computations are conducted in MATLAB symbolic software. The impact of selected parameters e.g. non-Newtonian couple stress parameter, Eringen micropolar parameter, Reynolds number, Grashof (thermal buoyancy) number, Hartmann magnetic number and Brinkman (viscous heating) number on thermofluid characteristics (velocity, temperature, Nusselt number) and on entropy generation number and Bejan number are studied. The prescribed ranges of parameters are physically representative of real magnetohydrodynamic solar energy systems employing non-Newtonian fluids. The computations show that increasing magnetic field effect reduces the entropy production at the channel walls, whereas the converse behaviour is observed for increasing couple stress parameter, Reynolds number, Grashof number and Brinkman number. Increasing Eringen micropolar parameter and Hartmann number are observed to decrease the entropy generation production in solar MHD systems. This aids designers in achieving thermally more efficient solar MHD duct performance.

Citation

Kadir, A., Jangili, S., Beg, T., & Beg, O. (2019, March). Simulating entropy generation in solar magnetohydrodynamic heat ducts with Eringen’s micropolar model and Bejan thermodynamic optimization. Poster presented at International Conference on Innovative Applied Energy (IAPE’19)., St Cross College, University of Oxford, UK

• Presentation Conference Type: Poster
• Conference Name: International Conference on Innovative Applied Energy (IAPE’19).
• Conference Location: St Cross College, University of Oxford, UK
• Start Date: Mar 14, 2019
• End Date: Mar 15, 2019
• Acceptance Date: Oct 29, 2018
• Deposit Date: Oct 29, 2018
• Publicly Available Date: Mar 16, 2019
• Publisher URL: http://iape-conference.org/
• Additional Information: Event Type : Conference