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Purpose
The purpose of this paper is to investigate conjugate heat transfer of natural convection and entropy generation of nanofluid in the presence of external magnetic field via numerical approach in an inclined square cavity enclosure.
Design/methodology/approach
Control volume finite volume method with collocated arrangement of grids was used for discretization of continuity, momentum, solid and fluid energy equations. Rhie and Chow interpolation technique was applied to avoid checkerboard problem in pressure field and the well-established SIMPLE algorithm was followed to deal with the pressure and velocity coupling. The cavity is filled with water and nanoparticles of the aluminum oxide (Al2O3). This study has been conducted for the certain pertinent parameters of the volume fraction of nanoparticle (φ = 0–0.08), the angle of inclination (ϴ = 0°–330°), the Ra number (Ra = 103–108), the solid to fluid conductivity ratio (ksf = 1–400), the Ha number (Ha = 0–80) and the wall thickness ratio (δ/L = 0–0.3).
Findings
The results indicate that averaged Nu number increases by approximately 9% by increasing volume fraction from 0.0 to 0.08. Nu increases with an increasing inclination angle to 40° and decreases abruptly in 90° because of the formation of two weaker vorticity with opposite circulation pattern intensifying the density of isotherm curves in a vertical direction. Nu increases sharply with increasing Ra more than 105. Nu also augments almost 67% by increasing ksf = 1 to ksf = 50 and remains constant by increasing ksf more than 50. Nu number reduction is almost 72% with a variation of wall thickness ratio from d/L = 0 to 0.3. Entropy generation because of fluid flow, magnetic field and heat transfer reduces linearly almost 30%, 19% and 16% by increasing volume fraction, respectively. With increasing ksf, entropy generation because of fluid flow, magnetic field and heat transfer increases asymptotically, but Bejan number decreases.
Originality/value
A brief review of conducted research studies in nanofluid flow and heat transfer reveals that the effect of wall thermal inertia was not investigated in MHD natural convection of nanofluids in an inclined enclosure. The aim of the present study is to analyze conjugate heat transfer in an inclined cavity filled with water and Al2O3.
This paper aims to study the operating mechanism of Stirling Pulse Tube Refrigerators (PTRs) by tracing the characteristics of working gas elements at the cold end of the system using both Eulerian and Eulerian-Lagrangian (E-L) methods. The main objective of the investigation is to demonstrate non-symmetry e ects in the pulse tube section of the system. Elemental cyclic-enthalpy transfer of Simple (S), Double-Inlet (DI) and Multi-Mesh regenerator (MM) PTRs are also investigated to demonstrate the e ects of DI and MM systems on the refrigeration mechanism of PTRs. It is shown that the elemental cyclic-enthalpy transfer of SPTR is less than that of DIPTR, MMPTR and MMDIPTR. Also, its elemental cyclic-temperature reduction is more than the others, because the mass ow rate upon the cold end of the SPTR is less than the others. Regarding the reduction of losses in DIPTR and MMPTR, their cold end mean pressure and density increase, and this, consequently, leads the cold end mass ow rate and cyclic-enthalpy transfer to increase. Increase in the enthalpy transfer of MM-PTR, MM-DIPTR and DIPTR consequently improves their cooling performance.
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